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B. Arteriovenous malformation.
A. Blood and lymph vessels.
B. Undifferentiated epithelial cells.
C. Nerve fibers.
D. Enterochromaffin cells.
F. Connective tissue.
DISCUSSION: The mucosa of the small intestine encompasses the epithelium, the lamina propria, and the muscularis mucosae. The lamina propria between the epithelium and the muscularis mucosae contains blood and lymph vessels, nerve fibers, smooth muscle fibers, fibroblasts, macrophages, plasma cells, lymphocytes, eosinophils, and mast cells, as well as connective tissue elements.
A. Produce the brush border appearance.
B. Contain amylase.
C. Contain dissacharidases.
D. Increase absorptive area.
E. Play an important role in digestion.
F. Contain trypsinogen.
DISCUSSION: The columnar epithelial cells are responsible for absorption. These cells exhibit a striated luminal border or brush border. The microvilli account for the appearance of the brush border. The microvilli greatly increase the absorption surface of the epithelial cell. The brush border contains disaccharidase in high concentrations. In addition to increasing surface area the microvilli perform an important digestive function.
A. Amylopectin has 1-4 straight chains and 1-6 side chains.
B. Amylase has 1-4 straight chains and 1-6 side chains.
C. Amylase breaks 1-4 glucose linkages.
D. Amylase breaks 1-6 side chains.
E. An adult may ingest about 350 gm. of carbohydrate daily.
F. Dietary starch contains two glucose polymers, amylopectin and amylase.
DISCUSSION: Amylopectin, the most abundant constituent of starch, is a 1-4–linked straight chain of glucose molecules. In addition, amylopectin possesses a 1-6 branching side chain at approximately every 25 glucose units along the straight chain. Amylase has only 1-4 linkages of glucose molecules. Pancreatic and salivary amylase break the interior 1-4 glucose linkages.
A. Micellar solution provides an optimal environment for the action of pancreatic lipase.
B. Decreasing the pH below 5.5 increases the effectiveness of pancreatic lipase in hydrolyzing fat.
C. Co-lipase blocks triglyceride hydrolysis.
D. Lipase catalyzes the hydrolysis of dietary triglyceride into 2-monoglyceride and fatty acids.
E. Fatty acids and 2-monoglyceride are held in micellar solutions.
F. Fatty acid and 2-monoglyceride enter the intestinal cell by active transport.
DISCUSSION: Micellar solution provides an optimal environment for the action of pancreatic lipase. Pro-co-lipase is converted to co-lipase by trypsin. Co-lipase binds to triglyceride, then lipase complexes with co-lipase, and triglyceride hydrolysis access. Pancreatic lipase hydrolyzes triglyceride into 2-monoglyceride and fatty acids. The 2-monoglyceride and fatty acid enter the micellae. An alkaline pH allows lipase to function optimally. Micellar fatty acids and 2-monoglyceride pass into the epithelial cell by diffusion.
A. Interfering with oral intake of water.
B. Inducing vomiting.
C. Decreasing intestinal absorption of water.
D. Causing secretion of water into the intestinal lumen.
E. Causing edema of the intestinal wall.
DISCUSSION: One of the most important events during simple mechanical small bowel obstruction, loss of water and electrolytes from the body, is caused mainly by intestinal distention. Distention may produce reflex vomiting. Distention causes intestinal secretion. Distention causes decreased absorption.
A. Crampy abdominal pain.
D. Abdominal distention.
E. Leukocyte count above 12,000.
F. Abdominal tenderness.
DISCUSSION: History and physical examination permit the diagnosis of intestinal obstruction. Any patient having crampy abdominal pain, vomiting, obstipation, abdominal distention, abdominal tenderness, and peristaltic rushes should be managed for intestinal obstruction until the diagnosis can confidently be excluded.
A. Distended small bowel identifiable by the valvulae conniventes.
B. Multiple air-fluid levels.
C. Modest amount of gas in the pelvis.
D. Peripheral, rather than central, distribution of gas.
E. Prominent haustral markings.
F. Free air.
DISCUSSION: Abdominal x-ray examination of patients with intestinal obstruction usually reveals abnormally large quantities of gas in the bowel. One can usually identify distended small intestine or colon. Gas in the small bowel outlines the valvulae conniventes, which usually occupy the entire transverse diameter of the bowel image. Colonic haustral markings occupy only a portion of the transverse diameter of the bowel.
Typically, the small bowel pattern occupies the more central portion of the abdomen, whereas the colon shadow is on the periphery of the abdominal files or in the pelvis. Patients with mechanical small intestinal obstruction usually have minimal colonic gas, if any.
A. Meckel's diverticulum usually arises from the ileum within 90 cm. of the ileocecal valve.
B. Meckel's diverticulum results from the failure of the vitelline duct to obliterate.
C. The incidence of Meckel's diverticulum in the general population is 5%.
D. Meckel's diverticulum is a true diverticulum possessing all layers of the intestinal wall.
E. Gastric mucosa is the most common ectopic tissue found within a Meckel's diverticulum.
DISCUSSION: Meckel's diverticulum is a true diverticulum containing all layers of the intestinal wall, usually arising from the antimesenteric border of the ileum 45–90 cm. proximal to the ileocecal valve. It is a vestige of the omphalomesenteric or vitelline duct, which usually undergoes complete obliteration during the seventh week of gestation. Autopsy studies have estimated the incidence of Meckel's diverticulum to be 1% to 2% with men being more commonly affected than women by a ratio of 2:1. Gastric mucosa is present in 50% of all Meckel's diverticula, but in over 75% of symptomatic individuals.
A. Gastrointestinal bleeding.
D. Intermittent abdominal pain.
DISCUSSION: It is estimated that only 4% of patients who possess a Meckel's diverticulum will become symptomatic during their lifetimes. The most common clinical presentation is incidental identification during abdominal exploration. Symptomatic presentations are secondary to hemorrhage, small bowel obstruction, diverticulitis, perforation, associated umbilical abnormalities, and tumors. Over half of patients presenting with symptoms are under the age of 2. The most common clinical problem associated with Meckel's diverticulum is gastrointestinal bleeding presenting as bright red blood per rectum. The usual source of the bleeding is a chronic acid-induced ileal ulcer in the ileum adjacent to a Meckel's diverticulum that contains gastric mucosa. Another common symptom associated with a Meckel's diverticulum is intestinal obstruction. The cause of this obstruction may be volvulus of the small bowel around a diverticulum associated with a fibrotic band attached to the abdominal wall, intussusception, or rarely, incarceration of the diverticulum in an inguinal hernia (Littre's hernia). Volvulus is usually an acute event and if allowed to progress, may result in strangulation of the involved bowel. In intussusception, a broad-based diverticulum invaginates and then is carried forward by peristalsis.
A. Carcinoid tumors should be treated by resection, regardless of the presence of metastases.
B. Appendiceal tumors larger than 1.5 cm. should be treated by ileocolectomy.
C. Local excision with margins is adequate for a rectal carcinoid of any size.
D. Carcinoid tumors are associated with a large percentage of other synchronous or metachronous neoplasms.
DISCUSSION: Carcinoid tumors should be treated by resection, regardless of the presence of metastases, because growth of the primary neoplasm is slow and local complications, such as obstruction and intussusception, are frequent. At clinical discovery a large percentage (as many as 70%) of small-intestinal carcinoids are metastatic to lymph nodes and/or liver. All tumors should be managed by wide en bloc resection, regardless of the size of the primary lesion or the presence of distant metastases. Lesions in the distal ileum require ileocolectomy. Appendiceal tumors larger than 1.5 cm. should be treated by ileocolectomy. The incidence of metastases depends on the size and location of the primary tumor. Appendiceal carcinoid tumors smaller than 1.5 cm. are rarely malignant and may be treated safely by routine appendectomy. This is not true of larger tumors. Like carcinoid tumors elsewhere in the gastrointestinal tract, the malignancy potential of rectal carcinoid tumors is directly proportional to their size. Tumors smaller than 1 cm. have little or no malignant potential and may be treated by endoscopic excision. Tumors measuring 1 to 2 cm. should be excised operatively with margins, but when they are larger than 2 cm. rectal carcinoid tumors may require anterior resection. In patients with ileal carcinoid tumors, the evidence of a second tumor has been reported as high as 40%. Thus, the search for synchronous metachronous and metastatic neoplasms should be undertaken.
A. Carcinoid syndrome occurs only when hepatic metastases are present.
B. Serotonin is thought to be responsible for the diarrhea, cardiac lesions, and flushing in patients with carcinoid syndrome.
C. Foregut carcinoid tumors cause atypical carcinoid syndrome; hindgut tumors are rarely, if ever, associated with the syndrome.
D. The long-acting somatostatin analog provides the best symptomatic treatment for carcinoid syndrome.
DISCUSSION: Carcinoid syndrome occurs when venous drainage from the tumor gains access to the systemic circulation, escaping hepatic degradation. Although hepatic metastases are most often responsible, retroperitoneal metastases and bronchial, ovarian, and testicular carcinoid tumors can also cause the carcinoid syndrome. Serotonin is thought to be largely responsible for both the diarrhea and the fibrosing cardiac lesions associated with the carcinoid syndrome. The vasomotor changes, however, are mediated by kinins and such vasoactive peptides as substance P, neuropeptide K, neurokinin A, and neurotensin. Other substances, such as histamine, vasoactive intestinal peptide (VIP), and prostaglandins, may also contribute to systemic manifestations in the carcinoid syndrome. Foregut carcinoid tumors, of which stomach and bronchial tumors are the most common, can cause atypical carcinoid syndrome. It is thought that these tumors are deficient in the enzyme dopa-decarboxylase and have impaired conversion of 5-hydroxytryptophan (5-HTP) into 5-hydroxytryptamine (5-HT), leading to secretion of 5-HTP into the vascular compartment. Some of the 5-HTP is converted into 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in extrarenal sites, and some is decarboxylated in the kidney and excreted into the urine as 5-HT; but some of the 5-HTP is excreted directly into the urine. Thus, in patients with foregut tumors, the urine contains relatively little 5-HIAA (but more than normal) but large amounts of 5-HTP and 5-HT, in contrast to patients with midgut carcinoid tumors in which large amounts of 5-HIAA are secreted into the urine but relatively little 5-HTP. Carcinoid tumors of the hindgut contain no argentaffin or argyrophil cells, they have no secretory products, and therefore they are not associated with the carcinoid syndrome. The long-acting somatostatin analog provides the best symptomatic therapy, because somatostatin inhibits both release and action of humoral mediators of the carcinoid syndrome. By contrast, serotonin antagonists are of little value and the efficacy of interferon therapy has yet to be established.
A. Microscopic examination.
B. D-xylose absorption.
C. A 72-hour stool collection for fats.
D. Small bowel x-ray series.
DISCUSSION: The 72-hour stool collection is quite sensitive and detects even mild malabsorption. As it requires careful stool collection timed by carmen red markers and documented dietary fat intake, it is not useful for screening. Microscopic examination of the stool can detect muscle fibers if protein malabsorption is present and with Sudan II staining can estimate fat content. D-Xylose absorption from oral ingestion of 5 gm., detected by a blood sample after 1 hour, is a simple and quite accurate test to identify carbohydrate malabsorption. Small bowel x-ray series, using barium contrast, can give very useful information on mucosal abnormalities, enteric fistulas, mechanical obstructions, and very importantly, intestinal motility and transit time.
A. Gastric hyperacidity and hypersecretion.
C. Hypermetabolic response.
D. Fat-soluble vitamin deficiency.
DISCUSSION: Once the stress of the surgical procedure is over, there is no further hypermetabolic response, nor does there appear to be any reduced energy expenditure from loss of the metabolically active small bowel. Energy needs are unaltered. Gastric secretion and hyperacidity are directly related to the extent of small bowel resection and is due in part to increased concentrations of gastrin in the serum. H 2 blockers are effective in reducing acidity and volume of gastric secretions. Hyperoxaluria develops owing to binding of calcium to fat in the diet with steatorrhea, leaving less to bind with dietary oxalate. The soluble oxalate is absorbed by the colon and excreted in the urine. If oxalate is excessive, oxalate kidney stones can form. With fat malabsorption due to bile salt depletion and rapid intestinal transit, absorption of the fat-soluble vitamins A, E, K, and D is reduced. Even with oral supplementation, deficiencies can develop.
A. The dimension of the radiation portals.
B. The number of portals.
C. The number of fractions.
D. The total amount of irradiation.
E. All of the above.
DISCUSSION: These physical factors are interactive. Less energy is delivered through a small portal than through a large one. Multiple portals permit concentration of the radiation in the area to be treated and spare skin and viscera from damage. There is less risk of injury from irradiation of a given intensity if more fractions are applied.
A. Small bowel obstruction.
B. Colonic perforation.
C. Rectovaginal fistula.
D. Malabsorption and diarrhea.
E. Rectal stenosis.
DISCUSSION: Patients who have symptoms of vascular compromise or evidence of perforation require urgent laparotomy. Patients with small bowel obstruction may require a laparotomy if a complete obstruction persists, but gastrointestinal decompression and hydration are first steps. Patients with radiation-induced rectovaginal fistula may require temporary or even permanent colostomy, but the first steps are evaluation and control of sepsis. Malabsorption and diarrhea can generally be controlled pharmacologically. Rectal stenosis can usually be managed without laparotomy.
a. The B lymphocytes of the small intestine do not produce immunoglobulin A (IgA)
b. Peyer’s patches, an example of an aggregated cellular portion of the gut-associated lymphoid system tissue, are large collections of lymphoid follicles found on the antimesenteric border of the ileum
c. The major immunoglobulin of the intestinal immune system is IgM
d. IgA produced by the intestinal immune system produces the classic Fc-mediated inflammatory reactions to antigen stimulus
Gut-associated lymphoid tissue (GALT) represent a major division of the immune system and is made up of aggregated (Peyer’s patches, lymphoid follicles, mesenteric lymph nodes) and nonaggregated cellular components. The lamina propria of the small intestine contains a wide array of nonaggregated lymphoid tissue including B cells, T cells, macrophages, eosinophils, and mast cells. Some 80% to 99% of B cells are active producers of immunoglobulin A (IgA). In comparison, only 2% to 5% of B cells found in other lymphoid tissues of the body secrete IgA. IgA is the major immunoglobulin of the intestinal immune system. The functional characteristics of IgA are unlike those of other antibodies. Unlike IgG or IgM, secretory IgA does not induce Fc-mediated inflammatory reactions. Antigen-IgA complexes do not activate the classic or alternate complement systems, nor does IgA promote the phagocytosis of bacteria by opsonization. Most of the protective effect of IgA derives from its ability to bind the threatening antigen efficiently, while resisting enzymatic degradation by gut enzymes.
a. This complex consists of a cyclic pattern of spike bursts and muscular contractions that migrate from the duodenum to the terminal ileum and can be divided into four phases
b. The major activity during the MMC occurs during phase I
c. In humans the MMC usually lasts less than one hour
d. Blood levels of the GI peptide, motilin, correlate closely with MMC activity and exogenous motilin can induce the MMC front
Answer: a, d
The migrating motor complex (MMC) is a cyclic pattern of spike bursts and muscular contractions that migrate from the duodenum to the terminal ileum. The MMC is divided into four phases: phase I-the period of quiescence with no activity; phase II-accelerating irregular spike activity; phase III-the activity front with a series of high-amplitude, rapid spikes corresponding to strong, rhythmic gut contractions; and phase IV-subsiding activity. In humans the cycle lasts about 90 to 120 minutes. Each phase passes in sequence along the bowel, and when the terminal ileum is reached, the process resumes in the proximal gut. This interdigestive cycle is interrupted and replaced by rapid spiking activity (similar to phase II) when the gut receives a food bolus. The duration of the interruption depends on the volume and nature of the food stuffs with fats causing the largest duration of rapid spiking. Blood levels of the GI hormone, motilin, correlate closely with MMC activity and exogenous motilin can induce the MMC front. Other hormones whose serum levels parallel MMC activity are pancreatic polypeptide and somatostatin. Drugs that can initiate the MMC front include histamine, metoclopramide, and morphine.
a. The second (descending), third (transverse) and fourth (ascending) portions of the duodenum lie in the retroperitoneum and are mobilized for surgical procedures via the Kocher maneuver
b. The identification of the superior mesenteric vein and artery can be facilitated by an extensive Kocher maneuver mobilizing the transverse portion of the duodenum and exposing the vessels as they course over the duodenum and under the neck of the pancreas
c. In only the minority of patients can the accessory pancreatic duct (the duct of Santorini) be seen on endoscopic exam entering the duodenum
d. The ileum is the widest portion of the small intestine, with the diameter of the small bowel progressively increasing as the ileocecal valve is approached
Answer: a, b
The duodenum is divided into four parts-the bulb, followed by the second (descending), third (transverse), and fourth (ascending) portion. The duodenal bulb begins at the pylorus and extends for the next 5 cm as the duodenum assumes a retroperitoneal position for the second, third, and fourth portion. The third and fourth portion of the duodenum complete the duodenal sweep. Mobilization of the duodenum from the retroperitoneum for a multitude of abdominal procedures can be facilitated by the Kocher maneuver where the retroperitoneal attachment is divided and the duodenum and head of the pancreas can be brought out of its retroperitoneal position. Endoscopically, the major papilla of the duodenum can be seen entering at the mid-point of the second portion of the duodenum. The papilla (ampulla of Vater) appears anatomically as a hooded fold, marking the confluence of the common bile duct and the main pancreatic duct (duct of Wirsung) and is surrounded by the muscular sphincter of Oddi. In some 50% to 60% of patients, an accessory pancreatic duct (the duct of Santorini) can be seen entering the duodenum proximal to the ampulla of Vater. Endoscopically, this lesser, or minor, papilla appears as a one-to-three mm sessile polyp. The jejunum is the portion of the small bowel that courses from the ligament of Treitz to an arbitrary point approximately two-fifths of the distance to the ileocecal valve. The length of the jejunum has been estimated at 100 cm although this distance can vary dramatically depending on the status of the small intestine. The jejunum is the widest portion of the small intestine, and the diameter progressively decreases as the ileocecal valve is approached. The ileum makes up the distal three-fifths of the combined jejunal/ileal length.
a. Cholecystokinin (CCK) is produced from cells in the mucosa of the duodenum and jejunum and is released in response to luminal fats and proteins
b. Secretin is released in response to rising intraduodenal pH, resulting in inhibition of pancreatic secretion
c. Motilin is a 22-amino acid peptide released during the fasting state with increased levels corresponding with the onset of the migrating motor complex (MMC)
d. Neurotensin is produced primarily in the duodenal mucosa and its release is stimulated primarily by carbohydrates and proteins
Answer: a, c
The endocrine functions of the small intestine are diverse with an ever increasing number of hormones, peptides, neurotransmitters, and paracrine substances identified. Cholecystokinin (CCK) is produced by cells located primarily in the mucosa of the duodenum and jejunum and released in response to luminal fats and proteins. After CCK release from the duodenum and jejunum, the gallbladder contracts and the sphincter of Oddi relaxes, emptying bile into the duodenum. Secretin is found in the S cells of the duodenum and jejunum. Secretin, a true hormone, is released in response to acid in the duodenum when luminal pH falls below 4.5. Intraduodenal secretion of pancreatic bicarbonate neutralizes duodenal pH and results in diminished release of secretin. CCK acts in a synergistic fashion with secretin to stimulate pancreatic exocrine function. Motilin is a 22-amino acid peptide localized in the enterochromaffin cells of the mucosa of the upper small intestine. Motilin likely has a physiologic role in the regulation of the migrating motor complex (MMC). Motilin is released during the fasting state, and increased levels correspond with the onset of the MMC. Neurotensin is a 13-amino acid neurotransmitter found in the central nervous system and in the gut. Specific endocrine cells that contain neurotensin are found in the ileal mucosa with smaller quantities found in the jejunum, stomach, duodenum, and colonic mucosa. Neurotensin is released by a mixed meal and fats, with carbohydrates and protein releasing much smaller increments. It has been proposed that neurotensin has a physiologic role in fat-initiated changes in gastric acid secretion, gastric emptying, pancreatic secretion, and intestinal motility.
a. The enterohepatic circulation is highly efficient with 80% to 90% of secreted bile salts reabsorbed and returned to the liver through the portal circulation
b. The reabsorption of bile is entirely an active process
c. The small amount of bile escaping in the colon is deconjugated by bacteria, promoting lipid solubility and passive colonic absorption
d. Ileal resection results in presenting high concentrations of bile salts to the colon which promotes diarrhea by bacterial overgrowth
Answer: a, c
Some 80% to 90% of bile salts secreted into the small intestine as micelles are reabsorbed and returned to the liver through the portal circulation. This circular flow of bile is termed the enterohepatic circulation. In the liver, bile salts are resecreted and stored in the gallbladder in preparation for the next meal. The reabsorption process of bile is both passive and active. Passive absorption occurs along the entire length of the small bowel and depends on the lipid solubility of the bile salt. Glycine bile conjugates are more soluble than taurine conjugates. As much as 50% of bile is passively reabsorbed. Active absorption of bile occurs only in the terminal ileum. A small amount of bile escapes into the colon, where it is deconjugated by bacteria, promoting lipid solubility and further passive absorption. High colonic concentration of bile salts promote diarrhea by inhibiting sodium and water absorption. This commonly occurs in patients with ileal resection and can be treated with the bile-binding resin, cholestyramine.
a. The jejunum is the site of maximum absorption for most ingested materials with almost all jejunal absorption performed via active transfer mechanisms
b. Eighty percent of water presented to the gastrointestinal system is reabsorbed by the small bowel
c. The absorption of carbohydrates requires digestion of large starch molecules by salivary and pancreatic amylase, therefore presenting smaller oligosaccharides to the brush border of the jejunum to complete the digestion and absorptive process
d. Dietary fiber represents poorly digestible carbohydrates which can absorb organic materials such as bile salts and lipids
Answer: b, c, d
The jejunum is the site of maximum absorption of all ingested materials expect for vitamin B12. Although its mucosa contains numerous specific transport processes, the presence of large intercellular pores produces a permeable membrane and allows for rapid passive transfer or solutes and water. The ileum is less permeable and makes greater use of active-transport mechanisms. Normally about 1 to 1.5 liters of water is ingested each day with another 5 to 10 liters secreted by the GI tract in some form. About 80% of this fluid is absorbed by the small bowel. Because of this large bidirectional movement of water, a small alteration in bowel permeability or transport can rapidly result in net secretion and diarrheal disease states. A major source of caloric nutrition comes in the form of carbohydrate. In the Western diet, this is made up primarily of starch (about 60%), sucrose (30%), and lactose (10%). The digestive process for starch begins with digestion of the polysaccharide first by salivary amylase and continues with pancreatic amylase yielding smaller oligosaccharides which along with sucrose and lactose are then presented to the brush border of the jejunum to complete the digestion and absorptive processes. Dietary fiber consists of nondigestible carbohydrate, such as cellulose. Fiber is found commonly in all-bran cereals, beans, partially cooked vegetables, and raw pulpy fruits. High fiber diets retain water within the bowel lumen and significantly shorten bowel transit time. Dietary fiber can absorb organic materials such as bile salts and lipids and inorganic materials such as zinc, calcium, magnesium and iron.
a. Most of gas seen on plane abdominal radiographs is produced by gas forming microorganisms
b. Elevation of luminal pressure contributes to fluid accumulation in the small bowel in closed loop but not open loop small bowel obstructions
c. Intestinal blood flow initially increases to the bowel wall in early bowel obstruction
d. In the face of obstruction, myoelectrical activity of the bowel is consistently increased
Answer: b, c
When a loop of bowel is obstructed, intestinal gas and fluid accumulate. Approximately 80% of the gas seen on plane abdominal radiographs is attributable to swallowed air. In the setting of acute pain and anxiety, patients with intestinal obstruction may swallow excessive amounts of air. Fluid accumulates intraluminally with open-or closed-loop small intestinal obstruction due to a number of factors. Experimental studies and clinical investigations demonstrate that elevation of luminal pressures above 20 cm H2O inhibits absorption and stimulates secretion of salt and water into the lumen proximal to an obstruction. In closed-loop obstruction, luminal pressures may exceed 50 cm H2O and may account for a substantial proportion of a luminal fluid accumulation. In simple, open-loop obstruction, distention of the lumen by gas rarely leads to a luminal pressure higher than 8–12 cm H2O. Thus, in open-loop obstruction, the contributions of high luminal pressures to hypersecretion may not be important. In response to heightened luminal pressure, total blood flow to the bowel may initially increase. Subsequently, however, blood flow to the bowel is compromised as luminal pressures increase, bacteria invade, and inflammation leads to edema within the bowel wall. Accumulation of gas and fluid in the obstructed lumen also leads to changes in myoelectrical function in the gut, proximal and distal to the obstructed segment. In response to distension, the obstructed segment itself may dilate, a process known as “receptive relaxation.” At sites proximal and distal to the obstruction, changes in myoelectrical activity are time-dependent. Initially, there may be intense periods of activity and peristalsis. Subsequently, myoelectrical activity is diminished and interdigestive migrating myoelectrical complex (MMC) is replaced by ineffectual and seemingly disorganized clusters of contractions.
a. Proximal small bowel obstruction
b. Distal small bowel obstruction
c. Acute appendicitis
d. Closed-loop small bowel obstruction
Distinguishing the various types of bowel obstruction can be difficult based on history, physical findings, and radiographic studies. The patient described has intermittent to constant pain with low volume feculent vomiting. Distension is marked and progressive, and tenderness is diffuse. This scenario most likely fits with an open-loop distal small bowel obstruction. The feculent vomiting suggests a more distal rather than proximal obstruction. The lack of severe pain and signs of peritoneal irritation suggests that a closed-loop obstruction is unlikely. A colon obstruction with an incompetent ileocecal valve would be another alternative to consider if gas in the colon had been seen on x-ray.
a. Simple obstruction secondary to an adhesion is most likely to resolve nonoperatively
b. It is most likely that the patient’s obstruction is secondary to recurrent malignancy
c. A history of colon cancer makes carcinomatosis the most likely diagnosis
d. Lower abdominal procedures are more likely to result in obstructive adhesions than are upper abdominal procedures
Answer: a, d
Peritoneal adhesions account for more than half of small bowel obstruction cases. Lower abdominal procedures such as appendectomy, hysterectomy, and abdominal perineal resection are common precursor operations to account for obstruction although adhesions may follow any abdominal procedure including cholecystectomy, gastrectomy, and abdominal vascular procedures. Simple adhesive obstruction is distinguished from other forms of obstruction by the capacity to resolve without surgical intervention. In recent surveys, as many as 80% of episodes of small bowel obstruction due to adhesions may resolve nonoperatively. The likelihood that an obstruction is due to recurrent malignancy relates to several factors including the origin of the primary malignancy, the stage of the primary malignancy, and the designation of original surgery as curative or palliative. Gastric and pancreatic cancers often present with, or are subsequently complicated by peritoneal carcinomatosis and subsequent obstruction. With respect to colon and rectal carcinomas, as many as 50% of cases presenting with obstruction after resection of the primary may be due to adhesions and not recurrent malignancy.
a. The presence of a white blood cell count > 15,000 would be highly suggestive of a closed-loop obstruction
b. Metabolic acidosis mandates emergency exploration
c. An elevation of BUN would suggest underlying renal dysfunction
d. There is no rapidly available test to distinguish tissue necrosis from simple bowel obstruction
There have been multiple attempts to use common clinical laboratory test criteria to identify the likelihood that obstruction is associated with strangulation. In most cases of simple obstruction, laboratory studies do not play a direct role in diagnosis but are helpful in understanding the extent of complications such as dehydration and fluid and electrolyte abnormalities. An elevation of the white blood cell count along with fever, tachycardia, and localized abdominal tenderness is one of the “cardinal signs” for risk for strangulation. However, such an elevation is nonspecific. Similarly, metabolic acidosis may be associated with intestinal ischemia as well as evidence of dehydration and fluid loss. Elevation of BUN and other electrolyte abnormalities also represent fluid loss and dehydration. Therefore, at present there is no non-invasive rapid laboratory tests that can provide information to suggest that tissue necrosis is eminent.
a. Contrast enema
b. Enteroclysis study with dilute barium
c. CT scan with dilute barium oral contrast
d. None of the above
Answer: a, b, c, d
Contrast studies such as those listed above may provide specific localization at the point of obstruction and the nature of the underlying lesion. When obstruction of the small intestine is not progressively resolving, a small bowel follow-through is indicated to confirm the presence and location of the obstruction. The history of a previous right hemicolectomy in this patient may also allow reflux through the colon to define the ileocolonic anastomosis and be able to define the site of obstruction in a retrograde fashion. The potential benefits for a CT scan include not only defining the obstruction and perhaps the nature of the lesion, but also in defining any other evidence of abdominal pathology such as metastases, ascites, or parenchymal liver abnormalities which might be present in a patient with a previous neoplasm. Although none of these tests would be contraindicated, failure of this patient to improve will likely mandate an operation and make contrast studies unnecessary. There would appear to be no evidence of strangulation or perforation therefore there are no contraindications to these studies.
a. Colon distension with a cecal diameter in excess of 12 cm should indicate the need for urgent operation
b. Endoscopic decompression may be attempted but seldom is successful
c. After successful colonoscopic decompression, recurrence is unlikely
d. A rectal tube as the primary treatment is generally not successful
Acute pseudo-obstruction of the colon, known as Ogilvie’s syndrome, is a paralytic ileus of the large bowel characterized by rapidly progressive abdominal distension often without associated pain. Plane radiographs of the abdomen may reveal air in the small bowel and distension of discrete segments of the colon (cecum or transverse colon) or the entire abdominal colon. Distension can become impressive, oftentimes in chronic cases distension in excess of 15 cm can be observed without evidence of colon perforation or wall ischemia. Major risk factors for the development of Ogilvie’s syndrome include severe blunt trauma, orthopedic trauma or procedures, acute cardiac events or coronary bypass surgery, acute neurologic events or neurosurgical procedures, and acute metabolic derangements. Initial management includes resuscitation and correction of the underlying metabolic and electrolyte abnormalities. A nasogastric tube is indicated if the patient is vomiting and will prevent swallowed air from passing distally. If distension is painless and the patient shows no signs of toxicity or bowel ischemia, expectant management can be successful in about 50% of cases. If distension worsens so that the cecal diameter increases beyond 10–12 cm or if it persists for more than 48 hours, colonoscopy is recommended. Endoscopic decompression is successful in 60–90% of cases, but colonic distension may recur in up to 40% of cases. Rectal tubes are ineffective in managing distension of the proximal colon, however, such tubes may be useful after colonoscopy.
a. In the United States, peritoneal adhesions account for over half of the cases of small bowel obstruction
b. A leading cause of bowel obstruction is early postoperative adhesions
c. Bowel obstruction cannot occur with a Richter’s hernia
d. Ninety percent of adult cases of intussusception are associated with a pathologic process, most commonly a tumor
Answer: a, d
Peritoneal adhesions account for more than half of the cases of small bowel obstruction in the United States. Obstruction in the immediate postoperative period following abdominal surgery, however, is uncommon, occurring in only 1% of patients in the four weeks following laparotomy. Hernias of all types are second only to adhesions as the most frequent cause of obstruction. External hernias such as inguinal or femoral hernias may present with symptoms of obstruction. Femoral hernias are particularly prone to incarceration and bowel necrosis, due to the small size of the hernia inlet. One important consideration is the Richter’s hernia. In this variant, only a portion of the bowel wall is incarcerated. These most frequently occur in association with femoral or inguinal hernias. Complete obstruction can occur if more than half to two-thirds of the bowel circumference is incarcerated. About 5% of intussusception cases occur as adults. Intussusception occurs when one segment of bowel telescopes into an adjacent segment, resulting in obstruction and ischemic injury to the intussuscepting segment. Ninety percent of adult cases are associated with pathological processes. Tumors, benign and malignant, can act as a lead point against the sussesception in over 65% of adult cases.
a. The use of intravenous patient-controlled analgesia has no effect on return of small bowel motor activity
b. The presence of peritonitis at the time of the original operation delays the return of normal bowel function
c. The routine use of metoclopramide will hasten the return of small intestinal motor activity
d. Contrast radiographic studies have no role in distinguishing early postoperative bowel obstruction from normal ileus
The term ileus reflects the underlying alterations in motility of the gastrointestinal tract, leading to functional obstruction. From a practical standpoint, ileus represents the interval between abdominal exploration and the reappearance of flatus and bowel movements. Distinguishing a normal postoperative ileus and the prolonged course of a “paralytic” ileus is based primarily on the time since operation and the clinical circumstances. Besides the location of the previous operation (upper abdominal, lower abdominal, pelvic., the nature of the previous operation and the findings may also contribute. Peritonitis or spillage of noxious material leads to an increase in the delay of return of normal bowel function. Distinguishing a paralytic ileus from mechanical obstruction can oftentimes be difficult. Abdominal x-rays in a postoperative ileus should reveal gas in segments of both the small and large bowel. Upper GI contrast or CT scan may also be helpful. Early postoperative obstruction is uncommon and is particularly rare for upper abdominal surgery, with most cases occurring after surgery of the colon, particularly abdominal perineal resection. There has been little success in the use of prokinetic agents to shorten recovery times after lower abdominal procedures. The use of intravenous patient controlled analgesia may delay the recovery of postoperative ileus when compared to the IM route of narcotic administration.
a. Fluid resuscitation with D5 half normal saline with 40 mEq of potassium chloride/liter
b. Placement of an indwelling urinary catheter
c. Nasogastric decompression with a nasogastric tube
d. Immediate surgery
e. The patient should be begun on broad spectrum antibiotics at the time of admission
Answer: b, c
The principles of management of a patient with small bowel obstruction include initial fluid resuscitation and restricting oral intake. The optimal fluid for resuscitation in this patient with a distal small bowel obstruction would likely be Ringer’s lactate or normal saline. Since gastric secretion is a small component of the fluid loss, potassium replacement is likely not particularly important. An indwelling urinary catheter should be placed to monitor the urine output to reflect the fluid status. Invasive hemodynamic monitoring with a central line is likely unnecessary unless concerns are raised about cardiac status. Nasogastric decompression is indicated in all but mild cases. The nasogastric tube serves to prevent distal passage of swallowed air and minimizes discomfort of reflux of intestinal contents and eliminates vomiting. There appears to be no clinical evidence suggesting the need for urgent operation and therefore resuscitation prior to surgery is of optimal importance in this patient.
It has been well established that perioperatively-administered antibiotics reduce wound infection and abdominal sepsis rates in patients undergoing operation to relieve intestinal obstruction, simple or strangulated. Once the decision has been made to proceed with surgery, broad spectrum antibiotics, covering gram-negative aerobes and anaerobes should be given. The use of antibiotics in patients who have not been committed to operation has not been evaluated systematically. Giving antibiotics to patients who are being observed can obscure the underlying process and, in the end, delay optimal therapy.
a. Urgent laparotomy because of the massive colon distension
b. An attempt at endoscopic decompression with a flexible sigmoidoscope
c. Elective laparotomy and sigmoid resection should follow if endoscopic decompression is successful
d. If at urgent laparotomy resected bowel is present, colon resection with primary anastomosis is in order
Answer: b, c
The most common site of volvulus is the sigmoid colon, accounting for 65% of cases. The preferred method and management involves endoscopic decompression. This conservative approach resolves the volvulus in 85% to 90% of cases, and elective resection of the redundant segment can then be planned. Following endoscopic decompression, recurrence of the volvulus is higher than 60% if sigmoid resection is not performed. If the patient presents with peritoneal findings, sepsis, and shock, rapid resuscitation followed by urgent resection and colostomy is warranted.
a. Perianal disease is the initial mode of presentation in the majority of patients
b. The prevalence of perianal disease is increased in patients with either ileocolitis or isolated colonic involvement
c. Metronidazole has been shown to be effective in the treatment of perianal disease secondary to Crohn’s
d. An aggressive surgical approach is appropriate in most cases due to the frequent rapid progression of perianal disease
Answer: b, c
A common manifestation of Crohn’s disease is perianal disease, including anal fistulas with extension into the adjacent organs and soft tissue regions, fissures, and perirectal abscesses. The prevalence of perianal disease approaches 25% for patients with ileitis, 50% for ileocolitis, and 40% for those with isolated colonic involvement. Perianal disease is one of the initial signs of presentation in one-third of patients. Although broad spectrum antibiotics are clearly indicated for septic complications of Crohn’s disease, their use as a primary treatment has generally been met without success. Metronidazole has been used effectively in the treatment of perianal disease. In general, a conservative surgical approach to perianal disease is usually prudent. Many patients who have indolent anal fistulas can live comfortably with their disease for years. Although the development of an abscess requires conventional drainage depending on the state of Crohn’s involvement of the rectum, standard surgical procedures can be applied to most forms of perirectal and perianal disease. Proctectomy may be indicated for patients with advanced perianal disease in direct continuity with active rectal involvement.
a. Renal calculi
Answer: a, b, c, d
Although Crohn’s disease is primarily a disease involving the alimentary tract, involvement of extraintestinal tissues (joints, skin, and eyes) is common and indicates that Crohn’s disease is a systemic disorder rather than a localized intestinal disease. In addition to specific processes, secondary consequences of impaired intestinal absorption and resulting malnutrition include anemia due to specific deficits in vitamins, trace elements, and bile acids and electrolytes. Growth retardation and delayed bone maturation are present in 10–40% of children and adolescents with this disease. Patients with terminal ileal disease are also prone to develop renal urate or oxalate stones. Furthermore, as the result of altered bile salt metabolism and the development of lithogenic bile,
patients with ileal disease and ileal resections are also at risk for cholelithiasis.
a. Recurrent disease on contrast radiographs frequently lags behind the development of clinical signs and symptoms
b. In 10% of cases, Crohn’s disease cannot be distinguished from chronic ulcerative colitis based on clinical, radiologic, and pathologic criteria
c. Although no specific laboratory tests exist for Crohn’s disease, the erythrocyte sedimentation rate has evolved as a useful measure of disease activity
d. Specific endoscopic features encountered in Crohn’s disease which allow differentiation from ulcerative colitis include aphthous ulcers, cobblestoning, and skip areas
Answer: b, c, d
A number of laboratory and radiographic studies as well as the role of endoscopy and biopsy are useful in the diagnosis and assessment of Crohn’s disease. Although no specific laboratory test exists for Crohn’s disease, acute-phase protein levels and erythrocyte sedimentation rate have evolved as measures of disease activity and severity. Endoscopic examination of the colon and rectum is often performed early in the diagnostic workup. In the presence of colorectal involvement, specific endoscopic features encountered which allow differentiation from ulcerative colitis include: aphthous ulcers, linear ulcers, cobblestoning, and asymmetric and discontinuous involvement. The radiologic examination is essential for differential diagnosis in delineating the extent or the severity of the disease primarily involving the small bowel. Barium contrast studies will disclose a number of specific features in patients with Crohn’s disease. A correlation, however, between the extent of the disease seen radiographically and clinical symptoms does not exist. Recurrent disease after surgical resection is often apparent radiologically before the development of clinical signs and symptoms.
The most important differential diagnosis is between Crohn’s disease and chronic ulcerative colitis, especially when the information is limited to the colon and rectum. Despite extensive clinical, radiologic, and pathologic evaluation, 5% to 10% of patients will be defined as having indeterminant colitis without clear-cut evidence of either condition.
a. Strictureplasty, although offering short-term benefits, is associated with a higher rate of recurrence when compared to resection
b. Frozen section examination of the margin of resection is essential to prevent both recurrent disease and early anastomotic complications
c. Conservative margins of resection are appropriate, resecting only grossly involved segments of bowel
d. Patients with Crohn’s disease confined to the colon may be treated with total proctocolectomy with construction of an ileal-anal pouch anastomosis
Surgical therapy for Crohn’s disease is curative not palliative, therefore is reserved for complications of the disease or failure of or debilitation, secondary to medical therapy. The lines of bowel resection should be chosen conservatively with only a few centimeters proximally and distally to the site of visible changes of Crohn’s disease. Microscopic evidence of Crohn’s disease at the resection margins does not compromise safe anastomosis and therefore frozen section examination of resection margins is not necessary. In patients with multiple strictures of the small bowel, resection may involve excessive resection of bowel. Therefore, strictureplasty is an appropriate surgical therapy. Long-term results using this approach indicate that recurrence rates are not substantially increased with strictureplasty, even though inflamed intestinal tissue is left in situ. In patients with diffuse disease of the colon or rectum, proctocolectomy with ileostomy is the treatment of choice. Both the risk of ileal involvement and transmural involvement of the rectum precludes the technique of ileal pouch-anal reconstruction in patients with Crohn’s disease.
a. The leading infectious agent thus far suggested is infection with a Mycobacterium species
b. Strong evidence linking viral pathogens to Crohn’s disease has been developed
c. Although many alterations in cellular and immune functions in patients with Crohn’s disease have been observed, no primary defect in the immune system has yet been identified
d. The identification of antibodies to enterocytes provides strong support for the theory that Crohn’s disease is an autoimmune process
Answer: a, c
Investigations for the last 60 years have tried to determine the etiology of Crohn’s disease. Although a number of theories have evolved and evidence is available supporting numerous theories, there is no conclusive evidence to support any etiologic theory for its development. Given the characteristic histologic findings of granuloma formation, early investigations focused on bacterial causes of Crohn’s disease, most notably infection with Mycobacterium species. Several reports have isolated Mycobacteria from mesenteric lymph nodes and intestine involved in Crohn’s disease but have not proven the Mycobacterial cause. Similarly, research in viral causes has been inconclusive, and although viral pathogens have been isolated from tissue extractions with Crohn’s disease, linkage to induction and persistence of the disease has not been convincing. Similar difficulties exist in theories concerning immunogenetic causes of Crohn’s disease, and although many alterations in cellular and immune functions associated with Crohn’s disease have been observed, no primary defect, either systemic or mucosal, humoral or cellular has been identified. A number of reports have described antibodies and lymphocyte reactivity to enterocytes, however the presence of antibody cannot be correlated with disease activity and furthermore antibodies have been found in patients with other diseases and in healthy volunteers.
a. Endoscopic evidence of recurrence is present in less than 50% of patients at five years
b. Radiographic or endoscopic evidence of recurrence is frequently not accompanied by symptoms
c. Clinical recurrence of Crohn’s disease is seen in 20% of patients at two years, and 40–50% at four years after surgery
d. Reoperation for Crohn’s disease is necessary in the majority of patients by five years
e. No solid evidence demonstrating prolongation of remission can be seen with corticosteroids, sulfasalazine, or antibiotics
Answer: b, c, e
The majority of patients with Crohn’s disease will recur. If recurrence is defined as alterations detected endoscopically, then 70% will recur within one year of surgery, and 85% within three years. However, in most of these patients clinical symptoms will not accompany the endoscopic or radiographic evidence of disease. A clinical recurrence (return of symptoms) confirmed as Crohn’s disease radiologically, endoscopically, or surgically, affects 20% of patients at two years, and 40–50% at four years after surgery. Reoperation becomes necessary in about 30% of the patients by five years. These statistics give impetus to maintain remission and prevent recurrence. Although it is common practice to stem recurrence with sulfsalazine, 5-ASA preparations, antibiotics, and possibly azathioprine, none of these (possibly excepting azathioprine) have definitely been proven effective.
a. Corticosteroids have been demonstrated to effectively treat acute exacerbations and to prolong remission in patients with Crohn’s disease
b. Sulfasalazine is indicated primarily for the treatment of patients with acute exacerbations of Crohn’s disease involving the small bowel
c. Azathioprine, an immunosuppressant, has been shown to be effective in maintaining remission of Crohn’s disease
d. Low dose cyclosporine has significant therapeutic benefit for patients with both low and high disease activity
Systemic corticosteroids have been used to treat Crohn’s disease since the 1940s. Although the exact mechanism of action is not clear, nonspecific immunosuppression is the likely effect. Several well designed trials have demonstrated that Prednisone (or its equivalent) is effective in the treatment of acute exacerbations. Patients with quiescent disease, or patients who have received remission through medical or surgical therapy, however, do not benefit from long-term continued corticosteroids. Sulfasalazine consisting of a sulfonamide linked to an aspirin analogue (5-ASA) is more effective than placebo in the treatment of acute disease. This agent, however, is most effective in patients with predominantly colonic disease and is less effective than corticosteroids in treating patients with small bowel disease. Asymptomatic patients do not appear to benefit from prophylactic treatment. The immunosuppressive agent azathioprine, which acts to inhibit nucleic acid metabolism, has been demonstrated to be highly effective in long-term use. The use of azathioprine has a steroid-sparing effect with reduction of steroid dose or discontinuation of therapy. In chronic treatment, azathioprine is effective in decreasing disease activity, steroid requirements, and complications leading to surgery, therefore, in contrast to corticosteroids and sulfasalazine, azathioprine appears effective in maintaining remission. Side-effects, however, can be significant including bone marrow suppression and acute pancreatitis. Finally, cyclosporine, an immunosuppressant, has undergone extensive review with the conclusion that low-dose oral cyclosporine treatment confers no therapeutic benefit for patients with low or high disease activity and in no reduction in the need for other forms of therapy.
a. The presence of granulomas involving the bowel wall and mesenteric lymph nodes
b. Transmural inflammation
c. Fissures and ulceration extending into the muscularis propria
d. Chronic fibrotic changes
Answer: a, b, c, d
Crohn’s disease can affect any part of the gastrointestinal tract with the most common site being the ileocecal region. The acute, active phase is marked by aphthous mucosal ulcerations, lymphoid aggregates, and granulomas present in both the bowel wall, adjacent lymph nodes, and in other organs. Transmural inflammation is present with characteristic fissures and ulcers extending deep into the muscularis propria. The acquiescent or healing phase of Crohn’s disease is marked by fibrosis with late stricture formation and chronic ulceration.
a. Crohn’s disease has an age distribution with peaks between the ages of 15 and 30 years and 65 and 75 years
b. There is a definite female predilection for Crohn’s disease
c. The disease is equally prevalent in industrialized versus underdeveloped countries
d. First and second generation relatives with Crohn’s disease have an increased prevalence when compared to the general population
Crohn’s disease arises most commonly between the ages of 15 and 30 years, with a second peak at 55 to 60 years. Men and women are equally affected. The disease is seen more commonly in urban residents than rural dwellers and is associated with higher levels of education. The disease is almost exclusively encountered in industrialized nations like Western Europe and the United States which suggests that environmental factors are important in the pathogenesis. Aggregation in families can occur with first-and second-generation relatives of patients with Crohn’s disease found to have a 10-and 3-fold increase, respectively, in the prevalence of Crohn’s disease when compared to other non-related individuals.
a. Radical pancreaticoduodenectomy (Whipple resection) is necessary for resection of most duodenal adenocarcinomas
b. Adenocarcinomas of the jejunum or ileum are managed by limited segmental resection including resection of the mesentery down to the first vascular arcade
c. Distal ileal carcinomas are best managed by right hemi-colectomy to include lymph node chains along the ileo-cecal blood supply
d. Small invasive adenocarcinomas of the ampulla and peri-ampullary duodenum can frequently be managed by local excision
Answer: a, c
Optimal surgical treatment of adenocarcinoma of the small intestine requires wide, segmental resection, including the draining nodal system. For most duodenal adenocarcinomas, a radical pancreaticoduodenectomy (Whipple procedure) is necessary to incorporate pertinent training lymph nodes. Although local excision of villous adenomas of the periampullary area has been reported, the presence of invasive carcinoma warrants wider resection as a pancreaticoduodenectomy. Jejunal and ileal carcinomas are removed with segmental resections with adequate margins on the bowel and wide resection of the mesentery with associated lymph nodes down to the superior mesenteric artery. Distal ileal carcinomas are drained by lymph nodes along the ileocolic artery and are best managed by right hemicolectomy.
a. Limited segmental resection without lymphadenectomy
b. Careful exploration of the remaining small bowel and colon
c. Non-anatomic resection of small multiple liver metastases
d. Postoperative adjuvant chemotherapy for all carcinoid tumors regardless of size or level of invasion
Answer: b, c
Operative management of a primary small bowel carcinoid tumor involves principals similar to those of small bowel carcinomas. Wide en bloc excision should include as many lymphatic drainage pathways as possible because of their frequent metastatic involvement. Because of the increased incidence of both multicentricity and a second unrelated malignancy, a diligent search for other primary carcinoids of the small bowel and for other synchronous malignancies of other organs is imperative. When localized hepatic metastasis are amenable to resection, hepatic resection should be considered to minimize the potential development of Carcinoid Syndrome. Adjuvant postoperative chemotherapy for patients with metastatic carcinoid tumor is of modest benefit with response rates in the 20–30% range with median duration response short-lived. At present, adjuvant therapy is confined only to those patients with Carcinoid Syndrome.
a. Peutz-Jegher Syndrome
b. Crohn’s disease
c. Simple tubular adenomas of the small intestine
d. Colon carcinoma
The incidence of adenocarcinoma of the small bowel is surprisingly low when compared to that of colon carcinoma when considering the vast length and surface area of the small intestine. The relative infrequency of these tumors has limited our knowledge of pathogenic factors. It appears, however, that the polyp-to-cancer sequence is not well established for simple tubular adenomas of the small intestine. Peutz-Jegher Syndrome is an inherited syndrome which is associated with multiple small intestinal polyps. These polyps are hamartomas with progression of dysplasia to carcinoma felt not to be a major concern. The chronic inflammatory changes of Crohn’s disease appears to predispose to the development of adenocarcinoma, thereby increasing the risk to 100 times that of the general population. There is no known association of carcinoma of the colon and small intestine.
a. Attempts at percutaneous biopsy of the mesenteric mass
b. Surgical exploration with aggressive resection of the localized disease including wide, en bloc lymphadenectomy
c. Liver biopsy and sampling of periaortic and mesenteric lymph nodes outside the field of resection
Answer: b, c
Most patients suspected of having small intestinal lymphoma require operation with the goals of treatment including diagnosis, staging, relief of obstruction and perforation, and resection or debulking. Because intraoperative staging affects postoperative management, liver biopsy and sampling of periaortic and mesenteric lymph nodes outside the field of resection are important aspects of the operative management. In contrast there is no role for splenectomy for primary small bowel lymphoma. For localized disease, aggressive resection with wide, en bloc lymphadenectomy is important. Percutaneous biopsy has no role in such cases both because the preoperative diagnosis will not eliminate the need for surgical intervention, and percutaneous biopsy is frequently inadequate to determine necessary information for the treatment of lymphoma.
a. Adenocarcinomas of the small intestine show a distinct polarity with decreasing frequency from duodenum to ileum
b. Adenocarcinoma of the small intestine associated with Crohn’s disease occurs primarily in the ileum
c. Lymphomas of the small intestine arise primarily in the jejunum
d. The vast majority of carcinoid tumors of the small intestine occur in the ileum
Answer: a, b, d
Anatomically, adenocarcinomas of the small intestine show a distinct polarity with a decreasing frequency from duodenum to ileum. Given the difference in length between the duodenum, jejunum and ileum, the duodenal epithelium shows a substantially greater propensity towards malignant transformation. Even within the duodenum, two-thirds of the carcinomas occur in the periampullary region suggesting that the periampullary mucosa or luminal content (ingested potential carcinogens) interacts with pancreaticobiliary secretions to induce local neoplastic changes. Crohn’s disease primarily is a disease involving the terminal ileum and therefore it is not surprising that most adenocarcinomas developing in association with Crohn’s disease occur also at this site. Small intestinal lymphomas arise from lymphoid tissue within the wall of the bowel. Therefore lymphomas predominate in the ileum, where the greatest concentration of gut lymphoid tissue occurs. Next to the appendix, which harbors 85% of all carcinoid tumors, the small intestine is by far the next most common site of origin. Approximately ninety percent of small intestinal carcinoids are located in the ileum with 40% found within two feet of the ileocecal junction. Multiple primary tumors may be present in 30% of patients.
a. Intestinal obstruction
b. Gastrointestinal bleeding
c. Small intestinal infarction
Answer: a, b, d
Many small intestinal carcinoids are small and asymptomatic and are found only incidentally or at autopsy. Clinical symptoms can arise either from the primary tumor, from sequelae of metastatic disease, or from the Carcinoid Syndrome. Obstructive symptoms can occur either from intussusception or more commonly as a submucosal tumor infiltrates the bowel wall and beyond, the bowel mesentery may become shortened, thickened and fixed by an intense desmoplastic reaction characteristic of carcinoid tumors. This leads to kinking and angulation of intestinal loops and may eventually result in mechanical obstruction. Intestinal ischemia or even infarction can occur secondary to an unusual type of mesenteric angiopathy characterized by vascular thickening and sclerosis that accompanies the desmoplastic mesenteric reaction. Although mucosal ulceration and bleeding can occur, such symptoms are unusual.
a. Many are asymptomatic and only found as incidental findings
b. Leiomyomas are the most common symptomatic benign neoplasm and may present with gastrointestinal bleeding
c. Villous adenomas carry a distinct malignant potential and occur most commonly in the periampullary duodenum
d. Peutz-Jegher Syndrome is associated with multiple adenomatous polyps throughout the small intestine
Answer: a, b, c
The most common benign small intestinal neoplasms are adenomas, leiomyomas, and lipomas. Hamartomas, fibromas, angiomas, and neurofibromas may also occur at a lesser frequency. Three types of adenomas occur, simple tubular adenomas, villous adenomas, and Brunner gland adenomas. Tubular adenomas have a very low malignant potential whereas villous adenomas carry a distinct malignant potential similar to that of colonic villous adenomas. These adenomas occur most commonly in the duodenum and especially in the periampullary region. Brunner gland adenomas represent hyperplasia of the exocrine glands within the proximal duodenal mucosa and have little risk of malignant change. The smooth muscle tumor, leiomyoma, are the most common symptomatic benign neoplasms. Most leiomyomas enlarge with an extraluminal orientation and, may reach considerable size. The tumors eventually may outgrow their blood supply leading to central necrosis, ulceration and intraluminal bleeding. Rupture of the tumor may also occur with intraperitoneal bleeding. Differentiation of larger leiomyomas from their malignant counterpart, leiomyosarcoma, may be difficult on pathologic review. Peutz-Jegher Syndrome is an inherited syndrome associated with multiple gastrointestinal polyps throughout the jejunum and ileum. Histologically these polyps are hamartomas and not adenomas and therefore offer little risk of malignant transformation.
a. Acquired immune deficiency syndrome (AIDS)
b. Celiac disease
c. Crohn’s disease
d. Rheumatoid arthritis
Answer: a, b, c, d
Although rare, small intestinal lymphomas are associated with several conditions. The chronic malabsorptive condition, celiac disease, is recognized to be associated with small intestinal lymphoma. Clinical deterioration in a patient with previously controlled celiac disease should immediately suggest the diagnosis of lymphoma. There is also an increased incidence of lymphoma in Crohn’s disease. Disorders of immunologic function have an increased incidence of extranodal gastrointestinal lymphoma. These disorders include autoimmune diseases such as rheumatoid arthritis, Wegener granulomatosis, systemic lupus erythematous, and congenital immunodeficiencies. Immunosuppressed patients after organ transplantation and patients with prolonged, high-dose chemotherapy are also at increased risk. AIDS has been associated with the development of aggressive, non-Hodgkin’s lymphoma presenting with primary gastrointestinal involvement. Although this is usually a diffuse systemic disease, extranodal lymphoma of the small bowel has been frequently recognized.