Gastroenterology and Hepatology Board Review: Pearls of Wisdom, Third Edition

Section V LARGE INTESTINE

CHAPTER 24. Large Intestinal Congenital and Structural Abnormalities

Ashok Shah, MD and Rajiv Sharma, MD

Image The colon and the rectum account for what percentage of all gastrointestinal duplications.

Five percent and 10%, respectively.

Image True/False: Asymptomatic rectal duplication should undergo surgical resection because of an increased risk of neoplasia.

True.

Image A child presents with chronic constipation, abdominal distension, volvulus, and perforation. What is the most likely diagnosis?

Hirschsprung’s disease.

Image What percentage of Hirschsprung’s disease involves the rectosigmoid colon?

75%–80%.

Image True/False: Anorectal manometry typically reveals a normal sphincter profile and an abnormal rectoanal inhibitory reflex in Hirschsprung’s disease.

True.

Image What cell type is absent in the submucosa and myenteric plexus of patients with Hirschsprung’s disease?

Ganglion cells that migrate from the neural crest region.

Image What pull-through operations have been used to surgically treat Hirschsprung’s disease?

Swenson technique, Duhamel procedure, and Soave procedure.

Image True/False: Hirschsprung’s disease may occur in combination with colonic atresia.

True.

Image True/False: Colonic atresia has been linked to congenital varicella syndrome.

True.

Image True/False: Malrotation of the colon occurs if the midgut fails to complete the 180-degree counterclockwise rotation as it returns from herniation during the 10th to 12th week gestational period.

False. It is a 270-degree counterclockwise rotation.

Image What associated anomalies have been reported in 30%–60% of patients with malrotation?

Small bowel atresia, intussusception, Hirschsprung’s disease, and abdominal wall defects.

Image An infant presents at 1 month of age with a proximal small bowel obstruction, volvulus, or colonic ischemia. What is the most likely diagnosis?

Malrotation.

Image True/False: Operative treatment of malrotation also includes an appendectomy because future diagnosis of appendicitis would be difficult.

True.

Image True/False: The midgut volvulus formed by malrotation is reduced by untwisting it in a clockwise rotation.

False. Reduction is performed in a counterclockwise rotation.

Image True/False: Gut nonrotation is not as dangerous as gut malrotation.

True. Because the base of the mesentery is wider than in malrotation, the risk of volvulus is less.

Image True/False: Imperforate anus occurs in 1:1,000,000 live births.

False. It occurs in about 1:20,000 live births.

Image True/False: Congenital abnormalities such as genitourinary, cardiac, and gastrointestinal anomalies are rarely associated with imperforate anus.

False. These anomalies occur in up to 50% of cases of imperforate anus.

Image What are three common chromosomal abnormalities associated with imperforate anus?

Down’s syndrome, trisomy 8 mosaicism, and fragile X syndrome.

Image True/False: Infants with imperforate anus cannot pass meconium at birth.

True. Some may have fistulae by which meconium can pass.

Image True/False: Imperforate anus is classified as either a high or a low lesion according to the relation of the rectum to the levator ani muscle.

True.

Image True/False: For the complete evaluation of the patient with imperforate anus, an intravenous pyelogram and voiding cystourethrogram are recommended.

True. Genitourinary defects are occasionally seen in association with imperforate anus.

Image Surgical treatment of high imperforate anus is successful in what percentage of the time?

70%–80%.

Image What are the prerequisites for colonic volvulus formation?

A dilated, redundant colon, and a narrow-based mesocolon.

Image True/False: Common symptoms of colonic volvulus are abdominal pain, obstipation, and abdominal distension.

True.

Image What percentage of colonic obstructions in the United States are caused by a volvulus?

Less than 10%.

Image True/False: A colonic volvulus occurs when a stool-filled segment of bowel twists about its mesentery.

False. A volvulus occurs when an air-filled segment forms a twist.

Image True/False: The sigmoid colon is involved in 90% of all colonic volvuli seen in the United States.

False. A more accurate range is from 40% to 70%.

Image In which type of colonic volvulus is a “coffee bean sign” seen on abdominal x-ray?

Cecal volvulus. It is seen in about 80% cases of cecal volvuli. In contrast, a “bird’s beak sign” is an x-ray finding suggesting the presence of a sigmoid volvulus.

Image What segments of the population are at risk for a colonic volvulus?

The elderly, institutionalized, and neuropsychiatric patients.

Image What action should be taken to reduce a colonic volvulus in a patient with peritoneal signs?

Emergency exploratory laparotomy. In a stable patient without peritonitis, sigmoidoscopy or a barium enema may reduce the volvulus.

Image What is the recurrence rate of a colonic volvulus after nonoperative reduction?

Greater than 40%.

Image True/False: Cecal volvulus generally occurs in younger patients.

True.

Image What percentage of all colonic volvuli involve the cecum?

About 40%–50% depending on the age and geographic location.

Image True/False: A cecal volvulus occurs because of an anomalous fixation of the right colon leading to a freely mobile cecum.

True.

Image What are some precipitating factors for a cecal volvulus?

Pregnancy, adhesions, and an obstructing lesion of the left colon.

Image What percentage of a cecal volvulus involves a full axial twisting of the associated mesentery and its blood vessels?

90%.

Image True/False: Cecal bascule and cecal volvulus refer to the same condition.

False. A cecal bascule may form when redundant mesentery or hypofixation, in combination with massive distention, allows the cecum to fold onto itself. With the cecum flipped upward on itself, a deep crease across the bowel forms, and occlusion of the gut lumen with bowel obstruction may develop.

Image True/False: The signs and symptoms of cecal bascule and cecal volvulus are similar.

True. Although abdominal pain and massive distention are common to both entities, the presence of previous abdominal surgery, especially appendectomy, is more often associated with the cecal bascule.

Image True/False: Plain films of the abdomen are similar in cecal bascule and cecal volvulus.

False. Massive distention of the small bowel and cecum are commonly noted on the plain abdominal radiograph; however, neither the typical “coffee-bean sign” associated with cecal volvulus nor the “bird’s beak” of sigmoid volvulus are present because there is no axial torsion of the bowel.

Image True/False: Colitis cystica profunda is characterized by the presence of submucosal mucus-filled cysts.

True.

Image True/False: The rectum is rarely involved in colitis cystica profunda.

False. Most lesions are found within 12 cm of the anal verge.

Image True/False: It is rare for patients with colitis cystica profunda to have rectal prolapse.

False. Rectal prolapse occurs about 50% of the time.

Image A plain radiograph of the abdomen shows linear, curvilinear, or cystic lucencies in the bowel wall. What is the diagnosis?

Pneumatosis intestinalis.

Image True/False: The amount of hydrogen in the cysts of pneumatosis intestinalis can approach 50% of the gas present.

True.

Image True/False: Pneumatosis cystoides intestinalis is characterized by multiple, thin-walled, noncommunicating, gas-filled cysts with epithelial lining in the wall of the small or large intestines, or both.

False. The gas-filled cysts have no epithelial lining.

Image True/False: Pneumatosis cystoides intestinalis is associated with chronic obstructive pulmonary disease, intestinal obstruction, collagen vascular disease (scleroderma), and iatrogenic conditions such as postendoscopy or surgery.

True.

Image True/False: Pneumatosis intestinalis is one cause of prolonged recurrent asymptomatic pneumoperitoneum.

True.

Image What are successful treatments of pneumatosis intestinalis?

High-flow oxygen breathing, hyperbaric oxygen, antibiotics, and surgical resection.

Image True/False: Surgical treatment has been shown to be curative in most cases of pneumatosis intestinalis.

False. Surgery is not always successful and more extensive pneumatosis may occur; therefore, surgery is indicated only in fulminant cases such as those with a likelihood of bowel necrosis, sepsis, and death.

Image Histologic examination of a colonic lesion shows von Hansemann’s cells and Michaelis–Gutmann’s bodies. What is the diagnosis?

Malakoplakia. A defect in macrophage phagocytic activity has been proposed as a mechanism for the pathogenesis of malakoplakia. Colonic malakoplakia is generally treated with antibiotics such as rifampicin, fluoroquinolones, and trimethoprim-sulfamethaxazole, which penetrate the cell membrane and concentrate within macrophages in combination with a cholinergic agonist like bethanechol to correct the lysosomal defect.

Image True/False: Malakoplakia is a rare chronic, granulomatous, inflammatory disorder that can affect the genitourinary and gastrointestinal tract.

True. It can also affect the skin, lung, bone, and brain.

Image What are the most common sites of the large bowel affected by malakoplakia?

Rectum, descending, and sigmoid colon. It can also affect appendix and stomach.

Image What other diseases or conditions are associated with colonic malakoplakia?

Colonic adenoma, carcinoma, chronic granulomatous disease, ulcerative colitis, and celiac disease.

Image What are the peak ages of incidence of malakoplakia?

The age of incidence is bimodal with an early peak at 13 years of age and a late peak around the age of 57.

Image Name three predisposing conditions associated with malakoplakia.

Chronic infection with Escherichia coli, sarcoidosis, and tuberculosis.

• • • SUGGESTED READINGS • • •

Berrocal T, Lamas M, Gutieerrez J, Torres I, Prieto C, del Hoyo ML. Congenital anomalies of the small intestine, colon, and rectum. Radiographics. 1999 Sep-Oct;19(5):1219-1236.

Morikawa N, Kuroda T, Honna T, Kitano Y, Tanaka H, Takayasu H, et al. A novel association of duodenal atresia, malrotation, segmental dilatation of the colon, and anorectal malformation. Pediatr Surg Int. 2009 Nov;25(11):1003-1005.

Vaos G, Misiakos EP. Congenital anomalies of the gastrointestinal tract diagnosed in adulthood—diagnosis and management. J Gastrointest Surg. 2010 May;14(5):916-925.