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

Section I GASTROENTEROLOGY

CHAPTER 5. Pediatric Gastrointestinal Diseases

Jon A. Vanderhoof, MD

Image Formula-fed and human milk-fed infants have different patterns of gut microbiota colonization. The stools of breast-fed infants have a predominance of which bacterial genus?

Bifidobacterium.

Image What is the coefficient of fat absorption in a normal individual?

In a normal individual, 93% of fat is absorbed. In newborn infants, the number drops to a level of 90% and even less in premature infants. Nevertheless, its caloric density (9 kcal/g) makes it an excellent source of calories, even in premature infants.

Image Absent responses to which gastrointestinal hormones occur in gluten-sensitive enteropathy prior to treatment?

Cholecystokinin, secretin, and glucose-dependent insulin trophic peptide.

Image In the medical evaluation of anorexia nervosa, laboratory studies to screen for pregnancy, inflammatory bowel disease, thyroid disease, central nervous system disorders, drug abuse, celiac disease, and metabolic disorders are routinely done. What additional serum study may be useful in this scenario?

Serum carotene. It is often elevated in anorexia nervosa.

Image What disorder should be suspected in a patient with a history of caustic ingestion who develops a late onset or worsening of dysphagia?

Esophageal carcinoma.

Image What percentage of school-age children have chronic abdominal pain to the extent that it interferes with normal daily activity?

10%.

Image What is the most useful diagnostic tool to identify the cause of chronic recurrent abdominal pain of childhood?

Careful history and physical examination.

Image Chronic, nonspecific diarrhea or ‘toddler diarrhea,’ the most common cause of chronic diarrhea in this age group, is best treated utilizing what dietary maneuvers?

High-fat, low-carbohydrate diet.

Image Constipation in school-age children has been identified as a possible consequence of intolerance to what dietary component?

Cow’s milk protein.

Image Why is cow’s milk allergy so common in infants?

The infant’s gut is more permeable to macromolecules in the first month of life permitting greater antigen exposure. Since cow’s milk is the only antigen utilized in infants under a month of age, allergy to this protein is more common than other dietary protein allergies.

Image An 8-month-old infant develops diarrhea and gas production every time he is given cow’s milk. Both mother and father have been diagnosed with lactose intolerance. The family physician has recommended the child undergo a lactose breath hydrogen test. Could this be done in an 8-month-old infant?

Yes. Breath hydrogen testing can be performed in infants and is useful in the investigation of bacterial overgrowth, specific carbohydrate malabsorption, and measuring intestinal transit. Lactose intolerance at this age is almost always secondary and is usually due to cow’s mild allergy.

Image True/False: Cow’s milk protein allergy results in life-long lactose intolerance.

False. Most children outgrow the allergy by 3 to 5 years of age. As a consequence, when suspected, allergy testing is rarely necessary and a trial of cow’s milk protein exclusion should be recommended.

Image What is the most common cause of acute abdomen in the infant age group?

Intussusception.

Image What is the most common cause of painless, lower gastrointestinal bleeding in school-age children?

Colonic polyp, usually of the juvenile type.

Image Infantile failure to thrive is a serious condition requiring early identification and treatment. What is responsible for nearly all the mortality in this condition?

Abused or seriously neglected infants.

Image What is the most common malignant tumor of the gastrointestinal tract in children, and occurs most frequently in the distal ileum?

Lymphoma.

Image What is the drug of choice if sedation is required for esophageal manometry?

Chloral hydrate, 50 mg/kg. It does not affect lower esophageal sphincter pressure or the amplitude of esophageal contractions.

Image What is the most common type of tracheoesophageal fistula?

Proximal esophageal atresia with a fistula between the trachea and the distal esophagus accounts for 85%.

Image What is the major value of an upper gastrointestinal x-ray in an infant with frequent emesis?

An upper gastrointestinal barium-contrast x-ray excludes anatomical lesions, gastric outlet obstruction, and proximal small bowel anomalies. It does not reliably diagnose or exclude gastroesophageal reflux.

Image What is the most common cause of idiopathic portal hypertension in a child without liver disease?

Portal vein thrombosis. Further history may reveal that a venous umbilical catheter was placed during the newborn period.

Image True/False: Newborn infants are achlorhydric.

False. Newborn infants have high serum gastrin levels and normal stimulated gastric acid production has been demonstrated in the first few days of life.

Image How long does an infant need to receive nothing by mouth after a pyloromyotomy for pyloric stenosis?

They can eat as soon as they wake up.

Image What is the most common cause of erosive gastritis associated with eosinophilic infiltrates on biopsy in a 6-week-old infant?

Cows’ milk protein allergy. Eosinophilia, more common in small bowel and rectal biopsies, may be seen in esophageal and gastric biopsies as well.

Image An institutionalized child with Down’s syndrome presents with abdominal pain and is found to have an iron-deficiency anemia. What is the most likely cause?

The child needs an upper gastrointestinal endoscopy as children with Down’s syndrome have a high incidence of celiac disease. It should also be kept in mind that institutionalized children also have a higher incidence of symptomatic Helicobacter pylori disease.

Image When should gut malrotation be surgically repaired?

Only if symptomatic; however, it is often difficult to determine if the symptoms, such as abdominal pain, are directly related to the malrotation.

Image How do you differentiate between gastroschisis and omphalocele?

An omphalocele involves the umbilicus but a gastroschisis does not. An omphalocele is also covered by peritoneal membrane, which may or may not be apparent, but a gastroschisis is not covered by this membrane.

Image What is a common cause of lactase deficiency in infants less than 6 months of age?

Infection or enteropathy due to cow’s milk protein intolerance. Primary acquired lactose intolerance does not occur until after the age of 5 years.

Image Bacterial proliferation in small bowel bacterial overgrowth is diminished by an increase in which macronutrient and concurrent decrease in which macronutrient?

Increase in fat and a decrease in carbohydrate.

Image What percentage of children with celiac disease present with chronic diarrhea and failure to thrive?

This is unknown. However, as the child ages, classic symptoms become less apparent and he/she may present merely with abdominal pain and short stature.

Image What is the most common, non-IgE-mediated food-related immunologic reaction?

Milk protein. Although IgE-mediated food allergies occur, they are manifested by gastrointestinal symptoms and, oftentimes, respiratory symptoms and/or skin reactions occurring within 2 hours after food ingestion.

Image What is the safest, most effective drug therapy for eosinophilic gastroenteritis in a child who does not respond completely to dietary restrictions?

Oral fluticasone, although a budesonide slurry and oral cromolyn sodium may also be effective. Although systemic corticosteroid therapy is highly efficacious, long-term treatment is often associated with numerous side effects.

Image What is the definition of short bowel syndrome?

The presence of malabsorption and malnutrition following massive small bowel resection. It is not based solely on the length of remaining bowel; however, it generally does not become clinically apparent until about three-quarters of the small bowel has been removed.

Image What is the most common and frequently unrecognized gastrointestinal complication in a child with short bowel syndrome?

Chronic small bowel bacterial overgrowth.

Image What type of triglyceride has the most potent effect on enhancement of intestinal adaptation after massive small bowel resection?

Long-chain triglyceride.

Image What would characteristically be found on upper endoscopy in a child who presents with stool lymphocytes, lymphopenia, hypoalbuminemia, and hyperlipidemia?

Scattered milky white spots with a snowflakelike appearance. These represent markedly dilated lymphatics in the lamina propria and/or the submucosa (lymphangiectasia).

Image Currant jelly stools in an infant with severe irritability and a palpable sausage-shaped abdominal mass is the classic description of what disorder?

Intussusception. This classic presentation is seen in only about 15%. More commonly, emesis and abdominal pain with various forms of rectal bleeding are seen.

Image What is the most likely consideration in a pediatric patient carrying the tentative diagnosis of pseudoobstruction who never demonstrates ileus or air fluid levels?

Munchausen-by-proxy.

Image Children presenting with significant abdominal pain may warrant screening by stool microscopy for what particular infectious agents?

Parasitic infections may present solely with abdominal pain in the absence of other gastrointestinal symptoms.

Image What is the most common anomaly of an omphalomesenteric duct remnant?

Meckel’s diverticulum.

Image What are the most common tumors of the lower gastrointestinal tract in children?

Benign polyps including the juvenile polyp, hamartomatous polyp, inflammatory fibroid polyp, and lymphoid polyp. Malignant adenomas of the colon are usually seen in conjunction with familial polyposis syndromes.

Image What is the most common cause of abdominal pain in children who present to the Emergency Room?

Gastroenteritis. The most common error is to diagnose gastroenteritis in a child who actually has a retrocecal appendicitis.

Image What single most important factor reduces the morbidity and mortality of Hirschsprung’s disease in children?

Enterocolitis is a major cause of mortality in infants with Hirschsprung’s disease. Therefore, the recognition and treatment of Hirschsprung’s disease before enterocolitis develops is important.

Image What is the most likely cause of acute diarrhea in school-age children who present with watery stools, vomiting, and a low-grade fever that spontaneously resolves within 24 hours?

Norovirus.

Image Continuing oral feedings in patients with acute infectious enteritis is done primarily to avoid what complication?

Weight loss.

Image A 6-year-old boy treated with amoxicillin-clavulanic acid for otitis media develops Clostridium difficile diarrhea requiring treatment with metronidazole. After successful treatment, he experiences a recurrence of C. difficile 3 weeks later. What would be the most beneficial course of action to prevent recurrence again?

Retreat with metronidazole and initiate and maintain a probiotic such as Saccharomyces boulardii for 2 to 3 months.

Image What fat soluble vitamin is least well absorbed in patients with cholestatic liver disease?

Vitamin E.

Image How reliable are IgA antigliadin antibodies in children under 2 years of age in screening for celiac disease?

The reliability of IgA antigliadin antibodies under 2 years of age deteriorates significantly. Consequently, the test cannot be reliably used as a screening test in this age group.

Image In IgA-deficient patients, is there a suitable alternative screening test for celiac disease?

Deaminated antigliadin IgG antibodies may be used in this population.

Image Persistent mild elevation of serum aminotransferase levels in an 8-year-old overweight boy is most likely suggestive of what disorder?

Nonalcoholic fatty liver disease (NAFLD) has now become commonplace even in the pediatric age group and carries with it a significant risk of ongoing chronic liver disease and metabolic syndrome.

Image Anti-tumor necrosis factor (TNF) alpha therapy for inflammatory bowel disease in children is commonly associated with what complication?

Infection is the most common complication of anti-TNF therapy. There is also a risk of lymphoma, especially associated with a combination of anti-TNF therapy and immunomodulators. The risk of lymphoma appears to be somewhat greater in children and adolescents than in adults, although the complication is still quite rare.

Image True/False: A 2-month-old infant has been constipated since birth. A barium enema is performed which shows no transition segment. Hirschsprung’s disease has been effectively excluded in this infant.

False. The barium enema is notoriously unreliable in infants as a screening tool for Hirschsprung’s disease as a definitive transition zone with dilated proximal bowel usually does not develop this early.

Image True/False: A 7-year-old girl with a history of unremitting bloody diarrhea for 2 years has continuous, acute, and chronic inflammatory changes on her colonoscopic biopsies throughout the colon, and has responded poorly to high-dose corticosteroids and immunomodulators. She has a normal small bowel x-ray and a normal upper gastrointestinal endoscopy. A decision has been made to refer her for colectomy. It is safe to assume that she has ulcerative colitis.

False. It is difficult to make a definitive diagnosis of ulcerative colitis in this age range. Video capsule endoscopy has been approved for use in children over 3 years of age and would provide additional reassurance that she does not have small bowel involvement suggestive of Crohn’s disease prior to proceeding with colectomy.

Image True/False: An infant with chronic spitting and regurgitation has been placed on a proton pump inhibitor for suspected gastroesophageal reflux. It is necessary to continue the child on this medication for the next 6 months.

False. There is no evidence that proton pump inhibitors symptomatically improve infants with uncomplicated gastroesophageal reflux. While this is a common practice, it is probably of little benefit in this setting.

Image Dysphagia in a 10-year-old child with a normal barium-contrast upper GI series is most likely to be due to what condition?

Eosinophilic esophagitis. This disorder is becoming quite common in the pediatric age group. In children, the diagnosis may be apparent endoscopically; however, the mucosa may appear normal early in the disease, so biopsies of the distal, middle, and proximal esophagus, preferably at least four at each location, are needed for making the diagnosis. A normal upper GI series would reliably exclude most other organic causes of dysphagia including achalasia and stricture.

Image What role does food allergy play in eosinophilic esophagitis in children?

It has been demonstrated that eosinophilic esophagitis can be treated effectively with an elemental diet strongly suggesting that food allergy plays a key pathogenic role. In children, initial therapy should consist of dietary management either by excluding the most common food allergens or by using a diet directed by allergy testing excluding highly reactive foods. Both approaches have been shown to be beneficial. If symptoms remain and histology does not improve, anti-inflammatory medications such as swallowed fluticasone or budesonide may be utilized.

• • • SUGGESTED READINGS • • •

Steele R. Diagnosis and management of coeliac disease in children. Postgrad Med J. 2011 Jan;87(1023):19-25.

Ruemmele FM. Pediatric inflammatory bowel diseases: coming of age. Curr Opin Gastroenterol. 2010 Jul;26(4):332-336.

du Toit G, Meyer R, Shah N, et al. Identifying and managing cow’s milk protein allergy. Arch Dis Child Educ Pract Ed. 2010 Oct;95(5):134-144.