Gastroenterology

Question 1

A 16-year-old boy presents with:

• Painful swallowing
• Chest discomfort
• History of nodular acne on oral doxycycline

What is the most likely diagnosis?

Answer 1

Pill-Induced Esophagitis

Pill-induced esophagitis is fairly common in adolescents who swallow their pills “dry.” The most common location for the pill to be stuck is the midesophagus. Symptoms usually begin soon after ingestion, and patients have retrosternal pain and dysphagia. Usually history is diagnostic and it resolves in 1–3 weeks. Generally, no specific therapy is necessary, other than advising the kid to take his pills with water. Think of this in a teenager with chest pain who is on doxycycline for acne.

Question 2

A newborn presents with an abdominal wall defect that is 3 cm in size and to the right of the umbilicus. There are exposed loops of small and large intestines.

What is the most likely diagnosis?

Answer 2

Gastroschisis

Gastroschisis is more common than omphalocele and is commonly associated with a midgut volvulus. Remember that with gastroschisis the intestines are not contained in the peritoneal sac as they are in omphalocele.

Question 3

You receive a phone call from a parent of a 5-year-old saying that her son has had diarrhea most of the day. She brings him into the office for evaluation, and you note that he is mildly dehydrated and does not have any other issues or diseases.

What is the best therapy?

Answer 3

Oral Rehydration Therapy

Oral rehydration is the best treatment for acute diarrhea. Commercial electrolyte formulations for children are available. Do not recommend “clear” liquids like juices, soft drinks, or sports drinks because they are hypertonic and have excess glucose or fructose, which prolongs the diarrheal state.

Question 4

A history of cyclic vomiting is associated with what other disorder?

Answer 4

Migraine Headaches

When cyclic vomiting occurs in a child – usually a girl between the age of 6 and 7 years – you should ask about a family history of migraines, because there appears to be a strong association between the two.

Question 5

Which hepatitis virus is composed of DNA?

Answer 5

Hepatitis B

Hepatitis B is the only hepatitis virus composed of DNA. The remainder are RNA viruses.

Question 6

A 3-day-old presents with severe, indirect hyperbilirubinemia. There is no conjugated bilirubin on lab testing.

What is the most likely diagnosis?

Answer 6

Crigler-Najjar Syndrome Type I—Severe (CN I)

There are 3 disorders of bilirubin conjugation that result in varying levels of unconjugated hyperbilirubinemia. These disorders are actually all the same disease (not enough glucuronosyltransferase), but with different mutations causing different enzyme levels. CN I, the most severe of the 3, is due to a complete absence of bilirubin uridine diphosphate glucuronosyltransferase (UDP-GT) activity. Therapy is phototherapy and/or exchange transfusions. Eventually the child may require liver transplantation.

Question 7

A 15-year-old girl presents with malaise, weight loss, and anorexia. She has occasional jaundice. She has anti-smooth muscle antibodies (ASMA).

What is the most likely diagnosis?

Answer 7

Autoimmune Hepatitis (AIH) Type I

AIH Type I is the “classic” form. It affects girls more than boys and presents between 10 and 20 years of age. ANA is almost always seen, and the more specific ASMA is seen in up to 80% of cases (positive titers for both are > 1:20 in children, > 1:80 in adults). Family history of other autoimmune diseases may be present as well. The key finding is the presence of ASMA!

Question 8

• Bowel involvement can be anywhere from mouth to anus.
• The lesions skip and are not continuous.
• Lesions are transmural.
• Granulomas may be seen in biopsy.
• Weight loss is much more common.
• Perianal lesions are common.
• Aphthous ulcers are more common.

Which inflammatory bowel disease is associated with these findings?

Answer 8

Crohn Disease

Crohn disease is mainly seen in adolescent children. It commonly presents with abdominal pain and bloody diarrhea. Weight loss and growth failure are much more common with Crohn’s than with ulcerative colitis. The terminal ileum is most commonly involved, with 70% of pediatric patients also having some colonic involvement (generally the cecum and/or ascending colon). Although granulomas are considered diagnostic of Crohn disease, they are only seen ~ 40% of the time.

Question 9

A 6-month-old presents with rectal prolapse.

Besides constipation and diarrhea, what is the next most likely cause of rectal prolapse?

Answer 9

Cystic Fibrosis (CF)

CF as a cause of rectal prolapse is commonly tested—so know it. Also remember that infectious diarrhea caused by Shigella can result in rectal prolapse. Whipworm can cause rectal prolapse as well.

Question 10

A child presents with:

• Peripheral pulmonary artery stenosis
• Tetralogy of Fallot
• “Butterfly” vertebrae
• Prominent forehead
• Moderate hypertelorism
• A small, pointed chin
• Saddle nose

What is the likely diagnosis?

Answer 10

Alagille Syndrome

Alagille syndrome (a.k.a. arteriohepatic dysplasia, Watson-Miller syndrome, or syndromic duct paucity) is an autosomal dominant disorder with variable penetrance that is caused by mutations in JAG1 on chromosome 20p. Alagille syndrome is associated with peripheral pulmonary artery stenosis, occasionally tetralogy of Fallot, and neonatal cholestasis. Classically, patients present with chronic cholestatic liver disease with a paucity of small intrahepatic ducts, “butterfly” vertebrae, abnormal radius/ulna, posterior embryotoxon of the eye (a prominent white ring of Schwalbe and iris strands that partially obscure the chamber angle), and characteristic facies (prominent forehead; moderate hypertelorism; a small, pointed chin; and a saddle or straight nose).

Question 11

A newborn with stigmata of trisomy 21 presents with history of polyhydramnios and dilated stomach seen in prenatal ultrasound. On delivery the child has an x-ray, and it shows a “double bubble” in the abdomen.

What is the most likely diagnosis?

Answer 11

Duodenal Atresia

Duodenal atresia accounts for over 50% of the intestinal atresias. It is commonly associated with cardiac, GU, anorectal, and esophageal problems. 40% of patients with duodenal atresia have trisomy 21. The double bubble sign is diagnostic.

Question 12

A newborn presents with the following findings:

• A defect in the abdominal wall at the umbilicus
• The defect contains both hollow and solid visceral organs.
• The defect is 6 cm and is covered by peritoneal membrane internally and amniotic membrane externally. (The defect with the abdominal contents is contained in a sac.)

What is the most likely diagnosis?

Answer 12

Omphalocele

Omphalocele can be differentiated from umbilical hernias because umbilical hernias are < 4 cm and contain only intestine. The contents are inside the peritoneal sac, which differentiates omphalocele from gastroschisis, where the organs are outside the peritoneum and are exposed to amniotic fluid.

Question 13

A 4-month-old presents with:

• Severe, unremitting pruritus
• Diarrhea
• Conjugated hyperbilirubinemia
• Normal GGT

What is the most likely diagnosis?

Answer 13

Progressive Familial Intrahepatic Cholestasis Type 1 (PFIC1)

PFIC refers to a group of inherited disorders in which bile is not formed properly. PFIC1 (formerly known as Byler disease) and PFIC2 are characterized by normal serum GGT but with severe cholestasis. PFIC3 has elevated serum GGT levels. PFIC1 usually presents between 3 and 6 months of age with conjugated hyperbilirubinemia and severe, unremitting pruritus, but remember: GGT is normal!

Question 14

• Hamartomatous polyps
• Hemihypertrophy
• Gigantism of the extremities
• Angiomas
• Pigmented nevi

What syndrome presents with these findings?

Answer 14

Proteus Syndrome

Proteus syndrome is an extremely rare disorder (< 100 cases have been reported in the medical literature) that results from a mutation in the AKT1 gene, which is responsible for regulating cell growth and division. The defect is not inherited but instead occurs randomly in one cell during fetal development. As the cells continue to divide, some will be affected and some will not (i.e., mosaicism). Remember this one on an exam if they describe a patient with hemihypertrophy and hamartomata.

Question 15

What is the usual treatment for gastroesophageal reflux in a 5-month-old with normal growth parameters?

Answer 15

Reassurance

Remember that 1/2 of infants 0–3 months of age vomit at least once daily, and 2/3 of those 4–6 months of age do, too! Try reassurance first; if this is not successful or the parents are adamant, you can try a 2-week trial of low-allergy formula due to the common occurrence of reflux in children with formula protein allergy. Acid suppression can have side effects and should be avoided if possible.

Question 16

A 6-week-old Caucasian boy presents with:

• Progressively worsening, nonbilious projectile vomiting
• An abdominal mass is palpable above the umbilicus.
• Hypochloremic alkalosis is present.
• Hypokalemia is present.

What is the most likely diagnosis?

Answer 16

Pyloric Stenosis

Pyloric stenosis occurs more commonly in boys (6:1) between 3 weeks and 2 months of age. Know that dehydration, hypochloremic alkalosis, and hypokalemia are commonly present and must be corrected before surgery!

Question 17

What is the laboratory test used to diagnose acute hepatitis A?

Answer 17

Anti-HAV IgM

Anti-HAV IgM are IgM antibodies directed against the hepatitis A virus. High titers of these antibodies in serum indicate an acute hepatitis A infection.

Question 18

What is the most common malignant liver tumor in children?

Answer 18

Hepatoblastoma

Tumors of the hepatobiliary system are rare in children, comprising about 1–4% of all solid tumors, and benign tumors are seen much more frequently than malignant ones. Hepatoblastoma is the most common malignant liver tumor in children. It presents in infancy as a single mass. With complete resection and postoperative chemotherapy, survival rates approach 50%.

Question 19

Children with Type 1 diabetes mellitus (DM) or selective IgA deficiency should be screened for what GI disease?

Answer 19

Celiac Disease

Celiac disease is becoming recognized as an extremely common disorder. Studies using serology-based screening have determined the incidence to be 0.5–2% in the general population of the developed world. Celiac disease is especially common in patients with Type 1 DM and in those with selective IgA deficiency. Also, children with Down syndrome have a 5- to 16-fold increased risk for celiac disease.

Question 20

A term infant has not passed meconium within 48 hours of birth.

What do you suspect?

Answer 20

Hirschsprung Disease

Hirschsprung disease is the most common cause of lower intestinal obstruction in neonates. It is due to the absence of enteric ganglionic neurons (aganglionosis), beginning at the anus and then extending proximally for a varying distance. 90% of normal, full-term infants pass meconium within 24 hours, and 99% within 48 hours. In children with Hirschsprung disease, 94% fail to pass meconium within the first 24 hours. Therefore, evaluate for Hirschsprung disease in any term infant who does not pass meconium within 48 hours of birth.

Question 21

What is the most reliable noninvasive test for lactase deficiency?

Answer 21

Breath Hydrogen Test

When carbohydrate is malabsorbed, bacteria in the colon produce hydrogen gas. This is then absorbed across the colon mucosa into the bloodstream, transported to the lungs, and expired. In the breath hydrogen test, breath is tested sequentially after the patient is given a test carbohydrate substance. If expired hydrogen rises > 10–20 ppm, then carbohydrate is not being absorbed properly. The best test for lactase deficiency is a direct assay from a mucosal biopsy, but this is rarely done today because of the invasiveness and expense.

Question 22

• Colon and rectum only
• Continuous pattern of lesions
• Mucosal lesions only
• No perianal lesions
• Rare or no aphthous mouth ulcers
• Migratory arthritis that is asymmetric, typically of the hip or knee
• Ankylosing spondylitis, erythema nodosum, and pyoderma gangrenosum can occur.

Which inflammatory bowel disease is associated with these findings?

Answer 22

Ulcerative Colitis (UC)

UC presents with abdominal pain and bloody diarrhea. The mean age of diagnosis is 12 years. One way UC differs from Crohn disease is that the inflammation in UC is restricted to the colon and does not involve the small intestine (UC = unanimously colon) .

Question 23

A breastfed 2-month-old only passes a stool once every 5-10 days.

What workup should you initiate?

Answer 23

None, Reassure

Some breastfed infants pass stool once every 5–10 days; in the absence of other signs or symptoms, they do not need evaluation or treatment. Some older children pass stool only every 3–4 days; they do not have any other symptom, and this pattern often continues into adulthood.

Question 24

A 12-year-old boy presents with:

• Fatigue and anorexia initially
• Indigestion and periumbilical discomfort follows
• Fever to 102.0° F (38.9° C) develops quickly with nausea and vomiting
• Complains of abdominal pain when you accidentally bump the examination table

What is the most likely diagnosis?

Answer 24

Acute Appendicitis

This is the classic cascade of events for acute appendicitis. The only thing missing was at the end, where the pain becomes localized to the right lower quadrant of the abdomen. This is obviously a surgical emergency.

Question 25

You receive a phone call from a parent of a 5-year-old that her son has had diarrhea most of the day. She brings him into the office for evaluation and you note that he is mildly dehydrated and does not have any other issues or diseases. What is the best therapy?

Answer 25

Oral Rehydration Ora rehydration is the best for treatment of acute diarrhea. Commercial formulations are available and include Infalyte, Pedialyte, and Rehydralyte as well as generic products. Do not recommend “clear” liquids like juices, soft drinks, or Gatorade because they are hypertonic and have excess glucose, which will prolong the diarrheal state.

Question 26

What is the most common identifiable cause of chronic gastritis in children?

Answer 26

Helicobacter pylori

An acute infection of H. pylori can result in nausea, vomiting, decreased appetite, and epigastric abdominal pain, with a short period of increased acid secretion followed by a marked decrease in acid production. The acute symptoms last only about 1 week. A large majority with chronic H. pylori do not have symptoms.

Question 27

A newborn presents with the rectum completely closed off and not communicating with the anus or skin. The rectum is about 2 cm above the perineal skin.

What is the most likely diagnosis?

Answer 27

Imperforate Anus Without Fistula

Imperforate anus without fistula occurs as described here, with the rectum completely closed off and having no communication with the anus or skin. Children with Down syndrome have a much higher incidence of imperforate anus than other children.

Question 28

A 2-year-old child is exposed to hepatitis A at day care and must be prophylaxed. He has not received any hepatitis A vaccine.

What is the best prophylaxis therapy for this child?

Answer 28

Hepatitis A Vaccine

Hepatitis A vaccine is the preferred prophylaxis for those ≥ 12 months of age and immunoglobulin is preferred for those < 12 months of age.

Groups who should receive prophylaxis:

• All household contacts
• Sexual or needle-sharing partners
• Day care and nursing home attendees and staff in close contact with a case

School, hospital, or workplace day-to-day contact does not warrant prophylaxis.

Question 29

Children with sickle cell disease are prone to developing what complication associated with their gallbladder?

Answer 29

Cholelithiasis (Gallstones)

Cholelithiasis is also common in children on chronic TPN and in pregnant adolescent females. The most common complication of gallstones is pancreatitis due to an obstructing stone in the common bile duct.

Question 30

Who is more likely to develop chronic hepatitis B if they are infected with hepatitis B virus: an infant, a 5-year-old, or a 17-year-old?

Answer 30

An Infant

This is important to know and is the reason we screen for hepatitis B so diligently in pregnancy and at delivery. Infants born to mothers with hepatitis B have a 90% risk of having chronic hepatitis B! For children 1–5 years, the risk is 25–50%; for older adolescents and adults, it is only 5%.

Question 31

A 4-year-old swallows drain cleaner product and presents with:

• Drooling
• Dysphagia
• Abdominal discomfort

When should he undergo upper endoscopy?

Answer 31

12-24 Hours After the Ingestion

Upper endoscopy is recommended 12–24 hours after a caustic ingestion because doing the endoscopy before 12 hours may not show the full extent of injury. After 24 hours, the risk of perforation increases if there is extensive injury.

Question 32

What is the most common infectious cause of chronic liver disease in the U.S.?

Answer 32

Hepatitis C Virus (HCV)

In fact, HCV is the most common bloodborne disease overall in the U.S. The prevalence of HCV infection in children is 0.1–0.2%, compared to 1.8% in adults.

Question 33

A child with mumps presents with:

• Abdominal pain that is midepigastric and steady
• Nausea and vomiting
• Tender abdominal examination
• Mildly elevated serum lipase

What is the most likely diagnosis?

Answer 33

Acute Pancreatitis

Acute pancreatitis is more common in children than previously recognized. Common etiologies include:

• Blunt abdominal trauma (child abuse)
• Mumps and other viruses
• Multisystem disease
• Biliary obstruction by gallstones and idiopathic microlithiasis
• In older adolescents, alcohol

The diagnosis is typically made by an elevated lipase (> 4× normal) and an imaging study (ultrasound or CT).

Question 34

What is the most common cause of rectal bleeding in children of all ages?

Answer 34

Anal Fissures

Anal fissures are generally located on the posterior or anterior anal verge. Frequently, they are due to passage of large stools in a constipated infant or child.

Question 35

A 4-year-old boy presents with the following:

• History of swallowing a quarter
• Some choking
• Retrosternal pain
• Plain films suggest the quarter is in the midesophagus.
• He is in no respiratory distress and can swallow his own secretions.

What is the best management?

Answer 35

Observe for up to 24 Hours

Coins in the esophagus can be observed for up to 24 hours after ingestion if the child is asymptomatic. In 20–30% of these cases, the coin will pass into the stomach during the observation period. If the patient is symptomatic or if the coin remains in the esophagus after 24 hours, removal with fiberoptic endoscopy is required. Coins can be observed if in the stomach or beyond.

Question 36

A 1-month-old presents with:

• Acute bilious emesis
• Abdominal distension
• Irritability
• Upper GI series shows “bird’s beak” of the 2^nd portion of the duodenum

What is the most likely diagnosis?

Answer 36

Malrotation of the Intestines

Malrotation of the intestines occurs in about 1/6,000 births. Nonrotation is the most common malrotation abnormality and presents with the cecum to the left and the small intestine to the right of the superior mesenteric artery. The “bird’s beak” is where the gut is twisted.

Question 37

• Macrocephaly
• Pigmented penile lesions
• Hamartomatous intestinal polyps with rectal bleeding and abdominal pain
• Café-au-lait spots
• Lipomas

What syndrome has these findings?

Answer 37

Bannayan-Riley-Ruvalcaba Syndrome (BRRS)

BRRS is a rare syndrome that most commonly (65%) results from mutations on the tumor suppressor gene PTEN. In cases of BRRS where the PTEN mutation is identified, the diagnosis becomes PTEN hamartoma tumor syndrome (PHTS). The key things to remember are the pigmented penile lesions and hamartomatous intestinal polyps.

Question 38

• Skin
• Mucous membranes
• Breast
• Thyroid with hyperkeratotic papillomas of the lips and tongue

What syndrome has multiple hamartomas of these areas?

Answer 38

Cowden Syndrome

Cowden syndrome is very rare. It is most commonly (85%) caused by a mutation on the PTEN tumor suppressor gene on chromosome locus 10q22–23. Cases of Cowden syndrome, along with Bannayan-Riley-Ruvalcaba syndrome (BRRS), are diagnosed as PTEN harmartoma tumor syndrome (PHTS) when the PTEN mutation is identified. For Cowden syndrome, the hyperkeratotic papillomas of the lips and tongue are characteristic.

Question 39

Which vitamin is absorbed in the ileum?

Answer 39

Vitamin B12

Short gut syndrome is a malabsorption disorder caused by shortened intestinal length due to congenital anomalies of the gut or due to resection of the small intestine. The ileum is responsible for absorption of vitamin B₁₂. If the short gut defect is in the ileum, the result is B₁₂ deficiency, which causes macrocytic anemia.

Question 40

A 7-month-old presents with:

• Abdominal pain
• Vomiting
• Bloody stools with development of “currant jelly” stool
• Palpable mass in the mid-upper abdomen

What is the diagnostic procedure of choice?

Answer 40

Air-Contrast Enema

This disorder is intussusception, and air-contrast enema is the diagnostic and therapeutic procedure of choice. Nearly 90% of cases are reduced with this procedure. Peak incidence is between 4 and 10 months of age, with most occurring between 2 months and 5 years of age.

Question 41

Wilson disease is a metabolism disorder of what mineral?

Answer 41

Copper

Wilson disease is an autosomal recessive disorder of copper metabolism that results in excessive accumulation of copper in the eyes, liver, kidneys, and brain. Kayser-Fleischer rings in the cornea are a classic presentation.

Question 42

You suspect that a newborn has Hirschsprung disease.

What is the best diagnostic test?

Answer 42

Suction Rectal Biopsy

Rectal biopsy is the gold standard procedure for diagnosis. The most commonly used tool is the suction rectal biopsy, a simple instrument that can be used on infants in the outpatient clinic. Diagnosis is based on the absence of any ganglion cells detected in a biopsy containing adequate submucosa.

Question 43

Painless rectal bleeding in children < 2 years of age is most commonly caused by what condition?

Answer 43

Meckel Diverticulum

While Meckel diverticula can cause serious lower GI bleeding in children, most are asymptomatic. The most common presenting symptom is painless rectal bleeding. Know the rule of 2s:

• 2% of the population
• Located within 2 feet of the ileocecal valve
• Measures 2 inches in length
• Measures 2 cm in diameter
• 2:1 male-female ratio
• Usually symptomatic before 2 years of age (if and when symptoms are actually present)

Question 44

What is the most common form of anatomical esophageal abnormality?

Answer 44

Esophageal Atresia with Distal Tracheoesophageal Fistula

The infant presents in the delivery room with excessive oral secretions and appears to be choking frequently, especially when trying to feed. Diagnose by trying to place an nasogastric tube into the stomach; the blind pouch of the esophagus prevents its passage.