GI

Question 1

A 12-year-old boy presents with:

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

What is the most likely diagnosis?

Answer 1

Acute appendicitis
Explanation
This is the classic cascade of events for acute appendicitis. The only thing missing is at the end, where the pain becomes localized to the right lower quadrant (RLQ) of the abdomen—localization to the RLQ is less likely to occur in children. The diagnosis can be confirmed with ultrasound (preferred) or abdominal CT. Treatment is preoperative broad spectrum antibiotics and then emergent surgical removal.

Question 2

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

Answer 2

Anal fissures
Explanation
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. Treat with stool softeners, warm sitz baths, and generous lubrication to the anal skin.

Question 3

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

Answer 3

An infant
Explanation
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 of age, the risk is 25–50%; for older adolescents and adults, it is only 5%.

Question 4

You suspect that a newborn has Hirschsprung disease.

What is the best diagnostic test?

Answer 4

Suction rectal biopsy
Explanation
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. Correction is with surgical resection of the aganglionic segment, and a ″pull-through″ of the bowel above the defect to create an intact colon.

Question 5

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

Answer 5

Anti-HAV IgM
Explanation
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 6

A 1-month-old presents with:

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

What is the most likely diagnosis?

Answer 6

Answer
Malrotation of the intestines
Explanation
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. The upper GI series will also demonstrate jejunum to the right of the midline, and failure of contrast to pass the midline at the ligament of Trietz. If not treated, this can lead to volvulus, small bowel obstruction, and bowel necrosis. Treatment is with the Ladd procedure

Question 7

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

Answer 7

Answer
Reassurance
Explanation
Most infants with normal growth and persistent vomiting have infant regurgitation. Remember that 50% 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 regurgitation in children with formula protein allergy. Acid suppression can have side effects and should be avoided if possible.

Question 8

A newborn presents with the following findings:

A defect in the abdominal wall located 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 8

Omphalocele
Explanation
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. Also, 50–75% of neonates with an omphalocele have an associated congenital anomaly, which is not the case with gastroschisis.

Question 9

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

What is the most likely diagnosis?

Answer 9

Answer
Crigler-Najjar syndrome Type I—severe (CN I)
Explanation
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 have different mutations causing different enzyme levels. CN I, the most severe of the 3 disorders, is due to a complete absence of bilirubin uridine diphosphate glucuronosyltransferase (UDP-GT) activity. Therapy is phototherapy and/or exchange transfusions. Eventually, the child in the scenario may require liver transplantation

Question 10

Wilson disease is a metabolism disorder of what mineral?

Answer 10

Answer
Copper
Explanation
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 11

A 2-year-old child is exposed to hepatitis A at day care and must receive prophylaxis. The child has not received any hepatitis A vaccine.

What is the best prophylaxis therapy for this child?

Answer 11

Answer
Hepatitis A vaccine
Explanation
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 unimmunized or underimmunized (have not completed the HepA vaccine series) 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 12

A newborn presents with an abdominal wall defect that is 3 cm in size and located to the right of the umbilicus. There are exposed loops of small and large intestines without a peritoneal covering.

What is the most likely diagnosis?

Answer 12

Gastroschisis
Explanation
Gastroschisis is more common than omphalocele and commonly is associated with a midgut volvulus. Remember that with gastroschisis the intestines are not contained in the peritoneal sac as they are in omphalocele, so bowel damage and the need for surgical resection is common. Surgical placement of the bowel back in the abdomen is essential.

Question 13

Hamartomatous polyps
Hemihypertrophy
Gigantism of the extremities
Angiomas
Pigmented nevi
What syndrome presents with these findings?

Answer 13

Answer
Proteus syndrome
Explanation
Proteus syndrome is an extremely rare disorder 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 on an exam if they describe a patient with hemihypertrophy and hamartomata

Question 14

A 6-month-old presents with rectal prolapse.

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

Answer 14

Cystic fibrosis (CF)
Explanation
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.

Question 15

Children with Type 1 diabetes mellitus (DM) should be screened for what gastrointestinal disease?

Answer 15

Celiac disease
Explanation
Celiac disease is 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 other disorders of DQ2/DQ8 haplotypes, such as autoimmune thyroiditis and Sjögren syndrome. Also, children with trisomy 21 have a 5- to 16-fold increased risk for celiac disease. Screening is accomplished by obtaining a tissue transglutaminase (tTG)-IgA antibody test and total IgA level. If results are positive, confirm with an upper endoscopy and small bowel biopsy. Treatment is avoidance of gluten from wheat products and similar proteins found in rye and barley.

Question 16

A 2-year-old girl presents to the emergency department with several hours of painless, brisk rectal bleeding. Her hemoglobin is falling, and she has needed an infusion of packed red blood cells. She has no other past medical history.
What is the most likely diagnosis

Answer 16

Meckel diverticulum
Explanation
Most Meckel diverticula are asymptomatic, and occur in 1% of the population. In children, the most common presentation is small bowel obstruction (e.g., intussusception), or brisk, painless rectal bleeding. Some diverticula contain ectopic gastric mucosa. Diagnosis is with a Meckel scan (if gastric mucosa is present) or laparoscopy. Treatment is surgical resection of the diverticulum

Question 17

Skin
Mucous membranes
Breast
Thyroid with hyperkeratotic papillomas of the lips and tongue
What syndrome has multiple hamartomas of these areas?

Answer 17

Cowden syndrome
Explanation
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, are diagnosed as PTEN hamartoma tumor syndrome when the PTEN mutation is identified. For Cowden syndrome, the hyperkeratotic papillomas of the lips and tongue are characteristic

Question 18

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

Answer 18

Answer
Hepatitis C virus (HCV)
Explanation
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. This is likely to change as newer antiviral treatments are highly effective at curing HCV.

Question 19

A history of cyclic vomiting syndrome (CVS) is associated with what disorder?

Answer 19

Migraine headaches
Explanation
When CVS occurs in a child, ask about a family history of migraines; there is a strong association between the two. Both disorders are thought to relate to dysfunction in the vasovagal axis. Many children with CVS also have migraines and vice versa. Postural orthostatic tachycardia syndrome has a similar pattern.

Question 20

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

What do you suspect?

Answer 20

Hirschsprung disease
Explanation
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

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 21

Pill-induced esophagitis
Explanation
Pill-induced esophagitis is fairly common in adolescents who swallow their pills “dry.” Think of this in a teenager with chest pain who is on doxycycline for acne. 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. History is usually diagnostic and symptoms resolve in 1–3 weeks. Generally, no specific therapy is necessary, other than advising the patient to take their pills with water.

Question 22

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

Answer 22

Helicobacter pylori
Explanation
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. Diagnose with biopsy, rapid urease test, urea breath test, or stool antigen test. Treatment is with a combination of antibiotics (typically a macrolide and amoxicillin) and a proton pump inhibitor

Question 23

What is the most common malignant liver tumor in children?

Answer 23

Answer
Hepatoblastoma
Explanation
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. There is an increased risk of hepatoblastomas in patients with Beckwith-Wiedemann syndrome. With complete resection and postoperative chemotherapy, survival rates approach 50%.

Question 24

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

What is the most likely diagnosis?

Answer 24

Autoimmune hepatitis (AIH) Type I
Explanation
AIH Type I is the classic form. It affects girls more than boys and most often 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, and > 1:80 in adults). Family history of other autoimmune diseases may be present as well. Definitive diagnosis is with a liver biopsy, and treatment is usually steroids and/or immunomodulators

Question 25

A child with mumps presents with: Abdominal pain that is midepigastric and steady Nausea and vomiting Tender abdominal examination Serum lipase of 700 U/L What is the most likely diagnosis?

Answer 25

Acute pancreatitis Explanation 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 26

What is the most reliable noninvasive test for lactase deficiency?

Answer 26

Breath hydrogen test Explanation 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 invasive and requires upper endoscopy to obtain a sample.

Question 27

What is the most common anatomical esophageal abnormality?

Answer 27

Answer Esophageal atresia (EA) with distal tracheoesophageal fistula (TEF) Explanation 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 a nasogastric tube into the stomach; the blind pouch of the esophagus prevents its passage. EA with distal TEF occurs in 87% of all EAs. Treatment is surgical repair.

Question 28

A 4-year-old swallows drain cleaner product and presents with: Drooling Dysphagia Abdominal discomfort When should he undergo upper endoscopy?

Answer 28

12–24 hours after ingestion Explanation 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 29

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 29

Imperforate anus without fistula Explanation 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 trisomy 21 (a.k.a. Down syndrome) have a much higher incidence of imperforate anus than other children. Surgery is needed to correct the defect.

Question 30

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 30

Oral rehydration therapy Explanation 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. Additionally, during an acute infectious diarrheal illness, the AAP recommends continuing a regular diet so that enterocytes can be quickly regenerated and normal digestion can resume

Question 31

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

Answer 31

Answer Cholelithiasis (gallstones) Explanation Cholelithiasis is more common in patients with hemolytic anemia, because the excessive turnover of bilirubin released from blood cells results in pigment gallstones. The most common complications of gallstones are pancreatitis, caused by an obstructing stone in the common bile duct, and cholecystitis from an obstruction of the cystic duct.

Question 32

Which vitamin is absorbed in the ileum?

Answer 32

Vitamin B12 Explanation Short bowel 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 (e.g., for necrotizing enterocolitis or Crohn disease). 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. The ileum is secondarily responsible for fat soluble vitamin absorption (A, D, E, and K), since it reabsorbs bile salts to be used again to absorb fats.

Question 33

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 33

Answer Alagille syndrome Explanation 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 34

A 4-month-old presents with: Severe, unremitting pruritus Diarrhea Conjugated hyperbilirubinemia Normal GGT What is the most likely diagnosis?

Answer 34

Answer Progressive familial intrahepatic cholestasis Type 1 (PFIC1) Explanation PFIC refers to a group of inherited disorders in which bile is not formed properly. PFIC1 (formerly Byler disease, caused by a mutation in the FIC1 gene on chromosome 18) 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 35

A breastfed 2-month-old only passes soft stool once every 5–10 days. What workup should you initiate?

Answer 35

Answer None, reassure Explanation 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 symptoms, and this pattern often continues into adulthood

Question 36

Which hepatitis virus has a DNA genome?

Answer 36

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

Question 37

A newborn with clinical features of trisomy 21 presents with a history of polyhydramnios and dilated stomach seen on prenatal ultrasound. On delivery, the child had an abdominal x-ray, and it shows a “double bubble” in the abdomen. What is the most likely diagnosis?

Answer 37

Duodenal atresia Explanation 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. Treatment is surgical

Question 38

A 6-week-old White boy presents with: Progressively worsening, nonbilious projectile vomiting An abdominal mass palpable above the umbilicus Hypochloremic alkalosis Hypokalemia What is the most likely diagnosis?

Answer 38

Pyloric stenosis Explanation Pyloric stenosis occurs more commonly in boys (4:1 to 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! Diagnose using a pyloric ultrasound which shows thickening and elongation of the pyloric channel. Treatment is a pyloromyotomy, and is curative

Question 39

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 39

Air contrast enema Explanation This disorder is ileocolic 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 6 and 36 months of age, with most occurring before 2 years of age. If not treated, this can quickly result in small bowel obstruction, necrosis, and perforation/sepsis. If the air contrast enema is ineffective, surgical reduction/bowel resection is necessary.

Question 40

Pigmented penile lesions Hamartomatous intestinal polyps with rectal bleeding and abdominal pain Café au lait spots Lipomas What syndrome has these findings?

Answer 40

Bannayan-Riley-Ruvalcaba syndrome (BRRS) Explanation 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. The key things to remember are the pigmented penile lesions and hamartomatous intestinal polyps.

Question 41

Colon and rectum only Continuous pattern of lesions Mucosal lesions only No perianal lesions or fistulas 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 41

Answer Ulcerative colitis (UC) Explanation 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 42

Bowel involvement can be anywhere from mouth to anus. The lesions often skip and are not continuous. Lesions are often transmural. Granulomas may be seen in biopsy. Weight loss is much more common. Perianal lesions can occur. Aphthous ulcers are more common. Fistulas can occur. Which inflammatory bowel disease is associated with these findings?

Answer 42

Crohn disease Explanation Crohn disease commonly presents with abdominal pain, weight loss, and, if the colon is involved, bloody diarrhea. Weight loss and growth failure are much more common with Crohn disease than with ulcerative colitis. The terminal ileum most commonly is 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.