Embryology USMLE Step 1 Practice Question
A 4-year-old boy presents to the emergency department with a 3-day history of fever (38.5°C), abdominal pain, and purulent drainage from his umbilicus. His parents report he was born with a small umbilical opening that never fully closed. On examination, you note a fistulous tract at the umbilicus with surrounding erythema and edema. Abdominal imaging reveals a small bowel diverticulum 18 inches from the ileocecal valve containing both gastric and pancreatic heterotopic tissue. Laboratory studies show WBC 15,200/μL. Which of the following best describes a violation of the embryologic 'rule of 2s' in this patient's Meckel diverticulum?
Answer choices
- APresent in 2% of the population but this patient has two different types of heterotopic tissueCorrect answer
- BLocated 2 feet from the ileocecal valve but contains two types of heterotopic mucosa
- CApproximately 2 inches in length but located at the umbilicus rather than along the ileum
- DLocated 2 feet from the ileocecal valve and measuring 2 inches in diameter
- EPresent in 2% of males but symptomatic complications occur in only 2% of cases
- FTwo times more common in males and presents in childhood rather than adulthood
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