A one-year-old boy presents with his father to the emergency department with bloody diarrhea, bilious vomiting, and irritability. The father states the symptoms developed yesterday and have persisted today. Past medical history is unremarkable. Vital signs are temperature 37.2°C (99°F), blood pressure 90/70 mm Hg, heart rate 165 beats/min, and respirations 22/minute. Physical examination reveals increased bowel sounds, a palpable mass in the abdomen, and tenderness to palpation in the lower right quadrant of the abdomen.
C) Failure of involution of the vitelline duct
Based on this patient's age and clinical presentation, the most likely etiology for this patient's symptoms is intussusception due to Meckel diverticulum, which is caused by persistence of the vitelline duct. Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract and is the most frequent cause of intussusception. Signs of intussusception include "currant jelly" stools, bilious vomiting, and increased bowel sounds. The rule of 2's is important to remember about Meckel diverticulum: 2 times as likely in males, 2 inches long, 2 feet from the ileocecal valve, 2% of the population, and most commonly presents within the first 2 years of life.
Answer choice A: Congenital failure of the duodenum to canalize, is incorrect. This refers to duodenal atresia. Although these patients will sometimes present with bilious vomiting, symptoms will typically present within the first 1 or 2 days of life.
Answer choice B: Enlargement of the pyloric smooth muscle, is incorrect. This refers to infantile hypertrophic pyloric stenosis. Although these patients will sometimes present with a palpable abdominal mass, symptoms will typically present within the first 3 to 5 weeks of life and usually include bilious vomiting.
Answer choice D: Failure of neural crest cells to descend into the myenteric and submucosal plexus, is incorrect. This refers to intussusception due to Peyer patch hypertrophy, which is most commonly associated with a recent viral infection. Although this could surely lead to this patient's symptoms, there is nothing in the question stem that suggests a possible viral infection.
Answer choice E: Obstruction of the appendix secondary to lymphoid hyperplasia, is incorrect. This refers to Hirschsprung disease, which is characterized by lack of nervous plexuses in the distal segment of the colon. Although these patients could present with bilious emesis, symptoms will typically present within the first 1-2 days of life, and no palpable mass is usually present although the abdomen may be distended due to chronic constipation.
Key Learning Point
Meckel diverticulum, which is caused by persistence of the vitelline duct, presents with currant jelly stools, bilious vomiting, and increased bowel sounds.
