Review Question - QID 109350

A 1-day-old boy is evaluated in the hospital nursery for bilious vomiting. The patient has urinated multiple times since birth but has not yet passed meconium. He was born at 38 weeks gestation to a 36-year-old gravida 3 via vaginal delivery. The pregnancy was complicated by gestational diabetes. The patient’s mother received routine prenatal care and declined 1st-trimester screening. She subsequently underwent a quadruple screen at 15 weeks of gestation that demonstrated decreased maternal serum alpha-fetoprotein (AFP), increased beta-hCG, decreased unconjugated estriol, and increased inhibin A. Her last ultrasound prior to the onset of labor demonstrated an amniotic fluid index (AFI) of 28 cm. The patient’s 2 older siblings are both healthy. His temperature is 97.8°F (36.6°C), blood pressure is 58/37 mmHg, pulse is 166/min, and respirations are 38/min. On physical exam, the patient is in moderate distress. His abdomen is firm and distended with hypoactive bowel sounds. Which of the following is the most likely etiology of this patient's presentation?