Review Question - QID 109171

A 2-day-old boy has an episode of vomiting in the hospital nursery. The vomitus was described as “bright green” without any traces of blood. The patient has urinated several times since he was born but has not passed any stool. He was born at 37 weeks of gestation to a 38-year-old G3P3 woman. The pregnancy was uncomplicated and the patient’s mother refused all prenatal testing. The patient’s 2 older siblings are both healthy. His temperature is 98.6°F (37°C), blood pressure is 67/43 mmHg, pulse is 135/min, and respirations are 34/min. On physical exam, the patient has upslanting palpebral fissures, epicanthal folds, and a single transverse palmar crease. His abdomen is non-tender, firm, and distended. Bowel sounds are hypoactive. Digital rectal exam evacuates a small amount of stool and flatulence. A nasogastric tube is placed to decompress the stomach. The patient’s abdominal radiograph can be seen in Figure A. Which of the following is the most likely diagnosis?