Index of Suspicion in the Nursery

Abstract

A 21-day-old male infant presents to a pediatrician's office because he has passed no stools for 14 days. He also has a history of progressive loss of appetite, excessive fussiness, and vomiting, with about three episodes occurring yesterday. The child is admitted to the hospital for further evaluation and management of failure to thrive, constipation, and dehydration. The infant had been born at 39 weeks’ gestation to a 39-year-old mother who had late prenatal care and gave birth via spontaneous vaginal delivery. Apgar scores were 9 and 9 at 1 and 5 minutes, respectively. The birthweight was 3,280 g (25th percentile), length was 52 cm (75th percentile), and head circumference was 35 cm (50th percentile). The infant experienced progressively greater emesis during the first 48 hours after birth. It resolved after changing to a lactose-free formula. Meconium was passed at 4 hours after birth. The infant's admission weight is 3.16 kg (<3rd percentile), length is 54 cm (50th percentile), and head circumference is 37.5 cm (50th percentile). His temperature is 96.4°F (35.8°C), pulse is 145 beats/min, respiratory rate is 20 breaths/min, and blood pressure is 82/40 mm Hg. He is small for age and appears emaciated and mildly dehydrated. His head is normocephalic, with a flat anterior fontanelle. Cardiovascular and respiratory examination findings are within normal limits. The abdomen is slightly protuberant but soft and without hepatosplenomegaly. He has normal male genitalia with bilateral palpable testes, his spine is normal to palpation, and his extremities exhibit full range of motion. He is fairly easy to arouse from sleep with painful stimulation and has a fair cry, but he immediately falls back to sleep. Pupils are equal and react to light; fundi are benign, with sharp disks and normal-appearing vessels. Facial movement is symmetric. Tongue is in the midline. Overall tone …