Index of Suspicion in the Nursery

Abstract

A 2,160-g term female is born to a 24-year-old G2P0010 mother. Pregnancy complications include iron-deficiency anemia; intrauterine growth restriction diagnosed by using a prenatal ultrasound during the third trimester; positive serologic result for maternal herpes simplex, with no active lesions present at delivery; and vaginal culture positive for group B Streptococcus . All other serologic test results were unremarkable. Before delivery, the mother received valacyclovir and multiple doses of penicillin. The infant was born at a community hospital via induced vaginal delivery due to intrauterine growth restriction status, without prolonged rupture of membranes. Apgar scores are 9 and 9 at 1 and 5 minutes, respectively. Physical examination at birth demonstrates the infant is small for gestational age but is otherwise within normal limits. Weight at birth is 2,160 g and length is 43.2 centimeters, both below the third percentile for gestational age and gender, and head circumference is 33.5 centimeters (15th percentile). On day 2, just before discharge, the infant is noted to be hypothermic (93°F) and hypoglycemic. She is transferred to the NICU of the community hospital and undergoes a partial sepsis evaluation, including blood, urine, and surface viral cultures. Presumptive treatment for clinical sepsis is initiated with ampicillin, gentamicin, and acyclovir. Subsequently, the infant is noted to have evidence of respiratory distress and requires continuous positive airway pressure support. An arterial blood gas sample is obtained, with the following results: pH, 7.1; Pco2, 9 mm Hg; bicarbonate, 7 mmol/L; and base excess, –25 mmol/L. She receives a 2-mEq/kg sodium bicarbonate bolus, and a repeat arterial blood gas sample shows a pH of 7.3, Pco2 of 15 mm Hg, and base excess of –20 mmol/L. Lactate levels are within normal limits, but ammonia levels are elevated to >400 μmol/L, and 3 hours later they increase …