Radiological Case of the Month FREE

A 1-MONTH-OLD MALE was brought to the emergency department with a 3-day history of vomiting. The parents stated that the infant had been feeding on a 1:1 ratio of water mixed with formula (Similac with iron; Abbott Laboratories, Abbott Park, Ill) (2.9 J/mL [20 cal/oz]), 120 mL every 4 hours, and he had been gaining weight appropriately. Three days prior to the visit, the child began to regurgitate more frequently than he had in the past. His emesis was nonbilious, nonbloody, and composed mainly of formula. His mother stated that the emesis had become more forceful and frequent during the previous 2 days. He also developed frequent, watery stools that were nonbloody in appearance. The pediatrician had recommended an oral electrolyte maintenance solution (Pedialyte; Abbott Laboratories) in small amounts for 24 hours in response to the symptoms; however, the child continued to have persistent and occasionally projectile vomiting. There were no contacts with ill people and no history of fever, nasal congestion, difficulty breathing, cyanosis, or pain. He was taking no medications or other formulas. His birth history was unremarkable, with a birth weight of 3.3 kg.

The initial examination revealed an awake, active, 1-month-old infant in no apparent distress. Vital signs were a rectal temperature of 37.5°C (99.4°F); heart rate, 150 beats/min; respiratory rate, 36/min; blood pressure, 97/62 mm Hg; and weight, 3.8 kg (500 g more than the birth weight). His anterior fontanelle was flat, open, and not depressed. His mucous membranes were pink and slightly dry, with several adherent white plaques on the buccal and gingival mucosa. The lungs were clear to auscultation. The results of cardiac examination revealed a sinus tachycardia with no murmurs, gallops, or rubs. His abdomen was slightly distended yet soft. No abdominal masses were palpated, and normal, active bowel sounds were heard. Capillary refill was less than 2 seconds, and palpated peripheral pulses were strong. The testes were palpated bilaterally in the scrotum. In a rectal examination, normal tone was appreciated and the stool specimen tested negative for blood. The results of a neurologic examination were normal.

Laboratory studies disclosed the following values: hemoglobin, 119 g/L; hematocrit, 0.33; white blood cell count, 1.4×10⁹/L, with neutrophils, 0.29; lymphocytes, 0.37; and monocytes, 0.26; platelet count, 4.2×10⁹/L; serum sodium, 136 mmol/L; potassium, 5.6 mmol/L; chloride, 99 mmol/L; bicarbonate, 29 mmol/L; serum urea nitrogen, 2.9 mmol/L (8 mg/dL); and creatinine, 30.5 µmol/L (0.4 mg/dL). A radiograph of the abdomen was obtained (Figure 1) followed by an upper gastrointestinal series, which was performed to rule out pyloric stenosis (Figure 2 and Figure 3).