Bilious Vomiting in a Neonate: A Diagnostic Challenge

A full-term male neonate, born via spontaneous vaginal delivery to a 27-year-old mother, presented at 24 hours of age with bilious vomiting. Newborn had not passed meconium in the first day.Twenty-seven-year-old gravida 6, para 3 womanNotable for the development of microcytic anemia in the second trimester without obvious blood loss or malabsorptionNormal noninvasive prenatal screening for chromosomal disordersApgar score was 8 and 9 at 1 and 5 minutes, respectivelyThe infant was primarily breastfed, initially latching well for 20 minutes, but demonstrated poor feeding efforts at subsequent attempts. Infant voided once, but no stool passage occurred within the first day. At 24 hours of age, the infant developed bilious emesis without preceding nonbilious episodes, prompting further evaluation for possible intestinal obstruction. An abdominal was performed as an initial evaluation for malrotation with midgut volvulus (Figure 1). Imaging showed nonspecific ascites; the whirlpool sign, which refers to the twisting of the superior mesenteric vein around the superior mesenteric artery on Doppler ultrasonography and suggests midgut volvulus, was absent. With bilious emesis and loss of bowel sounds, the neonatal intensive care unit (NICU) was consulted. A nasogastric tube was placed to decompress the bowel, and subsequent abdominal radiograph showed dilated small bowel loops (Figure 2). The newborn was transferred to the NICU for further workup and surgical consultation.Heart rate: 111 beats per minuteRespiratory rate: 43 breaths per minuteBlood pressure: 63/48Oxygen saturation: 100% on room airTemperature: 36.7 °C (98.1 °F)Birth weight 3650 g (74%), length 53.3 cm (89%), head circumference 35 cm (65%)General: term age, alert, non–ill-appearing infantHead, eyes, ears, nose, throat: normocephalic, atraumatic, mucous membranes moist, no clefts, anterior fontanelle open and flat, no caput, ears normally set and normal morphology, nares patent, red reflex present, red reflex presentNeck: supple, clavicles intact, full range of motion, and no mass palpatedRespiratory: clear to auscultation bilaterally; good air entry; and no grunting, flaring, or retractionsCardiovascular: regular rate and rhythm, no murmur, good color, pulses equal, and capillary refill less than 2 secondsAbdomen: distended abdomen and decreased bowel sounds, no hepatosplenomegaly, 3-vessel cord remnant, umbilical stump clean, dry and intactGenitourinary: normal-appearing term male genitalia, testicles bilaterally descended, anus patentNeurologic: Moro, suck, root and grasp reflexes intact; vigorous crySkin: no lesions, normal turgor, no tagsExtremities: warm, well perfused, no edema, and negative Barlow and Ortolani signsSpine: no sacral dimplePoint-of-care glucose: 63 mg/dL (3.5 mmol/L)White blood cell count: 16.2 × 109/LAbsolute neutrophil count: 11.08 × 109/LHemoglobin: 15.0 g/dL (150 g/L)Hematocrit: 44.4%MCV: 96.3 fLPlatelets: 445 × 109/LAnnular pancreasHirschprung diseaseIntestinal malrotationMeconium illeusMeconium plug syndromeSmall bowel atresiaSmall left colon syndromeHirschsprung diseaseIn the absence of radiological evidence of malrotation with volvulus on ultrasonography, the team proceeded to obtain a barium enema (Figure 3). Enema and additional radiographs were suggestive of Hirschsprung disease. Definitive surgical intervention was delayed because of the need for initial bowel decompression with twice-daily rectal irrigations before the suction rectal biopsy was performed. The patient remained on gastric decompression with Replogle tube to suction. Rectal irrigations were initially performed by the pediatric surgery team before transitioning to nursing. Once adequately decompressed, suction rectal biopsy at 8 days of age confirmed the diagnosis of Hirschsprung disease. Ganglion cells were present in the proximal segment of the colon (Figure 4) but absent distally, confirming the diagnosis (Figure 5). The neonate underwent a laparoscopic-assisted pull-through procedure at 12 days of age. The operative course was uneventful, and the patient was discharged home in stable condition at 21 days of age.Neonatal bowel obstruction encompasses a spectrum of pathologies. Imaging findings vary depending on the location of the obstruction, from proximal to distal bowel.1 Delayed or missed diagnosis of neonatal bowel obstruction can result in significant morbidity or mortality; therefore, timely imaging and informed decision-making are crucial.2 In neonates, classic bowel obstruction patterns may not be observed because of the time required for gas to traverse the intestinal tract, and diagnostic studies, such as a barium enema, may be necessary.3While timely and appropriate imaging is essential for the early diagnosis and intervention for neonatal bowel obstruction, the potential risks of radiation exposure must be carefully considered. According to the American College of Radiology appropriateness criteria for vomiting in infants, abdominal radiography is appropriate as an initial imaging modality for vomiting within the first 2 days after birth, particularly in the presence of poor feeding.4 Imaging studies should be carefully considered, weighing the risks and benefits to minimize radiation exposure. In the context of bilious emesis, while the initial step involves abdominal radiography, the subsequent imaging modality choice is guided by the clinical picture and the findings of the initial radiograph. If malrotation is suspected, an upper gastrointestinal series is critical, as it better defines small bowel anatomy compared with ultrasonography. In this case, given the patient’s age and urgency of symptoms present, ultrasonography was performed. Sensitivity and specificity of ultrasonography for diagnosing malrotation, with or without volvulus, are 94% and 100%, respectively, suggesting excellent diagnostic accuracy.5 The absence of a whirlpool sign on abdominal ultrasonography diminished the suspicion for midgut volvulus.6 In addition, volvulus was lower on the differential based on only a small amount of ascites present on ultrasonography.The initial plain film radiograph revealed diffuse bowel dilatation and, initially, was interpreted as consistent with a distal small bowel atresia. Small bowel atresia, considered early in the differential diagnosis, may be associated with vascular compromise of the mesenteric vessels or other conditions presenting in the newborn period, such as gastroschisis, meconium ileus, and cystic fibrosis.7 There was no antenatal history of polyhydramnios, which may occur because of the fetus affected by small bowel atresia not swallowing and absorbing amniotic fluid in a typical manner. The abdominal radiograph helped exclude annular pancreas, which causes duodenal obstruction and may manifest as double bubble sign, similar to duodenal atresia. Subsequent abdominal radiographs demonstrated large bowel dilatation, which is more commonly seen in Hirschprung disease, neonatal small left colon syndrome, and meconium plug syndrome. Neonatal small left colon syndrome and meconium plug syndrome were excluded based on the transition zone on the contrast enema and the absence of ganglion cells in the colon on the rectal biopsy. Ganglion cells are present in the colon in both neonatal small left colon syndrome and meconium plug syndrome.The mother’s laboratory findings at 24 weeks of gestation were indicative of iron deficiency anemia. While iron deficiency anemia is common during pregnancy, severe or prolonged anemia can have adverse effects on fetal development.8 Several potential mechanisms could link maternal iron deficiency to an increased risk of neonatal bowel disorders, although this association remains speculative. Iron is crucial for cell proliferation and differentiation, including the development of the enteric nervous system.8 The enteric nervous system, derived from neural crest cells, controls gut motility and function. The etiology of Hirschprung disease remains an area of investigation with multiple genes and pathways involved.9Neonatal bowel obstruction requires a broad differential diagnosis, including Hirschsprung disease. A contrast enema is a crucial diagnostic tool in suspected Hirschsprung disease, given the characteristic transition zone.3 Rectal biopsy remains the gold standard for confirming the diagnosis of Hirschsprung disease.10American Board of Pediatrics Neonatal-Perinatal Content SpecificationUnderstand intestinal obstruction in newborn infants.Know maternal medical disorders and medications affecting the fetus and newborn infant.