A Neonate With Vomiting and Decreased Bowel Sounds

A 3-day-old boy is referred to the pediatric ward for review after routine postnatal follow-up by midwifery staff with episodes of emesis and worsening feed intolerance. He was born at term, with no antenatal concerns. He passed meconium within the first 24 hours of life and was fully breastfed. He was discharged home on day 1 of life following a normal neonatal examination. He had some episodes of emesis after feeds on day 1 and 2 that have progressed to hourly vomits in addition to progressive lethargy. The episodes of emesis are nonbloody and nonbilious. He has no history of fever, infective symptoms, or signs including cough, rhinorrhea, diarrhea, rashes, or sick contacts. There are no perinatal risk factors for sepsis. He has normal urine output, and his last bowel motion was the day prior to review.Physical examination shows a jaundiced but alert baby. He has normal vital signs; oxygen saturation is 100% on room air, heart rate is 124 beats/minute, temperature is 37.1°C, and respiratory rate is 45 breaths/minute. He has normal tone and movement of all limbs. His fontanelle is normotensive, and he appears clinically euvolemic. Heart sounds are normal, and femoral pulses are present and equal bilaterally. His central capillary refill time is less than 2 seconds. Respiratory examination is normal. He has normal male genitalia and a patent anus. His spine is normal. Bowel sounds are present and there is no abdominal distension. A venous blood gas (VBG) test reveals borderline metabolic alkalosis. Complete blood count is normal, C-reactive protein is mildly elevated, and gamma-glutamyl transferase (GGT) is elevated. Serum bilirubin is elevated but below the threshold for treatment. Blood test results are presented in Table 1.A targeted ultrasound of the pylorus is performed and demonstrates normal pyloric function, and approximately 70 ml breastmilk is visualized in the patient’s stomach, 5 hours after the previous feed. Head ultrasound is normal. During a 7-hour period of observation in hospital, this child continues to have frequent nonbilious vomiting, with no association to feeding. An abdominal radiograph is performed and demonstrates a significant paucity of bowel gas (Figure 1). The child is then reexamined, and bowel sounds have diminished. This baby remains hemodynamically stable, continues to have good urine output, but has not passed stool for over 24 hours.In consultation with the pediatric surgical team, the infant is transferred to the local tertiary pediatric center for assessment. An upper gastrointestinal contrast study was done that helped lead to the actual diagnosis.Vomiting is a nonspecific symptom with a broad differential in a neonate and can be bilious or nonbilious depending on the cause. Causes of vomiting in a neonate include the following:1Infection including sepsis, urinary tract infection, pneumonia, or gastroenteritis. Infection was thought less likely given the absence of perinatal sepsis risk factors, absence of unwell contacts, normal white cell count, and absence of fever in this patient.Anatomical obstruction including volvulus, intestinal atresia, Hirschsprung, pyloric stenosis, or incarcerated hernia. Obstruction proximal to the ampulla of Vater was considered more likely given the recurrent nonbilious emesis, diminished bowel sounds, and the available results (abdominal radiograph, ultrasonography, and VBG result).Physiological reflux or gastroesophageal reflux disease. The frequency of emesis, paucity of bowel gas on abdominal radiograph, and diminished bowel sounds made this less likely.Inborn errors in metabolism including organic acidemias, urea cycle defects, galactosemia, or hereditary fructose intolerance. This was felt less likely, as this child had a normal neurological examination, a normal blood glucose level, and was no acidosis on VBG. Ammonia level should be checked if an inborn error of metabolism is suspected.Endocrine causes including adrenal insufficiency. Normal blood glucose, sodium, and potassium made this diagnosis less likely.Feed intolerance and allergy such as cow’s milk protein intolerance, although this is less common in the neonatal period, and this patient had normal eosinophil count.Raised intracranial pressure. This was felt less likely given the normal head ultrasonography and normal neurological examination.Poisoning. This was felt unlikely, as there were no concerns from the history regarding possible ingestion/poisoning.In the examples above, the emesis is usually nonbilious with the exception of an anatomical obstruction, in which case, depending on the level of obstruction, the emesis may be bilious or nonbilious. Because of the patient’s age, normal passage of meconium initially, persistent nonbilious emesis, and radiological findings on abdominal radiograph showing generalized paucity of bowel gas and ultrasonography demonstrating normal pylorus function and stasis of breastmilk in the patient’s stomach, intestinal obstruction proximal to the ampulla of Vater was considered the most likely diagnosis. The borderline hypochloremic metabolic alkalosis noted on VBG was significant, as this arises because of a loss of hydrogen and chloride ions from vomiting exclusively gastric contents. Obstruction as the most likely cause for this child’s presentation was further supported with the diminished bowel sounds. Other examination findings that can suggest intestinal obstruction are bilious vomiting, abdominal distension, abdominal pain, dehydration, and eventually signs of shock such as delayed capillary refill time, hypotension, and tachycardia.An upper gastrointestinal contrast study was performed and demonstrated complete obstruction at the level of the second part of the duodenum, highly suggestive of tight midgut volvulus secondary to malrotation (Figure 2). This patient underwent an urgent laparotomy. Intraoperatively, it was found that he had an annular pancreas surrounding the duodenum causing complete obstruction. A duodenoduodenostomy was performed. The distal bowel had normal continuity. There was normal rotation of the bowel and no volvulus. This patient also had Meckel’s diverticulum. A peripherally inserted central catheter was inserted at the time of surgery. Figure 3 illustrates the anatomy of annular pancreas.Annular pancreas (AP) is a rare congenital abnormality occurring in around 1 in 20 000 births and is associated with prematurity,2 although the true incidence of AP is difficult to ascertain because of varying severity of presentation. In AP, the second part of the duodenum is encircled by pancreatic tissue, causing stenosis or obstruction of the duodenum.3 It is thought to originate from an incomplete rotation of the ventral pancreatic bud3 and is associated with a number of other congenital issues including down syndrome, esophageal and duodenal atresia, congenital heart disease, imperforate anus. and Meckel’s diverticulum.4,5 There are case reports of familial annular pancreas,6–8 and additionally, overexpression of the ventral-specific gene transmembrane 4 superfamily member 3 in animal studies has also been associated with annular formation, both suggesting a genetic predisposition.9AP can present in the neonatal period with signs and symptoms suggestive of obstruction leading to feed intolerance, bilious or nonbilious emesis, and dehydration. In utero, there may be presence of polyhydramnios.10 The prognosis in children with AP is largely dependent on the associated congenital abnormalities11 as described above.Surgery is used to definitively diagnose and treat AP in neonates. Duodenoduodenostomy is the operation of choice in neonates to bypass the obstructing ring of pancreatic tissue and rejoin healthy duodenal tissue.3 Although rare, AP should be considered in a neonate presenting with feed intolerance and vomiting, even in the absence of other red flag symptoms or signs. Timely diagnosis and surgical intervention are key to improving prognosis.After the operation, the patient was admitted to the pediatric intensive care unit, and antimicrobial prophylaxis with intravenous cefazolin was continued for 24 hours. He progressed to extubation on postoperative day 2, and he was started on total parenteral nutrition with lipids. Enteral feeds of expressed breastmilk were restarted via nasogastric tube on post-op day 3 and advanced to goal feeding rate by postoperative day 7. At that point, the total parenteral nutrition and lipids were ceased, and the peripherally inserted central catheter line was removed. He was transitioned from nasogastric feeds to oral breastfeeds. After 24 hours of not requiring nasogastric top ups and tolerating direct breastfeeding, he was discharged home on postoperative day 9. It is unclear why GGT was elevated initially; however, GGT was down-trending during the admission and was 60 U/L when last checked (normal range is 5–50 U/L). His jaundice resolved with hydration and did not require phototherapy. Two weeks after the operation, he developed a minor surgical wound infection. Wound swab grew Staphylococcus aureus, and the infection was managed as an outpatient with oral antibiotics. There were no further surgical complications.As mentioned, AP can be an isolated finding, or it can be associated with other congenital defects. This patient was noted to have Meckel’s diverticulum but no intestinal malrotation intraoperatively. The patient did not have any features of the other anomalies associated with AP; therefore, no further investigations were undertaken.Annular pancreas is a rare congenital abnormality in which the second part of the duodenum is encircled by pancreatic tissue leading to duodenal stenosis or obstruction.Although rare, annular pancreas should be considered when a neonate presents with feed intolerance and vomiting. The vomiting may be bilious or nonbilious depending on the level of intestinal obstruction.Duodenoduodenostomy is the treatment of choice for annular pancreas.