Situs Inversus Totalis with Type I Duodenal Atresia and Preduodenal Portal Vein in a Preterm Neonate: A Case Report

Background: Situs inversus totalis is a rare congenital laterality disorder characterised by mirror-image transposition of the thoracic and abdominal viscera. It may coexist with congenital cardiac, gastrointestinal and vascular anomalies, including duodenal atresia and preduodenal portal veinboth independently recognised causes of neonatal duodenal obstruction. Simultaneous occurrence of all three anomalies is exceptionally rare and poses distinct diagnostic and operative challenges.
Case Presentation: A male neonate born at 35 weeks’ gestation, weighing 2.1 kg, presented on day 3 of life with bilious vomiting, feeding intolerance and failure to pass meconium. Examination revealed a scaphoid abdomen and a right-sided cardiac apex. Chest and abdominal radiography demonstrated dextrocardia and a right-sided gastric bubble; abdominal ultrasonography subsequently confirmed mirror-image visceral arrangement, consistent with situs inversus totalis. Echocardiography identified a secundum atrial septal defect and a small patent ductus arteriosus. Following resuscitation and preoperative optimisation, the infant underwent exploratory laparotomy through a left upper transverse incision, which confirmed complete situs inversus totalis and revealed a dilated proximal duodenum obstructed by an intraluminal mucosal web (Type I duodenal atresia). A preduodenal portal vein was also identified, crossing anterior to the first part of the duodenum immediately adjacent to the site of intrinsic obstruction.
Intervention and Outcome: The duodenal web was excised through a longitudinal duodenotomy. Because the preduodenal portal vein lay close to the obstructed segment, a diamond-shaped duodenoduodenostomy (Kimura technique) was performed to achieve a wide, tension-free bypass while preserving the anomalous vein. The postoperative course was uneventful; enteral feeding commenced on postoperative day 6 and was advanced without complication. The infant was discharged on postoperative day 10 in good clinical condition.
Conclusion: In neonates with situs abnormalities and congenital duodenal obstruction, surgeons should anticipate coexisting vascular anomalies. Careful intraoperative identification of a preduodenal portal vein is essential to avoid vascular injury and diamond-shaped duodenoduodenostomy can safely address combined intrinsic and extrinsic obstruction while preserving the anomalous vessel.

Keywords: Situs Inversus, Intestinal Atresia, Duodenal Obstruction, Portal Vein, Infant, Newborn, Infant, Premature.