Duodenal atresia in association with situs inversus abdominus.

We report a rare association of duodenal atresia with situs inversus abdominus in a newborn. The infantogram revealed "reverse double-bubble sign" without dextrocardia. The sonography and echocardiography confirmed the diagnosis of situs inversus abdominus with multiple cardiac anomalies. Laparotomy and a duodenoduodenostomy were carried out.

INTRODUCTION

Situs inversus is a rare condition with a frequency of about one in 10,000 of the normal population.[12] This condition is found to be associated with cardiac and splenic malformations.[3] However, the association of duodenal atresia with situs inversus is very rare, with just about 20 cases reported in the literature so far.[45] We report this case to highlight the “reverse double-bubble” sign as a means of identifying this condition, abdominal sonography for confirmation and the importance of keeping the “mirror” anatomy in mind while carrying out the surgery.

CASE REPORT

A 1.9-kg preterm (36 weeks) male child, born by caesarean section to a 2nd gravida mother, was seen on day 2 of life. The antenatal ultrasonogram at 32 weeks of gestation had revealed findings suggestive of duodenal atresia with left ventricular hypoplasia. The child had not passed meconium and had bilious nasogastric aspirates. The examination revealed upper abdominal fullness, more prominent in the right hypochondrium. The infantogram showed double-bubble sign with gastric shadow in the right and cardiac shadow normally placed [Figure 1]. The abdominal sonography confirmed situs inversus with the liver on the left side and the spleen on the right side. An echocardiography revealed situs solitus with hypoplastic left ventricle, double-outlet right ventricle, small atrial septal defect and small ventricular septal defect.

Figure 1

Reverse double-bubble

The child underwent laparotomy on the 4th day of life. The child had type 1 duodenal atresia with situs inversus abdominus. A side-to-side duodeno-duodenostomy was performed. Postoperatively, the baby required ventilatory support for a day and parenteral nutrition for 7 days. A contrast study confirmed a patent anastomosis without any leak. The feeds were initiated and gradually increased. The parents were advised to visit a higher cardiac center for the management of congenital cardiac anomalies.

DISCUSSION

Among the known congenital anomalies associated with duodenal atresia, the more common ones are Down's syndrome, cardiac anomalies, annular pancreas and malrotation.[6] Situs inversus abdominus, also called abdominal heterotaxia or isolated levocardia, is characterized by inversion of the abdominal organs but with a normally located left-sided heart. It is quite an uncommon condition, with a frequency ranging from one in 4,000 to one in 20,000 live births.[1] It is commonly associated with serious cardiac and splenic malformations.[7]

The association of abdominal situs inversus with congenital duodenal obstruction is very rare, with only about 20 cases reported so far in the literature. The majority of them, 10 cases, had either annular pancreas or duodenal web.[4] Preduodenal portal vein, duodenal stenosis and complete atresia have also been reported singly or jointly.[4]

The embryological explanation for the occurrence of duodenal atresia is the theory of “failure to recanalise” in the 12th week of intrauterine life from the solid cord stage. This can lead to duodenal stenosis, a web with or without central aperture or a complete atresia. Genetics and embryology of situs inversus is complex.[8]

Situs inversus can be totally asymptomatic and detected incidentally at laparotomy or autopsy. However, when associated with duodenal atresia, it is detected in the newborn period. The diagnosis can be made with a plain radiograph of the chest and abdomen, which reveals “reverse double-bubble.” In a case of situs inversus abdominus, one is likely to think, as we did initially in this case, of wrong labeling of the side on the radiograph, as it is the more common occurrence. An ultrasonography of the abdomen would clinch the condition and an echocardiogram is necessary to confirm the position of the cardia and detect any associated anomalies. The treatment does not differ whether or not duodenal atresia is associated with situs inversus. Duodenoduodenostomy remains the surgery of choice.

CONCLUSION

The association of duodenal atresia with situs inversus abdominus is extremely rare. With prompt recognition of the condition, surgical incision can be planned preoperatively. The “mirror anatomy” should be kept in mind while performing the surgery. The outcome is no different from the duodenal atresia without situs inversus, as the prognosis depends on the gravity of the associated cardiac anomalies.