Antenatal diagnosis of duodenal atresia: USG and MRI findings

A 33-year-old primiparous female patient with 8 months of amenorrhoea presented to the obstetric department. Obstetric examination and routine investigations were done, all were normal. The patient was sent for ultrasonography.

Ultrasonography showed distended stomach bubble and proximal duodenum giving Double Bubble appearance. Communication between stomach bubble and duodenum was noted. Amniotic fluid index (AFI) was increased to suggest polyhydramnios [Figs. 1, 2, 3]. Magnetic Resonance Imaging (MRI) T2-weighted image showed distended stomach and duodenal bulb giving double bubble sign. Also showed increased amniotic fluid suggestive of polyhydramnios [Figs. 4, 5]. Diagnosis of duodenal obstruction was made which was confirmed postnatally and baby was operated for this.

Duodenal atresia is one of the most common causes of foetal bowel obstruction with prevalence of up to one in 10 000 births [1]. Duodenal atresia is due to failure of recanalisation of epithelial solid cord or excessive endodermal proliferation [2]. In complete duodenal atresia, duodenum ends blindly and has no connection with distal bowel, thus distal bowel loops are collapsed and has no aeration. Usual site of atretic segment is just distal to ampulla of Vater, which clinically presents with bilious vomiting. In cases where atresia is proximal to ampulla, patient will have non-bilious vomiting [3]. Patient presents in early life with symptoms of duodenal obstruction such as abdominal distension, vomiting and absent bowel movements [3]. Can even be detected antenatally in second or third trimester. On both ultrasonography and Magnetic Resonance Imaging (MRI) typical double bubble appearance is seen due to distention of stomach and duodenal bulb. Rest of small bowel loops appears collapsed. Ultrasonography findings are sufficient to make diagnosis; however, MRI helps to exclude multiple intestinal atresias which has different postnatal prognosis and management [4]. T2-weighted images are important in making the diagnosis which shows double bubble sign due to hyperintense fluid in stomach and duodenal bulb to the level of obstruction. T1-weighted images help in excluding presence of additional atretic segments by demonstrating meconium in distal small bowel loops and colon [5]. Duodenal atresia is associated with polyhydramnios and other anomalies such as VACTERL, other intestinal atresias and rarely annular pancreas [5]. One-third of foetuses with duodenal atresia may have down syndrome (trisomy 21) [6]. Surgical treatment includes duodeno-duodenostomy and duodeno-jejunostomy and has excellent prognosis in isolated cases. Take home message: As duodenal atresia is associated with other congenital anomalies which alters the outcome, imagining is helpful in confirming the diagnosis and excluding other anomalies. Written informed patient consent for publication has been obtained.