Small bowel atresias

Case contributed by Dr Fabien Ho

Presentation

Incidental finding on routine thirst trimester US screening. No specific family history.

Patient Data

Age: Fetus to 34WG-born neonate
Gender: Female

Dr F. Cuillier, Dr M.Balu and Dr F.Frade also significantly contributed to this case.

Ultrasound

30WG US

Full stomach, dilation of duodenal and proximal jejunum right after stomach on dynamic examination. No ascites, no obvious volvulus.
Normal amniotic fluid. 
Otherwise normal findings. (not shown)

Ultrasound

33WG

Small bowel dilation worsens. 
Amniotic fluid remains normal. No ascitis. 

MRI

33WG MRI

Stomach is full.
Dilated small bowel with hyperT2w hypoT1w content, hence liquid-like which reveals proximal small bowel obstruction. Besides, on this examination, following the stomach to duodenum to proximal jejunum is relatively easy.
The expected microcolon in a digestive tract obstruction situation is not seen at all on T1w sequences. 

No ascitis, no obvious segmental volvulus, no obvious malrotation.

Photo

Surgical findings

Dilated bowel, upstream of a proximal jejunal atresia.
However, multiple (7) downstream atresias of the proximal jejunum and distal jejunum and ileum have been found.
Normal meso with healthy vascularization.

Case Discussion

Bowel obstruction usually occurs after 20WG.
The gestational age at onset onset of dilatation is actually not reliable enough to predict the level of obstruction between proximal or distal small bowel.
However, large bowel obtructions indeed tend to reveal themselves at later stages (although the dilation diameter alone in large bowel is far from being predictive of a pathologic condition alone).

The common underlying causes of small bowel prenatal obstruction are :
-single or multiple atresia(s), which may be associated with segmental volvulus.
-meconial ileus, in a fetus with Cystic Fibrosis
-complicated bowel duplication
-complicated bowel malrotation
-apple-peel syndrome (small bowel fed by archaid mesenteric arteries, rotating around a small meso in an "apple-peel" fashion)

The accuracy of US (2B and Doppler) alone is far from being conclusive on the underlying cause. Fetal abdominal MRI accuracy is still being investigated on several practical points : level of obstacle, prediction of multiple atresias, length of the remaining intact bowel, associated volvulus, associated malrotation, meconial ileus pattern. On the other hand, fetal abdominal MRI normal landmarks have been very well established according to gestational age.

We report a case of proximal small bowel obstacle with liquid-like/non meconium-like content signal and non visible colon. Upon neonatal surgery, the surgeon indeed found one proximal jejunal atresia, followed by seven small bowel atresias. Fortunately, the length of the remaining bowel was long enough (>1meter) not to induce short bowel syndrome. 

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Case information

rID: 59150
Published: 23rd Mar 2018
Last edited: 17th Apr 2018
Inclusion in quiz mode: Included
Institution: CHU de la Reunion

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