The role of sonography for depiction of a whirlpool sign unrelated to midgut malrotation in neonates

Background: The sonographic whirlpool sign of volvulus due to midgut malrotation is well recognized. However, variations of the whirlpool sign may be seen in other conditions, but this observation has received little attention in the literature.

Objective: This study presents a series of neonates with a variety of causes of congenital intestinal obstruction, all associated with a whirlpool sign (unrelated to midgut volvulus), which was correctly recognized preoperatively on sonography. We also emphasize the pivotal role of sonography in managing congenital obstruction of the intestinal tract in neonates.

Materials and methods: This is a retrospective analysis of clinical, imaging and surgical findings in 11 neonates with congenital intestinal obstruction associated with a whirlpool sign (unrelated to midgut volvulus) that was recognized preoperatively on sonography and in whom the cause for the whirlpool was documented at surgery.

Results: Eleven neonates (eight male, three female) had clinical and radiographic evidence of intestinal obstruction in whom sonography depicted a whirlpool sign, which was recognized on the initial sonogram in nine and on a repeat sonogram in two. The whirlpool was located in the upper abdomen in only two, mid-abdomen in five and right lower quadrant in four. The whirlpool was only 1-2 cm in diameter. An upper gastrointestinal series in three neonates failed to depict the cause of obstruction. Contrast enema in three cases had findings suggesting the site of obstruction was in the ileum but none depicted the exact cause of the obstruction. At surgery, the whirlpool sign correlated with a segmental volvulus of the small intestine in eight neonates and with the coiled distal small intestine associated with apple-peel atresia in the other three.

Conclusion: This study illustrates neonates in whom a whirlpool sign (unrelated to midgut volvulus) was correctly recognized on sonography before surgery. Sonography proved more useful than an upper gastrointestinal series or contrast enema in depicting the exact cause of the obstruction. Pediatric radiologists must make the effort to search throughout the entire abdomen and pelvis for a small whirlpool sign on sonography, even in the absence of midgut malrotation, in neonates with congenital intestinal obstruction. Its recognition preoperatively will facilitate a rapid diagnosis and will obviate the necessity for contrast examinations of the gastrointestinal tract, which require ionizing radiation.