Intestinal Malrotation in Infants: Whirlpool Sign and SMA/SMV Assessment on Ultrasound
Clinical Context
Assessment of the spatial relationship between the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) is performed to exclude midgut malrotation. This assessment becomes particularly significant when ultrasound examination is negative for hypertrophic pyloric stenosis (HPS).
Scanning Technique and Imaging Plane
According to Textbook of Diagnostic Sonography (Hagen-Ansert, 2023), the examination is performed in the transverse plane of the abdomen at the level of the pancreas. In this position, the normal relationship of the SMA/SMV is documented, which allows exclusion of anomalies associated with midgut malrotation.
Ultrasound Findings
Normal vessel relationship excludes malrotation anomalies. Findings suggestive of midgut malrotation include:
| Finding | Interpretation |
|---|---|
| Inability to demonstrate normal spatial relationship of SMA and SMV | Positive finding suggestive of malrotation |
| Whirlpool sign of the vessels | Positive finding suggestive of malrotation |
[clarification needed] Specific criteria for direction of vessel rotation and Doppler parameters of the whirlpool sign are not described in the provided sections.
Frequently asked questions
In which imaging plane should SMA and SMV be assessed in infants?
In the transverse plane of the abdomen at the level of the pancreas, where the normal relationship of the SMA/SMV is documented (Hagen-Ansert, 2023).
What ultrasound finding indicates malrotation?
Inability to visualize normal spatial orientation of the SMA and SMV or the 'whirlpool sign' of these vessels (Hagen-Ansert, 2023).
When is assessment of SMA/SMV orientation particularly important?
Particularly when ultrasound findings are negative for hypertrophic pyloric stenosis (HPS) (Hagen-Ansert, 2023).
Does normal vessel relationship exclude malrotation?
Visualization of normal spatial relationship of the SMA/SMV in the transverse plane at the level of the pancreas allows exclusion of midgut malrotation anomalies (Hagen-Ansert, 2023).