Purpose or Case Report: The Median Arcuate Ligament Syndrome (MALS) is a diagnosis of exclusion. It is a condition characterized by abdominal pain due to compression of celiac artery by the median arcuate ligament.
1. The purpose of this study is to review a single institutional experience in screening and diagnosing MALS in the pediatric population with emphasis on the diagnostic accuracy of ultrasound (US) Doppler against additional imaging and follow up.
2. We also describe our technical approach of performing Doppler US in suspected MALS and various diagnostic criteria.
Methods & Materials: We retrospectively reviewed all patients referred for Doppler ultrasound examination of the celiac artery for suspected MALS between February 2013 and August 2015. Sonographic images, reports, subsequent imaging, surgeries and plans for follow up were recorded. The ultrasound studies were classified as positive or negative based on whether the diagnosis of MALS was made or not. Subsequent imaging and clinical follow up are described and diagnostic accuracy of ultrasound is calculated. Detailed step-by-step sonographic approach and Doppler US protocol are discussed.
Results: 74 patients (61 F:13 M; 6 years-20 years, mean 14.9 years) were selected all of whom presented with chronic abdominal pain and symptoms of POTS.
US evidence of MALS was found in 27 patients (36.5%); 16 of these 27 patients (74%) underwent further imaging with CT (n=10) or MRI (n=6); and 11 patients had no further imaging. 14/16 patients had confirmatory CT(n=9) or MR (n=5). 2/16 were false positives where the US showed features of MALS but the CT/MR showed a normal celiac trunk. 4/11 who received no further imaging went directly to surgery (where MALS was confirmed), 3/11 were lost to follow up and the remaining 4/11 are currently either on conservative management or awaiting surgery.
47 (63.5%) patients had no evidence of MALS on US. 5 of these patients got additional imaging (CT n=4, MR n=1) due to severity of symptoms. 42 patients were managed conservatively. The specificity of US was 96%, sensitivity was 100%. There were no false negative cases. Our practice considered all US negative cases as true negative, hence accuracy was 90.5%.
Conclusions: Doppler US is a highly accurate screening and diagnostic tool for suspected MALS in children. Cross-sectional imaging confirmation is frequently performed but may not be necessary when the diagnosis is obvious on US exam. Following a standard Doppler US protocol is key to obtaining high sensitivity and specificity.