LETTERS

TO THE

Anticlockwise Swirl: A Potential Pitfall for Malrotation

T

o the Editor: We read with interest the article by Esposito et al (1). An upper gastrointestinal contrast study using a water-soluble contrast agent is the standard modality for diagnosing malrotation and volvulus (2). We would like to highlight the fact that swirl sign can also be caused by counterclockwise rotation of the superior mesenteric vein around the superior mesenteric artery in asymptomatic patients. This anticlockwise swirl was first described in 2005 (3). We, at our institute, retrospectively evaluated abdominal computed tomography (CT) scans of 200 pediatric patients to determine the frequency and degree of counterclockwise rotation of SMV around SMA on CT in normal otherwise asymptomatic pediatric patients undergoing CT scan (4). We found anticlockwise swirl in 72 (36%) of the total 200 otherwise asymptomatic patients (4). They were further classified into 3 groups based on the degree of counterclockwise rotation of SMV around SMA (group A: >908 to