Preoperative Trans-Perineal Sonographic Findings in Children with Imperforate Anus for Detection of Anal Sphincter Muscle Complex and the Anal Canal Pathway: A Pilot Study

The exact anus reconstruction is critical in patients with imperforated anus. It is related to the correct diagnosis of sphincter complex.
The aim of this study was accurate investigation of the perineal region for ultrasound detection of the location and pathway of sphincter muscle complex.
Patients and This descriptive cross-sectional study was performed at Mashhad University of Medical Sciences in 2016. Transperineal sonography was done in ten patients (6 - 12 week age, 8 males and 2 females) with imperforate anus.
The shortest distance between the rectal pouch and skin was 8 to 20 mm, but the distance between the rectal pouch and skin via the anal sphincter path was longer (11 to 23 mm). The multi-layer view of anal pit was seen in all patients except one. It had a curved and occasionally parasagittal path and it is more eccentric than the muscle complex. Thickness of the anal muscle sphincter complex could be seen in all patients with 2 - 3.6 mm, occasionally asymmetric.
The multi-layer view of anal pit and the anal sphincter complex are the two important sonographic findings that can better differentiate the level of anal malformation and act as an indicator for the location of pull through procedure.