Background: Early assessment and accurate diagnosis of the level of anorectal malformations (ARM) are essential.
Transperineal ultrasonography may be an excellent imaging modality for reviewing the distal end of the rectal pouch.
Objective: To assess sensitivity, specificity and the usefulness of transperineal ultrasonography in determination of ARM level
Materials and Method: Prospective study of all inborn ARM patients and those referred to Siriraj Hospital within the first day of life between 1 May 2011 and 30 April 2015 was conducted. Rectal pouch to perineum distance (P-P distance) was recorded and compared between transperineal ultrasonography and prone lateral cross-table film and correlated to operative findings.
Results: In our series 70 patients were recorded, 49 males and 21 females. Twenty-two patients were included; 14 patients
were low type ARM and 8 patients were non-low type ARM. The sensitivity, specificity and the accuracy of transperineal
ultrasonography in the determination of ARM level was 100%, 92.8% and 95.4% respectively (95% confidence interval was
77.1 to 99.8%).
Conclusion: Transperineal ultrasonography is a good modality for earlier diagnosis and accurate evaluation of ARM, no radiation exposure and simple technique, which can be done by pediatric surgeons.

Keywords: Anorectal malformations, Imperforate anus, Transperineal ultrasonography