Transperineal ultrasound to assess anal positioning in female neonates

Anterior anal displacement is a condition that is difficult to define: is it merely an anatomical variation within the range of normality or is it a genuine malformation? In order to improve early diagnosis of anterior displacement of the anus, this study assessed the feasibility of transperineal ultrasound (US) in routine practice for use as first-line management.

Sagittal perineal US was performed on 187 female infants aged between 3 and 9 weeks. The ultrasound was performed randomly, either by a senior or a junior radiologist. The imaging by the senior radiologists defined the sagittal plane quality criteria. Scores to define image quality were established and then validated. The percentage of satisfactory images was then compared according to the planes and the seniority (junior vs. senior) of the radiologists. The junior radiologists were evaluated from the beginning to determine the learning curve for optimal image acquisition.

The quality scores for the perineal ultrasounds revealed excellent intra-and inter-operator performances: 84.4% of the sagittal plane images were satisfactory. After the 20th examination, the success rate for the sagittal plane was independent of the seniority of the radiologist.

This preliminary study demonstrates that transperineal sagittal plane US is easy to learn and readily yields reproducible results. The possibility of using this technique provides a solid basis for further studies to evaluate its relevance in regard to clinical data and MRI results, with the aim of providing a reliable early diagnostic tool for routine practice.