Obstetric anal sphincter injuries (OASIS): using transperineal ultrasound (TPUS) for detecting, visualizing and monitoring the healing process.

PURPOSE: The aim of this study was to examine whether OASIS, and its extent, can be confirmed or excluded using transperineal ultrasound (TPUS). A further objective of this study was to monitor the healing process over a period of 6 months and to establish a connection between the sonographic appearance of obstetric anal sphincter injury (OASIS) and anal incontinence. MATERIALS AND METHODS: In this retrospective clinical study, women with OASIS who gave birth between March 2014 and August 2019 were enrolled. All the patients underwent TPUS 3 days and 6 months after delivery. A GE E8 Voluson ultrasound system with a 3.5-5 MHz ultrasound probe was used. The ultrasound images showed a third-degree injury, with the measurement of the width of the tear and its extent (superficial, partial, complete, EAS and IAS involvement). A positive contraction effect, a sign of sufficient contraction, was documented. Six months after delivery, a sonographic assessment of the healing (healed, scar or still fully present) was performed. A Wexner score was obtained from each patient. The patients' medical histories, including age, parity, episiotomy and child's weight, were added. RESULTS: Thirty-one of the 55 recruited patients were included in the statistical evaluation. Three patients were excluded from the statistical evaluation because OASIS was excluded on TPUS 3 days after delivery. One patient underwent revision surgery for anal incontinence and an inadequately repaired anal sphincter injury, as shown sonographic assessment, 9 days after delivery. Twenty patients were excluded for other reasons. The results suggest that a tear that appears smaller (in mm) after 3 days implies better healing after 6 months. This effect was statistically significant, with a significance level of alpha = 5% (p = 0.0328). Regarding anal incontinence, women who received an episiotomy had fewer anal incontinence symptoms after 6 months. The effect of episiotomy was statistically significant, with a significance level of alpha = 5% (p = 0.0367). CONCLUSION: TPUS is an accessible, non-invasive method for detecting, quantifying, following-up and monitoring OASIS in patients with third-degree perineal tears. The width, as obtained by sonography, is important with regard to the healing of OASIS. A mediolateral episiotomy seems to prevent anal incontinence after 6 months.

Perianal ultrasound (PAUS): visualization of sphincter muscles and comparison with digital-rectal examination (DRE) in females.

BACKGROUND: The aim of this study was to determine the reproducibility and tolerance of perianal ultrasound (PAUS) and detect differences in sphincter muscles between various measuring positions and different maneuvers. PAUS was compared to digital-rectal examination (DRE) to see if sphincter contraction is visible and gradable in ultrasound volumes. METHODS: Fifty women underwent a medical history, DRU and PAUS by two uro-gynecologists in a prospective trial. PAUS volumes were measured via different parameters in different maneuvers. Examiners' DRE impressions of sphincter tone were scaled with the DRESS-score. All patients completed a questionnaire. RESULTS: Thirty-five patients with complete PAUS and DRE were included in the study. Fifteen patients were excluded due to poor ultrasound volume quality or sphincter defects. Comparison of sphincter muscle thickness at different positions in PAUS showed significant differences between 6 and 12 o'clock positions (12 > 6 o'clock) and diameters (horizontal > vertical). No difference was found between the examiners. In comparison of rest and contraction only the vertical diameter changed. There was a negative but not significant correlation between PAUS measurements and DRESS-scores. Twenty-six patients completed the questionnaire that revealed women preferred PAUS over DRE. CONCLUSION: PAUS is a reproducible and good tool to visualize the anal canal. It is comfortable for patients and easily handled by examiners. Sphincter muscle contraction is iso-volumetric. Vertical diameter changes during contraction leading the anal canal change its shape to oval due to external influence. PAUS is the ideal additional tool to visualize relevant structures that are palpable on DRE.