Is endoanal, introital or transperineal ultrasound diagnosis of sphincter defects more strongly associated with anal incontinence?

Abstract

Introduction and hypothesis Our aim was to explore the association between anal incontinence (AI) and persistent anal sphincter defects diagnosed with 3D endoanal (EAUS), introital (IUS) and transperineal ultrasound (TPUS) in women after obstetric anal sphincter injury (OASI) and study the association between sphincter defects and anal pressure. Methods We carried out a cross-sectional study of 250 women with OASI recruited during the period 2013-2015. They were examined 6-12 weeks postpartum or in a subsequent pregnancy with 3D EAUS, IUS and TPUS and measurement of anal pressure. Prevalence of urgency/solid/liquid AI or flatal AI and anal pressure were compared in women with a defect and those with an intact sphincter (diagnosed off-line) using Chi-squared and Mann-Whitney U test. Results At a mean of 23.6 (SD 30.1) months after OASI, more women with defect than those with intact sphincters on EAUS had AI; urgency/solid/liquid AI vs external defect: 36% vs 13% and flatal AI vs internal defect: 27% vs 13%, p < 0.05. On TPUS, more women with defect sphincters had flatal AI: 32% vs 13%, p = 0.03. No difference was found on IUS. Difference between defect and intact sphincters on EAUS, IUS and TPUS respectively was found for mean [SD] maximum anal resting pressure (48 [13] vs 55 [14] mmHg; 48 [12] vs 56 [13] mmHg; 50 [13] vs 54 [14] mmHg) and squeeze incremental pressure (33 [17] vs 49 [28] mmHg; 37 [23] vs 50 [28] mmHg; 36 [18] vs 50 [30] mmHg; p < 0.01). Conclusions Endoanal ultrasound had the strongest association with AI symptoms 2 years after OASI. Sphincter defects detected using all ultrasound methods were associated with lower anal pressure.

Reply

“…We have shown previously using EAUS that, in the immediate postnatal period and in a subsequent pregnancy, anal incontinence symptoms and anal manometry (which correlate with anal sphincter function) are significantly worse in women with an anal sphincter defect > 30 • in comparison to those with smaller defects 6 . Moreover, we found that, in comparison to TPUS, EAUS has the strongest association with anal incontinence symptoms up to 2 years following OASI 7 . The take-home message of our study 1 is that the defect angle measurement obtained on EAUS is not equivalent to that of TPUS for the same reason acknowledged by Dietz and Shek, namely, that EAUS distends the anal canal.…”

An International Continence Society (ICS)/ International Urogynecological Association (IUGA) joint report on the terminology for the assessment and management of obstetric pelvic floor disorders

“…Its most common clinical indication is the assessment of sphincter integrity following obstetric trauma. It is the reference standard for imaging of the anal sphincters and diagnosis of sphincter defects and correlates with symptoms and histological diagnosis [ 53 ]. Translabial/transperineal approach overcomes the limitations of endovaginal and transrectal techniques providing minimal pressure on local structures and it is least likely to alter surrounding anatomy.…”

Follow up of women after Obstetric Anal Sphincter Injuries (OASI)- what is the role of anorectal studies? An observational study.

“…Three dimensional images of the sphincter complex were studied across three levels of 'high', 'mid' and 'low' as per the Liverpool Ultrasound Pictorial chart (LUPIC) [15]. Defects in the muscles of the EAS or IAS were identified as those exceeding 1 hour (>30 degrees) [16] on a clock face.…”