Correlation between anal manometry and endosonography in females with faecal incontinence

Female faecal incontinence (FI) is largely because of sphincter injury at childbirth. Sphincter assessment aims to identify surgically correctable defects. We aimed to identify endoanal ultrasonography (EAUS) parameters that correlate with sphincter function.

One hundred females with FI and 28 healthy asymptomatic females were prospectively assessed. Wexner FI score was recorded and all subjects underwent anorectal manometry and EAUS. Multiple EAUS parameters were assessed and correlated with external (EAS) and internal (IAS) anal sphincter function, determined by maximum squeeze pressure (MSP) and maximum resting pressure (MRP) respectively. Parameters included sphincter quality (echogenicity), thickness, perineal body thickness (PBT) and defect characteristics (angle, length). Results are expressed as medians and interquartile range (IQR).

Median Wexner score was 14 (12-17). Maximum EAS thickness significantly correlated with MSP (P = 0.019). EAS defects were detected in 84 patients and seven controls (P < 0.0001). Full-length EAS defects were only detected in FI group and had significantly lower MSP [MSP mmHg: full length 85 (65-103) vs partial length 119 (75-155), P = 0.006]. FI patients were more likely to have a mixed echogenicity of EAS compared with controls. EAS ring quality, PBT and defect angle were not significant. IAS quality was significantly associated with MRP [MRP mmHg: uniform 62 (43-82) vs mixed 47 (30.5-57.5), P = 0.002].

Certain EAUS parameters can be predictive of anal sphincter function. These include the presence of an EAS defect and its length, EAS maximum thickness, IAS ring quality. Integration of these parameters can give better EAUS correlation with manometry for FI evaluation.