AIM: To determine the accuracy and predictive value of transperineal (TPU) and endovaginal
ultrasound (EVU) in the detection of anal sphincter defects in women with obstetric anal
sphincter injuries and/or postpartum symptoms of faecal incontinence.
MATERIALS AND METHODS: One hundred and sixty-five women were recruited, four
women were excluded as they were seen years after their last delivery. TPU and EVU, followed
by endonanal ultrasound (EAU), were performed using the B&K Viking 2400 scanner. Sensitivity
and specificity, as well as predictive values with 95% confidence intervals, for detecting
anal sphincter defects were calculated for EVU and TPU, using EAU as the reference standard.
RESULTS: On EAU a defect was found in 42 (26%) women: 39 (93%) had an external (EAS) and
23 (55%) an internal anal sphincter (IAS) defect. Analysable images of one level of the EAS
combined with an analysable IAS were available in 140 (87%) women for EVU and in 131 (81%)
for TPU. The sensitivity and specificity for the detection of any defect was 48% (30e67%) and
85% (77e91%) for EVU and 64% (44e81%) and 85% (77e91%) for TPU, respectively.
CONCLUSION: Although EAU using a rotating endoprobe is the validated reference standard
in the identification of anal sphincter defects, it is not universally available. However while TPU
and/or EVU with conventional ultrasound probes can be useful in identifying normality, for
clinical purposes they are not sensitive enough to identify an underlying sphincter defect.