EDITOR—The finding by Signorello et al that midline episiotomy may impair anal continence is valuable and highlights the effect of perineal trauma on the anal continence mechanism.1 The authors acknowledge the limitations of the study, which was retrospective, non-randomised, and may have included misclassifications of perineal trauma.

We investigated 161 nulliparous women in the third trimester and 12 weeks post partum. A symptom questionnaire and anorectal investigations were performed at both visits and anal endosonography was performed post partum.2

Women with an intact perineum had a mean squeeze pressure of 105.8±26.4 mmHg, those who sustained second and third degree perineal tears had a mean squeeze pressure of 92.3±30.3 mmHg (P=0.022), and those who had mediolateral episiotomies had a mean squeeze pressure of 92.2±29.7 mmHg (P=0.032).

Sphincter trauma was associated with perineal trauma at delivery: of 59 women with second or third degree tears, 41 (69%) had sphincter trauma versus 39 out of 97 women (40%) with an intact perineum (P=0.001). Sphincter trauma was also significantly more common in women who underwent vaginal delivery: 58 out of 130 (45%) women had sphincter defects in the vaginal delivery group versus 1 out of 26 women (4%) women who underwent a caesarean section (P=0.0005). However, the difference between our study and that of Signorello et al is that the patients in our study had a mediolateral and not a midline episiotomy, and it …