How large does a rectocele have to be to cause symptoms? A 3D/4D ultrasound study

Rectocele is a common condition, which on imaging is defined by a pocket identified on Valsalva or defecation. Cut-offs of 10 and 20 mm for pocket depth have been described. This study analyses the correlation between rectocele depth and symptoms of bowel dysfunction to define a cut-off for the diagnosis of "significant rectocele" on ultrasound.

A retrospective study using 564 archived data sets of patients seen at tertiary urogynaecological clinics. Patients underwent a standardised interview including a set of questions regarding bowel function, and translabial 3D/4D ultrasound. Assessments were undertaken supine and after voiding. Rectocele depth was measured on Valsalva.

Out of 564, data on symptoms was missing in 18 and ultrasound volumes in 25, leaving 521. Mean age was 56 years (range 18-86), mean BMI 29 (17-56). Presenting symptoms were prolapse (51 %), constipation (21 %), vaginal digitation (17 %), straining at stool (46 %), incomplete bowel emptying (41 %) and faecal incontinence (10 %). A clinically significant rectocele (ICS POPQ stage ≥2) was found in 48 % (n=250). In 261 women a rectal diverticulum was identified, of an average depth of 17 (SD, 7) mm. On ROC statistics a cut- off of 15 mm in depth provided optimal sensitivities of 66 % for vaginal digitation and 63 % for incomplete emptying, and specificities of 52 and 57 % respectively.

Rectocele depth is associated with symptoms of obstructed defecation. A "clinically significant" rectocele may be defined as a diverticulum of the rectal ampulla of ≥15 mm in depth, although poor test characteristics limit clinical utility of this cut-off.