Defects of anterior vaginal wall fascia are generally assumed to be factors in the aetiology of cystocele. However, to date, there is very little information on diagnosis by imaging.

To document the appearance of vaginal fornices before and after childbirth using 4D ultrasound volume data sets as an aid in diagnosing paravaginal defects of the anterior vaginal wall.

Materials and Methods
This study was performed by re‐analysing data sets obtained in a previously published study involving ante‐ and postpartum pelvic floor assessment by ultrasound. Two hundred and two nulliparous women had been seen at a mean gestation of 37.2 weeks at two tertiary hospitals. One hundred and sixty‐three returned 3 months postpartum. All the participants underwent an interview and 4D translabial ultrasound at both antepartum and postpartum appointments. The integrity of vaginal fornices and levator ani was assessed by tomographic ultrasound.

Vaginal fornices were assessed in both ante‐ and postnatal volumes, and loss of forniceal tenting was found in 85 patients (52%). On average, seven slices were affected (range, 1–16). On multivariate analysis, controlling for potential confounders, including partial/complete avulsion, loss of forniceal tenting remained independently associated with increased cystocele descent (P = 0.005).

Vaginal childbirth is associated with loss of tenting of the vaginal fornices, independent of levator trauma, and also with impaired anterior vaginal wall support. This evidence suggests the existence of paravaginal defects and may imply a role for such defects in the causation of anterior vaginal wall prolapse.