Vaginal delivery may cause levator ani trauma

December 1, 2005

Montreal--Vaginal delivery may cause significant pelvic floor trauma in as many as one-third of first-time deliveries. This trauma appears, upon ultrasound, to primarily affect the levator ani muscle, according to new research from Australia.

Montreal-Vaginal delivery may cause significant pelvic floor trauma in as many as one-third of first-time deliveries. This trauma appears, upon ultrasound, to primarily affect the levator ani muscle, according to new research from Australia.

Years ago, physicians believed that when damage to the pelvic floor occurred during delivery, it primarily affected the fascia or connective tissue, Dr. Dietz said.

Ultrasound operators were blinded to all clinical data about the patients, including their delivery outcome. Patients were considered to have avulsion of the pubovisceral muscle (detachment from the arcus tendineus) when they showed a loss of continuity between the muscle and pelvic sidewall in volume data sets that were obtained at rest, on levator contraction, and on Valsalva. When the diagnosis was in doubt, the investigators directly compared antenatal and postnatal rendered volumes and axial plane single frames.

Overall, 50 of the original 63 women returned for a second ultrasound 2 to 6 months after childbirth. Among these women, 39 had given birth vaginally, and 36% of those who had recently undergone a vaginal delivery had levator avulsion. None of the 11 women who had delivered by Cesarean section had these defects.

"Of 39 women who delivered vaginally, there were 14 who had significant changes to the levator ani. The prevalence was more than twice as high as expected," Dr. Dietz told Urology Times.

"Do those defects heal? If you have a muscle that's pulled off its insertion, it's never going to grow back on because the natural elasticity of the muscle and every contraction you ever produce with that muscle tends to open it further," he explained.

The presence of soft tissue trauma to the levator ani in women who delivered vaginally was significantly associated with higher maternal age. Nonsignificant trends toward an association with vaginal operative delivery and worsened stress incontinence postpartum also were seen. Bladder neck descent was dramatically increased postpartum, particularly among those with defects.

"We know that the older you are when you have your first child, the less likely you are to have your baby normally. It now seems that, if you do manage to avoid a Cesarean, you're more likely to suffer damage to the pelvic floor muscle than younger women," he said.

"In future research, we'll have to work out how to detect the women most at risk of such damage and how to stop the trauma from occurring."