Forceps linked to levator ani problems. (Vacuum Also Implicated).

SAN FRANCISCO--Having an operative vaginal delivery nearly quadrupled a woman's risk of developing an abnormality of the levator ani muscle--an important muscle for pelvic organ support--in a study of 280 women.

An operative vaginal delivery increased the risk of developing a levator ani abnormality by 3.5 times. A total of 60% of women with major defects had operative vaginal deliveries. Major defects developed in half of women who had a forceps delivery, 23% who had a vacuum delivery, and 7% who had a normal, nonoperative vaginal delivery, Dr. Rohna Kearney said at the annual meeting of the American Urogynecologic Society.

In the study, blinded reviewers scored pelvic MRIs of 80 nulliparous women; 80 primiparous, continent women; and 80 primiparous women who developed urinary incontinence for the first time after vaginal delivery. The reviewers found levator ani abnormalities in 32 (20%) of the 160 primiparous women but in none of the nulliparous women, according to Dr. Kearney of the University of Michigan, Ann Arbor.

The second stage of labor averaged an hour longer in women who developed levator ani defects, according to Dr. Kearney Although fetal head circumference and birth weight tended to be greater in women with levator ani injuries, compared with those with normal levator ani muscles, these differences were not significant.

The study design did not allow investigators to compare the need for an operative delivery with its effects to assess the risks and benefits of the procedures.

Women with a defect were twice as likely to have had an episiotomy and three times as likely to have had an anal sphincter rupture as those without the defect.

In a ...