Levator ani injury in primiparous women with forceps delivery for fetal distress, forceps for second stage arrest, and spontaneous delivery

Objective

To compare levator ani muscle injury rates in primiparous women who had a forceps delivery owing to fetal distress with women delivered by forceps for second stage arrest; and to compare these injury rates with a historical control group of women who delivered spontaneously.

Methods

Primiparous women who delivered by forceps were recruited retrospectively into 2 groups: forceps for fetal distress with short second stage (25 ± 11 minutes; n = 19); and forceps delivery for second stage arrest (137 ± 26 minutes; n = 19). MR images of the levator ani muscles were compared with a historical control group of women from a previous study who had delivered spontaneously (n = 129).

Results

Major defect rates were: 42% for forceps and short second stage; 63% for forceps and second stage arrest; and 6% for spontaneous delivery. The odds ratios for major injury were: 11.0 for forceps and short second stage compared with spontaneous delivery; 25.9 for forceps and second stage arrest compared with spontaneous delivery; and 2.3 for forceps and second stage arrest compared with short second stage (P = 0.07).

Conclusion

Women delivered by forceps have a higher rate of levator ani injury compared with spontaneous delivery controls; the difference between the forceps groups did not reach significance.