Comparison of Levator Ani Muscle Avulsion Injury After Forceps-Assisted and Vacuum-Assisted Vaginal Childbirth

Abstract

Objective Using three-dimensional transperineal ultrasound, we compared the prevalence of levator ani muscle injury after forceps with vacuum-assisted vaginal delivery. Methods This was a retrospective cohort study. Women who experienced at least one forceps delivery (across all deliveries) were compared to women who had at least one vacuum birth. On average, participants were 10 years from the index delivery. Three-dimensional transperineal ultrasound volumes were captured as cine loops at rest, with Valsalva and with pelvic floor muscle contraction. The primary outcome was levator ani muscle avulsion. Secondary outcomes included hiatal diameter and area. Prevalence of pelvic floor disorders was also compared between the two delivery groups. Results Among 45 participants in the forceps group and 28 participants in the vacuum group, there were no differences between groups in maternal age at first delivery, parity, body mass index, birth weight, episiotomy, and duration of second stage. History of anal sphincter laceration was more common in the forceps group. The prevalence of levator ani muscle avulsion was significantly higher after forceps compared with vacuum delivery {22/45 (49%) versus 5/28 (18%), p=0.012, prevalence ratio = 2.74 (95% CI: 1.17, 6.40), odds ratio = 4.40 (95% confidence interval: 1.42, 13.62)}. Controlling for delivery type, levator ani muscle avulsion was associated with symptoms of prolapse (p=0.036), although objective evidence of prolapse was not significantly different between groups (p=0.20). Conclusion Ten years after delivery, the prevalence of levator avulsion is almost tripled after forceps compared with vacuum-assisted vaginal delivery.

O uso de analgesia farmacológica influencia no desfecho de parto?

“…The importance of this finding is due to the fact that instrumental vaginal delivery is an intervention that can be associated with maternal and neonatal morbidities, (10,12,13) such as pelvic floor injuries and fecal and urinary incontinence in the mother, (10,12) in addition to shoulder dystocia and facial nerve palsy in the neonate. (10,13) It is important to highlight that these instruments are handled only by qualified professionals, as this reduces the chances of injury.…”

“…(10) In contrast, it has been associated with a higher risk of fetal morbidity and mortality, as well as maternal morbidities. (10,12,13) Laceration of the anal sphincter and of the birth canal, and displacement of the muscles of the pelvic floor are among maternal morbidities; (10,12,13) the neonatal morbidities are facial lesions, cephalo-hematomas, intracranial hemorrhage, ocular lesions, and fractures of the skull bones. (10) Obvious benefits are achieved by analgesia, despite the adverse conditions of its use.…”

The Epidemiology of Pelvic Floor Disorders and Childbirth

“…In a study of women delivered by operative vaginal birth, LAM avulsion observed on 3D transperineal ultrasound was associated with symptoms of prolapse (p=0.036) but not objective evidence of prolapse (p=0.20). 53 Others have found that objective evidence of prolapse is more common among those with levator ani muscle injury. 43 For example, among primiparous women 12 months after delivery, 54 levator avulsion was associated with objective and subjective measures of POP (OR 4.8, 95% CI 1.99–11.34).…”

A comparable rate of levator ani muscle injury in operative vaginal delivery (forceps and vacuum) according to the characteristics of the instrumentation

“…25 A recent meta-analysis described an odds ratio (OR) of 7.02 (5.04-9.78) comparing delivery with forceps with normal delivery. 26,28,29 It must be taken into account that some of the studies published to date 24,25,30,31 include a small sample size, so obtaining a clear conclusion regarding this association can be difficult. Although some authors report a higher rate of injuries associated with vacuum deliveries than with normal vaginal deliveries, 27 other researchers have not found significant differences.…”