Influence of the disengagement of the forceps on levator ani muscle injuries in instrumental delivery: A multicenter study

Abstract

Introduction Forceps use is the main risk factor for levator ani muscle (LAM) injuries. We believe that the disengagement of the forceps branches before delivery of the fetal head could influence LAM injuries, so we aimed to determine the influence of the disengagement of the forceps on the occurrence of LAM avulsion during forceps delivery. Material and methods A prospective, observational, multicenter study was conducted with 261 women who underwent forceps delivery. The women were classified according to whether the branches of the forceps had been disengaged before delivery of the fetal head. LAM avulsion was defined using a multislice mode (3 central slices). Results In all, 255 women completed the study (160 without disengagement and 95 with disengagement). LAM avulsions were observed in 37.9% of women in the group with disengagement and in 41.9% of women in the group without disengagement. The crude OR (without disengagement vs with disengagement) for avulsion was 0.90 (95% CI 0.49‐1.67, P = 0.757) and an adjusted OR of 0.82 (95% CI 0.40‐1.69, P = 0.603). Conclusions We did not observe a statistically significant reduction in the LAM avulsion rate with disengagement of the forceps branches before delivery of the fetal head.

Diagnosis of Levator Ani Muscle Avulsion in Instrumented Delivery: Meta-analysis

“…Five studies were retrospective and the rest prospective. The ultrasound examination was performed in most studies within 6 months after delivery [11][12][13][14][15][16][17]19,20,22,23,[25][26][27][28][29][30][31][32][33][34][35], though some performed an ultrasound examination only or also after this period [17,18,21,24,35,36]. Some papers included a small number of VDs [12,20,27] and FDs [12][13][14]27], a possible source of bias.…”

“…The majority of articles that specified the type of vacuum used in the RV reported that a metal vacuum bird's cup was 50 mm [19,[24][25][26]29,30,[32][33][34], although one of them also assessed LAM avulsion after a Kiwi vacuum was used [32]. The majority of studies on FD described the rates of LAM avulsion with Kielland's forceps [28][29][30][31]33,34,36], though one of them studied Anderson forceps and Wrigley forceps [19].…”

“…uum, with an OR of 0.977 (0.426; 2.241; p = 0.957) and an adjusted OR of 2.90 (0.691; 12.20; p = 0.146). Something similar was true of the studies that specified the type of forceps used during the FD, as most describe the rate of LAM avulsion caused by only one type of forceps (Kielland's forceps) [28][29][30][31]33,34,36]. Only one study included different forceps [19], with a small number of participants (20 Anderson forceps and 22 Wrigley forceps), and did not compare the rate of LAM avulsion between the two types.…”

“…4.93) [36]. One study analyzed whether the disarticulation of the forceps before the delivery of the fetal head could benefit the rate of LAM, and it found a crude OR (without disengagement vs. disengagement) for avulsion of 0.90 (95% CI 0.49-1.67; p = 0.757) and an adjusted OR (adjusted for maternal age, induced labor, epidural period, second stage of labor, perineal tear, and fetal head circumference) of 0.82 (95% CI 0.40-1.69; p = 0.603) [31]. However, when comparing the rates of LAM avulsion between VD and FD considering the position (anterior or other) and the station (low or medium instrumentation) of the fetal head at the time of instrument placement, no differences were found [29,33].…”

“…This aspect has not only been described by transperineal ultrasound [47] but has also been established in anatomical studies and by MRI [48]. In this meta-analysis, the vast majority of studies performed ultrasound examinations up to 6 months after delivery [11][12][13][14][15][16][17]19,20,22,23,[25][26][27][28][29][30][31][32][33][34][35], but they did not assess its evolution over time. LAM avulsion produces an alteration in the support of the pelvic floor structures, however this fact should not influence the decision to implement a delivery.…”