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

The Role of Transperineal Ultrasound for the Assessment of the Anorectal Angle and Its Relationship with Levator Ani Muscle Avulsion

The relationship between the anorectal angle (ARA) and the levator ani muscle (LAM) is well known. In this study, we aimed to demonstrate that the ARA changes when LAM avulsion occurs after vaginal delivery. This was a secondary, observational retrospective study with data obtained from three previous studies. Using transperineal ultrasound, the presence of avulsion was assessed when abnormal insertion of the LAM was observed in three central slices. In addition, the ARA was assessed in the midsagittal plane (at rest, in Valsalva and at maximum contraction) as the angle between the posterior border of the distal part of the rectum and the central axis of the anal canal. The ARA was higher in patients with bilateral LAM avulsion than in patients without LAM avulsion at rest (131.8 ± 14.1 vs. 136.2 ± 13.8), in Valsalva (129.4 ± 15.5 vs. 136.5 ± 14.4) and at maximum contraction (125.7 ± 15.5 vs. 132.3 ± 13.2). The differences between both groups expressed as the odds ratio (OR) adjusted for maternal age were 1.031 (95% confidence interval (CI), 1.001–1.061; p = 0.041) at rest, 1.036 (95% CI, 1.008–1.064; p = 0.012) in Valsalva and 1.031 (95% CI, 1.003–1.059; p = 0.027) at maximum contraction. In conclusion, LAM avulsion produces an increase in the ARA at rest, during contraction and in Valsalva, especially in cases of bilateral LAM avulsion.

The evolution of levator ani muscle trauma over the first 9 months after vaginal birth

INTRODUCTION AND HYPOTHESIS

The objective was to investigate the evolution of levator ani muscle (LAM) trauma over the first 9 months after birth and to evaluate their agreement between different assessment periods.

METHODS

From March 2017 to April 2019 we prospectively evaluated LAM states (intact, hematoma, partial or complete avulsion) of primiparous women after vaginal birth by using 4D translabial ultrasound (TLUS) at three different assessment periods. All women were examined 1-4 days (A1) and 6-10 weeks (A2) postpartum, and women with a trauma additionally 6-9 months postpartum (A3). Cohen's Kappa analysis was performed to evaluate the test agreement between the assessment periods.

RESULTS

Thirty-two percent of the women at A1 had a LAM trauma and 24% at A2. The higher number of LAM injuries at A1 can be explained by hematomas (14%), of which 51% spontaneously resolved at A2, 35% revealed themselves as partial, and 12% as complete avulsions. At A3, we observed anatomical improvement from complete to partial avulsions (23%) and few partial avulsions changed into an intact LAM (3%); none of the complete avulsions changed into an intact LAM. The agreement of 4D TLUS between A1 and A2 was moderate to good (0.64 for the right-sided LAM/0.60 for the left-sided LAM) and between A2 and A3 good to very good (0.76 right-sided/0.84 left-sided).

CONCLUSIONS

Levator ani muscle trauma can reliably be diagnosed during all assessment periods. However, the agreement between A1 and A2 was only moderate to good. This can be explained by hematomas inside the LAM that were only observed early postpartum. We observed some anatomical improvement at A3, but no complete avulsion improved to an intact LAM.

Ultrasonographic evaluation of pelvic floor structure at antepartum and postpartum periods using three-dimensional transperineal ultrasound

PURPOSE

To examine the changes in the pelvic floor structure caused by pregnancy and delivery.

METHODS

A total of 141 nulliparous women were examined with three-dimensional transperineal ultrasound (3D-TPU) at the 24th and 34th weeks of gestation, 5th day postpartum, and 1 month postpartum. Puborectalis muscle trauma was diagnosed and the area of levator hiatus (ALH) was measured.

RESULTS

One hundred and five normal vaginal deliveries, 19 vacuum/forceps deliveries, and 17 cesarean deliveries were included. In the normal delivery group, the rate of puborectalis muscle trauma was low and showed no significant change between the 24th and 34th weeks of gestation (12.5% vs. 17.2%, p = 0.42). The rate of trauma significantly increased to 70.2% at the 5th day postpartum (p < 0.001). There was no significant difference between the rates at the 5th day postpartum and 1 month postpartum (73.7%, p = 0.60). The same trend was found in the vacuum/forceps group. In the cesarean section group, no significant change was observed throughout pregnancy and postpartum periods. In the normal delivery group, ALH significantly increased between the 24th and 34th week (14.1 ± 2.6 cm² vs. 14.6 ± 3.4 cm², p = 0.007). ALH markedly increased to 20.9 ± 4.8 cm² at the 5th day postpartum (p < 0.001). ALH at 1 month postpartum decreased to 17.0 ± 4.3 cm² (p < 0.001), but did not return to the value at the 24th week (p < 0.001).

CONCLUSIONS

Vaginal childbirth results in enlargement of the levator hiatus. Pelvic floor muscles in pregnant women are affected not only by mechanical damage associated with delivery but also by physiologic changes during pregnancy. The effects of pregnancy and delivery on pelvic floor muscles may persist after delivery.

Prevalence of levator hiatal overdistension after vacuum and forceps deliveries

INTRODUCTION

Levator ani avulsion rates after assisted vaginal delivery have been reported in the literature. However, there are no definitive data regarding the association between overdistention and assisted vaginal delivery. Therefore, our aim is to report overdistention rates after assisted vaginal delivery with a postpartum ultrasound examination.

MATERIALS AND METHODS

This multicenter study involved a retrospective analysis of data from primiparous women (n = 602) who had previously been recruited at three tertiary hospitals between January 2015 and January 2017. Overdistention was assessed at 6 months postpartum using three-/four-dimensional transperineal ultrasound. Patients with levator ani muscle avulsion were excluded. Overdistention was defined as a levator hiatal area ≥ 25 cm² on Valsalva.

RESULTS

Of the 602 primiparous patients, 250 patients who satisfied the inclusion criteria (139 patients who underwent forceps delivery and 111 patients who underwent vacuum delivery) were evaluated. Overdistention occurred in 20% (50 of 250) of these patients. Overdistention was observed for 1% (1/111) of vacuum deliveries and 35.3% (49 of 139) of forceps deliveries. We found an increased risk of overdistention following forceps delivery compared to vacuum delivery, with a crude odds ratio (OR) of 59.9 (95% confidence interval [CI]: 8.1, 442.2) and an adjusted OR (adjusted for maternal age, second-stage duration, and head circumference) of 17.6 (95% CI: 2.3, 136.7).

CONCLUSIONS

Postpartum overdistention occurred for 20% of assisted vaginal deliveries, with an increased risk of overdistention following forceps delivery compared to vacuum delivery.

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

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.