Levator Ani avulsion: The histological composition of this site. A cadaveric study

Levator ani muscle volume and architecture in normal vs. muscle damage patients using 3D endovaginal ultrasound: a pilot study

INTRODUCTION AND HYPOTHESIS

This study aimed to compare the difference in levator ani muscle (LAM) volumes between 'normal' and those with sonographically visualized LAM defects. We hypothesized that the 'muscle damage' group would have a significantly lower muscle volume.

METHODS

The study included patients who had undergone a 3D endovaginal ultrasound. The normal (NM) and damage (DM) muscle groups' architectural changes were evaluated based on anterior-posterior (AP), left-right (LR) diameter, and minimal levator hiatus (MLH) area. The puboanalis-puboperinealis (PA), puborectalis (PR), and pubococcygeus-iliococcygeus (PC) were manually segmented using 2.5 vs. 1.0 mm to find the optimal sequence and to compare the volumes between NM and DM groups. POPQs were compared between the NM and DM groups.

RESULTS

The 1.0-mm segmentation volumes created superior volume analysis. Comparing NM to the DM group showed no significant difference in LAM volume. Respectively, the mean total LAM volumes were 17.27 cm³ (SD = 3.97) and 17.04 cm³ (SD = 4.32), p = 0.79. The mean MLH measurements for both groups respectively were 10.06 cm² (SD = 2.93) and 12.18 cm² (SD = 2.93), indicating a significant difference (p = 0.01). POPQ analysis demonstrated statistically significant differences at Ba and Bp parameters suggesting that the DM group had worse prolapse (p = 0.05, 0.01, respectively).

CONCLUSIONS

While LAM volumes are similar, there is a significant difference in the physical architecture of the LAM and the POPQ parameters in muscle-damaged patients compared to the normal group.

A review of levator ani avulsion after childbirth: Incidence, imaging and management

Key Content • Levator ani muscle (LAM) avulsion injury occurs occultly during childbirth, most commonly during operative vaginal deliveries. • Injuries of levator ani have long term sequelae for pelvic floor health. As life expectancy increases the burden of disease upon urogynaecology services will need to be considered. • Diagnosis of this condition can be difficult as there is no agreed 'gold standard' imaging modality. • There is no consensus regarding surgical management of LAM avulsion. Learning objectives • Review anatomy and function of levator ani muscle • Identify the risk factors for levator ani avulsion injury • Role of imaging to appropriately identify LAM injury and current management options including appropriate follow up • Management of subsequent pregnancy following LAM avulsion Ethical issues • Is there value to the patient in diagnosing levator ani avulsion when there is no recommended treatment for these injuries?

Pelvic floor muscle injury during a difficult labor. Can tissue fatigue damage play a role?

Pubovisceral muscle (PVM) injury during a difficult vaginal delivery leads to pelvic organ prolapse later in life. If one could address how and why the muscle injury originates, one might be able to better prevent these injuries in the future. In a recent review we concluded that many atraumatic injuries of the muscle-tendon unit are consistent with it being weakened by an accumulation of passive tissue damage during repetitive loading. While the PVM can tear due to a single overstretch at the end of the second stage of labor we hypothesize that it can also be weakened by an accumulation of microdamage and then tear after a series of submaximal loading cycles. We conclude that there is strong indirect evidence that low cycle fatigue of PVM passive tissue is a possible mechanism of its proximal failure. This has implications for finding new ways to better prevent PVM injury in the future.