Mechanisms of hiatus failure in prolapse: a multifaceted evaluation

Postpartum Changes in Levator Plate Shape and Genital Hiatus Size After Vaginal Delivery

INTRODUCTION AND HYPOTHESIS

Vaginal delivery is a risk factor for pelvic organ prolapse. We sought to quantify changes in level III pelvic support measurements at 7 weeks and 8 months following vaginal delivery.

METHODS

This secondary analysis included primiparous women who underwent pelvic MRI and clinical examinations at 7 weeks and 8 months after vaginal delivery. Demographics and obstetrical data were abstracted. Mid-sagittal resting MRIs were used to perform level III measurements including urogenital hiatus (UGH), levator hiatus (LH), and mid-sagittal levator area (LA), and to trace the levator plate (LP). Using principal component analysis, 7-week and 8-month principal component scores (PC1s) and MRI measurements were compared using paired t test. If the PC1 score change from 7 weeks to 8 months was > 0, women were considered to have a more dorsally oriented LP shape.

RESULTS

Of 76 participants, POP-Q values did not significantly differ between 7 weeks and 8 months, but MRI measurements improved (UGH: 3.9 ± 0.8 vs 3.5 ± 0.8, p < 0.001; LH: 5.4 ± 0.8 vs 5.2 ± 0.8, p = 0.01; LA: 18.0 ± 6.0 vs 15.2 ± 6.5, p < 0.001). Approximately 30% (22 out of 76) had a more dorsally oriented LP shape and larger level III measurements at 8 months than women with a more ventrally oriented LP shape (LA: 86.4% vs 1.9%, p < 0.001; LH: 16% vs 12%, p < 0.001; UGH: 59.1% vs 3.7%, p < 0.001).

CONCLUSIONS

After vaginal delivery, most women had "recovery" of level III support-defined by smaller UGH, LH, and LA measurements-and a more ventrally oriented LP shape. However, nearly 30% had larger level III measurements and a more dorsally oriented LP shape, indicating "impaired recovery" of support.

Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?

Pelvic floor disorders after childbirth have distressing lifelong consequences for women, requiring more than 300,000 women to have surgery annually. This represents approximately 10% of the 3 million women who give birth vaginally each year. Vaginal birth is the largest modifiable risk factor for prolapse, the pelvic floor disorder most strongly associated with birth, and is an important contributor to stress incontinence. These disorders require 10 times as many operations as anal sphincter injuries. Imaging shows that injuries of the levator ani muscle, perineal body, and membrane occur in up to 19% of primiparous women. During birth, the levator muscle and birth canal tissues must stretch to more than 3 times their original length; it is this overstretching that is responsible for the muscle tear visible on imaging rather than compression or neuropathy. The injury is present in 55% of women with prolapse later in life, with an odds ratio of 7.3, compared with women with normal support. In addition, levator damage can affect other aspects of hiatal closure, such as the perineal body and membrane. These injuries are associated with an enlarged urogenital hiatus, now known as antedate prolapse, and with prolapse surgery failure. Risk factors for levator injury are multifactorial and include forceps delivery, occiput posterior birth, older maternal age, long second stage of labor, and birthweight of >4000 g. Delivery with a vacuum device is associated with reduced levator damage. Other steps that might logically reduce injuries include manual rotation from occiput posterior to occiput anterior, slow gradual delivery, perineal massage or compresses, and early induction of labor, but these require study to document protection. In addition, teaching women to avoid pushing against a contracted levator muscle would likely decrease injury risk by decreasing tension on the vulnerable muscle origin. Providing care for women who have experienced difficult deliveries can be enhanced with early recognition, physical therapy, and attention to recovery. It is only right that women be made aware of these risks during pregnancy. Educating women on the long-term pelvic floor sequelae of childbirth should be performed antenatally so that they can be empowered to make informed decisions about management decisions during labor.

Functional Anatomy of Urogenital Hiatus Closure: the Perineal Complex Triad Hypothesis

INTRODUCTION

Urogenital hiatus enlargement is a critical factor associated with prolapse and operative failure. This study of the perineal complex was performed to understand how interactions among its three structures: the levator ani, perineal membrane, and perineal body-united by the vaginal fascia-work to maintain urogenital hiatus closure.

METHODS

Magnetic resonance images from 30 healthy nulliparous women with 3D reconstruction of selected subjects were used to establish overall geometry. Connection points and lines of action were based on perineal dissection in 10 female cadavers (aged 22-86 years), cross sections of 4 female cadavers (aged 14-35 years), and histological sections (cadavers aged 16 and 21 years).

RESULTS

The perineal membrane originates laterally from the ventral two thirds of the ischiopubic rami and attaches medially to the perineal body and vaginal wall. The levator ani attaches to the perineal membrane's cranial surface, vaginal fascia, and the perineal body. The levator line of action in 3D reconstruction is oriented so that the levator pulls the medial perineal membrane cranio-ventrally. In cadavers, simulated levator contraction and relaxation along this vector changes the length of the membrane and the antero-posterior diameter of the urogenital hiatus. Loss of the connection of the left and right perineal membranes through the perineal body results in diastasis of the levator and a widened hiatus, as well as a downward rotation of the perineal membrane.

CONCLUSION

Interconnections involving the levator ani muscles, perineal membrane, perineal body, and vaginal fascia form the perineal complex surrounding the urogenital hiatus in an arrangement that maintains hiatal closure.

Is there an association between 6-month genital hiatus size and 24-month composite prolapse recurrence following minimally invasive sacrocolpopexy?

INTRODUCTION AND HYPOTHESIS

Although an enlarged postoperative genital hiatus (GH) size has been identified as a predictor of recurrence following pelvic organ prolapse (POP) surgery, the protective role of concurrent level III support procedures to reduce the GH size at the time of minimally invasive sacrocolpopexy (MI-SCP) remains unclear. The objective of this study was to compare 24-month composite prolapse recurrence following MI-SCP between patients with a 6-month postoperative GH measurement of <3 cm versus ≥3 cm; and to explore the impact of concurrent level III support procedures on prolapse recurrence, bowel, and sexual function.

METHODS

This was a secondary analysis of two randomized controlled trials of women who underwent MI-SCP from 2014 to 2020. Our primary outcome was composite prolapse recurrence defined as retreatment with either pessary or surgery, and/or subjective bothersome vaginal bulge. A receiver operating characteristic (ROC) curve was generated to identify a 6-month GH cutoff point associated with 24-month composite recurrence.

RESULTS

Of the 108 women who met the inclusion criteria, 13 (12%) had composite prolapse recurrence at 24 months: 12 patients (11.1%) reported a bothersome vaginal bulge, and 3 patients (2.8%) underwent retreatment with surgery. A ROC curve demonstrated that a 6-month postoperative GH size of 3 cm had 84.6% sensitivity to predict vaginal bulge and/or retreatment at 24 months (area under curve = 0.52). There was no difference in the composite prolapse recurrence between the groups; however, only patients with a 6-month GH >3 cm underwent retreatment.

CONCLUSIONS

Twenty-four-month composite prolapse recurrence does not differ based on 6-month GH size; however, surgical failure may be more common in those with a GH size greater than 3 cm.

Hiatal failure: effects of pregnancy, delivery, and pelvic floor disorders on level III factors

INTRODUCTION AND HYPOTHESIS

The failure of the levator hiatus (LH) and urogenital hiatus (UGH) to remain closed is not only associated with pelvic floor disorders, but also contributes to recurrence after surgical repair. Pregnancy and vaginal birth are key events affecting this closure. An understanding of normal and failed hiatal closure is necessary to understand, manage, and prevent pelvic floor disorders.

METHODS

This narrative review was conducted by applying the keywords "levator hiatus" OR "genital hiatus" OR "urogenital hiatus" in PubMed. Articles that reported hiatal size related to pelvic floor disorders and pregnancy were chosen. Weighted averages for hiatal size were calculated for each clinical situation.

RESULTS

Women with prolapse have a 22% and 30% larger LH area measured by ultrasound at rest and during Valsalva than parous women with normal support. Women with persistently enlarged UGH have 2-3 times higher postoperative failure rates after surgery for prolapse. During pregnancy, the LH area at Valsalva increases by 29% from the first to the third trimester in preparation for childbirth. The enlarged postpartum hiatus recovers over time, but does not return to nulliparous size after vaginal birth. Levator muscle injury during vaginal birth, especially forceps-assisted, is associated with increases in hiatal size; however, it only explains a portion of hiatus variation-the rest can be explained by pelvic muscle function and possibly injury to other level III structures.

CONCLUSIONS

Failed hiatal closure is strongly related to pelvic floor disorders. Vaginal birth and levator injury are primary factors affecting this important mechanism.

Analysis of long-term structural failure after native tissue prolapse surgery: a 3D stress MRI-based study

INTRODUCTION AND HYPOTHESIS

We sought to identify postoperative structural failure sites associated with long-term prolapse recurrence and their association with symptoms and satisfaction.

METHODS

Women who had a research MRI prior to native-tissue prolapse surgery were recruited for examination, 3D stress MRI, and questionnaires. Recurrence was defined by Pelvic Organ Prolapse Quantification System (POP-Q)Ba/Bp > 0 or C > -4. Measurements were performed at rest and maximum Valsalva ("strain") including vaginal length, apex location, urogenital hiatus (UGH), and levator hiatus (LH). Measures were compared between subjects and to women with normal support. Failure frequency was the proportion of women with measurements outside the normal range. Symptoms and satisfaction were measured using validated questionnaires.

RESULTS

Thirty-one women participated 12.7 years after surgery-58% with long-term success and 42% with recurrence. Failure site comparisons between success and failure were: impaired mid-vaginal paravaginal support (62% vs. 28%, p = 0.01), longer vaginal length (54% vs. 22%, p = 0.03), and enlarged urogenital hiatus (54% vs. 22%, p = 0.03). Apical paravaginal location had the lowest failure frequency (recurrence: 15% vs. success: 7%, p = 0.37). Patient satisfaction was high (recurrence: 5.0 vs. success: 5.0, p = 0.86). Women with bothersome bulge symptoms had a 33% larger UGH strain on POP-Q (p = 0.01), 8.7% larger resting UGH (p = 0.046), 11.5% larger straining LH (p = 0.01), and 9.3% larger resting LH (p = 0.01).

CONCLUSIONS

Abnormal low mid-vaginal paravaginal location (Level II), long vaginal length (Level II), and large UGH (Level III) were associated with long-term prolapse recurrence. Patient satisfaction was high and unrelated to anatomical recurrence. Bothersome bulge symptoms were associated with hiatus enlargement.