Posterior Vaginal Compartment Anatomy: Implications for Surgical Repair

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.

Pelvic Organ Prolapse Quantification (POP-Q) system needs revision or abandonment: The anatomy study

OBJECTIVE

To examine the female urogenital hiatus (UGH) and perineal body gross and topographic anatomy; to analyze the POP-Q recommendation for evaluating UGH and PB.

STUDY DESIGN

A prospective case series study on fifteen fresh human adult female cadavers was conducted in international settings. Stratum-by-stratum, macro-, and micro-anatomical dissections to study the UGH and PB gross-topographic anatomy. In addition, HGH and PB descriptive anatomy presented in the medical literature were analyzed. The primary outcome measured the accuracy of POP-Q in the assessment of UGH and PB. Additionally, digital photos were taken to document UGH and PB gross and topographic anatomy.

RESULTS

The present study confirmed that the urogenital hiatus was a well-described structure in the medical literature. It is an oval-shaped structure that originated at the inferior pubic bone and was inserted into the posterior anal wall and superior surface of the PB. In all subjects, the location of UGH was in the Retzius space. Therefore, the recommendation by the POP-Q to evaluate UGH from the middle urethral meatus to the posterior hymeneal ring was incorrect because it did not accurately reflect the total longitudinal diameter of UGH. The PB topographic anatomy was not appropriately described in the literature. PB was an oval-shaped, solid, muscular mass without the central point of the perineum or fascia and rested between the posterior-distal vaginal wall and the anterior anorectal wall in a horizontal orientation and was not a part of the posterior perineum as the POP-Q system indicated. Therefore, a vertical measurement of the perineal body as recommended by POP-Q was impossible to obtain due to its horizontal orientation under the posterior-distal vaginal wall; PB had to be measured horizontally. The median length was 4.2 cm ± 1.6 (SD).

CONCLUSIONS

The POP-Q system does not adequately assess UGH and PB and needs revision.

Recommended standardized anatomic terminology of the posterior female pelvis and vulva based on a structured medical literature review

BACKGROUND

Anatomic terminology in both written and verbal forms has been shown to be inaccurate and imprecise.

OBJECTIVE

Here, we aimed to (1) review published anatomic terminology as it relates to the posterior female pelvis, posterior vagina, and vulva; (2) compare these terms to "Terminologia Anatomica," the internationally standardized terminology; and (3) compile standardized anatomic terms for improved communication and understanding.

STUDY DESIGN

From inception of the study to April 6, 2018, MEDLINE database was used to search for 40 terms relevant to the posterior female pelvis and vulvar anatomy. Furthermore, 11 investigators reviewed identified abstracts and selected those reporting on posterior female pelvic and vulvar anatomy for full-text review. In addition, 11 textbook chapters were included in the study. Definitions of all pertinent anatomic terms were extracted for review.

RESULTS

Overall, 486 anatomic terms were identified describing the vulva and posterior female pelvic anatomy, including the posterior vagina. "Terminologia Anatomica" has previously accepted 186 of these terms. Based on this literature review, we proposed the adoption of 11 new standardized anatomic terms, including 6 regional terms (anal sphincter complex, anorectum, genital-crural fold, interlabial sulcus, posterior vaginal compartment, and sacrospinous-coccygeus complex), 4 structural terms (greater vestibular duct, anal cushions, nerve to the levator ani, and labial fat pad), and 1 anatomic space (deep postanal space). In addition, the currently accepted term rectovaginal fascia or septum was identified as controversial and requires further research and definition before continued acceptance or rejection in medical communication.

CONCLUSION

This study highlighted the variability in the anatomic nomenclature used in describing the posterior female pelvis and vulva. Therefore, we recommended the use of standardized terminology to improve communication and education across medical and anatomic disciplines.