Pelvic organ prolapse: Understanding anatomy does make a difference - To effectively repair a vaginal prolapse, surgeons will first want to spend some time understanding the three most common "pathome
The statistics speak for themelves: Posterior organ prolapse causes a great deal of distress for our patients, being responsible
for over 225,000 operations a year in the United States, with repair of the posterior wall in 87% of these surgeries.1-4 Before one can adequately manage these patients, it's important to understand the complex structural mechanics of posterior
vaginal wall failure.
Our goals here are to review the anatomy of the posterior compartment and to describe three types of posterior wall failure:
(1) failure that's distal in the perineal body (2) failure of the levator ani muscles to close the genital hiatus, and (3)
failure that's more proximal with the loss of upward suspension of the posterior wall by the uterosacral ligaments. Clinically,
loss of support at any of these levels results in the formation of a rectocele with or without an enterocele and perineocele.
The surgical correction of the posterior wall can be tailored by specifically approaching the underlying mechanistic defect,
in an attempt to restore normal anatomic support.
Understanding the anatomy
FIGURE 1. Anatomy of the posterior compartment. PVW – posterior vaginal wall, PB – perineal body, LP – levator perineal EAS
– external anal sphincter, USL – uterosacral ligaments
You can liken the posterior compartment to an open container. Like all containers, it has sides and a bottom (Figure 1). The
front wall of the container is formed by the posterior vaginal wall, while the bottom is made up of the perineal body and
anal sphincter. The levator ani muscles form the lateral walls (sides) of the container and the "levator plate," where the
muscles decussate behind the rectum to create the iliococcygeal raphé, forms the back wall.
The upper suspension of the posterior vaginal wall (top of the container) is created by its attachment to the uterosacral
ligaments, which extend below the peritoneum and can be seen in MRI imaging.5 All of these boundaries are subject to defects that can give rise to different structural failures.
Where do posterior wall failures occur?
FIGURE 2. Distal structural failure in the area of the perineal body.
TYPE 1. In the distal part of the vagina, the dorsal fibrous sheets of perineal membrane are united through the perineal body to
connect the two sides for structural support (Figure 2A).6 The bulky fibromuscular tissue of the dorsal perineal body that extends into the internal anal sphincter7 along with the superficial transverse perineal and bulbocavernosus muscles that insert into the central tendon of the perineal
body8,9 can become compromised; midline disruption can give rise to a structural failure that might be associated with a downward
protrusion in the area where this union has been compromised (Figure 2B). Clinically, disruption of this fibromuscular sheath
or a "broken" perineal body, can manifest as a distal rectocele, with or without a perineocele.
DR. LEWICKY-GAUPP is a Fellow in Female Pelvic Medicine and Reconstructive Surgery at the Univeristy of Michigan, Ann Arbor, MI.
Articles by Christina Lewicky-Gaupp, MD
Dee Fenner, MD
DR. FENNER is Professor of Gynecology, University of Michigan Medical School, Ann Arbor, MI.
Articles by Dee Fenner, MD
John O.L. DeLancey, MD
DR. DELANCEY is Professor of Gynecology, director of Pelvic Floor Research, University of Michigan Medical School, Ann Arbor, MI.
Articles by John O.L. DeLancey, MD
Rate this page
Would you recommend this page to a friend?
Your original vote has been tallied and is included in the ratings results.
Practice Tools
