A 54-year-old postmenopausal woman comes to the office due to increasing vaginal pressure for the past 3 months. The patient has had no vaginal bleeding or abnormal discharge. BMI is 18 kg/m2. Vital signs are normal. On speculum examination, the anterior vaginal wall bulges with the Valsalva maneuver. On bimanual examination, the uterus is small and mobile. Which of the following is the most likely underlying cause of this patient's presentation?
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This patient with vaginal wall bulging and pressure has pelvic organ prolapse, the herniation of pelvic organs (eg, bladder, rectum) into the vagina due to pelvic floor weakness. The most common risk factor is vaginal delivery, which can either directly damage the pelvic musculature or injure the pudendal nerve that provides motor and sensory innervation to the pelvic floor muscles and external urethral and anal sphincters.
Although some women have symptoms of prolapse immediately after delivery (typically due to complete transection of the pudendal nerve), most patients develop prolapse months to years later due to slow degeneration of the pelvic floor muscles. Delivery-related muscle injury, in addition to age-related tissue atrophy, can also contribute to pelvic floor laxity and resultant herniation of pelvic organs through the vaginal wall.
Patients typically have vaginal pressure; other symptoms (eg, bladder dysfunction, constipation) may develop, depending on whether the prolapse is located at the anterior vaginal wall (ie, herniated bladder [cystocele]) or the posterior vaginal wall (ie, herniated rectum [rectocele]). On examination, patients typically have a vaginal bulge exacerbated with the Valsalva maneuver (ie, increased intraabdominal pressure).
(Choice A) The uterosacral ligaments run along the lateral pelvic wall and support the uterus and vaginal apex by lifting and anchoring them to the sacrum. Excessive ligament laxity contributes to uterine and vaginal prolapse; in contrast, chronic endometriosis causes fibrosis and scarring that can shorten the ligaments and fix pelvic organs in place.
(Choice B) Ligation of the uterine artery decreases blood flow to the uterus to shrink uterine fibroids. However, the pelvic floor muscles are supplied primarily by the internal pudendal artery (another branch of the internal iliac artery); therefore, uterine artery ligation would not compromise pelvic floor strength.
(Choice D) The presence of uterine leiomyomas increase pressure on the pelvic floor and place greater strain on the pelvic floor muscles. However, this patient has a small mobile uterus on examination, making uterine leiomyomas an unlikely cause of her pelvic organ prolapse.
Educational objective:
Pudendal nerve injury during vaginal delivery leads to gradual denervation and weakness of the pelvic floor muscles. In combination with age-related tissue atrophy, this injury contributes to pelvic organ prolapse (eg, cystocele).