External anal sphincter
nswer B) Rectovaginal fascia
In a multiparous, postmenopausal woman presenting with pelvic pain, constipation, and bulging of the posterior vaginal wall during Valsalva maneuver, rectocele is the most likely diagnosis.
The rectovaginal fascia is part of the fibromuscular structure of the perianal body, and it separates the vagina and the rectum.
Acquired weakness of the rectovaginal fascia, e.g., due to multiple vaginal deliveries or low estrogen levels during menopause, can cause herniation of the posterior vaginal wall, which is associated with protrusion of the rectum into the vaginal canal (i.e. rectocele), which can become visible during Valsalva maneuver.
Typical symptoms of rectocele include increased fecal urgency and a sensation of incomplete evacuation following defecation, which are seen here.
Patients with large rectoceles may report needing to insert their fingers into the vagina to press against the rectovaginal fascia, thereby facilitating the emptying of stool.
First-line therapy consists of conservative strategies, such as Kegel exercises, weight loss, a high-fiber diet, and vaginal pessaries.