CASE: Pelvic organ prolapse or Pouch of Douglas hernia?
A 42-year-old G3P2 woman is referred to you by her primary care provider for pelvic organ prolapse. Her medical history reveals that she has been bothered by a sense of pelvic pressure and bulge progressing over several years, and she has noticed that her symptoms are particularly worse during and after bowel movements. She reports some improved bowel evacuation with external splinting of her perineum. Upon closer questioning, the patient reports a history of chronic constipation since childhood associated with straining and a sense of incomplete emptying. She reports spending up to 30 minutes three to four times per day on the commode to completely empty her bowels.
Physical examination reveals an overweight woman with a soft, nontender abdomen remarkable for laparoscopic incision scars from a previous tubal ligation. Inspection of the external genitalia at rest is normal. Cough stress test is negative. At maximum Valsalva, however, there is significant perineal ballooning present.
Speculum examination demonstrates grade 1 uterine prolapse, grade 1 cystocele, and grade 2 rectocele. There is no evidence of pelvic floor tension myalgia. She has weak pelvic muscle strength. Visualization of the anus at maximum Valsalva reveals there is some asymmetric rectal prolapse of the anterior rectal wall. Digital rectal exam is unremarkable.
Are these patient’s symptoms due to pelvic organ prolapse or Pouch of Douglas hernia?
Pelvic organ prolapse: A common problem
Pelvic organ prolapse has an estimated prevalence of 55% in women aged 50 to 59 years.1 More than 200,000 pelvic organ prolapse surgeries are performed annually in the United States.2 Typically, patients report:
- vaginal bulge causing discomfort
- pelvic pressure or heaviness, or
- rubbing of the vaginal bulge on undergarments.
In more advanced pelvic organ prolapse, patients may report voiding dysfunction or stool trapping that requires manual splinting of the prolapse to assist in bladder and bowel evacuation.
Similar to pelvic organ prolapse, Pouch of Douglas hernia also can present with symptoms of:
- pelvic pressure
- vague perineal aching
- defecatory dysfunction.
The phenomenon has been variably referred to in the literature as enterocele, descending perineum syndrome, peritoneocele, or Pouch of Douglas hernia. The concept was first introduced in 19663 and describes descent of the entire pelvic floor and small bowel through a hernia in the Pouch of Douglas (FIGURE 1).
FIGURE 1: Pouch of Douglas hernia. The pelvic floor and small bowel descend into the Pouch of Douglas.
How does it occur? The pathophysiology is thought to be related to excessive abdominal straining in individuals with chronic constipation. This results in diminished pelvic floor muscle tone. Eventually, the whole pelvic floor descends, becoming funnel shaped due to stretching of the puborectalis muscle. Thus, stool is expelled by force, mostly through forces on the anterior rectal wall (which tends to prolapse after stool evacuation, with accompanied mucus secretion, soreness, and irritation).
Clinical pearl: Given the rectal wall prolapse that occurs after stool evacuation in Pouch of Douglas hernia, some patients will describe a rectal lump that bleeds after a bowel movement. The sensation of the rectal lump from the anterior rectal wall prolapse causes further straining.
Your patient reports pelvic pressure and bulge.
How do you proceed?
Look for perineal ballooning. Physical examination should start with inspection of the external genitalia. This inspection will identify any pelvic organ prolapse at or beyond the introitus. However, a Pouch of Douglas hernia will be missed if the patient is not examined during Valsalva or maximal strain. This maneuver will demonstrate the classic finding of perineal ballooning and is crucial to a final diagnosis of Pouch of Douglas hernia. Normally, the perineum will descend 1 cm to 2 cm during maximal strain; in Pouch of Douglas hernias, the perineum can descend up to 4 cm to 8 cm.4
Clinical pearl: It should be noted that, often, patients will not have a great deal of vaginal prolapse accompanying the perineal ballooning. In our opinion, this finding distinguishes Pouch of Douglas hernia from a vaginal vault prolapse caused by an enterocele.
Is rectal prolapse present? Beyond perineal ballooning, the presence of rectal prolapse should be evaluated. A rectocele of some degree is usually present. Asymmetric rectal prolapse affecting the anterior aspect of the rectal wall is consistent with a Pouch of Douglas hernia. This anatomic finding should be distinguished from true circumferential rectal prolapse, which remains in the differential diagnosis.
Basing the diagnosis of Pouch of Douglas hernia on physical examination alone can be difficult. Therefore, imaging studies are essential for accurate diagnosis.