Causes of Procidentia (Complete Rectal or Uterovaginal Prolapse)
Primary Etiologic Factors
Procidentia results from progressive weakening of pelvic floor support structures, primarily caused by stretch injury and denervation of the levator ani muscles during childbearing, which is then aggravated by aging. 1
Obstetric and Mechanical Factors
Childbearing trauma represents the dominant causative mechanism, where stretch injury to the pudendal nerve during delivery causes denervation of the pelvic floor muscles (levator ani and coccygeus), progressively weakening the levator plate over time 1
Multiparity is strongly associated with procidentia development, particularly in white multiparous women, with incidence increasing substantially with age 2
Chronic straining from constipation or defecatory disorders contributes to progressive descent of pelvic organs through the pelvic floor hiatus 3
Structural and Anatomic Defects
Pelvic floor muscle weakness from loss of the firm muscular levator plate (formed by fusion of levator ani muscles between coccyx and anus) allows herniation of pelvic contents 1
Fascial defects in anterior, posterior, and apical compartments permit simultaneous prolapse of multiple pelvic organs (bladder, uterus/vagina, rectum) 3
Rectal wall abnormalities including full-thickness intussusception can progress to external prolapse (procidentia) when the rectal wall protrudes beyond the anal verge 3
Associated Pathologic Conditions
Colorectal malignancy may present initially as sudden rectal procidentia, with patients exhibiting a 4.2-fold increased relative risk for rectosigmoid cancer compared to age-matched controls (5.7% vs 1.4% prevalence) 3
Chronic constipation and mucosal irritation related to prolonged straining may increase cancer incidence in this population 3
Rectocele is an independent risk factor (OR=4.9) for developing fecal incontinence and associated prolapse 3
Iatrogenic and Secondary Causes
Prior pelvic surgery can alter tissue force vectors or remove barriers that previously prevented prolapse, creating both prolapse and potential incontinence 1
Aging-related changes compound the initial childbearing injury through progressive muscle denervation and weakening 1
Increased intra-abdominal pressure from obesity (higher BMI associated with OR=1.1 per unit increase), chronic cough, or heavy lifting accelerates pelvic floor descent 3
Clinical Pitfalls
Do not overlook colorectal cancer screening in patients presenting with procidentia, as endoscopic examination should be performed given the significantly elevated cancer risk, particularly in older patients with new-onset prolapse 3. The combination of age, altered bowel habits, chronic constipation, and mucosal irritation creates a high-risk profile requiring systematic evaluation 3.
Recognize that acute incarceration can occur, presenting as a surgical emergency with urinary retention, obstipation, and potential bowel obstruction if small bowel becomes trapped in the prolapsed tissue 4, 5. Immediate reduction is required, though this should be performed carefully to avoid iatrogenic complications 4.