What Causes Pelvic Organ Prolapse?

Pelvic organ prolapse is a common condition in women, especially following one or more vaginal deliveries. It refers to the descent of one or more pelvic organs through the genital hiatus. This is the opening in the pelvic supporting structures that gives way for these organs to pass through to the outside.

The pelvic organs in women comprise the urinary bladder and urethra, the uterus, cervix and vagina, and the rectum, as well as part of the small intestine.

Pelvic organ prolapse is not a serious condition in terms of danger to life or health. However, it can cause immense psychological stress and inconvenience and may lead to incompetence of the bladder and bowel. Urinary incontinence, sexual dysfunction, and bowel problems may result from pelvic prolapse. As a result, it can significantly reduce the quality of life of those affected.

The incidence of pelvic organ prolapse is rising with the aging population, or the increasing number of elderly people in developed nations.

Causes

Prolapse of the pelvic organs occurs because the supporting structures of the pelvic floor become or are too weak to resist their weight. It can also happen if the downward pressure exerted on these organs is repeated or excessive, causing the supports to weaken.

The pelvic supports are formed of a thin but strong sheet of muscle and fibrous connective tissue, which covers the muscles. In addition, the connective tissue thickens into stronger bands called the pelvic ligaments. These anchor the whole of the pelvic supports to the ring of bone around it.

The pelvic muscles are vital to the integrity of the ring. When these are too weak, more strain is put upon the fibrous tissue which stretches as a result. Finally, the fibrous tissue fails, and the pelvic organs drop downwards, pushing down through the overlying vaginal wall and producing a prolapse.

Risk Factors

The weakness of the pelvic supporting tissues is usually acquired, but may rarely be congenital. Acquired weakness of the pelvic supports may be caused by:

• Increasing age: as age increases, the connective tissue becomes weaker, and accumulated stretching and strain take their toll, pushing up the prevalence of prolapse
• Childbirth: prolonged and difficult labor, and giving birth to big babies, may both be associated with pelvic organ prolapse. Multiparous women (who have given birth more than once) have a higher incidence. Approximately 50% of all parous women have some degree of prolapse.
• Hormonal changes: in the peri-menopausal and post-menopausal age group, the lowered hormone levels contribute to the loss of strength of the vaginal mucous membrane and the fibrous pelvic supports, which weakens the pelvic diaphragm.
• History of pelvic surgery: removal of the uterus or pulling up the urinary bladder may eliminate one source of pelvic support

Factors that increase the pressure on the pelvic organs push them against the pelvic supports and weaken the latter include:

• Excess weight (e.g. overweight or obese)
• Chronic or violent cough (e.g. pulmonary disease, lung allergies, smoker’s cough)
• Repeated sneezing or straining to defecate due to constipation
• Participation in heavy lifting activities
• Presence of pelvic tumors or cysts

Congenital conditions such as the connective tissue disorders lead to weakness of the collagen fibers, so that the pelvic supports are already unnaturally thin. These include joint hypermobility syndrome, Marfan syndrome, and Ehlers-Danlos syndrome.

References

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3056425/
• http://www.nhs.uk/conditions/Prolapse-of-the-uterus/Pages/Introduction.aspx
• http://www.health.harvard.edu/family-health-guide/what-to-do-about-pelvic-organ-prolapse