A cystocele is one manifestation of a pelvic floor prolapse, and it is defined as an anterior vaginal wall descent in such a way that the urethrovesical junction (or any point behind it) is found 3 centimeters or less above the hymenal plane.
Pathophysiology of the condition
A common functional symptom associated with a cystocele is stress incontinence, which has been explained in various ways. In one hypothesis, a sudden increase in intra-abdominal pressure couples with a reflex contraction of the levator ani, a broad muscle which forms the pelvic floor.
Such action is associated with passive closure of the urethra, provided pelvic support is normal. This further depends on the approximation of the mucosal lining of the walls of the urethra, with the smooth muscle in the urethral wall and the blood vessels running below the mucosa contributing largely to the firmness of the seal.
The urethra also closes actively because of the contraction of the pelvic floor. Since the bladder neck and the first part of the urethra in females lie above the pelvic floor, contraction of these muscles leads to increase in pressure inside the bladder and the urethra. This prevents the escape of urine with increased abdominal pressure.
Another theory is that pelvic floor contraction compresses the urethra against the firm ligamentous condensations of the pelvic fascia and vagina, closing it against the increased pressure. This is also called the “hammock hypothesis.”
Causes of a cystocele
The urinary bladder, along with other pelvic organs in the female, lies upon and is supported by the strong endopelvic fascia and pelvic floor muscles. The pelvic muscle tone is vital to hold these organs, including the uterus, urinary bladder, urethra, cervix and vagina.
But in cases when these supports are torn or excessively stretched, they are seriously weakened. This allows the bladder to bulge through the vagina, even as far as into or beyond the opening of the vagina. This is how a cystocele is formed. Cystoceles are covered by the vaginal mucosal membrane.
This kind of damage occurs following many types of stresses, such as:
- Vaginal delivery: this is by far the most common factor underlying a cystocele. The process of delivery stretches the pelvic floor as the baby presses against it in its downward journey through the pelvis and vagina. The risk is higher if:
- The delivery was assisted by forceps or ventouse
- The baby was large for the woman’s size
- The woman had multiple deliveries
- The labor was a prolonged process
- Chronic strain on the pelvic floor such as with:
- Habitual constipation
- Straining at stools
- Chronic or very heavy coughing
- Overweight or obesity
- Lifting heavy weights repeatedly
- Nulliparous bladder prolapse: this is a cystocele which occurs in a woman who has never given birth. In some cases it may be due to a congenital weakness of the pelvic muscles.
- Some conditions in which the connective tissues are excessively weak may lead to cystocele, such as:
- Marfan syndrome
- Ehlers-Danlos syndrome
- Joint hypermobility syndrome
Reviewed by: Dr Tomislav Meštrović, MD, PhD