Pelvic organ prolapse (POP) is the bulging of one or several pelvic organs (uterus, bowel, vagina and bladder) into the vagina. It is often caused by weak pelvic floor muscles (PFM) and can occur in mothers after childbirth, either directly or several decades later. The most common risk factors are: vaginal birth, young age at first birth, the number of vaginal deliveries, heavy lifting, increased abdominal pressure, increased BMI and weight and size of the infant (1). Symptoms can vary making it sometimes difficult to diagnose. POP can portrait itself as an inner chafing sensation around the lower pelvis, lower back pain, stress incontinence, urine retention, discomfort during penetrative sex or feeling or seeing a vaginal bulge. Symptoms may result in women becoming inactive and passive. It may have a negative effect on body image and psychological wellbeing. In the end POP may have server effects on quality of life (QoL) (2) (3). There are several levels of severity, ranging from the feeling of something pushing down and out of the vagina to a complete prolapse where one or several pelvic organs protrude through the vaginal opening. Prolapsed organs might not give noticeable symptoms. As a result, there are several ways of defining and diagnosing female POP. Depending on whether the diagnosis is based on symptoms or morphological deviations – that might not generate noticeable symptoms – the prevalence varies hugely. To give an exact number of effected individuals is therefore difficult. However, according to data by the National Health Services (NHS) in United Kingdom one in ten women have had POP surgery by the time they reach 80 (4). According to a study by Swift (5), defining POP simply as a morphological defect would result in a definition that could include around 95% of all adult women. It is important to note that symptoms and not the morphological severity of prolapse are the main reasons for women seeking medical attention and treatment (6).
1.2 Anatomy of the pelvic floor
Understanding the anatomy of the pelvis and pelvic floor muscles is central in order to understand how POP occurs and how it can be treated. The pelvic floor or pelvic diaphragm is a muscular plate, constituted by m. levator ani and m. coccygeus. The main function of the pelvic floor is to keep organs of the bowel and pelvis elevated and prevent them from following the laws of gravity. Together with the diaphragm at the top of the abdominal cavity the pelvic floor keep the organs in one place through the pressure that is built up between the two different diaphragms.
1.2.1 M. levator ani
There are two structural principals that keep uterus and vagina in position. The first of these two is levator ani. It is sling shaped and the largest muscle of the pelvic floor. Stretching from the lateral edge of os coccygeus posteriorly to the symphysis of the pubic bone anteriorly it makes out the main part of the pelvic floor. It is usually divided into three segments. First is pubococcygeus. It is the most anterior segment. It is Y-shaped – stretching past the anus, all the way to the coccyx. Anteriorly it leaves an opening through which the urethra and vagina can access the perineum. This hernial opening is called the urogenital hiatus and is the hernial opening through which the pelvic organs prolapse. The medial part and second segment of levator ani is puborectalis. It is the part that contracts around the rectum and creates a barrier between the colon and anus. Thirdly and most posteriorly – attaching to the coccyx is the iliococcygeus. Levator ani is a constantly contracting muscle making it an occlusive barrier for the lumens of the pelvic organs.
1.2.2 M. coccygeus
The coccygeus muscle is a much smaller muscle compared to m. levator ani, originating from the ischiadic edge. It “folds out” like a hand-held fan and attaches to the lateral surfaces of the sacrum and coccyx, creating the sidewalls of the cradle that the pelvic organs rest in.
1.2.3 Endopelvic fascia
The second structural principle that keeps uterus and vagina in position (the first being levator ani) is the endopelvic fascia. The endopelvic fascia is a set of ligaments. These ligaments attach to the pelvic wall and suspend the organs. They only have 1/100 of the carrying capacity compared to that of levator ani (7); therefore making it an unreliable structure for support if the other structures should fail. The structures have sometimes been likened to a ship moored to a dock with ropes on either side. The ship is the uterus, the ropes are the suspending ligaments and the water is the pelvic floor. Should the water level decrease the ship would have to rely on the support of the ropes. However, the ropes would only be able to hold the weight of the ship for a short period of time before they fail. This is what happens when pelvic organs prolapse.
To make an appointment with Anna Wallin specialist in women’s health please call the clinic on 020 8546 6464.