Next Lesson - Development of the Reproductive System
Core
Support is facilitated by 3 main methods.
Suspension - this maintains the pelvic organs in the pelvic cavity by providing a strong, sling-like support inferiorly in the pelvis.
Attachment - the vagina is supported by its attachments to the endopelvic fascia (the connective tissue that surrounds and supports the pelvic organs), levator ani muscles and the perineal body.
Fusion - support from the fusion of the urogenital diaphragm and the perineal body.
A key function of the pelvic floor is to facilitate urination and defecation and to maintain continence when not attempting to use the toilet.
The pelvic floor maintains the position of the pelvic organs during episodes of high intra-abdominal pressure, such as sneezing, coughing, or laughing.
The birth canal passes through the pelvic floor, which stretches to facilitate childbirth.
Composition of the Pelvic Floor
The levator ani are a U-shaped set of muscles that encircle the urethra, vagina and rectum. Anchored to the pubis (the front of the hip bone) and ischial spine (a bony point on the side wall of the pelvis), with fibres arising from the obturator fascia (the connective tissue covering the obturator internus muscle on the side wall of the pelvis), they spread in a fan shape and act like a sling to support the pelvic organs. The levator ani has three components: pubococcygeus, puborectalis and iliococcygeus. The names of the muscles denote their attachments. For example, pubococcygeus starts at the pubis (its origin) and ends at the coccyx (its insertion). Some fibres, particularly from pubococcygeus, contribute to the perineal body in the midline, while others form slings around the pelvic viscera (the pelvic organs).
The levator ani muscles sit very close to the coccygeus muscle, which is one of the deep muscles of the pelvic floor but is not part of the levator ani group.
There are also three superficial muscles: bulbospongiosus (surrounds the vaginal opening in females or sits around the base of the penis in males), ischiocavernosus (along the line of the ischium), and the superficial transverse perineal. They aid in continence. If there is traumatic injury to the perineum these muscles can be damaged. For example, in childbirth a second degree tear (a tear into the perineal muscles) involves bulbospongiosus, and sometimes the superficial transverse perineal. In some episiotomies (cuts made in the perineum to widen the birth canal), fibres of the superficial transverse perineal may be cut to aid childbirth. An episiotomy does not reliably prevent perineal tears and is performed only when clinically indicated.
Diagram - Muscles of the pelvic floor. It is divided into superficial and deep layers (shown together on the top image and then separately in the next two images)
SimpleMed original by Dr. Maddie Swannack
The three ligaments below all aid in the support of the uterus.
The cardinal ligaments (also known as the transverse ligaments) are situated along the inferior border of the broad ligament of uterus (a sheet of tissue draped over the uterus, tubes and ovaries). They arise from the side of the cervix and the lateral fornix of the vagina (the side of the recess around the cervix), and attach to the lateral pelvic wall at the level of the ischial spine.
The pubocervical ligaments attach from the cervix to the posterior surface of the pubic symphysis (the joint at the front of the pelvis where the two pubic bones meet).
The uterosacral ligaments attach the cervix to the sacrum. They are also known as the rectouterine ligaments and support the uterus.
Diagram - Ligaments of the pelvic floor
SimpleMed original by Dr. Maddie Swannack
The perineal body is a mass of muscle and fibrous tissue at the central point of the perineum (the area between the external genitalia and the anus). Several muscles of the pelvic floor and perineum attach to it. It lies between the vagina and the anus. It is key in maintaining support for the organs of the pelvis.
This term is traditionally used to describe the structures of the deep perineal pouch (a space below the pelvic floor muscles that contains part of the urethra, the external urethral sphincter and the vagina) in the anterior part of the pelvic floor, including muscles and associated fascia related to the urethra, vagina and perineal body.
The pudendal nerve, pudendal arteries and pudendal veins supply the pelvic floor and perineum. The word pudendal comes from a Latin word meaning ‘to be ashamed’, because the nerve supplies the perineum and genitalia.
The uterus, bladder or rectum can all collapse into the vaginal space if inadequately supported. This can have various sexual, urinary or gastrointestinal side effects including pain or discomfort during sex, constipation and a feeling that the bladder is not emptying fully, and can be very psychologically troubling for the patient. Prolapses will often present with a feeling of dragging, bulging or a sensation of tissue descending into the vagina.
Prolapses can be classified by their origin.
An anterior prolapse involves organs anterior to the vagina including:
- Cystocele - bladder prolapses into the vaginal space
- Urethrocele - urethral collapse
- Cystourethrocele - both bladder and urethra
A central prolapse is a uterine prolapse in which the uterus collapses down into the vaginal space. Central prolapses can occur even after a hysterectomy has removed the uterus. This is known as a ‘vault’ prolapse, in which the superior portion of the vagina collapses downwards.
A posterior prolapse can involve:
- Rectocele - rectum prolapses into vaginal space
- Enterocele - a peritoneal sac (a pouch of the thin lining of the abdominal cavity) containing bowel, typically small bowel, descends into the rectovaginal space (between the rectum and the vagina) and bulges against the upper vagina.
Risk factors for pelvic organ prolapse: increased age, parity (having given birth, the more children the higher the risk), number of vaginal deliveries, oestrogen deficiency (usually seen during the menopause), and chronically increased abdominal pressure (for example caused by obesity, long-term constipation or a persistent cough).
Management strategies depend on how the patient is coping, severity of prolapse and their general health:
- Non-surgical - supervised pelvic floor muscle training for at least 16 weeks can be the first option for women with symptoms from a prolapse of stage 1 or 2 (on the POP-Q grading scale, which runs from 1 to 4, where 4 is the most severe). A pessary (a device placed in the vagina to support the organs) can be used alone or with the training. Vaginal oestrogen can be added if there are menopausal vaginal symptoms. Losing weight (if the BMI is over 30), minimising heavy lifting and preventing or treating constipation also help.
- Surgical - offered to women whose symptoms have not improved with non-surgical treatment, or who have declined it. The operation depends on the site of the prolapse and on whether the patient wants to keep the uterus. For uterine prolapse the options include hysterectomy (removal of the uterus) or an operation that keeps the uterus. For vault prolapse the top of the vagina can be fixed back in place, using sutures or mesh. An anterior (front wall) repair is done without mesh, and vaginal mesh is now used only if there is no alternative.
Discuss with the patient what each operation involves, the risk of the prolapse coming back and what recovery to expect, so that the choice reflects the patient’s wishes.
There is risk of stress urinary incontinence (SUI) if the pelvic organs are inadequately supported. SUI occurs when urine leaks from the bladder during episodes of increased abdominal pressure. Usually increased pressure will not cause leakage, however, if the pelvic floor muscles are not adequately supporting the urethra, the pressure cannot be resisted and leakage occurs.
Risk factors include increased age, pregnancy and vaginal birth, obesity, and oestrogen deficiency (usually due to menopause).
Management strategies include pelvic floor muscle training through pelvic floor exercises. NICE advises a supervised programme lasting at least 3 months, with at least 8 contractions three times a day. If non-surgical treatment is not effective, surgical interventions can be considered. These include a sling placed under the urethra to support it, made either from the patient’s own tissue or from synthetic mesh tape.
Vaginal childbirth can be traumatic to the pelvic floor because the fetal head stretches the structures of the pelvic floor. Up to 9 in 10 first-time mothers who have a vaginal birth have some sort of tear, graze or episiotomy. In more severe cases, tearing of the perineum (the area between the vagina and the anus) can also involve the underlying structures.
Perineal tears in childbirth are graded as follows:
- First degree: tear involves the perineal skin only
- Second degree: tear extends into the perineal muscles
- Third degree: tear extends into the anal sphincter complex (the muscles that close the anus)
- Fourth degree: tear extends through the anal sphincter complex and anal epithelium (the lining of the anal canal)
Tears of a higher grade and severity can have lifelong consequences through the damage they cause to the structures of the perineum especially to the perineal body. This factor links to why increased parity is a risk factor for pelvic floor dysfunction.
An episiotomy is a surgical incision made to the perineum in selected situations such as suspected fetal compromise (signs that the baby is unwell) or instrumental delivery (birth with forceps or a ventouse suction cup). NICE advises that it should not be done routinely, only when there is a clinical need.
It involves the cutting of bulbospongiosus and, in some women, the superficial transverse perineal muscle at an oblique angle (NICE advises 45 to 60 degrees to the vertical axis) to relieve pressure on the perineum, allowing more space to deliver the child. In some births, particularly forceps deliveries, an episiotomy may reduce the risk of a high grade tear (one that reaches the anal sphincter, such as a third-degree tear). NICE advises against doing an episiotomy routinely to prevent damage. A Cochrane review of births where an unassisted vaginal birth was expected found that using episiotomy only when needed may result in about 30% fewer women having severe perineal or vaginal trauma than routine use (low-certainty evidence).
The pelvic floor can be weakened through childbirth, age and chronically increased intra-abdominal pressure. This can have many consequences, such as urinary incontinence and pelvic organ prolapse. Prolapse can cause a feeling of heaviness, and pain during sex.
To help strengthen the pelvic floor, a number of exercises can be performed. A common regimen is the Kegel exercises. The first step is to identify the pelvic floor muscles. This can be done by briefly stopping urination mid-stream to identify the muscles, but this should not be practised regularly. The muscles that are clenched to stop the stream of urine are the muscles of the pelvic floor. Another method of finding the pelvic floor muscles is less technical and more unconventional. Imagine sitting in a bath of eels and clenching the muscles to stop the eels getting into the vagina. This upward clenching motion uses the pelvic floor.
Once the muscles of the pelvic floor are identified, Kegel exercises can be performed. The muscles should be contracted for 5 seconds, then relaxed for 5 seconds. This should be repeated 10 times, ideally three times per day. The exercises should be continued even when improvement is noticed. This will help to strengthen the pelvic floor to lessen the effects of or prevent the symptoms of pelvic floor weakness.
Edited by: Dr. Ben Appleby and Dr. Thomas Burnell
Reviewed by: Dr. Marcus Judge
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