Updated: Oct 2, 2020
The Uterosacral Ligaments are 2 ligaments that are there to support the structure of the Uterus and often affected in Deep Infiltrating Endometriosis (DIE). These ligaments are composed of smooth muscle and connective tissue along nerve fibres. The paired uterosacral ligaments are extraperitoneal structures which extend posteriorly from the uterine cervix to sacrum, forming the lateral boundaries of the rectouterine and rectovaginal spaces.
The Uterosacral Ligament (Rectouterine ligament; posterior ligament) consists of the rectovaginal fold of peritoneum, which is reflected from the back of the posterior fornix of the vagina on to the front of the rectum. It forms the bottom of a deep pouch called the rectouterine excavation, which is bounded in front by the posterior wall of the uterus, the supravaginal cervix, and the posterior fornix of the vagina; behind, by the rectum; and laterally by two crescentic folds of peritoneum which pass backward from the cervix uteri on either side of the rectum to the posterior wall of the pelvis. These folds are named the sacrogenital or rectouterine folds. They contain a considerable amount of fibrous tissue and non-striped muscular fibres which are attached to the front of the sacrum.
2. Round Ligament
3. Broad Ligament
4. Fallopian Tube
5. Ovarian Ligament
6. Infundibular Pelvic Ligament
8. Uterosacral Ligament
9. Pouch of Douglas
10. Sigmoid Colon
DIE of the Uterosacral Ligaments is the most common site of DIE in the pelvis. A nodule within the Uterosacral Ligament may infiltrate the parametrium, increasing the complexity of surgical resection. Larger nodules noted on transvaginal ultrasound greater than 17mm should raise suspicion for ureteral involvement. Nodules may also invade the Torus Uterinus, the thickening between the insertion of the USLs behind the posterior cervix. However, with untrained sonographers this is hard to detect.
Substantial endometriosis around the Sacro-uterine ligaments
Corresponding laparoscopic depiction of Type 2P uterosacral ligament deep endometriosis nodule before excision and ureteral resection and reimplantation
It is possible to separate nerves associated with the voiding function from the uterosacral ligament. Thus, we can remove uterosacral ligaments safely. If there are adhesions between the uterus and rectum, it is possible to remove adhesion after opening the perirectal space. In our study, endometrial tissue was confirmed histologically in the tissue removed with the uterosacral ligament, and no other organs were inadvertently injured. The results suggest that laparoscopic resection of the uterosacral ligament is useful and safe
(Dr Omar Gailani https://doi.org/10.1016/j.jmig.2015.08.408)
Infiltrating endometriotic lesion in the rectovaginal septum involving the sigmoid and the uterosacral ligament. https://www.hindawi.com/journals/amed/2018/3461209/
Early stage of rectovaginal endometriosis with the rectum shown tented up. Still most of the upper part of the vagina could be seen underneath the posterior part of the cervix between the two uterosacral ligaments
NICE guidelines for treatment (UK)
published in 2007
The evidence on Laparoscopic Uterine Nerve Ablation (LUNA) for chronic pelvic pain suggests that it is not efficacious and therefore should not be used.
LUNA is normally performed under general anaesthesia. The peritoneal cavity is insufflating with carbon dioxide gas and small incisions are made in the abdomen to provide access for the laparoscope and surgical instruments. The uterus is anteverted with a uterine manipulator and the uterosacral ligaments are identified and transected close to their attachment to the cervix. One or both of the ligaments may be transected. A small portion of ligament is sometimes resected and examined histologically to confirm the presence of nerve fibres. LUNA is often carried out during the course of other surgical treatment for endometriosis. The Specialist Advisers stated that potential adverse events include vascular, bowel or ureter injury, bleeding, the need for conversion to open surgery, and prolapse https://www.nice.org.uk/guidance/ipg234/chapter/1-Guidance
Surgical nerve ablation has been used for a long time in the treatment of chronic pelvic pain. The three techniques used are laparoscopic uterosacral nerve ablation [LUNA] and excision [LUNE] and laparoscopic presacral neurectomy [LPSN]. All these techniques are useful to different extent in treating midline lower abdominal pain mainly dysmenorrhoea.
Laparoscopic Uterosacral Nerve Ablation (LUNA)
This procedure involves cutting those nerves that run in the uterosacral nerve region, which lead to the superior hypogastric plexus that is removed during a PSN. Uterosacral ligaments that lie behind the uterus carry these nerves. However, the majority of the nerves actually lie adjacent to the ligaments and when a LUNA is performed, the nerves may not be completely transected. Most studies do not find as good, long-term relief following LUNA, and few find any significant relief beyond 6 months. Because of little long-term benefit, most endometriosis specialists or pelvic pain specialists do not perform LUNA any more. LUNA partly denervates the uterus and has up to 80% success rate in the short term, but pain usually recurs within one year or so. It is a simple procedure to perform.
Laparoscopic Uterosacral Nerve Excision (LUNE)
However, it is not the appropriate procedure to perform when the ligament is heavily involved with bowel adhesions or endometriosis. In these cases, proper dissection of these adhesions and excision of the ligament will be the more effective technique [LUNE]. This will have a double benefit of reducing the endometriotic load, as well as denervating the uterus.
It has already been reported that 73% of removed specimens from women with such a combination of both LUNA and LUNE showed histological evidence of endometriosis. This emphasises the recommendation of the American College of Obstetrician and Gynaecologists Practice Bulletin which suggested using GnRH-a for treating patients with chronic pelvic pain and negative findings during laparoscopy, with no other detectable nongynecological abnormality. It is also reassuring that second look laparoscopy did not show significant adhesions formation following this procedure when it was performed as part of a more extensive surgery to remove all deep pelvic endometriosis. [Chapron et al, 2001].
Laparoscopic Presacral Neurectomy [LPSN]
LPSN is a procedure that can be performed through a larger incision in the abdomen (laparotomy), or preferably, through the minimally invasive laparoscopic approach. The nerves coming from the uterus, which conduct pain signals, are interrupted or cut to prevent those signals from reaching the brain. Most studies suggest that PSN helps approximately 75% of the patients who have it performed. Most commonly, the results are immediate and last for many years. There have been some studies that suggest the nerves can grow back, but this cobweb-like group of nerves does not usually have a sheath along which they could grow back.
LPSN is more effective than LUNA in relieving central lower abdominal pain and dysmenorrhoea for longer periods of time, when the procedure is properly performed [Tjaden et al, 1990]. However, Candiani et al in 1992 reported no significant difference in frequency and severity of dysmenorrhoea, pelvic pain or dyspareunia after long term follow-up in two groups of patients who had conservative surgery for endometriosis with or without presacral neurectomy. This emphasises the need for complete excision of all classical and non-classical endometriotic lesions to improve the therapeutic results and not to rely only on such nerve ablation techniques.
LPSN is a more elaborate procedure than LUNA and care should be taken to avoid vascular injury and retroperitoneal haematoma formation. The removal of the nerves is performed in the area near the sacral promontory between the major blood vessels. This surgery must be performed carefully and meticulously in order to avoid injury to these vessels and the right ureter, which delineates the lateral border of the dissection for the PSN. Few gynaecologists have training in PSN.
As with all surgery, there are some potential side effects that could occur, but these are uncommon, occurring in less than 5-10% of patients. They include constipation, which is usually mild and often improves over time or with dietary modification, and urinary complaints, that include urgency, which can usually be managed with timed voiding. Often, bladder urgency is improved, while about 5% may note a worsening of urgency, which can often be managed with timed voiding.
Because it is an organ-sparing option, PSN has no impact on fertility or pregnancy; it also does not affect the activity of the uterus during labour. There has been some suggestion that PSN may result in “painless labour”, and we usually recommend that patients mention to their obstetricians that they have had a PSN so that their cervical length can be followed to make sure they are not having premature labour they cannot feel. The likelihood of this occurring is said to be minimal.