Endometriosis

More Chronicity
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Diagnosis and reasoning

Chronic pelvic pain is a common presenting complaint in women of reproductive age. Despite the traditional association with gynecology, it is important to appreciate that a number of non-gynecological causes may also present in this manner. In this patient, the presence of cyclic worsening of pain, heavy periods and dyspareunia is admittedly more in favor of a gynecologic etiology, with endometriosis, adenomyosis, pelvic inflammatory disease (PID) and fibroids being important diagnoses to consider. Note both interstitial cystitis and irritable bowel syndrome can also present with cyclic pain, and are frequent enough to warrant consideration here. However, the absence of other supportive symptoms argues against these diagnoses. Examination shows the uterus to be normal in size, making adenomysis (where the uterus is typically bulky and enlarged) less likely. In addition, the absence of palpable pelvic or abdominal masses is against fibroids (but does not exclude this possibility). The presence of tenderness and nodularity in the pouch of Douglas provides an important clue - this is strongly suggestive of endometriosis. Note also that endometriosis is the most common cause of chronic pelvic pain in this age group. Tenderness in the pouch of Douglas may also occur in PID - however, the absence of cervicitis or a purulent vaginal discharge argue against this diagnosis (but do not definitively exclude it). Transvaginal ultrasonography is the preferred first line imaging modality in patients with suspected endometriosis, and in this patient may also be useful in excluding the other differentials. The sonographic findings here definitively exclude fibroids and adenomyosis. Note that pelvic endometriotic deposits are extremely difficult to visualize via ultrasonography. However, the fact that the ovaries are displaced and attached to each other provides indirect evidence in support of endometriosis, as this is suggestive of pelvic adhesions (which are a common accompaniment). While the evidence so far is strongly in favor of endometriosis, it should not be forgotten that chronic PID may also result in intraperitoneal adhesions. Thus, there is justification in excluding the two most common pathogens implicated in PID - gonorrhea and chlamydia. In conclusion, given the strong clinical and imaging evidence, this is most likely pelvic endometriosis indeed. Note that a urine culture is not of particular benefit in this patient - especially considering that interstitial cystitis is sterile. In addition, CA-125 is not of diagnostic value here; note also that peritoneal irritation due to endometriotic deposits can result in mild elevation of CA-125 levels. While oral contraceptive pills (OCPs) are the first line treatment in endometriosis, these are not an option in this patient, who is attempting to conceive. Laparoscopy and ablation of the endometriotic deposits is perhaps the best option here. This should be performed by an experienced operator, in view of the pelvic adhesions. Note that antibiotics and antispasmodics are not indicated in her management.


Discussion

Endometriosis is the presence of endometrial tissue outside the uterine cavity, primarily on the ovaries, pelvic peritoneum, uterosacral ligaments and pouch of Douglas. Endometrial deposits may also be found in other pelvic organs such as the bladder and bowel; in extrapelvic locations such as the liver, umbilicus and surgical scars, and even as far away as the lungs. It is a very common gynecological disorder, affecting an estimated 6% to 10% of women of reproductive age. The exact etiology of endometriosis is unclear, although several theories have been postulated. The most commonly accepted is that of retrograde reflux of menstrual tissue. Prolonged exposure to endogenous estrogen (e.g. early menarche, and shorter menstrual cycles) is known to increase the risk for endometriosis. In addition, twin and family studies have suggested a genetic component to the disease. Common presenting symptoms include pelvic pain, dysmenorrhea, deep dyspareunia and back pain; in addition, painful micturition and defecation may occasionally occur. Note however that a significant number of patients are completely asymptomatic. It should also be appreciated that subfertility is a major problem in these patients; an estimated 21% of women undergoing investigation for infertility are found to have the disease. Examination is often unremarkable; positive findings include tender nodularity of the posterior vaginal fornix, tender adnexal masses, a fixed retroverted uterus, or uterine motion tenderness. Transvaginal ultrasonography is the imaging modality of choice in these patients. However, this is mainly sensitive for uterosacral lesions and endometriomas; it does not accurately identify peritoneal lesions. Direct visualization of the pelvis at laparoscopy is the gold standard of diagnosis; histological confirmation is generally unnecessary. In patient who are not aiming to conceive, empirical medical treatment (without laparoscopic confirmation) is usually acceptable. However, if pregnancy is desired, surgical management is usually necessary. Medical therapeutic options include OCPs, progestogens (e.g. medroxyprogesterone acetate), GnRH agonists, androgenic agents (e.g. danazol) and antiprogestogens (e.g. gestrinone). In addition, analgesics (NSAIDs) are of symptomatic value. OCPs and progestogens are considered first line treatment agents, while GnRH agonists and danazol are usually considered at a later point, due to their cost and side effect profiles. In particular, GnRH agonist usage results in deterioration of bone mineral density (BMD). Thus, it is prudent to commence add-back therapy with estrogen and progestogen in these patients. Note also that the levonorgestrel intrauterine system (LNG-IUS) can also be used in the treatment of pelvic pain and dysmenorrhea associated with endometriosis. Surgical options include laparoscopic excision or ablation of endometriotic deposits on the peritoneum; excision, drainage, or ablation of endometriomas; adhesiolysis; resection of rectovaginal nodules; and interruption of neural pathways (eg: presacral neurectomy). Note however that symptoms usually recur after discontinuation of medication, or following conservative surgical treatment. When medical management has failed, definitive surgical management (hysterectomy and bilateral salpingo-oophorectomy) may be considered in women who do not desire future fertility.


Take home messages

  1. Endometriosis is the most common cause of chronic pelvic pain in women of reproductive age.
  2. Ultrasonography is the imaging modality of choice, although the sensitivity varies by type of endometriotic lesion.
  3. While laparoscopy is the gold standard for diagnosis, this may be avoided in patients suitable for pure medical management.
  4. Endometriosis tends to recur following cessation of medication, or following conservative surgery.

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  1. AFP: Chronic Pelvic Pain in Women (2008)
  2. AFP: Diagnosis and Management of Endometriosis (August 2006)
  3. BMJ: Endometriosis (Feb 2007)
  4. NEJM: Endometriosis (2010)
  5. NEJM: Treatment of Endometriosis (2001)