Does Endometriosis Always Cause Pain?

Frederick R. Jelovsek MD

Pelvic pain is estimated to be responsible for almost 25% of gynecology visits. When a laparoscopy is performed and mild or minimal endometriosis is found, doctors and patients alike may attribute the pain to the endometriosis when in fact, the endometriosis is asymptomatic and not the cause of the pain. We know that up to 15% of women may have endometriosis without having any pain symptoms. How then, do we determine when endometriosis is present, whether it is the cause of pelvic pain so we can stop looking for another cause.

In a recent clinical commentary article, Hurd WW: Criteria that indicate endometriosis is the cause of chronic pelvic pain. Obstet Gynecol 1998;92:1029-32, several conditions are identified that should be met before attributing chronic pain to endometriosis:

• the pelvic pain should be cyclical, worsening right before and during menses
• the endometriosis should be diagnosed surgically, not just by clinical history and pelvic exam alone
• appropriate treatment of endometriosis should be associated with a prolonged pain relief (not resume immediately after stopping medical therapy for example)

Cyclical pain - The nature of pain production by endometriosis is not completely known but the implants are hormonally receptive to varying levels during the normal menstrual cycle. Sometimes pain with a period can just be due to high intrauterine pressure caused by the uterine muscle cramping to expel menstrual tissue. If there is any degree of cervical narrowing (stenosis) that acts to block the quick expulsion of tissue, intrauterine pressures get extremely high and cause pain independent of any endometriosis present. While endometriosis can cause pain and painful intercourse throughout the entire menstrual cycle, if there is no worsening at the time of menses, chronic pain is very less likely to be due to endometriosis.

Diagnosis by surgery necessary - Although history and physical exam and even response to medical therapy that blocks ovulation can be suspicious for the diagnosis of endometriosis, these criteria often prove to be wrong when surgery is finally undertaken. Medical therapy that blocks ovulation will help dysmenorrhea of any cause, not just that of endometriosis. A second question that occurs, does endometriosis need to be diagnosed by biopsy at the time of surgery? If there are obvious blue or red spots (powder burns), the general consensus is that it is not cost effective to biopsy. If, however, there are just the hint of tiny clear vesicles, then a biopsy may be needed to confirm the diagnosis. Keep in mind that these clear vesicles may represent minimal endometriosis which is not actually responsible for pelvic pain compared to the blue and red forms of endometriosis.

Prolonged pain relief from adequate treatment - Whether medical or surgical resection is chosen for endometriosis treatment, the average duration of significantly decreased pain symptoms is about 10 months after cessation of medical therapy or the date of surgical therapy. Since many women have a 1-3 month period of pain reduction after laparoscopy in which no pain cause was found, recurrence of pain less than 6-8 months after surgery or discontinuance of medical therapy, should be viewed with suspicion that the pain is caused by endometriosis. Many physicians and women are mislead by temporary pain relief with ovulation suppression medications and assume that if the pain resumes immediately after therapy, that means endometriosis is recurring and causing the pain.

On the basis of studies of asymptomatic and symptomatic women, it is possible that some endometriosis may be a normal variant in some women. If you have endometriosis and pain, it may be wise to see if your pain meets these criteria; if not, you and your doctor may need to continue looking for causes of your pain.