Normal menstruation is painless. Does dysmenorrhea always indicate endometriosis?

Recently, there is a saying that has been widely circulated on the Internet: "Normal menstruation is not painful, and dysmenorrhea is caused by endometriosis." Some people also left a message in the background asking whether this statement is true.

First of all, I must say that this view is of course incorrect. In order to reduce unnecessary anxiety, let's talk about the topic of dysmenorrhea today~

Normal menstruation can also cause dysmenorrhea

Just like the human body is covered with skin, the uterus is also covered with endometrium. The skin is divided into the epidermis and dermis, and the endometrium is also divided into the functional layer and the basal layer. Every month, the basal layer of the endometrium will grow a new functional layer of endometrium. The functional layer of endometrium contains abundant glands and small blood vessels from the uterus. If the egg is fertilized, the glands and small blood vessels of the functional layer can support the further development of the early embryo after implantation; if no fertilized egg arrives, the functional layer of endometrium will shrink and peel off due to the loss of hormone support, and the small blood vessels inserted into it will also break by themselves. The resulting mixture of bleeding, exudate and endometrium is menstruation.

After menstruation, the muscles of the uterus will contract automatically, squeezing the uterine cavity and promoting the discharge of menstruation. But just like some people are born with a lot of hair and some are born with oily skin, some completely healthy people will produce too much prostaglandin F2-α in the endometrium during menstruation, or the ratio of prostaglandin F2-α to prostaglandin E2 will increase, causing the uterine muscles to contract too strongly and produce spasmodic pain. This kind of menstrual uterine spasm caused by individual differences without any disease is called primary dysmenorrhea.

Primary dysmenorrhea is very common. In social surveys, the incidence of primary dysmenorrhea can be as high as 93%[1]. This shows that a large number of women with dysmenorrhea are simply troubled by normal physiological phenomena and are not affected by any disease.

The symptoms of primary dysmenorrhea are relatively stable and are basically similar every month. They usually occur shortly before the onset of menstruation or during menstrual bleeding, and most cases can be relieved within 12 to 72 hours. The solution to primary dysmenorrhea is also very simple. Take oral nonsteroidal anti-inflammatory drugs (such as ibuprofen, naproxen, ketoprofen, etc.) as soon as possible after the onset of menstruation to block the continuous synthesis of prostaglandin F2-α, which can significantly relieve dysmenorrhea. The sooner you take the medicine, the better. If you take it too late, although it can prevent the continued synthesis of prostaglandins, the prostaglandins that have been synthesized previously will still cause dysmenorrhea. Primary dysmenorrhea is related to regular ovulation [2]. Therefore, if you happen to need contraception or cannot use nonsteroidal anti-inflammatory drugs, combined oral short-acting contraceptives can relieve dysmenorrhea by inhibiting ovulation. In clinical practice, when the symptoms of primary dysmenorrhea are severe, a combination of two drugs is also used for treatment.

Endometriosis dysmenorrhea is different

Under normal circumstances, the endometrium should grow in the uterine cavity, regulated by the body's hormones, growing, shedding, bleeding, and being expelled from the body, and this cycle repeats. But in some people, the endometrium not only grows in the uterine cavity, but also grows in other strange places such as the pelvic and abdominal cavities, the surface of the ovaries, the lungs, the navel, and the cesarean section incision. These endometriums that grow in the wrong places are also affected by systemic hormone levels, and they shed and bleed periodically in sync with the endometrium in the uterine cavity, which leads to progressively worsening dysmenorrhea, persistent pelvic pain, infertility and other consequences. This is the so-called endometriosis.

This type of dysmenorrhea caused by disease is called secondary dysmenorrhea, which is completely different from the primary dysmenorrhea mentioned above in terms of etiology.

The ectopic endometrium bleeds repeatedly, but the blood has no normal cavity to be discharged, so it is easy to accumulate locally and form cysts. This means that if no intervention is taken, the pain will gradually worsen each time. Due to the presence of lesions, some patients with more typical conditions will also experience symptoms such as persistent abdominal pain, painful urination, painful defecation, constipation or diarrhea, nausea and vomiting, and irregular bleeding that are not related to menstruation [3]. Endometriotic lesions can also destroy normal pelvic structures, induce inflammatory reactions, interfere with implantation, and increase the incidence of infertility. Depending on the site of onset, endometriotic lesions in special locations can also lead to other difficult situations. For example, thoracic endometriosis can cause hemothorax and hemoptysis with repeated menstruation; bladder endometriosis can cause repeated hematuria with menstruation; intestinal endometriosis can cause abdominal distension, abdominal pain, and blood in the stool with menstruation.

Compared with primary dysmenorrhea, which is basically stable and has no significant harm except pain, dysmenorrhea caused by endometriosis needs to be diagnosed and intervened in time to prevent the condition from becoming more serious, complications from increasing, and the individual's quality of life from being increasingly affected.

There are many types of abnormal dysmenorrhea

In addition to endometriosis, uterine hematoma caused by abnormal reproductive tract structure, surgery or other reasons, pelvic inflammatory disease or fallopian tube and ovarian abscesses, adenomyosis, etc. can also cause dysmenorrhea symptoms. These dysmenorrhea caused by congenital abnormalities or acquired diseases are all secondary dysmenorrhea, and the causes need to be identified and addressed accordingly.

So, let’s go back to the point of view provided by the netizen at the beginning of the article: “Normal menstruation is not painful, and dysmenorrhea is caused by endometriosis.” In fact, both the previous and the next sentences are wrong. Normal menstruation can also be painful, which is primary dysmenorrhea; “abnormal dysmenorrhea” is secondary dysmenorrhea, which is not always caused by endometriosis, but may also be other diseases.

So how do ordinary people like us determine whether our dysmenorrhea is primary dysmenorrhea or secondary dysmenorrhea?

Primary dysmenorrhea often begins after menstruation becomes regular during adolescence, which can be months to years after menarche. Each episode of primary dysmenorrhea is generally stable, occurring shortly before the onset of menstruation or during menstrual bleeding, and most episodes can be relieved within 12 to 72 hours. Secondary dysmenorrhea is often not "stable", such as later onset age, sudden increase in pain, increasing pain, persistent discomfort outside of menstruation, dysmenorrhea accompanied by a significant change in menstrual bleeding pattern, or other abnormalities.

In short, if you feel that your condition has been stable and you don’t feel any discomfort, you don’t need to worry too much; if you feel that your dysmenorrhea seems to be wrong and you are not sure, go to the hospital for a check-up. It is best to avoid a false alarm. If you find any problems, you can deal with them in time.

References:

[1] Campbell MA, McGrath PJ. Use of medication by adolescents for the management of menstrual discomfort. Arch Pediatr Adolesc Med. 1997;151(9):905-913. doi:10.1001/archpedi.1997.02170460043007

[2] Willman EA, Collins WP, Clayton SG. Studies in the involvement of prostaglandins in uterine symptomatology and pathology. Br J Obstet Gynaecol. 1976;83(5):337-341. doi:10.1111/j.1471-0528.1976.tb00839.x

[3] Hansen KE, Kesmodel US, Baldursson EB, Kold M, Forman A. Visceral syndrome in endometriosis patients. Eur J Obstet Gynecol Reprod Biol. 2014;179:198-203. doi:10.1016/j.ejogrb.2014.05.024

Author: Doctor Flying Knife Cutting Rain

Reviewer: Lan Yibing, deputy chief physician, Department of Obstetrics and Gynecology, Zhejiang University School of Medicine

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