There is a common misconception that every woman suffers from period pain and that this pain is very severe. In fact, only one half of woman experience period pain meaning that other woman may experience mild discomfort or almost no sensation at all. Most women who do experience period pain have mild pain for a day or two. This is often manageable with little or no pain-relieving medication and does not affect daily function.
A minority of women experience severe period pain which is so debilitating that it can affect all aspects of daily life and even cause women to dread menstruation. Period pain is more common in young women and can persist throughout the menstruating years in a woman’s life. It tends, however, to ease significantly after having the first child although not every woman who suffers with period pain will find this relief after childbirth. Painful periods that are not associated with any underlying gynecological disorder also tends to ease with age, irrespective of childbirth.
What is dysmenorrhea?
Dysmenorrhea is the term for menstrual pain, particularly severe period pain. The pain is mainly muscular in origin and therefore period pain may also be referred to as menstrual cramps. It is important to note that menstrual pain arises from cramping of the muscular uterus and should be differentiated from ovarian pain. It is also referred to as ovulation pain and can occur when there is peritoneal irritation associated with slight bleeding from the rupture follicle ovarian follicle (Mittelschmerz) or with certain gynecological disorders like PCOS (polycystic ovarian syndrome).
Period pain is a result of menstrual cramps. The uterus, specifically the uterine wall, is largely muscular. This muscular layer is known as the myometrium. It is has a rich supply of blood vessels, as it is has higher metabolic needs as with any muscle in the body. Period pain is a combination of cramping of the uterus, decreased blood flow to the myometrium and increased sensitivity. This is a rather simple description of period pain but the actual process is a bit more complex. It is important to also consider whether the pain is occurring on its own with no underlying disease, where it is then known as primary dysmenorrhea, or if it is associated with certain gynecological disorders in which case it is referred to as secondary dysmenorrhea.
Causes of Period Pain
In order to understand the pathophysiology of dysmenorrhea, it is important to have a knowledge of the menstrual cycle. The average cycle lasts 28 days and is a carefully coordinated, hormone driven process that prepares the uterus for pregnancy and essentially ‘renews’ the uterus for the next cycle. The menstrual cycle starts on the first day of menstruation – the first day of the bleed. It is during menstruation and sometimes just a day or two before it when period pain is most prominent.
The menstrual cycle is marked by by two major events – ovulation and menstruation. Ovulation is the release of egg cell (ovum) from the ovary and into the fallopian tube. This is a result of many ovarian follicles maturing and only one rupturing to release the egg. Ovulation occurs around day 14 of the menstrual cycle and sometimes blood from the ruptured follicle leaks into the abdominal cavity and causes peritoneal irritation.
This may result in pain known as Mittelschmerz, mid-cycle or ovulation pain. The ovum awaits fertilization by a sperm cell following intercourse. During this first half of the menstrual cycle, the inner lining of the uterus (endometrium) thickens to sustain the fertilized ovum until implantation occurs.
Should fertilization not occur, the hormone levels drop and the uterus prepares for menstruation. The endometrium is shed and passes out through the vagina along with blood and sometimes clots. The expulsion of the menses is aided by uterine contractions. It is at this point in time that period pain is experienced and in most women it only lasts for a day or two. The contraction of the uterus is a result of prostaglandin secretion by the endometrium. Prostaglandin levels increase just before the period and peaks at the start of menstruation. It subsequently decreases. This rise and peaking of the prostaglandin levels is the reason why period pain is experienced at the beginning of menstruation.
Prostaglandins are also known to have a vasoconstrictor effect on the blood vessels, meaning that the blood flow to the uterus is reduced. This is necessary in menstruation as it prevents excessive bleeding. However, muscle contractions coupled with decreased blood flow to the myometrium can increase the chances of cramping which results in pain. This may be due to a combination of increased prostaglandin levels and hypersensitivity of the uterus during this time. In women with severe menstrual pain, these factors may be attenuated by various factors which leads to excessive muscle contraction and greater than normal uterine hypersensitivity. This in turn presents as severe pain.
Dysmenorrhea is more likely to occur in women with the one or more of the following risk factors :
- Earlier age of menarche
- Cigarette smoking
- Alcohol use
- Heavy periods
Family history appears to be a strong risk factor, however, it has to be differentiated between primary and secondary dysmenorrhea. Some gynecological disorders may be associated with a family history and this could be the cause of the pain (secondary dysmenorrhea).
Types of Dysmenorrhea
There are two types of dysmenorrhea – primary and secondary. Most cases of period pain are primary dysmenorrhea.
This is the common type of period pain due to menstrual cramping. There is no underlying disorder of the reproductive organs or any other pelvic disease. It tends to start a year or two after menarche (the onset of menstruation) and can vary from mild to severe. The pain is typically felt in the lower abdomen and back. It often ceases after having the first child or may ease with age.
This is the mild to severe period pain seen with underlying disorders of the reproductive organs. It does not often arise just after menarche as is the case with primary dysmenorrhea. The pain tends to lasts for longer periods in the menstrual cycle, and pain may even be present throughout the cycle and exacerbated during menstruation. Overall secondary dysmenorrhea is less commonly seen but may arise with the following conditions :