Dysmenorrhoea

What is dysmenorrhoea?

Dysmenorrhoea is a term used to describe low anterior pelvic pain which occurs in association with periods.

Pathogenesis¹

It is thought to be due to an excess or imbalance of prostaglandins and leukotrienes in the menstrual fluid, which in turn produces vasoconstriction in the uterine vessels, causing the uterine contractions which produce the pain. The prostaglandin release may also be responsible for the symptoms of diarrhoea, nausea, headache and light-headedness which may occur in association with dysmenorrhoea.

Classification

Dysmenorrhoea may be thought of as either primary or secondary.

Primary dysmenorrhoea²

Primary dysmenorrhoea is idiopathic. It often begins with the onset of ovulatory cycles six months to one year after the menarche. The pain begins with the onset of the period, or just before, and may last for 24-72 hours.

Secondary dysmenorrhoea

Secondary dysmenorrhoea occurs in association with some form of pelvic pathology:

• It is more likely to start years after onset of menstruation.

• The pain can precede the start of the period by several days and may last throughout the period. As the pathology progress, there may be pelvic pain which is constant and not cyclical.

• There may be associated dyspareunia.

• Secondary dysmenorrhoea may occur as a result of:

  • Endometriosis/adenomyosis.

  • Pelvic inflammatory disease.

  • Fibroids, when it is often associated with heavy menstrual bleeding.

  • Adhesions.

  • Developmental abnormalities.

  • The copper-containing intrauterine contraception device (Cu-IUCD) may cause increased dysmenorrhoea, though there is little long-term data.

How common is dysmenorrhoea? (Epidemiology)²

• Dysmenorrhoea is common. Prevalence rates vary widely and range from 17-91% in women of reproductive age, with severe pain reported in 2-29% of women.

• Longer duration of menses, early menarche and smoking are all risk factors associated with dysmenorrhoea.

• A weight which is over or under the ideal range may increase the risk of dysmenorrhoea; one review found that this decreased for women with obesity who lost weight, but persisted for women who were underweight and then gained weight. However a 2022 systematic review said that more research was needed to clarify the increased risk, if any, relating to obesity.³⁴

• Childbirth may reduce dysmenorrhoea, with the most significant reduction occurring after the first birth and the severity of primary dysmenorrhoea may reduce with age.⁵⁶⁷

Assessment²

A presumptive diagnosis of primary dysmenorrhoea may be made on history and abdominal examination alone in young patients who are not sexually active, and vaginal examination is not normally required in this group of patients. All women should have an abdominal examination, which will detect a large fibroid uterus and other masses.

Investigation of dysmenorrhoea is primarily aimed at ruling out underlying pathology and may include any or all of the following as appropriate to the individual.

History

• Age at menarche.

• Cycle length.

• Whether the cycle is regular.

• Duration of bleeding.

• Timing of pain in relation to period.

• Location of pain. Dysmenorrhoea is typically suprapubic but may be felt in the back of the legs or lower back

• Smoking history.

• Whether the patient is sexually active. Always see a teenager alone to ask this question, rather than in the presence of parents or friends.

• Obstetric history.

• Contraceptive history.

• Any features suggestive of underlying pathology (for example, vaginal discharge, intermenstrual or postcoital bleeding, dyspareunia).

• Dyschezia and/or rectal pain or bleeding - this is particularly suggestive of endometriosis, as are cyclical symptoms elsewhere in the body for example, cyclical nosebleeds or shoulder tip pain.

Examination

A vaginal examination is indicated if the woman is sexually active. However, a normal examination doesn't exclude pathology such as endometriosis and should not be used as reassurance if there are clinical features that suggest secondary dysmenorrhoea.

• Adenomyosis - the uterus may be enlarged and tender with a typical 'boggy' feel.

• Endometriosis - generalised tenderness in the pelvic area. The uterus may be fixed ± retroverted due to adhesions, and nodules may be palpable in the uterosacral ligaments.

• Partially imperforate hymen (rare).

• Vaginal septum (rare).

Additional investigations

• Speculum examination to visualise the cervix.

• High vaginal swab, chlamydial swabs.

• Cervical smear, if due.

• Pelvic ultrasound - if uterine enlargement or adnexal mass is present or there is suspicion of a secondary cause. As with examination, a normal ultrasound doesn't exclude endometriosis. A transvaginal scan will be more sensitive at picking up pathology than an abdominal one.

Specialist investigations

• MRI scan.

• Laparoscopy.

• Laparotomy with biopsy.

Treatment for dysmenorrhoea

General measures²

• Patients may be concerned about the possibility of underlying pathology and, when appropriate, reassurance and an explanation of the mechanism of menstrual pain may be helpful.

• Lifestyle changes - longitudinal studies have looked at risk factors for dysmenorrhoea and have found a clear association between smoking and dysmenorrhoea, with former smokers having a lower odds ratio for dysmenorrhoea than current smokers; patients should therefore be informed of this relationship and assisted in any attempts to stop smoking.⁸

• There is low-quality evidence that exercise, performed for about 45 to 60 minutes each time, three times per week or more, regardless of intensity, may provide a clinically significant reduction in menstrual pain intensity. This includes activities such as relaxation exercises (progressive muscle relaxation and self-administered massage) and yoga, as well as aerobic exercise and strength training.⁹¹⁰

• Self-help techniques:

  • There is some evidence for benefit to primary dysmenorrhoea from transcutaneous electrical nerve stimulation (TENS) use (high-frequency) and locally applied heat.

  • There is evidence for the use of chamomile, mint and ginger, in tea or capsule form, in reducing primary dysmenorrhoea.¹¹¹²¹³

• Spinal manipulation - there is no evidence for this, and a possibility of harm.¹⁴¹⁵

Pharmacological

• NSAIDs appear to be a very effective treatment for dysmenorrhoea. However there is a significant risk of adverse effects.¹

• Ibuprofen is most often used due to its low incidence of side-effects. Although licensed specifically for dysmenorrhoea, there are concerns that mefenamic acid is more likely to induce seizures in overdose and has a low therapeutic window, increasing the risk of accidental overdose.²

• Weak opioids - there is no evidence of beneficial effect and the potential for addiction means they are not recommended.

Hormonal treatments for dysmenorrhoea
If the woman with dysmenorrhoea does not wish to conceive, offer her hormonal contraception. Ovarian suppression appears to control cyclical pelvic pain, whether or not caused by endometriosis. Adolescents and young adults who do not respond to hormonal treatment after 3-6 should be evaluated for secondary causes of dysmenorrhoea. This is likely in approximately 10% of patients.

• Combined hormonal contraception (CHC) is often used; tailored pill taking, including regimes such as three packets back to back followed by a four day break, or continuous pill taking, may improve dysmenorrhoea more than the traditional 21 day on, 7 days off regimens. Tailored pill taking is unlicensed but recommended in FSRH guidelines. ¹⁶¹⁷¹⁸

• Oral progestogen-only contraception may also be used, with evidence for both desogestrel and drospirenone pills.¹⁹

• Depo-medroxyprogesterone acetate (Depo-Provera^®) is also sometimes used, as many women become amenorrhoeic within a year of starting treatment; even for those who don't, dysmenorrhoea often improves.²⁰

• The levonorgestrel-containing intrauterine device (LNG-IUD) has been shown to reduce the severity of dysmenorrhoea despite not being anovulatory; none of the brands currently available in the UK have a license for this. It could also be considered, even in adolescents.²¹

Surgery

• Hysterectomy. In severe refractory cases, particularly in women who have completed their families, hysterectomy may be considered.