INTRODUCTION

Pain during menstruation is an almost universal experience among women and, when severe, it has a significant economic impact through loss of time from work or education. Pain related to or exacerbated during menstruation or sexual intercourse may be a consequence of underlying pelvic pathology, although not all women with pelvic pain have a gynecological causes of cyclical pelvic pain but some reference is made to the multifactorial nature of the problem.

DEFINITIONS

Dysmenorrhea is pain that occurs during menstruation. Primary dysmenorrhea is also known as primary spasmodic dysmenorrhea. This is a useful descriptive term for a condition of cramping lower pain that may radiate to the lower back and thighs, often associated with gastrointestinal and neurological symptoms. It typically lasts for between 8 and 72 hours, although young women almost universally experience milder symptoms.

Secondary dysmenorrhea is menstrual related pain, which is secondary to identifiable pelvic pathology. It is characteristically associated with deep painful intercourse and the pain may precede the onset of menstrual bleeding. It is regarded as distinct from the condition of chronic pelvic pain in which pain of at least 6 months’ duration is present continuously or intermittently, not associated exclusively with menstruation or sexual intercourse. However, there is considerable overlap between the two conditions. 

PREVALENCE

The prevalence of chronic pelvic pain among women aged 18-50 years is around 15 per cent.

CAUSES

Uterine hyperactivity has been demonstrated in women with primary dysmenorrhea. The response represents the extremes of the normal physiological response of the uterus to progesterone withdrawal, as primary dysmenorrhea is not regarded as pathological condition.

Severe dysmenorrhea in young women is rarely due to any underlying abnormality. One exception is pain secondary to congenital abnormalities that are associated with obstruction to menstrual flow, for example cryptomenorrhoea in an accessory uterine horn. 

Many of the conditions that cause secondary dysmenorrhea may also present with chronic pelvic pain, in particular endometriosis, which occurs in around one-third of laparoscopies carried out for pelvic pain . Adenomyosis is a cause of secondary dysmenorrhea in older multiparous women. Uterine fibroids do not characteristically cause pain unless there is an acute complication such as torsion or expulsion. 

Around one-third of laparoscopies carried out for the investigation of pelvic pain or secondary dysmenorrhea are negative . This must not be interpreted as implying that the pain is psychogenic. Non-gynecological conditions can be exacerbated or enhanced during menstruation. In particular, irritable bowel syndrome is commonly diagnosed following negative investigations for pelvic pain. Pelvic pain may be musculoskeletal or nerve-related. Psychosocial factors are also important. Factors such as personality traits, coping strategies, health beliefs and influences of family members may predispose an individual to the development of chronic pain. There is also a high prevalence in women with a history of physical or sexual abuse.

Pelvic venous congestion is a condition described in multiparous women of reproductive age. Chronic dull, aching pain is characteristically exacerbated perimenstrually, by activity and by sexual intercourse, and relieved by lying down. It is attributed to the presence of dilated veins in the broad ligament and ovarian plexus. 

MANAGEMENT

Investigation

Primary dysmenorrhea does not require investigation . If symptoms are atypical, giving rise to a suspicion of endometriosis or other pathology pelvic ultrasound is indicated. Although a simple pelvic examination can provide reassurance, this is not indicated in a teenager who is not sexually active . A transabdominal ultrasound scan will exclude uterine abnormalities or significant ovarian pathology and should provide reassurance if negative. 

Abdominal and pelvic examination may be helpful in identifying tenderness and the presence of any masses. As endometriosis can only be diagnosed with certainty by laparoscopy , the nature and risks of the procedure require adequate discussion. 

Management of primary dysmenorrhea

Non -steroidal anti- inflammatory drugs

These drugs inhibition of the enzyme cyclo-oxygenase. Ibuprofen, mefenamic acid and aspirin are all effective in primary dysmenorrhea. The overall incidence of side effects is low and generally related to the gastrointestinal tract

Combined oral contraceptive pill

These preparations have been widely used for many years for the relief of primary dysmenorrhea. The theoretical basis for their action is via inhibition of ovulation. 

Alternative therapies

These are popular with the public and are widely used. These comprised vitamin B1 , vitamin B6 , vitamin E ( in combination with ibuprofen), magnesium , omega -3 fatty acids, and Japanese herbal combination. 

New therapeutic approaches in primary dysmenorrhea

Non-steroidal anti-inflammatory drugs (NSAIDs) in current use inhibit two different is forms of the enzyme cyclooxygenase, known as COX- 1 and COX-2 . Selective inhibitors of the enzyme COX-2 may have similar analgesic efficacy but fewer of the side effects of the drugs in current use. 

Secondary dysmenorrhea and chronic pelvic pain

Management of secondary dysmenorrhea will depend on its underlying cause. In cases of chronic pelvic pain where a diagnosis of endometriosis is suspected, laparoscopic confirmation of the diagnosis is unnecessary and a trial of medical therapy is justified provided that there are no other indications for surgery such as the presence of a suspicious adnexal mass . 

Antidepressants

In the absence of pelvic pathology, there is a tendency for chronic pain to be attributed to depression. Although symptoms of depression and sleep disturbances may be more prevalent among women with chronic pain, the interaction is likely to be complex and not necessarily causative.

Progestogen for pain secondary to pelvic venous congestion

Although there is some dispute about the existence of the condition, treatment with continuous medroxyprogesterone acetate (MPA) has been advocated for women with chronic pelvic pain and dyspareunia attributed to the presence of pelvic varicosities. 

KEY POINTS

• Primary dysmenorrhea is experienced by more than two-thirds of women and a minority are severely incapacitated.
• Investigation is unnecessary unless there are atypical symptoms or abnormal findings on pelvic examination .
• Ultrasound is a useful non-invasive method for the detection of pelvic abnormalities.
• NSAIDs are effective for the first-line management of primary dysmenorrhea.
• COCPS are effective in primary dysmenorrhea .
• Dietary supplements (magnesium, vitamin B1) may have a role in the management of dysmenorrhea. 
• Pain attributed to pelvic venous congestion is relieved by continuous high-dose MPA 
• Antidepressants are not effective in the management of chronic pelvic pain 
• Where possible, chronic pelvic pain should be managed in a multidisciplinary clinic.