Initial investigation of amenorrhoea

The patient

A 25 year old woman presented to her general practitioner, saying that she had not had a period for 10 months since discontinuing the combined oral contraceptive pill. She had no important gynaecological history and had never been pregnant. She had had a regular 28 day menstrual cycle before taking the contraceptive pill for two years. Her body mass index was 19.5. Although she was not currently planning a family, she was concerned about the impact on her future fertility and whether there was a serious underlying problem.

What is the next investigation?

Primary amenorrhoea is the failure to start menses by the age of 16 (or absence of secondary sexual characteristics by age 14); secondary amenorrhoea is the cessation of established, regular menstruation for six months or longer. Many of the causes of primary and secondary amenorrhoea are the same, so initial investigation in primary care is similar for both.

The most common causes of amenorrhoea are hypothalamic amenorrhoea (34% of cases), polycystic ovarian syndrome (28%), hyperprolactinaemia (14%), and premature ovarian failure (12%).1 Anatomical factors account for 7% of cases. In the general population, secondary amenorrhoea has a prevalence of 3-4%2 and primary amenorrhoea has a prevalence of 0.3%,3 but in women with subfertility the prevalence of amenorrhoea is 10-20%,4 and it can be as high as 44% in competitive athletes.5

History taking should include duration of amenorrhoea, contraceptive history, exercise levels, weight loss or gain, eating habits, and recent stressful events, as well as inquiry about galactorrhoea, hirsuitism (and other signs of hyperandrogenism), and vasomotor symptoms. A thorough drug history should be taken, as several drugs can cause menstrual irregularity or amenorrhoea, such as the antipsychotic phenothiazines or previous treatment with cytotoxic agents. A basic examination of the genital tract …