Primary infertility occurs in couples with no previous history of conception. Secondary infertility exists when a prior conception has been, at a minimum, documented by a positive human chorionic gonadotropin (hCG), histology, or ultrasound. The causes of infertility are equally distributed between males and females and often the physician encounters multiple etiologies during the investigation. Most infertile couples have one or more of three major causes: a male factor, ovulatory dysfunction, or tubal-peritoneal disease.

Males without stigmata of endocrinopathies or general medical illnesses require an analysis of their semen as the minimum initial step of evaluation. Those suspected of deficient androgen production and/or action and those with abnormal sperm counts, motility, and/or morphology need assessment of their serum concentrations of selected reproductive hormones. 

When these initial investigations are negative and there are no demonstrable etiologic female factors underlying the state of infertility, specialized sperm function and sperm allergy testing needs to be performed. The initial investigation of the female partner is best served by assessing the frequency of ovulation and adequacy of corpus luteum function. 

Women without ovulatory defects should be assessed for the presence of the hostile cervical mucus and structural anomalies of the reproductive tract. Investigations of patients with menstrual dysfunctions should be based upon the presence or absence of hirsutism, changes in body weight, and evidence of other endocrinopathies or medical illnesses. Following the identification and normalization of causes of anovulation, further work-up of patients who remain infertile is similar to those with regular menstrual cycles. The diagnosis of idiopathic infertility is essentially by exclusion of all other causes. Algorithms for the diagnostic evaluation of most infertile couples are provided.