The postcoital test has poor diagnostic and prognostic characteristics. Nevertheless, some physicians believe it can identify scanty or abnormal mucus that might impair fertility. One way to avoid 'hostile' cervical mucus is intrauterine insemination. With this technique, the physician injects sperm directly into the uterine cavity through a small catheter passed through the cervix; the theory is to bypass the "hostile" cervical mucus. Although most gynaecological societies do not endorse use of intrauterine insemination for hostile cervical mucus, some physicians consider it an effective treatment for women with infertility thought due to cervical mucus problems.