Infertility in humans is defined as the failure to conceive after one year of unprotected sexual intercourse. Approximately 10-15% of couples, or one in every seven marriages in the United States, is affected by infertility. In approximately 40% of cases, the cause of infertility is due to a female factor, 40% of cases are due to a male factor, and in the remaining instances no cause can be found despite thorough evaluation. In addition, in as many as 35% of couples, multiple conditions causing infertility can be identified.
Male factors of infertility include decreased sperm production, obstruction of the male reproductive tract preventing passage of semen, and failure to deposit semen in the vagina. Impaired sperm production may be a result of a varicocele (a varicose vein in the testicles), testicular failure, endocrinologic dysfunction, undescended testicles, or systemic infection. Infection of the genital tract can lead to ductal obstruction, and congenital absence of the vas deferens will also prevent the passage of semen. Failure to deposit the semen in the vagina results from impotence and ejaculation disorders.
In female infertility, ovulatory dysfunction, including lack of ovulation and poor progesterone production, is responsible for approximately 15% of infertility. Fallopian tube obstruction and pelvic adhesions, which may result from pelvic inflammatory disease, endometriosis, and postpartum infections, account for 30% of infertility. Cervical factors, which may impede the passage of sperm into the uterus, are responsible for approximately 5% of infertility.
Uterine factors, including polyps, adhesions, leiomyomata (fibroid tumors), and congenital anomalies, may interfere with implantation of the embryo. Approximately 5% of infertility is caused by these abnormalities. Rarely, an immunologic incompatibility between the partners exists.
Male factor infertility is most commonly treated by artificial insemination. If a severe problem is found, use of donor sperm may be necessary. In women with ovulatory problems, medication such as clomiphene citrate or human menopausal gonadotropins can be used to induce ovulation. Problems with progesterone production can be corrected with clomiphene citrate or progesterone supplementation. Fallopian tube disease or pelvic adhesions are treated with surgery. If this is not successful, in vitro fertilization may be indicated. Endometriosis can be treated with medication that suppresses its development and growth, although adhesions associated with endometriosis may require surgical removal. Poor cervical mucus or cervical narrowing can be bypassed with artificial insemination. Uterine problems generally require surgical correcti