For about one in 10 couples in the U.S., trying to have a baby changes from a pleasure into a struggle. If you're among those couples, you may need to have testing to find out what's causing the problem.

Finding the cause of infertility sometimes involves a good deal of detective work. Doctors usually start with the simple blood and semen tests first. If those don't provide answers, more invasive testing may be needed.

Don't give up hope if testing doesn't reveal a cause of infertility. In about one in 10 cases, no cause can be found. Still, testing will yield information you and your doctor need to make a logical treatment plan.

Tests for women
Blood tests are done to check hormones that affect a woman's fertility. Hormones that may be tested include:

• Follicle-stimulating hormone (FSH). High levels point to a low egg supply and the possibility of poor-quality eggs.
• Luteinizing hormone (LH), which triggers ovulation. A high ratio of LH to FSH may be a sign of polycystic ovary syndrome.
• Progesterone, which can be tested to confirm that ovulation occurred.
• Prolactin. High levels can prevent ovulation.
• Thyroid-stimulating hormone (TSH). Abnormal levels can interfere with fertility.

Tests to check the pelvic organs may be the next step. Some tests a doctor may recommend include:

• Hysterosalpinogram (HSG). This test is commonly done to check the pelvic organs. For the test, dye is injected through the cervix into the uterus and fallopian tubes. The pelvic area is then scanned by a special x-ray machine. The images can help the doctor diagnose blocked fallopian tubes, fibroids, an abnormally shaped uterus or scar tissue.
• Hysteroscopy. If the HSG suggests that the uterus is abnormal, the doctor may do this test. A thin lighted telescope is passed through the cervix into the uterus. This lets the doctor sees any growths or abnormalities inside the uterus and capture images of them. An endometrial biopsy (tissue sample) may be done at the same time.
• Laparoscopy. A narrow fiber-optic telescope is inserted into the abdomen through a tiny incision. This lets the doctor inspect the uterus, fallopian tubes and ovaries for any signs of endometriosis, pelvic adhesions (scar tissue) or other problems.
• Endometrial biopsy. During hysteroscopy, the doctor takes a small sample of tissue from the endometrium (uterine lining). This test is done to find out if the woman has a luteal phase defect. This is a progesterone deficiency that can prevent successful pregnancy.

Tests for men
Semen analysis is the first test a man will have. Male infertility is often due to sperm problems. Sperm are less likely to fertilize an egg if their numbers are low or they're sluggish or misshapen. A semen analysis checks the number of sperm, their speed and shape. The test also looks for white blood cells in the semen, which can be a sign of infection. This test may be repeated.

If the semen analysis shows problems, other tests may be needed, such as:

• Blood tests to check hormone levels. These may be done if the doctor thinks hormones are lowering sperm counts.
• Genetic tests. These may be done if the doctor suspects genetic or chromosome problems.
• Transrectal ultrasound to look for a blockage in the reproductive tract.
• Testicular biopsy.The doctor may use a very thin needle to take a sample of tissue from the testes if the man has no sperm or a very low sperm count.

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External Sources International Council on Infertility Information Dissemination, Inc. (INCIID). Basic testing with a reproductive endocrinologist. . Accessed March 31, 2009 Lobo RA. Infertility: etiology, diagnostic evaluation, management, prognosis. In: Katz VL, Lentz GM, Lobo RA, Gershenson, DM, eds. Comprehensive Gynecology. 5th edition. Philadelphia, PA: Mosby Elsevier; 2007.. Accessed April 17, 2009 American Fertility Association. Worked up over the infertility workup? . Accessed March 31, 2009 American Society for Reproductive Medicine. How doctors evaluate infertility in women. . Accessed March 31, 2009