Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

Your health care provider may advise you to stop taking drugs that may affect the test. Drugs that can interfere with the test include progesterone and birth control pills.

For infants and children:
The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics:

• infant test or procedure preparation (birth to 1 year)
• toddler test or procedure preparation (1 to 3 years)
• preschooler test or procedure preparation (3 to 6 years)
• schoolage test or procedure preparation (6 to 12 years)
• adolescent test or procedure preparation (12 to 18 years)

This test is performed to evaluate disorders associated with abnormal progesterone levels. Progesterone is a steroid hormone that is made in, and released from, the corpus luteum, placenta, and adrenal gland.

In men, progesterone probably has no normal function except as an intermediate in the synthesis of other steroid hormones. In women, progesterone prepares the uterus for pregnancy and the breasts for milk production. After ovulation, progesterone blocks proliferation of the endometrium and stimulates the uterus to prepare for implantation of a fertilized egg. Progesterone levels continue to rise in early pregnancy.

Blood progesterone levels start to rise with the LH surge, midway through the menstrual cycle, continue to rise for about 6 to 10 days, and then fall in the absence of fertilization.

Urinary pregnanediol levels are an indirect measure of progesterone production. Progesterone is converted to pregnanediol by the liver before being secreted in the urine.

• female (preovulation): less than 1 ng/mL
• female (midcycle): 5 to 20 ng/mL
• male: less than 1 ng/mL

• pregnancy
• adrenal cancer
• ovarian cancer

• amenorrhea
• fetal death
• threatened abortion
• toxemia of pregnancy

• ectopic pregnancy
• infertility

• excessive bleeding
• fainting or feeling lightheaded
• hematoma (blood accumulating under the skin)
• infection (a slight risk any time the skin is broken)
• multiple punctures to locate veins