A clot inside a blood vessel is called a thrombus. Sometimes the thrombus can travel in the bloodstream and get stuck in your lungs. This kind of clot (called a pulmonary embolus) keeps blood from getting to your lungs. A pulmonary embolus can be life-threatening.A clot that blocks a blood vessel in the brain can cause a stroke. A clot in a blood vessel in the heart can cause a heart attack. Blood clots can cause some women to have miscarriages.
The coagulation of blood is a complex process during which blood forms solid clots. It is an important part of hemostasis (the cessation of blood loss from a damaged vessel) whereby a damaged blood vessel wall is covered by a fibrin clot to stop hemorrhage and aid repair of the damaged vessel. Disorders in coagulation can lead to increased hemorrhage and/or thrombosis and embolism.
One of the newest forms of hormonal birth control to come onto the market is the Patch, which is sold under the brand name Ortho Evra. It is available through a prescription. But women who use a contraceptive patch appear to be more than twice as likely to develop a dangerous blood clot in their veins as those who use an oral contraceptive, new research shows.
The Patch operates on the same premise as the combination birth control pill. It uses estrogen and progesterone to suppress ovulation, thicken cervical mucus and possibly thin the uterine lining. However, instead of taking these hormones orally, this contraceptive allows the hormones to be continuously delivered directly into the bloodstream through the skin via a thin patch.
Currently, there is ongoing research into the thromboembolic risks of Ortho Evra as compared to combined oral contraceptive pills. Data from a recent unpublished study found that users of the contraceptive patch may have a two-fold increased risk for non-fatal venous thromboembolic events compared with women who took a norgestimate-containing oral contraceptive with 35 micrograms of estrogen .
Dr. Alexander M. Walker and colleagues, from i3 Drug Safety in Auburndale, Massachusetts, note that it was not known if users of the patch system ran the same risk of stroke, heart attack and venous blood clots as users of oral contraceptives.
They point out that the FDA changed the labeling for the patch contraceptive system in 2005 to warn of a possible increased risk of so-called "thrombotic events," because of a higher average circulating estrogen levels with the product.
"Blood clots occurring in the legs or lungs are serious and rare events that are a potential risk for all hormonal contraceptive therapies," Dr. Daniel Shames, the acting deputy director of FDA's Office of Drug Evaluation in the Center for Drug Evaluation and Research, told a press conference.
Risk factors for blood clots associated with contraceptives include smoking, obesity, inactivity, surgery and high doses, Shames said.
The FDA has also asked Johnson and Johnson for a longer follow-up of women using the patch to look for cases of blood clots, heart attack and stroke.Women using the weekly patch -- the only birth-control patch approved by the FDA -- receive substantially more estrogen than women taking a daily birth-control pill. The pills typically contain 35 micrograms of estrogen.
Higher levels of estrogen may put some women at increased risk of blood clots. The FDA is urging women to talk to their doctors to see if the patch is appropriate for them.
The investigators' study, reported in the journal Obstetrics and Gynecology, involved 49,000 women using the Ortho Evra patch and 202,000 who used oral contraceptive pills between April 2002 and December 2004.
The researchers found that the occurrence of blood clots or "venous thromboembolism" in patch users was 2.2-times higher than in pill users: 40.8 vs. 18.3 cases per 100,000 women per year.
Because heart attacks and strokes were so rare, the researchers could not tell from their data if the risk of these outcomes was any different, statistically speaking, between the pill and the patch users.
Women who have a family history of breast cancer, diabetes, high blood pressure, high cholesterol, headaches or epilepsy, depression, gallbladder disease, kidney disease, heart disease, irregular periods, or are breastfeeding may not be able to use The Patch. Women over 198 pounds may not receive a large enough hormone dose for the Patch to be effective.
A woman gets more estrogen in her body from the Patch than she would get from low-dose birth control pills or the Ring.
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