Women who use diaphragms are twice as likely to get urinary tract infections as women using oral contraceptives, according to a recent study.

"I don't want to make women paranoid about yet another form of contraception. For the average woman, the diaphragm should not be rejected outright because of increased risk" of infection, says Dr. Stephan D. Fihn, author of two studies published last week in Journal of the American Medical Association.

For the 2 million women who use diaphragms, Fihn does not believe his results linking diaphragm use and urinary tract infection, or UTI, are cause for alarm. But he does think diaphragm users with recurrent or chronic UTI may want to to consider other contraceptives.

"It's a trade-off of risks and benefits, since diaphragms also protect against other more serious diseases like gonorrhea," says Fihn, assistant professor of medicine at University of Washington in Seattle.

Most women have at least one bout of UTI, which affects the urethra, bladder, ureters or kidneys, at some time in their lives. These common infections (cystitis or bladder infection being the best known) account for more than 5 million visits to physicians and cost $500 million in health care each year.

Though rarely considered life-threatening, UTI can cause extreme discomfort or pain. The symptoms (frequent urination, and burning sensations while urinating) can be frightening, especially since there may be blood in the urine. The cause of urinary tract infections remains unknown. "We really don't know very much about why any woman gets UTI," says Fihn. Nor does Fihn know why diaphragm-users are more prone to UTI than other women. However, several possibilities are currently being studied.

In some women, the normal flora, bacteria such as the lactobacilli that commonly are present in the vagina, are replaced by bacteria like Escherichia coli, or E. coli, which usually reside in the large intestine. When E. coli enters the bladder, it can cause an infection.

"For reasons that are unclear, this abnormality in vaginal flora is more common among diaphragm users," says Fihn, who speculates that the change in flora could be caused by introducing foreign bacteria into the vagina either from spermicide used with the diaphragm or the diaphragm itself.

Another possiblity is that the diaphragm may obstruct the urethra, a short tube leading from the urinary opening to the bladder. This would leave a small amount of urine in the bladder, allowing bacteria to accumulate and multiply. Fihn believes urethral obstruction may be a contributing factor to some but not every diaphragm-related infection. "It's certainly not universal among all diaphragm users," he says.

There are other causes for UTI that do not relate to diaphragm use. These include irritating the urethra, pressuring the bladder or introducing foreign bacteria into the vagina. Pregnant women, for instance, may get infections if the enlarged uterus pressures the bladder or ureter, tubes connecting the bladder to kidneys. And increased sexual activity or resumption after abstinence can also trigger an infection, sometimes known as "honeymoon cystitis."

However, diaphragms, particularly ill-fitting ones, are a frequently cited cause for infection. In fact, when Fihn and four colleagues from the University of Washington first undertook the studies, he says, "the nurse practitioners just yawned and said, 'Tell us something we don't know.' " But Fihn wanted to see if this view could withstand scientific analysis.

In the course of examining 277 diaphragm users, Fihn found a large range in how the diaphragm fit each woman. "There doesn't appear to be a well standardized method for fitting diaphragms," says Fihn.

One of the first steps in preventing UTI, according to Fihn, is to make sure the diaphragm fits properly. Every woman can do this by either examining herself or seeing a health care provider.

"The diaphragm should completely cover the cervix, and the rim must be fully open. And although it should fit snugly, there must be no tension on the tissue," says Dr. Martin Goldstein, associate clinical professor of obstetrics and gynecology at Mount Sinai School of Medicine in New York.

Since body contours can change, most physicians recommend having an expert check the fit annually. But any woman who is uncomfortable wearing her diaphragm for the mandatory six to eight hours following intercourse should immediately get a check-up.

Fit, however, should not be the only concern for diaphragm users, according to Dr. Sally Faith Dorfman, director of family planning program development at Albert Einstein College of Medicine in New York.

"It may not be that a 'goof-off doc' gave the wrong size. A diaphragm could be the right size but it might be placed incorrectly," says Dorfman.

Besides making sure her diaphragm fits and is placed properly, there are several other ways a woman can decrease her risk of UTI.

"Women have a much greater rate of UTI than men because there's less plumbing -- the tubes are shorter and the distance between the rectal and bladder opening is smaller," says Dorfman. "Cutting down transportation of gut flora in the direction of the bladder will decrease risk of infection."

To do this, Dorfman advises basic hygienic practices: Wear clean undergarments, wipe from front to back after urinating or defecating, make sure hands and genitals are clean before intercourse, drink enough fluids to urinate frequently, and empty the bladder before and after intercourse and before inserting the diaphragm.

For women who get UTI, many experts suggest waiting 48 hours before consulting a physician. Symptoms don't always signify infection and mild symptoms can be treated at home by drinking lots of liquids, particularly juices with high vitamin C content. Symptoms must not be ignored, because infection can ascend to the kidneys and pose serious problems.

When a urine culture test shows infection, physicians generally prescribe antibiotics like ampicillin, nitrofurantoin or tetracycline. These medications can be administered in a single large dose or spread out over two weeks.

Some physicians may also prescribe a local analgesic such as Pyridium, which numbs the urinary tract and helps relieve pain. Other physicians also prescribe an antispasmodic such as Pyridium Plus or Urised, to relieve muscle spasms and discomfort.

For his patients with infections, Goldstein suggests drinking large amounts of fluids, eating acidic foods like citrus, and avoiding caffeine, stimulants and spices. "Often a warm bath with bicarbonate of soda will help," he adds.

"Women who are really plagued by recurrent or chronic infections should consider alternatives to diaphragms," says Fihn. However, women particularly prone to UTI don't have to discontinue using diaphragms. Low doses of antibiotics, taken either as a preventive measure or after intercourse, enable women to use diaghrams without risk of UTI. This solution, though, may also pose problems since the bacteria in these women can develop resistance to the drug, or the woman can become allergic or suffer other side affects.

Fihn does not want to scare women who use diaphragms, which, he says, have many advantages even though they can contribute to UTI. "With diaphragms, like anything else in medicine," he says, "you pay a price for most any gain."