You Don't Have to Live With Cystitis by Dr. Larian Gillespie with Sandra Blakeslee (Rawson Associates) 290 pp., $18.95

Finally, there is a sensible, hopeful book to explain an infection that virtually every woman will get at some point in her life.

"You Don't Have to Live With Cystitis" by Dr. Larian Gillespie with Sandra Blakeslee adopts a practical, problem-solving approach to cystitis, the common name for a painful infection of the lower urinary tract.

Many sufferers have been told that such infections cannot be prevented or cured. Gillespie disagrees.

The book is written for women, who often are treated incorrectly or get misleading advice from doctors, according to Gillespie. She debunks many common theories, including the popular idea that cranberry juice will help treat a urinary infection. It won't.

Gillespie begins by discussing bias in a field dominated by male doctors, in the process clearly explaining the functions and purpose of the urinary system. She comments that there is "a still widely held belief that female bladder function is affected by our 'peculiar' female anatomy -- that the urethra is 'too close' to the anus and 'too short' to keep bacteria out of the bladder. The perineum, the skin bridge between the anus and the vagina, is said to be a 'breeding ground' for bacteria that get into the bladder.

"Let me assure you, there is nothing wrong with the design of the female perineum! The perineum wouldn't have survived the trial of human evolution if it were such a handicap. The female urethra is not a shortened, amputated version of the male urethra but a separate, integrated unit with different functions," Gillespie writes.

Perhaps the most valuable aspect of this book is its clear explanation of female anatomy. The most encouraging words to read are those early in the book, where Gillespie promises, "Contrary to what you, your mother, your grandmother and all your family's doctors have been taught for generations, cystitis is curable." For people who have had repeated infections and are still looking for the cause, that promise makes this book a "must" read.

Several myths about infection are exploded in the book. For example, Gillespie says, the fact that bacteria get into the bladder during sexual intercourse is normal and does not represent a cause of the infection, as women may be told by doctors. Under normal conditions, bacteria are then flushed out of the system and away from the perineum by the efficient urinary system. The problem is not that bacteria get into the bladder, says Gillespie, but that they do not get out.

The book covers several possible problems that may prevent bacteria from leaving the system, in the process listing a number of case histories. The first and most common cause is a diaphragm that is too tight.

Gillespie was among the first physicians to postulate and study this link to infections. It is now commonly accepted in the field that poorly fitted diaphragms account for many urinary infections in women.

Another cause postulated by Gillespie is that during intercourse the urethra may be damaged. The frequency of intercourse, she says, is not a factor in infections.

Gillespie encourages the sufferer to explore the possible causes of infection for herself, using common sense, and discuss possibilities with her doctor. She even includes a chapter on communicating effectively with the doctor.

Back pain is a common and often underdiagnosed indicator of urinary infections, Gillespie writes. Even if the discomfort is not painful, back strain can damage the nerves that signal the bladder, and the patient's urine flow will be affected, no longer strong enough to clear bacteria from the system.

Back strain can be caused by high-heel shoes as well as by lifting items improperly. In general, she recommends that the patient identify when she first began to get urinary tract infections and examine changes in behavior that might have caused a problem.

To treat an infection once pain and urgency are felt, Gillespie says a urine culture as soon as possible is critical. If no infection is discovered, another problem, such as internal scarring of the urethra (interstitial cystitis), may be causing the pain.

If the problem is something other than a urinary infection, it can be made worse by antibiotics. Meanwhile, pain can be eased by one teaspoon (no more) of baking soda in a glass of water or by a prescription bladder analgesic such as Pyridium, she writes.

Do not take cranberry juice or vitamin C, she says. They are not acidic enough to kill bacteria and may actually encourage growth. Drinking lots of water is a good idea.

Do not get a urethral dilation, which Gillespie refers to as the "rape" of the urethra, unless every other possibility has been explored. It is highly unlikely that the cystitis sufferer has a narrow urethra.

A uroflow exam is important in diagnosing possible causes of repeat infections, she says.

Some of the advice in this book, such as one large dose of antibiotics instead of a 10-day course of treatment, is a subject of medical dispute. In general, however, the book is a reasoned, common-sense approach to a subject clouded by too many misconceptions. In her attitude toward cystitis as something explainable and curable, Gillespie is on the right track.Beth Schwinn is a Washington Post news aide.