Ask Doctor K: Different conditions cause painful urination

DEAR DOCTOR K: I’m a woman in my 50s, and every so often it is painful for several days when I urinate. The doctor tests me, says I don’t have a urinary tract infection, and that there’s nothing to do. It’s true that it goes away, but I’d like some relief when it hurts. Is there anything I can do?

DEAR READER: Urinary tract infections are a common cause of painful urination, but there are other causes as well. And those other causes can be treated. Here’s what you need to know before you talk again to your doctor.

There are three different types of common urinary tract infections, involving three different parts of the urinary tract.

• URETHRITIS is an inflammation of the urethra. The urethra is the short tube that goes from the bladder to the outside world. Urethritis can be caused by the bacteria that produce the other two types of urinary tract infections. It also can be the result of organisms that cause several sexually transmitted diseases, or by irritating chemicals (such as bubble bath or spermicides). Be sure your doctor tested for the sexually transmitted diseases.
• A BLADDER INFECTION (cystitis) often is caused by bacteria that live around the opening of the urethra, then travel through the urethra to the bladder. The bladder stores urine that has been made by the kidneys, then eliminates it during urination. Sometimes, bacteria travel up into the bladder without any clear cause. More often, this happens following sex, because sex tends to push the bacteria back up into the bladder. (There is a widely held belief that women and girls who wipe with toilet tissue from back to front following a bowel movement can also push bacteria up into the bladder. However, I once did a study that did not confirm this belief.)
• KIDNEY INFECTION. Sometimes bacteria travel all the way up the urinary tract, into the kidneys, through long tubes called ureters. The symptoms of a kidney infection, in contrast to a bladder infection, include fever, pain in the side of the back, nausea, shaking chills and sometimes low blood pressure. Kidney infections always need urgent medical attention.

A urine culture test is commonly used to diagnose these three types of urinary tract infections. Many doctors were taught that a bacterial infection is not present if fewer than 100,000 bacteria are found in each milliliter of urine. However, newer research finds that an infection is likely if as few as 100 bacteria are found in each milliliter. You might check with your doctor on the results of your urine culture.

Another type of condition also can cause pain on urination: vaginitis, an inflammation of the vagina. Often it is caused by bacterial, yeast or trichomonas infections. Usually vaginitis produces discharge from the vagina, but sometimes it just causes pain with urination. It also can be the result of irritating chemicals (spermicide, douche, bath soap), irritation from tampons, or low levels of estrogen after menopause.

So, if your doctor did not do a pelvic examination to look for vaginitis as a cause of your painful urination, you might suggest that.

(This column is an update of one that ran originally in March 2013.)

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.