NOTE: “Urinary Tract Infection” (UTI, pronounced letter-by-letter “You-Tee-Eye”) (NOT “Youtee” nor “Ootee”) can mean anywhere from the urethra, to bladder, to kidney (see Diagram — Urinary System, and also Female Genital System). Clinically, when we say “UTI“, we mean “bladder infection”.
Women with painful urination from a UTI usually seek care within a day or two, in person or by telephone. But I’ve had some come in after 1-2 weeks of symptoms, which makes me wonder a little, but doesn’t change management at all. Our goal is not only accurate diagnosis, but also providing care as simply & cheaply as possible. The possible causes are straight-forward:
- Bladder Infection (Cystitis; “UTI“)
- Kidney Infection (Pyelonephritis; “Pyelo” [pronounced PIE-low] for short)
- Urethral Infection (Urethritis)
- External Sores (on labia, etc)
- Vaginal Infection (see Vaginal Discharge)
We start by assuming that a woman with painful urination has a UTI [due primarily to E. coli, or similar bacteria that live in all our bowels], & try to convince ourselves she doesn’t.
History & Physical Exam
Some simple questions:
- Is the pain felt inside (UTI), or on the skin (external / vaginal condition)
- Frequent & urgent need to urinate, but just small quantities (UTI), or not (not UTI)
- Blood in Urine → probably UTI (but see below)
- Vaginal discharge (new, same time as urinary symptoms) → not UTI
- Recent STD risk → maybe Urethritis (chlamydia, gonorrhea, mycoplasma)
- Pain right at the urinary opening (meatus) → probably Urethritis
- Fever, pain in flank or mid-back, nausea / vomiting → Pyelo
- Is she pregnant? → a UTI in pregnancy makes us worry it could be Pyelo
Past episodes may be quite common with UTIs, though obviously also with other types of infection, including Herpes simplex virus (sores on skin that hurt when urine touches them). Painful urination is especially common among women during the very first episode of Herpes.
Blood in the urine (assuming it’s not a menstrual period) practically guarantees a UTI (or Pyelo). However, blood clots from kidney stone or other conditions can hurt when stuck in the urethra. Sometimes we suspect this if the patient describes her pain as very localized to the urinary opening (meatus), as opposed to pain in the bladder area right above the pubic bone (i.e. UTI). Women over 50 with blood in the urine need a repeat urinalysis a few weeks after treatment; if blood persists after infection is gone, we work it up (see below).
If symptoms have been present a week, and we diagnose UTI, we assume the infection has crept up to the kidney. Then we treat as if Pyelo, even if there are no specific symptoms. Pyelo (infection of the kidney, not just the bladder) requires longer treatment courses, and some common drugs can’t be used.
We also treat as if Pyelo in high-risk women, e.g. pregnant, elderly, debilitated, or with a weak immune system from other disease. In fact, we’re more likely to hospitalize high-risk patients, to give IV antibiotics that are sure to cover all germs, to prevent complications like Sepsis (germs spread to the blood stream).
If a woman clearly describes external pain or new vaginal discharge, we may need to do a pelvic exam regardless of Urinalysis findings. I’ve seen painful urination caused by a variety of skin conditions, & also very localized irritation of the urinary opening (meatus).
A Urinalysis usually makes or breaks the diagnosis of either UTI or Pyelo. We can do a quick test with a dipstick in 2 minutes, that can detect the presence of blood, sugar, protein, & especially “leukocyte esterase,” an enzyme present in white blood cells (WBCs).
No WBCs = No Infection. Causes of false-negative UA’s include:
- Very dilute urine (specific gravity <1.005 on dipstick)
- Had recently urinated (specimen not in bladder very long)
- Staff who did UA didn’t wait the full 2 minutes to read results
- Old dipsticks (even if not expired, simply exposed to air every time the container had been opened)
Unfortunately, if any WBCs that happen to be in the vagina wind up washed into the urine, the dipstick can’t tell the difference. A urinalysis by microscope might help decide, but that’s often not available. So it’s important for women to give a “clean catch,” which is more than just wiping with a towelette. We spend a minute or so explaining step-by-step as follows:
- We want to know what germ is inside you, not on the skin. So try as hard as possible that the urine doesn’t touch the skin.
- Spread your legs wide apart, & hold the labia apart. Clean them with the towelette, but don’t let go.
- Start to pee in the toilet to wash outside germs away, then without stopping, catch some directly into the cup. Finish peeing in the toilet.
- Try real hard to make sure the urine doesn’t touch the skin (this is the most important point of all; it’s the reason for instructions above & lets the patient figure it out herself).
I’ve heard people tell women to, “wipe from front to back,” which makes absolutely no difference at all. There are no data to even suggest it prevents infections, and some data to suggest it’s irrelevant.
A truly clean-catch urinalysis that’s positive for WBCs means there’s an infection: either a common bladder infection (cystitis, UTI), or more serious kidney infection (pyelonephritis), or maybe a urethral infection (urethritis) from chlamydia (or even gonorrhea).
A negative UA means no infection. But if I have a female patient with just a few days of classic symptoms, I may well assume a false-negative & treat anyway. Once. If “classic symptoms” occur various times with negative UAs, it’s something else.
By the way, you may also hear about a “Nitrite” test on the UA dipstick, which identifies a chemical released from bacteria. But nitrite on the dipstick is set up to detect over 100,000 bacteria / ml. of urine, way too high to be meaningful [see below]. So a “positive nitrite” may well mean UTI, whereas a negative doesn’t mean anything.
Urine Culture & Sensitivities (C&S)
A “Culture” determines if any bacteria are present that will multiply in 24-hours. “Sensitivity” (or “Susceptibility”) results 1-2 days later identifies what antibiotics will work on them. See also Culture & Sensitivities.
For bladder infections, it’s not so important, because many drugs work well despite sensitivity results. Nobody dies from a bladder infection, treatment is almost always effective, & the C&S isn’t worth the cost. But it’s essential for the more dangerous kidney infection (pyelonephritis). The following persons with urinary symptoms should have a C&S ordered:
- Fever, nausea/vomiting, very tender in the flank or mid-back
- Elderly and others with weak immune systems due to other diseases (who can certainly have a simple UTI, but are more likely to get Pyelo)
- All men & children with UTIs (even though I said this topic is about Women)
- Women with simple UTI symptoms that have gone on a week or more, since the germ is more likely to have moved up to the kidney.
Since 1982, studies have shown that merely 100 or more bacteria per ml urine correlates with women who have symptoms of bladder infection and WBCs in the urine, i.e. UTI. However, many clinicians can’t shake the older standard of “100,000” from their heads. Neither can laboratories, which only do sensitivity testing if there are over 10,000 – 25,000. And if a few different bacteria grow in the culture, meaning a contaminated specimen, they can’t perform the sensitivity testing, even though one of the various species may be the actual cause of infection.
Bottom Line: A “no-growth” urine culture rules out UTI, unless of course the patient had happened to somehow obtain and take even one dose of an antibiotic beforehand. Otherwise, any number of organisms is compatible with the diagnosis. So is a contaminated specimen.
See also Painful Urination in Women for the clinician’s condensed thought-process when face-to-face with a patient.