Seems like the easiest of complaints to manage, but fascinates me by its subtleties, potential pitfalls, & misunderstandings. Even if this posting doesn’t fundamentally change your practice, hopefully you’ll learn a few things you’d never thought of.
We’ll deal with Acute Dysuria, usually presenting within a few days of onset, occasionally 1-2 weeks. Our goal is not only accurate diagnosis, but also expeditious care (including telephone diagnosis). The Differential is straight-forward:
- Cystitis (UTI)
- Pyelonephritis (Pyelo)
- Labial Lesions
Start by assuming that a woman with dysuria has a UTI [due primarily to E. coli, or other enteric bacteria], & try to convince yourself she doesn’t.
HISTORY & PHYSICAL
Some simple questions:
- Is the pain felt internally (UTI), or on the skin (labial / vaginal etiology)
- Urgency & Frequency (UTI), or not (not UTI)
- Hematuria → probably UTI (but see below)
- Vaginal discharge (new, concurrent with symptoms) → not UTI
- Recent STD risk → maybe Urethritis (chlamydia, gonorrhea)
- Fever, CVA/flank pain/tenderness, nausea / vomiting → Pyelo
Recurrence may be quite common with UTIs, though obviously also with any type of infection. Including Herpes simplex virus (HSV). Dysuria is especially common among women with primary HSV.
Hematuria (after excluding menses) practically guarantees a UTI (or Pyelo). However, blood clots from kidney stone or other lesion can hurt during urethral passage. Sometimes this can be suspected if the patient describes her pain as very localized to the meatal area, versus suprapubic dysuria (i.e. UTI).
If symptoms have been present a week, and you diagnose UTI, assume the infection has ascended to the renal pelvis. Treat as if Pyelo, even if no telltale symptoms.
If History strongly suggests a vaginal or labial etiology, you may need to do a pelvic exam regardless of Urinalysis findings.
First step is a dipstick, invariably done at point of care without sending to lab. It includes a variety of tests.
Leukocyte Esterase, an enzyme in WBCs, is key. It’s a proxy for WBCs on microscopic analysis, a virtual sine qua non for UTIs. No WBCs = No Infection.
The dipstick is sensitive for >10 WBCs per HPF (high-power field) by microscopy. Causes of false-negatives may include:
- Very dilute urine (note specific gravity reading on dipstick; <1.005 = very dilute)
- Recent prior void (specimen not in bladder very long)
- Assistant who did UA didn’t wait full time
- Old dipsticks
The latter doesn’t mean expired, rather that there’d been too much air exposure from repeatedly opening the container (or leaving it open). This is more likely to occur toward the end of the batch. It might be advisable to place 10-15 dipsticks in an old container for first use, then refill it when out, instead of opening the original one 100 times.
Dipsticks aren’t at all specific, because they can’t distinguish bladder WBCs from vaginal ones. The only way to suspect contamination is to do a microscopic, for the presence of epithelial cells (“Epis”). Anything more than “rare” or “few” Epis (not “a few”) means there’s no way to tell where the WBCs originated. Unless otherwise specified, “Epis” means the quadrilateral vaginal cells. Uroepithelial cells are smooth, oval-shaped, but rarely present.
A word about microscopics. They’re performed on centrifuged specimens, which have no standardization. A clump of cells layers out at the bottom of the tube; you pour the supernatant off, & examine the sediment. However, each lab tech & clinician extracts it their own way. I used a Q-tip handle to tease it out, but many just tap the side of the tube until it falls. I’ve seen drops of mere supernatant examined, yielding absurdly false negatives.
Of course, anyone with a bona fide UTI is allowed to give a dirty specimen, so you can’t rule it out due to contamination. How to strive for a clean catch? Certainly not by just handing a towelette and preaching, “Clean yourself well & pee in the cup.”
I spend around 30-60 seconds 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 real wide apart, & hold the labia apart (demonstrate in the air with thumb & index finger). Clean with the towelettes, 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.
- Remember, try real hard to make sure the urine doesn’t touch the skin.
I don’t have any data, but seem to get decent specimens. I’m a firm believer that if a person understands a rationale, they’re more likely to do it right. Never tell a woman, “wipe from front to back;” it makes absolutely no difference, & only serves to confuse.
True pyuria also occurs with, of course, Pyelonephritis, and with Urethritis due to chlamydia or gonorrhea.
Nitrites are secreted by E. coli and other coliforms. However, the dipstick is calibrated to correlate with a culture result of ≥105 colonies, which is so high as to be almost useless [see below]. If Nitrites are positive, you’ve probably got a UTI. But a negative isn’t helpful at all.
Blood (microscopic hematuria) is very suggestive of UTI, as long as menses isn’t present. A UTI with hematuria is no different than one without; same treatment, same prognosis. But in anyone over 50, be sure to repeat the UA after cure, to R/O coincidental bleeding from a tumor.
Protein isn’t helpful. If found, repeat the UA after cure to R/O persistent proteinuria from another condition.
pH is important, because urine should be acidic. A pH ≥7.0 suggests infection with a urea-splitting species such as Proteus, which is associated with renal stones, possibly a nidus for recurrent infection. Recurrent UTIs with high pH warrant a renal image.
Specific Gravity, as mentioned, alerts us to a dilute urine, and possibly associated false-negative dipstick results if <1.005.
Glucose, Ketones, Bilirubin, & Urobilinogen aren’t useful here, unless you happen to accidentally find occult Diabetes.
URINE CULTURE & SENSITIVITIES (C&S)
It’s instructive to the point of hilarity how medical lore and “Old Doctors’ Tales” survive through generations of practicing clinicians. Ask almost anyone [even yourself???] how to define a UTI by culture, & you’ll undoubtedly hear/say, “100,000 (105)” colony-forming units (CFU) per ml. Says who?
Says (Said) Harvard’s Edward Kass in the late 1950s, who published several papers showing that 100,000 CFU/ml was the best way to distinguish between pyelonephritis on the one hand, & urine contamination among asymptomatic healthy women on the other. Not particularly relevant to diagnosing plain old cystitis for one. And even for Pyelo, it didn’t mean that lower numbers aren’t positive, just that ≥100,000 CFU/ml can’t be dismissed as contamination.
Of course, Dr. Kass would never have expected the clinical world to latch onto his number as magic. In 1982, Stamm et al. found that a mere 100 (102) CFU/ml was able to identify women with acute dysuria & pyuria (sure sounds like a UTI to me) versus those without. Subsequent studies reproduced similar results.
Yet numerous clinicians, trained over the last 30 years, still quote “100,000.” Clinical labs are a little better, but often won’t perform susceptibility tests on <10,000 – 25,000 CFUs. And as we noted, Nitrite tests on dipstick are calibrated to correlate with 100,000 CFU/ml. Alas.
Bottom Line: A “no-growth” urine culture rules out UTI, unless of course the patient had happened to somehow score even one dose of an antibiotic. Otherwise, any number of organisms is compatible with the diagnosis. So is a contaminated specimen.
The main role for Urine Cultures is to obtain susceptibility tests. In simple cystitis it’s not worth a C&S, since most antibiotics work well. Even if there’s in vitro resistance, a drug may be so heavily excreted in the urine that intra-bladder concentrations do just fine. Susceptibility results, both MICs & Bauer-Kirby disk diffusion methods, calibrate to hematogenous drug levels.
The C&S is essential for Pyelo, where treatment requires hematogenous delivery to renal parenchyma. Pyelo is also more serious, in that urosepsis can result. Order a urine C&S if you suspect Pyelo due to:
- Fever, nausea/vomiting, flank or CVA tenderness
- At-risk hosts (who can certainly have garden-variety cystitis, but are more likely to get Pyelo)
- All men & children with UTIs (even tho I said this is about Women)
- Women with simple UTI symptoms that have gone on a week or more, since the bug is more likely to have ascended to the renal pelvis.
SUMMARY — A woman presents with acute dysuria.1. Urinalysis positive for Leukocyte Esterase → Diagnose UTI, if…
- No concurrent vaginal discharge
- Pain is internal, NOT felt on labia
- Frequency / Urgency present
- Hematuria strongly suggests UTI (unless menses)
- No Sx of Pyelo
- If STD risks, also send urine for GC / Chlamydia
Treat empirically [3-day antibiotic course].If NOT BETTER in 3 days:
- Repeat UA. If still Leukocyte Esterase → send for micro
- C&S (spaced a few days from antibiotics, if possible)
- Consider Urethritis → Test for GC / Chlamydia
- If suggestion of “external” pain, consider pelvic exam
- Specific Gravity <1.005 → Repeat
- Careful history for external dysuria
- Consider pelvic exam
- Internal dysuria; AND Frequency / Urgency
- No Sx Pyelo
- Non-pregnant, no significant co-morbidites (incl. age)
- Obtain C&S
- Treat empirically
- Give ER precautions if getting worse, or vomits up meds
Though this Blog doesn’t address treatment, a brief word. Whenever you see urine C&S results, keep a mental [or better, written] record of resistance patterns in your locale. Then you’ll know what drugs to save for Pyelo, and not waste them on simple cystitis. For example, I never give Quinolones for simple UTI; the more they’re Rx’d, the sooner resistance emerges.
Nitrofurantoin is excellent for cystitis, because it can’t be used for possible Pyelo. Doesn’t penetrate renal parenchyma; same for Fosfomycin.
And that’s it for Dysuria & UTIs in women. Did you learn anything interesting? Next posting: Dysuria in Men.