Am Fam Physician. 2002;66(10):1943-1944
A wide range of evaluations are used to diagnose cystitis. However, symptoms referable to cystitis (e.g., dysuria) may also be caused by urethritis or vaginitis. Bent and Saint reviewed the optimal evaluation of women presenting with symptoms of cystitis.
The major causes of acute dysuria are compared in the accompanying table on page 1944. Most of the time, a thorough history is sufficient to diagnose acute uncomplicated cystitis, because acute and multiple symptoms are usually caused by cystitis, whereas urethritis symptoms are often mild with a gradual onset. Vaginitis, on the other hand, is associated with fairly copious vaginal discharge, odor, dyspareunia, or pruritus. In one study, only 9 percent of women who had cystitis reported vaginal discharge compared with 93 percent of those with vaginitis.
The risk of cystitis increases in women with certain symptoms (e.g., dysuria, frequency, urgency, hematuria), a history of cystitis, recent intercourse, recent diaphragm or sper-micide use, failure to urinate after intercourse, asymptomatic bacteriuria, or single status. In addition, combinations of symptoms are more likely to be associated with a diagnosis of cystitis. For example, patients with dysuria plus frequency without discharge have a 77 percent probability of cystitis, whereas patients without dysuria and frequency but with discharge have only a 4 percent probability of having cystitis. Being able to predict based on symptoms alone allows the physician to make the diagnosis with no other testing.
Physical examination may be useful and is necessary in all women reporting symptoms of vaginal discharge and cystitis. Other findings that may be helpful include presence of fever, costovertebral angle tenderness, and evaluation of vaginal discharge.
The laboratory examination in women with suspected cystitis has often included a midstream clean-catch urine specimen. One study published in 2000 compared three groups of women: the first group collected midstream clean-catch urine samples, the second collected a urine specimen in a clean (nonsterile) container (without any perineal or labial cleaning), and the third group collected a midstream clean-catch urine specimen with a vaginal tampon inserted. The contamination rates among the three groups did not differ significantly, and the authors of that study concluded that costs and patient embarrassment could be reduced by merely collecting the sample in a clean container. However, any urine samples not analyzed within several hours must be refrigerated.
Urine culture should be obtained in patients with suspected upper urinary tract infection (pyelonephritis). Pyuria (i.e., 10 or more white blood cells per high-power field in an unspun urine specimen) can easily be detected; similarly, leukocyte esterase and nitrites can be detected on a “dipstick” test. A combination of the latter two tests can provide high specificity and sensitivity.
| Condition | Pathogen | Pyuria | Hematuria | Urine culture* | Symptoms/signs/factors |
|---|---|---|---|---|---|
| Cystitis | Escherichia coli Staphylococcus saprophyticus Proteus spp. Klebsiella spp. | Usually | Sometimes | ≥102 to 105 | Abrupt onset, severe symptoms, multiple symptoms (dysuria, increasedfrequency/urgency), suprapubic/low back pain, suprapubic tenderness on examination |
| Urethritis | Chlamydia trachomatis Neisseria gonorrhea Herpes simplex virus | Usually | Rarely | <102 | Gradual onset, mild symptoms, vaginal discharge/bleeding, lower abdominal pain, new sexual partner, cervicitis/vulvovaginal herpetic lesions on examination |
| Vaginitis | Candida spp. Trichomonas vaginalis | Rarely | Rarely | <102 | Vaginal discharge/odor, pruritus, dyspareunia, external dysuria, no increased frequency/urgency, vulvovaginitis on examination |
Quantitative urine culture results are considered positive in asymptomatic women if there are at least 100,000 colony-forming units (CFU) per mL, whereas they are considered positive in women with symptoms of acute cystitis if there are at least 100 CFU per mL. However, it is unusual that a woman with acute uncomplicated cystitis would need a urine culture. Decision to treat is based on the probability that the patient has cystitis. Because the prevalence of cystitis is approximately 50 percent, any additional symptoms to support this diagnosis will be more likely to make treatment beneficial.
Based on the above evidence, the authors conclude that telephone diagnosis and management of women with acute cystitis may be warranted in certain cases. This would not include women with a fever greater than 38°C (100°F); dysuria or urgency for more than one week; vaginal discharge; abdominal pain, nausea, or vomiting; chronic medical conditions including immunodeficiency; diabetes mellitus; chronic renal failure; or recent treatment for urinary tract infection; or recent hospital discharge. Telephone management of women who meet inclusion criteria is safe, effective, and appreciated by patients.