Diagnosis of urinary tract infection
The diagnosis of urinary tract infection is symptomatic (suspected due to the existence of symptoms), except in hospitalised and sedated patients. Depending on the symptoms, the parts of the urinary system affected and the type and severity of infection can be determined.
The main symptoms that depend on the affected part are:
- Urethritis: Indicated by urethral secretion of pus and a burning sensation when urinating.
- Cystitis: Suprapubic pain, burning when urinating and high urination frequency.
- Prostatitis: Pain between the anus and scrotum, fever and chills, increased urination frequency and burning when urinating. In addition to performing a digital rectal examination (which will be painful), an ultrasound will be performed to rule out a prostatic abscess (an infrequent complication).
- Pyelonephritis: Low back pain, fever and chills and itching during urination. When the evolution of the disease is torpid or there is a history of kidney stones, an ultrasound will be performed to rule out obstruction of the ureter.
- Orchitis: Testicular pain, increased testicle size and fever.
Prostatitis, pyelonephritis and orchitis can be associated with sepsis, and even septic shock.
To diagnose a urine infection, the first diagnostic method to be used should be urine analysis. Viewing urine in a transparent glass container shows whether it is cloudy (due to leukocytes in the urine).
Infection diagnostic methods
Urinalysis can be done by two main methods:
Using a plastic urine strip, which has a series of small pads with different chemical reagents which determine if there are white blood cell enzymes or nitrites in the urine. If so, this confirms the presence of leukocyturia.
Urine sediment: Much more accurate than a urine strip, it involves centrifuging a urine sample then studying it under a microscope. After removing the supernatant liquid, the sediment is studied for leukocytes. Leukocyturia is a constant in urinary tract infection.
A urine culture test is done to find the bacteria causing the infection. This is done by placing a small amount of urine on a sterile plate with a culture medium (a kind of gelatine with nutritional products). The bacteria are identified after growing on the plate. An antibiogram is then performed, to find out the sensitivity of the germ to different antibiotics. Sometimes, a molecular technique is needed to detect DNA fragments from the germs and speed up the diagnosis.
If a patient does not recover well from an infection, it may be necessary to perform an ultrasound, a CT scan or even a nuclear medicine test to investigate possible complications of the infection.
Substantiated information by:
Published: 30 March 2022
Updated: 30 March 2022
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