What Is Pyuria?
Pyuria is considered to be present when a positive result in gram staining of an unspun urine specimen or a urinary dipstick test is positive for leukocyte esterase. Sterile pyuria is the chronic finding of white blood cells in the urine in the absence of any bacterial infection. Sterile pyuria is a common condition and can be found in 13.9 % of women and 2.6 % of men. Pyuria is important for spotting urinary tract infections in non-catheterized patients. Fever with pyuria is considered a urinary tract infection, and antibiotics are started soon after the urine culture. However, when Kawasaki disease is diagnosed, urinary tract infection is not considered and is neglected because pyuria in patients with Kawasaki disease is always considered sterile and originates from the urethra or the kidneys as a result of mild and subclinical renal injury or vasculitis.
What Causes Pyuria?
Pyuria can be classified as infectious or non-infectious.
Infectious Causes of Pyuria :
Bacterial Infections - Bacterial infections like urinary tract infections are very common. Sterile pyuria is The absence of bacteria in the urine but the presence of urinary tract infection symptoms. Genitourinary tuberculosis is a form of non-pulmonary tuberculosis, which is a common type of bacterial infection. Hematuria and pyuria are the findings in genitourinary tuberculosis. This condition affects the kidneys, ureters, bladder, prostate, and genitalia. On urine culture, mycobacterium tuberculosis can be found.
Sexually Transmitted Diseases - These include chlamydia, gonorrhea, genital herpes, syphilis, mycoplasma, trichomonas, human papillomavirus infection, and HIV.
Viral Infections - Infections caused by Adenovirus, Cytomegalovirus, and BK Polyomavirus can cause hemorrhagic cystitis in immunocompromised patients.
Fungal Infections - Fungal infections like Candida albicans are generally found in hospitalized patients. However, C. glabrata, C.tropicalis, C. krussei, and other Candida albicans can also cause infection. Patients with diabetes and renal transplant are more prone to have aspergillosis, and patients with HIV infection are more prone to cryptococcus. Genitourinary infection associated with pyuria urea also occurs in areas with disruption of the environment by construction, tornadoes, or exposure to the high concentration of bird excrement. The infections include blastomycosis, coccidioidomycosis, and histoplasmosis.
Parasitic Infections - Trichomonas vaginalis is the most common nonviral sexually transmitted disease. Infection is diagnosed by detection of the parasite in microscopic examination of a wet mount cervicovaginal secretion in women and urethral discharge in men.
Inflammatory and Autoimmune Conditions - Kawasaki disease is manifested with sterile pyuria, microscopic hematuria, and proteinuria associated with renal involvement. Analgesic naturopathy can also cause sterile pyuria in association with chronic interstitial nephritis and renal papillary necrosis.
Non-infectious Causes of Pyuria :
Secondary to Appendicitis - Pyuria in the absence of infection is called sterile pyuria. Pelvic inflammation secondary to appendicitis can also cause pyuria if the appendix lies in close proximity to the bladder and ureter. Another reason for sterile pyuria is the instrumentation of the urinary tract following cystourethroscopy or nephroscopy.
Systemic Diseases - It can be present in patients with underlying systemic diseases such as benign conditions like renal calculus and neoplasms. Systemic conditions like systemic lupus erythematosus, Kawasaki disease, diabetes sarcoidosis, and malignant hypertension or associated with pyuria.
Drugs Causing Pyuria - Drugs like Olsalazine and Nitrofurantoin are found to cause pyuria. Drugs like non-steroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors, Aspirin, and diuretics are found to cause acute drug reactions causing interstitial nephritis with sterile pyuria.
What Are the Symptoms of Pyuria?
Symptoms of urinary tract infection include -
Pyuria caused by other infection include symptoms like -
How Is Pyuria Diagnosed?
Clinical history is the most important step in the diagnostic pathway. Urinary tract symptoms such as dysuria and hematuria should be diagnosed carefully. General findings such as pallor, hypertension, skin rashes, edema, muffled heart sound, organomegaly, swollen joints, and lymphadenopathy can be signs of serious underlying pathology. Diagnosis should be made by -
Urinalysis - Urine analysis is the prime investigation for sterile pyorrhoea. If pyorrhoea is not sterile, repeat cultures, and there is a positive result. Contamination with vagina leukocytes in females commonly occurs, so midstream clean catch should be collected, and the use of antiseptic solutions prior to the collection should be avoided to rule out false-negative tests.
Hematological Tests - Routine blood tests for full blood count and renal and liver function tests are of immense importance. Swabs for chlamydia and gonorrhea are advised for sexually active patients. Eosinophilia is an important identification of drug-induced interstitial nephritis. In the suspected schistosomiasis, a terminal urine sample needs to be collected between noon and 3 pm to coincide with maximum egg excretion.
Imaging Tests - Imaging tests depend upon history and findings on clinical examination. Renal ultrasound or computerized tomography can be done to diagnose renal stones, masses, or nephritis. Cystourethroscopy and tissue sample sampling are done if tumors are suspected. The technique also can diagnose and treat benign pathology such as bladder stones.
How Is Pyuria Treated?
Treatment of pyuria depends on the cause. Urinary tract infection is generally treated with a round of antibiotics. The antibiotic regimen lasts for two weeks, and the drugs are taken orally. Antifungal drugs can be used to treat fungal infections and pyuria. Pyuria not responding to antibiotics can be caused by other underlying causes like Kawasaki disease is treated with immunoglobulins. Frequent cases of pyuria caused by medications should be treated by stopping certain medications by consulting the physician. If pyorrhoea is left untreated, it can lead to blood poisoning and organ failure. It can also cause permanent kidney damage, and severe cases, if left untreated, can be fatal. Pyuria is common during pregnancy due to excessive vaginal discharge. It is important to do a routine urinalysis to rule out urinary tract infections or another type of infection. Severe pyuria associated with untreated urinary tract infection can cause premature birth or low birth weight in full-term babies.
Sterile pyuria can be a real challenge for clinicians to diagnose a disease. A good clinical history and examination with diagnostic aids for appropriate investigation need to be done. Urine cultures need to be done before confirming a disease. Pyuria generally gets treated with prompt treatment. The best method to prevent complications is to be aware of the symptoms and consult a physician. Immunocompromised patients need to be aware of their susceptibility to diseases and should take extra precautions.