AFB testing involves microscopic examination and culture of urine samples for Mycobacterium tuberculosis and other acid‑fast organisms.

Clinical uses include:

Detecting genitourinary tuberculosis (kidneys, bladder, ureters).

Supporting diagnosis in patients with persistent urinary symptoms, sterile pyuria, or hematuria.

Confirming TB in cases where pulmonary TB is absent but extrapulmonary TB is suspected.

Often performed alongside AFB smear, culture, PCR, and imaging studies for comprehensive evaluation.

Analyte: Acid‑fast bacilli in urine (microscopy, culture, or PCR).

Normal Result: No AFB detected.

Abnormal Findings:

Positive AFB smear/culture: Indicates presence of Mycobacterium tuberculosis or related species.

Multiple samples (usually 3 consecutive morning urine specimens) improve diagnostic yield.

Clinical Use:

Provides a direct test for urinary tract tuberculosis.

Helps guide diagnosis, treatment, and monitoring of TB infections.

Supports urology, infectious disease, and internal medicine evaluations.