Micturition (Voiding) Abnormalities

1. Dysuria refers to painful urination. It may be accompanied by a burning sensation in the urethra or urinary urgency.

Causes: Diseases of the urethra (most frequently urethritis), bladder (most frequently urinary tract infection [UTI]/cystitis), prostate (prostatitis); less commonly disorders of ureters, renal pelvis, kidneys (pyelonephritis), and ulcerations on external genitals (male or female).

Diagnosis: Take a history (remember about the possibility of sexually transmitted diseases). Pain at the initiation of micturition suggest urethritis. Pain towards the end of micturition may suggest bladder infection. Deep-seated perineal pain may indicate prostrate infection. Investigations may include urinalysis with microscopic examination of the urinary sediment and urine culture in patients with a suspected UTI; examination, culture, or both of urethral discharge if a sexually transmitted disease is suspected; and urinary tract ultrasonography. Repeated sterile urine culture raises the suspicion of renal tuberculosis. Physical examination may include, as needed, examination of the external urethral orifice and genitals; in men, examination of the prostate; and examination of inguinal lymph nodes. In women gynecologic examination is performed if the cause is not apparent.

2. Prostatism refers to a complex of symptoms including increased urinary urgency and frequency accompanied by hesitancy and a weak urinary stream.

Causes: Most commonly obstruction of urine flow in the area of the bladder neck by an enlarged prostate.

3. Oliguria refers to a urine output <500 mL (<70 mL/10 kg) over 24 hours.

4. Anuria describes a urine output <100 mL over 24 hours.

Causes: Acute kidney injury (AKI) (prerenal azotemia, renal or postrenal AKI), end-stage kidney disease requiring renal replacement therapy.

Diagnosis: Consider different types and causes of AKI (see Acute Kidney Injury). Differential diagnosis should include chronic kidney disease (see Chronic Kidney Disease).

5. Polyuria is defined as a persistent urine output >2500 mL per 24 hours. It may result from inadequate renal reabsorption of water (eg, diabetes insipidus), osmotic diuresis (eg, hyperglycemia), or less frequently from excessive intake of fluids. It is usually accompanied by polydipsia (see Thirst). The causes and diagnostic evaluation of polyuria are the same as in polydipsia.