Types and severity grades
The presence of blood in the urine can be determined visually or exclusively through laboratory tests.
- Gross hematuria is visible to the naked eye. Urine acquires a distinct red hue or the characteristic "meat wash" appearance. The appearance of visible blood is always pathological. The only physiological exception is the admixture of blood in women during menstruation.
- Microscopic hematuria is diagnosed exclusively through sediment microscopy or the use of test strips. The criterion is the detection of more than 5 red blood cells per high-power field or over 1000 red blood cells in 1 ml of urine. Transient microscopic hematuria is sometimes encountered after strenuous physical exertion.
Before establishing a diagnosis, false hematuria must be excluded. The red color of the urine may be the result of consuming coloring foods (beets, red berries) within the preceding 24 hours.
Topical Diagnosis
Observing which specific portion of urine is discolored helps assess the level of the urinary tract where the bleeding originated (analogous to the three-glass test):
- Initial hematuria (only the first portion is discolored) indicates a lesion in the distal (mobile) segment of the urethra.
- Terminal hematuria (the final portion is discolored) points to pathology of the fixed segment of the urethra, the prostate gland, or the bladder neck.
- Total hematuria (urine is uniformly discolored throughout the entire act of urination) is a sign of upper urinary tract involvement (kidneys, ureters) or bladder pathology.
Causes and pain syndrome
Differential diagnosis largely depends on whether the bleeding is accompanied by pain in the abdomen or lower back.
Main causes:
- Inflammation and infections: glomerulonephritis, renal tuberculosis, nonspecific urethritis, cystitis.
- Obstruction and anomalies: urolithiasis, polycystic kidney disease.
- Vascular and traumatic factors: renal infarction, mechanical trauma to the lower back and perineum.
- Oncology: renal tumors.
A special place is occupied by renal hematuria. It is typically bilateral, persistent, and painless. Its distinctive feature is the combination with proteinuria, leukocyturia, and the presence of casts in the sediment. A specific bleeding mechanism occurs with prostate adenoma: straining leads to the rupture of varicose veins at the bladder neck.
Drug-induced etiology
A number of pharmacological agents have a direct toxic effect on the kidneys or increase the risk of hemorrhagic complications. Taking a thorough history must include inquiring about the following drug classes:
- Cytostatics: the use of cyclophosphamide is associated with a high risk of developing hemorrhagic cystitis.
- Antibiotics: aminoglycosides (gentamicin, kanamycin, streptomycin), sulfonamides.
- Analgesics: phenacetin, analgin, phenylbutazone.
- Other agents: anticoagulants, heavy metal salts.
Patient examination algorithm
The diagnostic workup begins with a detailed patient interview. The physician investigates the chronology of the bleeding, the presence of dysuria (burning, strangury, alteration of the urinary stream), and a tendency toward bruising and nosebleeds. The epidemiological status is evaluated: athletic activities, recent travel, and relation to sexual contacts.
Physical examination includes:
- Assessment of vital signs (blood pressure, pulse, body temperature) and skin inspection (checking for pallor due to anemia or a hemorrhagic rash in vasculitis and coagulopathies).
- Auscultation of the heart to check for signs of infective endocarditis, which can be complicated by embolism and renal infarction.
- Palpation of the flank and abdomen: detection of hydronephrosis, tumors, polycystic kidneys, or a distended bladder above the pubic symphysis.
- Per rectum examination in men (size and tenderness of the prostate) and gynecological examination in women.
Patients with gross hematuria or recurrent microscopic hematuria are invariably referred for instrumental imaging: renal ultrasound, excretory urography, and cystoscopy (the most informative method for assessing the bladder mucosa).
Briefly: answers to topical questions
How to differentiate glomerular from non-glomerular erythrocyturia using phase-contrast microscopy?
Phase-contrast microscopy of the urinary sediment is the preferred method for distinguishing altered (dysmorphic) from unchanged red blood cells. The detection of dysmorphic RBCs serves as a reliable sign of a glomerular source of bleeding; the presence of dysmorphic RBCs warrants the exclusion of glomerulonephritis. Sediment microscopy also enables the identification of erythrocyte casts; renal hematuria is typically combined with cylindruria, proteinuria, and leukocyturia.
What is the management strategy for a patient with isolated asymptomatic microscopic hematuria?
In asymptomatic patients, referral to a urologist is indicated only if more than 3 RBCs per high-power field are present in 2 out of 3 urinalyses. In cases of isolated microscopic hematuria without risk of progression, routine administration of steroids and/or immunosuppressive therapy is not recommended; the goal is to avoid unwarranted medication use and adverse side effects.
Topical localization by urine portions (ITT rule): Initial — initial tract (mobile urethra), Terminal — termination point (fixed urethra, prostate), Total — all of the above (kidneys, ureters, bladder).
Class and exam questions
Is gross hematuria always a sign of disease?
Yes, visible blood in the urine is always pathological. The only physiological exception is the presence of blood during menstruation in women.
How to identify renal hematuria through laboratory tests?
True renal hematuria is frequently painless and persistent. Urinalysis reveals accompanying proteinuria, cylindruria, and leukocyturia.
Which examination is most informative when bladder pathology is suspected?
For detailed visualization of the bladder mucosa, cystoscopy is the gold standard.
Can pain relievers cause blood in the urine?
Yes, certain analgesics (e.g., analgin, phenacetin, phenylbutazone) exert a toxic effect and can cause red blood cells to appear in the urine.
What else to study on this topic
- Acute and chronic glomerulonephritis: mechanisms of glomerular injury
- Drug-induced hemorrhagic cystitis secondary to cytostatics
- Infective endocarditis as a cause of embolism and renal infarction
- Differential diagnosis of space-occupying lesions: tumor vs. polycystic kidney disease
- Specific urinary tract lesions in tuberculosis
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