Hematuria: A Comprehensive Guide for MCCQE1
Introduction
Hematuria, defined as the presence of red blood cells (RBCs) in the urine, is a frequent clinical presentation encountered in both primary care and emergency settings. For MCCQE1 preparation, it is crucial to distinguish between glomerular and non-glomerular causes, understand the risk stratification for malignancy, and apply Canadian Urological Association (CUA) guidelines for evaluation.
Hematuria is broadly classified into:
- Gross (Macroscopic) Hematuria: Visible to the naked eye (red or brown urine).
- Microscopic Hematuria: Detected only on urinalysis.
Definition of Microscopic Hematuria: According to Canadian guidelines, significant microscopic hematuria is defined as ≥ 3 RBCs per high-power field (HPF) on a single properly collected urine specimen in the absence of an obvious benign cause (e.g., menstruation, trauma, vigorous exercise).
Etiology and Differential Diagnosis
For the MCCQE1, you must be able to categorize hematuria to narrow down your differential diagnosis. The most clinically useful distinction is between Glomerular and Non-Glomerular causes.
Glomerular Causes
Characteristics: often associated with proteinuria, RBC casts, and dysmorphic RBCs.
- IgA Nephropathy (Berger’s Disease): Most common cause of glomerulonephritis. Synpharyngitic (occurs with URI).
- Post-Infectious Glomerulonephritis: Occurs 1-3 weeks after Strep infection. Associated with low C3.
- Alport Syndrome: X-linked; associated with sensorineural hearing loss and ocular abnormalities.
- Thin Basement Membrane Disease: Benign familial hematuria.
- Lupus Nephritis: Systemic signs (rash, arthralgias).
Mnemonic for Common Causes: I PEE RBCS
- Infection (UTI, Pyelonephritis)
- Polycystic Kidney Disease
- Exercise
- External Trauma
- Renal Stones / Renal Cancer
- BPH / Bladder Cancer
- Coagulopathy / Cysts
- Strictures / Sickle Cell
Clinical Evaluation
The goal of the evaluation is to rule out malignancy and significant renal disease.
1. History
- HPI: Duration, timing (initial, terminal, total), presence of clots (suggests non-glomerular), pain (stones/infection) vs. painless (malignancy).
- Risk Factors for Malignancy:
- Smoking (Most important modifiable risk factor).
- Age > 40 years.
- Male gender.
- Occupational exposure (chemicals, dyes, rubber).
- History of pelvic radiation or cyclophosphamide use.
- Family History: PKD, Alport syndrome, deafness, renal failure.
2. Physical Examination
- Vitals: Hypertension (renal parenchymal disease).
- Abdomen: Palpable masses, CVA tenderness (pyelonephritis, obstruction).
- Pelvic/Rectal: Prostate exam (DRE) in men; pelvic exam in women to rule out gynecological sources.
- General: Edema (nephrotic syndrome), rashes (SLE, vasculitis), hearing loss (Alport’s).
🚩 MCCQE1 Red Flags
Immediate referral and urgent workup are required for:
- Painless gross hematuria (High risk of malignancy).
- Hematuria with hemodynamic instability.
- Hematuria with acute urinary retention (clot retention).
3. Diagnostic Approach
Step 1: Confirm Hematuria
Perform a Urine Dipstick.
- False Positives: Myoglobinuria (rhabdomyolysis), Hemoglobinuria (hemolysis), beets, rifampin.
- False Negatives: Vitamin C (high doses).
Step 2: Microscopic Urinalysis
If dipstick is positive, confirm with Microscopy.
- Look for RBCs, WBCs, Casts, Crystals, Bacteria.
- Dysmorphic RBCs / RBC Casts → Nephrology Referral (Glomerular cause).
- Isomorphic RBCs → Urology approach.
Step 3: Assess Renal Function
Order Serum Creatinine and eGFR.
- Evaluate for acute kidney injury (AKI) or chronic kidney disease (CKD).
Step 4: Imaging and Cystoscopy (Based on Risk)
Follow the Canadian Urological Association (CUA) guidelines for imaging (CT Urography, Ultrasound) and Cystoscopy.
Canadian Guidelines: CUA Approach to Microscopic Hematuria
The Canadian Urological Association (CUA) 2020 guidelines provide a risk-stratified approach to Asymptomatic Microscopic Hematuria (AMH).
Who requires evaluation?
All patients with Gross Hematuria require a full workup (CT Urography + Cystoscopy). For Microscopic Hematuria, evaluation is based on risk factors.
CUA Risk Stratification for AMH
| Risk Category | Criteria | Recommended Workup |
|---|---|---|
| Low Risk | Age < 40 years Non-smoker No risk factors | Repeat Urinalysis in 6-12 months. If persistent, consider ultrasound. |
| Intermediate Risk | Age 40-60 years Current smoker (or past) No other high-risk factors | Renal Ultrasound + Cystoscopy |
| High Risk | Age > 60 years Gross Hematuria Heavy smoker (>30 pack-years) History of pelvic radiation/chemo | CT Urography (multi-phasic) + Cystoscopy |
Canadian Context: In Canada, CT Urography (CTU) is the gold standard imaging for hematuria because it evaluates the renal parenchyma (masses) and the urothelium (upper tract tumors). However, due to radiation, Ultrasound is preferred for low/intermediate risk or younger patients.
Management
Management is entirely dependent on the underlying etiology identified during the workup.
- UTI: Antibiotics based on local resistance patterns (e.g., Nitrofurantoin, Fosfomycin).
- Nephrolithiasis: Analgesia, hydration, medical expulsive therapy (Tamsulosin), or surgical intervention (lithotripsy/ureteroscopy).
- Malignancy (Bladder/Renal): Refer to Urologic Oncology.
- Bladder Cancer: TURBT (Transurethral Resection of Bladder Tumor) + BCG/Chemo.
- RCC: Partial or Radical Nephrectomy.
- Glomerular Disease: Refer to Nephrology. Management often involves blood pressure control (ACEi/ARBs) and immunosuppression depending on the specific pathology.
- Benign/Idiopathic: If workup is negative, reassure the patient. Monitor BP and urinalysis annually (CanMEDS: Health Advocate).
Key Points to Remember for MCCQE1
High-Yield Summary
- Painless gross hematuria in an adult is malignancy until proven otherwise.
- Smoking is the #1 risk factor for urothelial (bladder) carcinoma.
- IgA Nephropathy presents with gross hematuria during an upper respiratory infection (Synpharyngitic).
- Post-Strep GN presents with tea-colored urine 1-3 weeks after an infection.
- Red Cell Casts are pathognomonic for glomerular bleeding.
- The CUA Guidelines dictate that not every patient with microscopic hematuria needs a CT scan; risk stratify first.
- Anticoagulation (e.g., Warfarin, DOACs) does not exempt a patient from a hematuria workup. Do not attribute hematuria solely to blood thinners without ruling out pathology.
Sample Question
Clinical Scenario
A 62-year-old male presents to his family physician complaining of two episodes of seeing “blood in the toilet bowl” over the past week. He denies any pain, dysuria, fever, or flank pain. He has a 40-pack-year smoking history but quit 2 years ago. His past medical history is significant for hypertension managed with amlodipine. Physical examination reveals a blood pressure of 135/85 mmHg, a normal abdominal exam, and a benign prostate on digital rectal examination. Urinalysis confirms large blood, trace protein, and no leukocytes or nitrites.
Which one of the following is the most appropriate next step in the management of this patient?
- A. Prescribe a 7-day course of ciprofloxacin and reassess
- B. Measure serum Prostate Specific Antigen (PSA)
- C. Reassure the patient that this is likely due to benign prostatic hyperplasia
- D. Refer for renal ultrasound and repeat urinalysis in 6 months
- E. Refer for CT Urography and Cystoscopy
Explanation
The correct answer is:
- E. Refer for CT Urography and Cystoscopy
Detailed Explanation
This patient presents with painless gross hematuria and has significant risk factors for malignancy, specifically urothelial carcinoma (bladder cancer). His risk factors include:
- Gross hematuria: This places him automatically in the High Risk category according to CUA guidelines.
- Age > 60.
- Significant smoking history.
Why E is correct: The standard of care for high-risk hematuria (especially gross hematuria) is complete evaluation of the upper urinary tract (kidneys and ureters) and the lower urinary tract (bladder). CT Urography is the gold standard for upper tract imaging, and Cystoscopy is mandatory to evaluate the bladder, as imaging often misses small bladder tumors.
Why A is incorrect: Empiric antibiotics are inappropriate without evidence of infection (e.g., dysuria, leukocytes/nitrites on UA). This delays the diagnosis of potential cancer.
Why B is incorrect: While PSA screening might be considered in this age group, hematuria is not a classic presenting symptom of early prostate cancer. The immediate concern is bladder or renal cancer. PSA does not address the hematuria.
Why C is incorrect: Reassurance is dangerous. Painless gross hematuria in a smoker is highly suggestive of cancer. Attributing it to BPH without exclusion of malignancy is a common pitfall.
Why D is incorrect: Renal ultrasound is insufficient for a high-risk patient presenting with gross hematuria. It is less sensitive than CT for small renal masses and upper tract urothelial lesions. Furthermore, delaying follow-up is inappropriate.
References
- Canadian Urological Association (CUA). (2020). CUA guideline on the management of patients with asymptomatic microscopic hematuria. Link to CUA Guidelines
- Medical Council of Canada. (n.d.). MCCQE Part I Objectives: Hematuria.
- Toronto Notes. (2023). Urology & Nephrology Sections.
- UpToDate. (2024). Etiology and evaluation of hematuria in adults.