From the Guidelines
To work up microscopic hematuria, follow a systematic approach that includes confirmation of the diagnosis, medical history, physical examination, laboratory tests, and imaging studies, as recommended by the most recent guidelines 1. The approach to evaluating microscopic hematuria should prioritize the identification of potential urologic and renal causes, while minimizing unnecessary testing and procedures.
Key Steps in the Evaluation of Microscopic Hematuria
- Confirm the diagnosis with repeat urinalysis to rule out transient hematuria, as defined by the presence of 3 red blood cells per high power field on microscopic evaluation of a single specimen 1.
- Obtain a detailed medical history and perform a physical examination to identify risk factors for urologic malignancies, recent infections, medication use, and family history of kidney diseases.
- Order laboratory tests, including complete blood count, serum creatinine, and urine culture, to assess overall kidney function and rule out infection.
- Perform imaging studies, such as CT urography or renal ultrasound with cystoscopy, to evaluate the upper and lower urinary tracts, with cystoscopy recommended for all patients over 35 years old or those with risk factors for bladder cancer, regardless of age 1.
- Refer to a urologist for further evaluation if needed, and consider referral to nephrology if no cause is identified after the initial workup.
Importance of Risk Stratification
The evaluation of microscopic hematuria should also involve risk stratification, based on factors such as age, sex, smoking, and other urothelial cancer risk factors, degree and persistence of microhematuria, and prior gross hematuria, to guide the diagnostic evaluation and follow-up 1.
Recent Guidelines and Recommendations
The most recent guidelines from the American Urological Association (AUA) and the Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) recommend a risk classification system for patients with microhematuria, stratified as low-, intermediate-, or high-risk for genitourinary malignancy, to guide the diagnostic evaluation and follow-up 1.
From the Research
Approach to Evaluating Microscopic Hematuria
The approach to evaluating microscopic hematuria involves a series of questions and tests to determine the underlying cause of the condition.
- The need to perform a detailed work-up of microscopic hematuria is based on the following set of questions:
- Does the history or physical examination findings suggest systemic or renal disease?
- Is the patient able to acidify and concentrate urine?
- Is proteinuria present?
- Do other family members have hematuria or other renal problems?
- Does the microscopic analysis show casts, crystals, or WBCs?
- Are the RBCs eumorphic or dysmorphic? 2
- Initial evaluation may include a urine culture, urine calcium-to-creatinine ratio, and renal and bladder sonography, or a very detailed evaluation for renal parenchymal disease, stones, tumors, or anatomic abnormalities 2.
- The presence of dysmorphic red blood cells (dRBCs) is indicative of glomerular disease and considered a first step in evaluating microscopic hematuria (MH) 3.
- However, the predominance of dRBCs does not preclude urological disease, and urological evaluation should not be omitted in patients with MH 3.
Diagnostic Tests
- Microscopic urinalysis for red blood cell morphology can be used to evaluate asymptomatic microscopic hematuria in a pediatric population 4.
- However, the use of refined microscopic urinalysis for RBC morphology may not be necessary in children, as it offers little additional information to the evaluation of microscopic hematuria 4.
- A complete urinalysis with a microscopic examination is the only laboratory test uniformly required for children with hematuria 5.
- Other tests, such as cystoscopy, computed tomography (CT) imaging, and renal biopsy, may be necessary in some cases to determine the underlying cause of hematuria 3, 6.
Evaluation and Management
- The evaluation and management of microscopic hematuria should be tailored according to the patient's history, physical examination, and other abnormalities on the urinalysis 2, 5.
- A standardized care pathway can be used to optimize decision-making among providers and ensure that patients receive appropriate evaluation and treatment 6.
- Patients with microscopic hematuria should be risk-stratified, and those with high-risk features should undergo further evaluation, including cystoscopy and axial upper urinary tract imaging 6.