AUA GUIDELINE: DIAGNOSIS, EVALUATION AND FOLLOW-UP OF ASYMPTOMATIC MICROHEMATURIA IN ADULTS 2016
See UPDATED AUA Asymptomatic Microscopic Hematuria Guidelines 2020
See CUA Asymptomatic Microscopic Hematuria Guidelines 2008
Background
- Definition of asymptomatic microhematuria (AMH): ≥ 3 RBCs per high powered field on microscopic examination of 1 properly collected, non-contaminated urinary specimen in the absence of an obvious benign cause. (CUA Guidelines recommend 2 positive samples)
- A positive dipstick does not define AMH
- Evaluation should be based solely on findings from microscopic examination of urinary sediment and not on a dipstick reading
- A positive dipstick reading merits microscopic examination to confirm or refute the diagnosis of AMH.
- Patients who have a positive dipstick test but a negative specimen on microscopy should have 3 additional repeat tests. If ≥1 of the repeat tests is positive on microscopy, then workup should be undertaken. If all 3 specimens are negative on microscopy, no further workup is needed.
- The origins of microhematuria are either urologic or nephrologic
- Most common urological causes of microhematuria are benign prostatic enlargement, infection and urinary calculi; ≈2.6% of patients with AMH are found to have a urological malignancy
- Other conditions that would benefit from active clinical management are frequently diagnosed: benign prostatic enlargement, urolithiasis, and urethral stricture disease
- Other benign causes of AMH: infection, menstruation, vigorous exercise, medical renal disease, viral illness, trauma, or recent urological procedures
- The presence of dysmorphic red blood cells, proteinuria, cellular casts, and/or renal insufficiency, or any other clinical indicator suspicious for renal parenchymal disease warrants concurrent nephrologic workup but does not preclude the need for urologic evaluation
Diagnosis and Evaluation
- Recommended (4):
- H+P
- Cr (NOT required in CUA guidelines)
- CT urogram (CUA Guidelines recommend US)
- Cysto
- History and physical exam
- Rule out benign causes (see above); once benign causes have been ruled out, the presence of asymptomatic microhematuria should prompt a urologic evaluation
- Microhematuria that occurs in patients who are taking anti-coagulants requires urologic evaluation and nephrologic evaluation regardless of the type or level of anti-coagulation therapy
- Laboratory
- Assessment of renal function (NOT required in CUA guidelines)
- May include calculated eGRF, creatinine, and BUN
- Abnormal renal function warrants evaluation to include establishing the etiology of renal dysfunction either as it relates to, or independent of, the cause of hematuria
- Renal dysfunction increases the risk of contrast or gadolinium radiologic studies and needs to be considered in the selection of these diagnostic procedures.
- If procedures are considered for the treatment of urologic diseases that may result in a reduction in renal function, then the implications of this reduction may be more pronounced for patients who have baseline abnormal renal function
- Imaging
- CT urography (without and with intravenous (IV) contrast) (CUA Guidelines recommend US)
- Imaging of choice because it has the highest sensitivity and specificity for imaging the upper tracts
- US with or without IVU presents significant risks for missed diagnoses; use of these modalities is an alternative, but less optimal imaging strategy
- Phases (4) to evaluate the renal parenchyma to rule out a renal mass and an excretory phase to evaluate the urothelium of the upper tracts; [some sources say 3 phases]
- Non-contrast: establish baseline densities of tissues and high or variable densities such as calculi, hematomas or fat-containing structures
- Arterial: identifying neoplastic or inflammatory neovascularity
- Cortico-medullary or parenchymal: defining evidence of renal parenchymal changes and equating it to sustained damage
- Excretory: demonstrates the collecting system, ureters and bladder
- In patients with renal insufficiency, hydration, either intravenous or oral, is recommended for contrast risk reduction
- Consideration should be given for pre-medication with steroids be given to patients with a documented history of contrast reaction
- For patients with relative or absolute contraindications that preclude use of multi-phasic CT (such as renal insufficiency, contrast allergy, pregnancy), magnetic resonance urography (MRU) (without/with IV contrast) is an acceptable alternative imaging approach.
- Although MRU appears to provide high sensitivity/specificity imaging of the renal parenchyma, its role in visualizing collecting system detail is indeterminate; its role in working up AMH patients is unclear given the lack of literature in this population
- For patients with relative or absolute contraindications that preclude use of multiphase CT where collecting system detail is deemed imperative, combining MRI with retrograde pyelograms provides alternative evaluation of the entire upper tracts
- For patients with relative or absolute contraindications that preclude use of multiphase CT and MRI (presence of metal in the body) where collecting system detail is deemed imperative, combining non-contrast CT or renal US with retrograde pyelograms provides alternative evaluation of the entire upper tracts.
- US has limited detection of small solid renal lesions and urothelial carcinoma in the kidney or ureter.
- Pregnant AMH patient
- Given that malignancies in this low risk group (typically < 40 years of age) are rare, it is recommended to use MRU, MRI with RPGs, or US to screen for major renal lesions with a full workup after delivery once gynecological bleeding and persistent infection have been ruled out
- Cystoscopy
- Should be performed on all patients aged ≥35 (CUA Guidelines say >40)
- In patients age < 35, cystoscopy may be performed at the physician’s discretion
- Regardless of age, a cystoscopy should be performed on all patients who present with risk factors for urinary tract malignancies:
- Past or current smoking
- Occupational or other exposure to chemicals or dyes (benzenes or aromatic amines)
- Analgesic abuse
- History of pelvic irradiation
- History of chronic UTI
- Exposure to known carcinogenic agents or chemotherapy such as alkylating agents
- Chronic indwelling foreign body
- History of irritative voiding symptoms
- History of gross hematuria
- History of urologic disorder or disease
- Blue light cystoscopy should not be used in the evaluation of patients with asymptomatic microhematuria.
- Cytology
- Urine cytology and urine markers (NMP22, BTA-stat, and UroVysion FISH) are NOT recommended as a part of the routine AMH evaluation (CUA Guidelines recommend cytology)
- Urine cytology may be useful in patients with persistent microhematuria following a negative work up or those with other risk factors for carcinoma in situ (e.g., irritative voiding symptoms, current or past tobacco use, chemical exposures)
Negative evaluation
- If the appropriate evaluation of the asymptomatic microhematuria patient does not reveal clinically significant urologic or nephrologic disease, then yearly urinalyses should be conducted for at least 2 years following initial evaluation
- CUA guidelines recommend urinalysis, urinary cytology, and blood pressure checks at 6, 12, 24 and 36 months
- If a patient with a history of persistent AMH has 2 consecutive negative annual urinalyses (one per year for 2 years from the time of initial evaluation or beyond), then no further urinalyses for the purpose of evaluation of AMH are necessary.
- If the urinalysis is negative for 2 consecutive years, then the risk of urologic or nephrologic disease may be no greater than that of the general population.
- For persistent or recurrent asymptomatic microhematuria after initial negative urologic work-up, repeat evaluation within 3-5 years should be considered
- The threshold for re-evaluation should take into account patient risk factors for urologic pathologic conditions such as malignancy as well as the fact that patients who had had a thorough initial workup with negative findings are likely to remain cancer-free.