Editing Microscopic Hematuria (2020 AUA Guidelines) (section)

== Background ==

* '''<span style="color:#ff0000">Causes of hematuria (14):</span>'''
*# '''<span style="color:#ff0000">Malignancy:</span>''' 
*##'''<span style="color:#ff0000">Kidney</span>'''
*##'''<span style="color:#ff0000">Renal pelvis/ureter</span>'''
*##'''<span style="color:#ff0000">Bladder</span>'''
*##'''<span style="color:#ff0000">Prostate</span>'''
*##'''<span style="color:#ff0000">Urethra</span>'''
*# '''<span style="color:#ff0000">Non-oncologic</span>'''
*##'''<span style="color:#ff0000">Infection</span>'''
*## '''<span style="color:#ff0000">Inflammation</span>'''
*## '''<span style="color:#ff0000">Stones</span>'''
*## '''<span style="color:#ff0000">Benign prostatic hyperplasia (BPH)</span>'''
*## '''<span style="color:#ff0000">Benign tumor in urinary tract</span>'''
*##'''<span style="color:#ff0000">Congenital or acquired anatomic abnormalities</span>'''
*## '''<span style="color:#ff0000">Urethral strictures and diverticula</span>'''
*## '''<span style="color:#ff0000">Trauma</span>'''
*## '''<span style="color:#ff0000">Recent urological procedures/catheterization</span>'''
* '''Risk of urinary tract malignancy in patients with hematuria: 10%'''
** '''13% for patients with gross hematuria and 1-3% among patients with microscopic hematuria (MH)'''
** Vast majority are bladder cancers
* Prevalence of MH among healthy volunteers: 2-30% depending on the specific population evaluated.
* '''<span style="color:#ff0000">Urine dipstick</span>'''
** Detects the peroxidase activity of hemoglobin using benzidine
** '''<span style="color:#ff0000">Causes of false-positive dipstick (5):</span>'''
**# '''<span style="color:#ff0000">Myoglobinuria</span>'''
**# '''<span style="color:#ff0000">Dehydration</span>'''
**# '''<span style="color:#ff0000">Exercise</span>'''
**# '''<span style="color:#ff0000">Menstrual blood</span>'''
**# '''<span style="color:#ff0000">Povidone-iodine (betadine)[https://pubmed.ncbi.nlm.nih.gov/4032677/ §]</span>'''
* '''Urine may appear red in color from ingestion of certain foods and drugs'''
* '''<span style="color:#ff0000">Definition of microscopic hematuria: ≥ 3 RBCs per high powered field on microscopic examination of a single properly collected, urinary specimen. (CUA Guidelines recommend 2 positive samples)</span>'''
** '''For most initial evaluations, a random midstream clean-catch collection is sufficient.'''
*** Patients should discard the initial 10 mL of voided urine in order to collect the midstream void.
** If a significant number of squamous cells are present in the sample, contamination is possible and a repeat specimen collection or catheterization should be considered.
** Catheterization may be necessary in order to obtain an appropriate specimen in some patients such as obese female patients and patients with a non-intact urinary tract, a Foley catheter, a suprapubic catheter, or who use intermittent catheterization.
** '''Females with concurrent menstruation should be reevaluated after its cessation or should undergo catheterization to determine if the blood is in fact present in the urine or is only noted as a result of vaginal contamination.'''
** '''<span style="color:#ff0000">A positive dipstick merits microscopic examination of the urinary sediment, but does not warrant full evaluation unless microscopic evaluation confirms ≥3 RBC/HPF.</span>'''
*** If <3 RBC/HPF but suspicious that the findings could reflect true MH, then repeat microscopic testing may be reasonable after assessing patient risk and preference.
*'''Proper Sample Collection'''
**'''For most initial evaluations, a random midstream clean-catch collection is sufficient.''' 
***Patients should be instructed to discard the initial 10 mL of voided urine into the toilet in order to collect the midstream void
**Urine specimens collected immediately after prolonged recumbency (first void in morning) or the first voiding after vigorous physical or sexual activity should not be examined to assess for microhematuria.