Non-visible haematuria
Also known as microscopic haematuria or 'dipstick positive haematuria', non visible haematuria is further sub-divided into:
- symptomatic Non-Visible Haematuria (s-NVH) - symptoms such as voiding lower urinary tract symptoms (LUTS): hesitancy, frequency, urgency, dysuria
- asymptomatic Non-Visible Haematuria (a-NVH) - incidental detection in the absence of LUTS or upper urinary tract symptoms
Non-visible haematuria (NVH) is the presence of three or more red blood cells (RBCs) per high-power microscope field on a midstream, clean-catch urine sample. A positive dipstick result for blood (trace blood or greater) does not confirm NVH, but should prompt further investigation with microscopy. (1)
The significance of microscopic haematuria varies with age:
- in young people
- urinary tract malignancies are uncommon in this age group, hence prevalence of significant underlying pathology for haematuria found at screening is low (in the range 0-7.2%)
- glomerular causes are mainly responsible for haematuria
- prevalence of significant pathologies is said to increase with age
- in patients over 60 years who were screened positive for macroscopic haematuria, 5% had bladder tumours
Causes of non-visible haematuria include: (2,3)
- transient
- urinary tract infections
- exercise related
- spurious
- menstrual contamination
- sexual intercourse
- foods such as beetroot, blackberries and rhubarb
- rhabdomyolysis
- drugs - doxorubicin, chloroquine, rifampicin
- chronic lead or mercury poisoning
References:
- Barocas DA, Boorjian SA, Alvarez RD, et al. Microhematuria: AUA/SUFU Guideline. J Urol. 2020 Oct;204(4):778-86.
- Cohen RA, Brown RS. Microscopic hematuria. N Engl J Med. 2003;348:2330-2338.
- Kelly JD, Fawcett DP, Goldberg LC. Assessment and management of non-visible haematuria in primary care. BMJ. 2009;338