Non visible haematuria

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:

1. Barocas DA, Boorjian SA, Alvarez RD, et al. Microhematuria: AUA/SUFU Guideline. J Urol. 2020 Oct;204(4):778-86.
2. Cohen RA, Brown RS. Microscopic hematuria. N Engl J Med. 2003;348:2330-2338.
3. Kelly JD, Fawcett DP, Goldberg LC. Assessment and management of non-visible haematuria in primary care. BMJ. 2009;338