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Published: September 24, 2018

Blood In The Pee: To See Or Not To See… How Scared Should You Be!

Definition Of Non Visible Hematuria

Microhematuria is defined by the presence of three or more red blood cells (RBCs) per high-powered field (HPF), 6-8 on microscopic examination of one properly-collected, non-contaminated urinalysis with no evidence of infection for which a combination of microscopic urinalysis and dipstick excludes other abnormalities such as pyuria, bacteriuria, and contaminants.

The assessment of the asymptomatic microhematuria patient should include a careful history, physical examination, and laboratory examination to rule out causes of AMH such as infection, menstruation, vigorous
exercise, medical renal disease, viral illness, trauma, or recent urological procedures.

The origins of microhematuria are either urologic or nephrologic. The most common urological etiologies are benign prostatic enlargement, infection and urinary calculi.

Three sets of studies indicate that only a small proportion of patients with microhematuria will ultimately be diagnosed with a urinary tract malignancy. These studies include the following:

  • Screening studies in which individuals without known health conditions were diagnosed with AMH and worked up;
  • initial work-up studies in which patients who had AMH diagnosed incidentally during a medical encounter such as a check-up were worked up;
  • and further work-up studies in which AMH patients not diagnosed during an initial workup process were referred on for a specialized work-up.

Findings from 17 screening studies revealed an overall urinary tract malignancy rate of approximately 2.6%.

However, The Rates May Be Higher…

Rates in individual studies ranged from 0% to 25.8%, with repeated testing in high-risk individuals (e.g., male smokers aged 60 years or greater) yielding higher rates. Thirty-two studies reported findings from initial work-ups and reported an overall malignancy rate of 4.0%.

Common Risk Factors for Urinary Tract Malignancy in Patients with Microhematuria:

  • Male gender
  • Age (> 35 years)
  • Past or current smoking
  • Occupational or other exposure to chemicals or dyes (benzenes or aromatic amines)
  • Analgesic abuse
  • History of gross hematuria
    • History of urologic disorder or disease
    • History of irritative voiding symptoms
    • History of pelvic irradiation
    • History of chronic urinary tract infection
    • History of exposure to known carcinogenic agents or chemotherapy such as alkylating agents


Previously any painless visible haematuria of any age was referred by the 2WW guidelines. However as the Positive predictive value of any haematuria was 0.99 for men <45 years and 0.22 for women <45years, a 2WW referral is recommended only for people with visible haematuria age>45 without a UTI or persisting/recurring despite treatment of a UTI.

BAUS 2016

Asymptomatic non-visible haematuria has a PPV of 0.79% and 1.6% for patients aged 40-59 years and >60 years respectively and no longer require an urgent referral. (Previously, any patients over 50 years who were found to have unexplained microscopic haematuria –an urgent referral was suggested).

What We Usually Do

  • Apart from the history and physical assessment
  • 1st Line is a USG KUB as its cheap and safe
  • +/- Cystoscopy if indicated
  • Sometimes it's more cost effective to do a CTU upfront and that decision whether its contrasted or plain will take a clinical assessment.

So What To Do

  • Help by investigating for common benign problems especially UTI and treat. Don't forget to repeat the urine sample after a certain period i.e 2 weeks.
  • Refer for evaluation if unsure or if high risk.

Refer To The Nephrologist If

  • The presence of proteinuria, red cell casts, or dysmorphic red blood cells on a microscopic exam and/or an elevated creatinine is suggestive of a glomerular cause of hematuria.


  • Any blood in the pee above recommended guidelines is rarely idiopathic.
  • The risk of cancer is low but real.
  • There cannot be enforced guidelines on what to do albeit only recommendations as resources vary from place to place.
  • We have a world standard system thus we should do what's best and not more unless required.

Ask Dr.Datesh

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