Visible blood in urine — even if painless and gone by the next day — still warrants a check-up

Among people aged 60 and older, the chance of ultimately being diagnosed with bladder cancer after experiencing one episode of visible blood in urine is about 2.8%. For those aged 40–59, that figure is roughly 1.2%. These percentages may not seem very high, but they’re high enough to justify getting checked — even if the bleeding stops the very next day.

A routine urine test costs just a few dozen yuan, while a urinary-system ultrasound runs around 100–200 yuan. If a doctor deems it necessary, a cystoscopy can be added at a cost of roughly 1,000 yuan.

A UK study analyzed electronic medical records from primary-care clinics, comparing 4,915 patients diagnosed with bladder cancer against 21,718 controls. Among patients with visible blood in urine, the proportion ultimately found to have bladder cancer was 2.8% for those aged 60+, with a 95% confidence interval of 2.5–3.1. For ages 40–59, the figure was 1.2%, with a 95% CI of 0.6–2.3. This proportion is known as the positive predictive value. Blood visible only under a microscope also carries significance; the odds ratio is 20, with a 95% CI of 12–33. For those over 60, this figure is 1.6%, with a 95% CI of 1.2–2.1.

The absence of pain is a key clue. Blood in urine caused by kidney stones or infections usually comes with abdominal or flank pain, plus frequent, urgent, or painful urination. Cancer-related bleeding, however, often causes no discomfort at all and may disappear for a few days before returning — which is why many people overlook it. Taking anticoagulant medications is not a valid reason to skip testing. Blood in urine after intense exercise or during a woman’s menstrual period can be re-evaluated before deciding on further checks. The benefit is rated “low” because it reflects only detection rates, not any measurable reduction in mortality resulting from early diagnosis.

Price SJ, Shephard EA, Stapley SA, Barraclough K, Hamilton WT (2014). Non-visible versus visible haematuria and bladder cancer risk: a study of electronic records in primary care. British Journal of General Practice, 64(626), e584-e589. https://doi.org/10.3399/bjgp14X681409；NHS. Blood in urine：「Blood in your pee must be checked out because it can be a sign of cancer.」「But do not self-diagnose.」「It may not be blood in your pee if: you've recently eaten beetroot … you're taking a new medicine … it's happening during your period」. https://www.nhs.uk/symptoms/blood-in-urine/；NHS. Symptoms of bladder cancer：「You have blood in your pee, even if: you do not have any other symptoms; it's the first time it's happened; there's only a small amount of blood; you're not sure if it's blood」. https://www.nhs.uk/conditions/bladder-cancer/symptoms/