What should you know about menstrual blood in a urine test?

A urine test may detect blood cells or blood pigments, but it cannot always show where the blood came from. Vaginal bleeding during menstruation can mix with urine in the container. Tell the clinician when your period started, whether the sample was visibly contaminated and whether you had urinary symptoms.

Blood that remains in a properly collected sample outside menstruation may have causes such as a Urinary Tract Infection, Kidney Stones or Kidney Infection. Less common urinary conditions also need consideration based on age, sex, medical history and the result. A positive result does not by itself diagnose cancer.

Follow the laboratory's collection instructions. Wash your hands, clean the genital area as directed, begin urinating into the toilet, then collect the midstream portion without touching the inside of the container. If possible, ask whether to repeat testing after the period has ended.

Do not delay advice if you have burning, fever, flank pain, clots, difficulty passing urine or visible blood. A clinician may arrange microscopy, culture or other tests according to your symptoms.

Seek urgent care for heavy visible blood, clots blocking urine flow, severe side or back pain, fever with urinary symptoms, vomiting or feeling faint. Arrange follow-up if blood is found again in a clean sample, even when you feel well. Persistent haematuria needs an explanation rather than being attributed automatically to menstruation.

Ask whether the sample should be repeated, which symptoms change the urgency, whether a culture is appropriate, and what follow-up is planned if blood remains after menstruation.