Blood in the Urine Without Pain: Could It Be Bladder Cancer?

最終更新日： 2026年8月15日

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Bladder cancer is the commonest cancer of the urinary tract, and it announces itself in a very particular way: blood in the urine, without any pain at all. That absence of pain is exactly what makes it dangerous, because pain is what usually sends people to a doctor.

One point before anything else, because it is the reason diagnoses get delayed. The bleeding is usually intermittent. It appears for a day or two, then stops completely, and the urine looks entirely normal again. That is not the problem resolving — the tumour does not go away when the bleeding does. A single episode of painless blood in the urine deserves investigation, even if it never comes back. Waiting to see whether it happens again is the most common and most costly mistake with this disease.

The two major リスク要因

1. Smoking

Tobacco is by far the largest risk factor: roughly 50% of bladder cancer patients have smoked, and smokers carry up to six times the risk of non-smokers. The risk rises with both how long and how heavily you smoked.

Two things are worth knowing about that. First, the elevated risk persists for decades after quitting — which means a man who stopped fifteen years ago should still take painless hematuria seriously rather than assuming smoking is behind him. Second, quitting is still worth it: the risk falls over time, and it also lowers the chance of a tumour coming back after treatment. The risk from electronic cigarettes is not yet established.

2. Occupational exposure

10–20% of cases are attributed to work exposure — chemicals used in making dyes, paint, rubber and petroleum products, inhaled over years. This is a modifiable risk: proper industrial safety practice and protective equipment genuinely reduce it. If your work has involved these, it is worth mentioning to your doctor, since it changes how seriously a single episode of hematuria should be taken.

What the assessment involves

The purpose of the workup is to find or exclude a tumour, and to distinguish it from the other things that cause blood in the urine — infection and stones being the commonest.

A full history and examination come first, then urine tests, then CT with contrast to image the whole urinary tract. The decisive investigation is cystoscopy — passing a telescope into the bladder to look directly at the lining. Nothing else sees the inside of the bladder as reliably, and the same procedure allows a suspicious area to be biopsied and a tumour resected, so it is diagnostic and therapeutic at once.

The encouraging part is that bladder cancer found early is very treatable. Most cases are non-muscle-invasive at diagnosis and are managed endoscopically, without removing the bladder. What decides the outcome, more than almost anything else, is how quickly the first episode of bleeding is investigated. If a tumour is found and treated, regular surveillance afterwards becomes part of the picture too.

If you have experienced painless blood in urine or would like a bladder cancer evaluation, Dr. Soarawee Weerasopone offers specialist consultations at Bangkok Hospital Headquarters. 診療をご予約. サミティウェート・シーラチャ病院のご予約は、泌尿器科（電話番号：）までお問い合わせください。 088-022-1445.

Frequently Asked Questions about Bladder Cancer

免責事項 この記事は、バンコク病院本部のボード認定泌尿器科医であるソアラウィー・ウィーラソポン医師（Dr. Soarawee Weerasopone）によって執筆および監修されています。教育目的のみを意図しており、医学的なアドバイスを構成するものではありません。個人的なメッセージチャンネルを通じて、医学的なアドバイス、診断、処方箋が提供されることはありません。医療処置を開始する前に、必ず資格を持った医療従事者にご相談ください。.