Blood in Stool

Rectal bleeding is common and the great majority of it comes from piles or a small tear. That is genuinely reassuring — but only once someone has looked properly.

The pattern that matters most is where the blood is. Bright red on the paper or in the pan usually comes from the anus itself. Blood mixed through the stool, or darker in colour, has come from further up and needs investigating.

Common and benign

• Piles — bright red blood, itching, sometimes a lump. Much the commonest cause
• Anal fissure — a small tear, causing sharp pain on passing stool and blood on the paper. Usually follows constipation
• Gastroenteritis, causing brief bloody diarrhoea

Needing investigation

• Inflammatory bowel disease — blood with diarrhoea, urgency, abdominal pain and weight loss, often in a younger person
• Diverticular disease — common with age, sometimes causing sudden painless bleeding
• Polyps and bowel cancer — the reason this symptom is never assumed. Bowel cancer is highly treatable when found early and the symptoms are often unremarkable

IBS does not cause bleeding. If you have an IBS diagnosis and are bleeding, that needs a fresh look.

The consultation establishes the pattern — colour, whether it is mixed through, pain, bowel habit change, weight, family history — and that history determines urgency more than anything else.

We arrange a FIT test, which detects blood not visible to the eye and is the gateway investigation for bowel symptoms, alongside full blood count and ferritin — iron deficiency alongside bleeding raises the priority considerably.

Where the picture warrants it we arrange colorectal referral for colonoscopy. Where it is clearly piles or a fissure, we treat it and address the constipation driving it.

What we cannot do: examine you. Where examination is needed to settle it, we will say so and refer rather than guess.

Is it just piles?

Never assume so — this is the most important thing on the page. Piles are extremely common, which means plenty of people have piles and something else. Bowel cancer causes bleeding that can look identical. Any new rectal bleeding over 50, or bleeding alongside a change in bowel habit, weight loss or anaemia, needs proper assessment rather than an assumption.

What does the colour tell you?

• Bright red on the paper or in the pan — usually from close to the anus: piles or a fissure. The most common and least concerning pattern
• Dark red, or mixed through the stool — from higher in the bowel, and more significant
• Black and tarry, with a strong smell — bleeding in the stomach or duodenum. Urgent

It's painless. Isn't that reassuring?

Counter-intuitively, no — painless bleeding is generally more concerning than painful bleeding, not less. Severe pain on passing stool usually indicates an anal fissure, which is benign. Painless bleeding is the classic presentation of both piles and bowel cancer, which is exactly why it cannot be assumed to be the former.

I'm young. Do I still need it checked?

Yes. Bowel cancer is much less common under 50, but rates in younger adults have been rising, and young people are more likely to be reassured without investigation — which is why their diagnoses tend to come later. Bleeding at any age warrants an explanation, particularly if it persists, recurs, or comes with a change in bowel habit or weight loss.

What is a FIT test?

A simple home test that detects blood in the stool invisible to the eye. You collect a tiny sample and post it. It is used to decide who needs urgent bowel investigation, and it is a genuinely good test — but only if the kit is actually returned. Unreturned kits are a real and avoidable source of delay.

Could it be something I ate?

Occasionally — beetroot and red food colouring can redden stool, and iron tablets turn it black, though iron gives a dull black rather than the sticky, tarry, strong-smelling black of genuine bleeding. If there is any doubt, treat it as blood and get it checked.

How urgent is this really?

Black tarry stools, heavy bleeding, or bleeding with dizziness or breathlessness — same day, or A&E. New bleeding over 50, or bleeding with weight loss, anaemia or a change in bowel habit — urgent appointment. Small amounts of bright red blood in a young person with obvious piles or a painful fissure — a routine appointment, but still an appointment.

Can this be sorted out remotely?

Partly. We can take the history, arrange blood tests and a FIT test, and make an urgent referral where one is warranted — which is often the most valuable thing, since getting onto the right pathway quickly is what matters. What we cannot do is examine you, and rectal bleeding that needs explaining generally needs examining as well.