Quick answer. Blood in the stool is common and often due to piles (haemorrhoids), but it should never be assumed to be harmless. Persistent bleeding, dark or tarry stools, a change in bowel habit or weight loss are red flags that need prompt assessment, often with a colonoscopy, because blood in the stool can be an early sign of colorectal cancer.
Seeing blood when you go to the toilet is alarming but common. Bright red blood is often from piles or an anal tear, while dark, tarry stool (melena) can mean bleeding higher up in the gut.
The danger is assuming it is “just piles”. People with haemorrhoids can also have a cancer, so any unexplained or persistent bleeding deserves to be checked properly.
At a glance
| What you notice | What it may suggest | Urgency |
|---|---|---|
| Bright red blood on paper or surface of stool | Piles (haemorrhoids) or anal fissure | See a doctor; do not assume — get persistent bleeding checked |
| Blood mixed into the stool | Possible source higher in the colon, including polyps or cancer | See a doctor promptly for assessment |
| Black, tarry, foul-smelling stool (melena) | Bleeding from the stomach or upper gut | Urgent — seek medical care the same day |
| Bleeding with change in bowel habit or weight loss | Possible colorectal cancer | See a doctor promptly; colonoscopy often needed |
| Heavy bleeding, dizziness, fainting | Significant blood loss | Emergency — call 995 or go to A&E |
Bright red blood versus dark or tarry stool
The colour of the blood gives a clue to where it comes from. Bright red blood usually comes from the lower bowel, rectum or anus — for example from piles or an anal fissure. Blood that is mixed through the stool can come from higher in the colon. Black, tarry, strong-smelling stool (called melena) usually means bleeding from the stomach or upper digestive tract, where the blood has been partly digested.
Melena is treated as a more urgent sign and should be assessed the same day.
Common versus serious causes
The commonest cause of bright red rectal bleeding is haemorrhoids (piles), followed by anal fissures — both are benign. Other causes include inflammation of the bowel, infections, diverticular disease, and polyps. The serious cause everyone wants to exclude is colorectal cancer.
Blood in the stool can be an early sign of colorectal cancer, one of the most common cancers in Singapore. Importantly, blood mixed into the stool, rather than just on the surface, raises the concern further. Having piles does not protect you from also having a cancer, which is why bleeding should not simply be blamed on piles without proper assessment.
When to see a doctor urgently
Call 995 or go to A&E immediately if you have:
- Large amounts of blood, or you feel faint, dizzy or short of breath
- Black, tarry stools with abdominal pain or vomiting blood
- Bleeding with a fast heartbeat, sweating or collapse
See a doctor promptly (do not wait) if you have:
- Blood mixed into the stool
- Bleeding that is persistent, recurrent, or new for you
- A change in bowel habit (looser stools, constipation, narrower stools) lasting more than a few weeks
- Unexplained weight loss, tiredness or pallor (possible anaemia)
- Any rectal bleeding if you are over 40 or have a family history of colorectal cancer
Why a colonoscopy may be recommended
For bleeding with red flags — blood mixed in the stool, a change in bowel habit, weight loss, anaemia, or older age — doctors often recommend a colonoscopy. This is a camera test that examines the lining of the entire large bowel. It can find and remove polyps before they become cancer, take biopsies, and identify the source of bleeding.
In Singapore, routine colorectal cancer screening is recommended from age 50 for people without symptoms, often starting with a stool test (FIT) that detects hidden blood. Anyone with symptoms, or a family history, may need to be assessed earlier and with colonoscopy directly.
Which specialist should you see?
Start with your GP or polyclinic, who can examine you and arrange initial tests. For blood in the stool with any red-flag features, you will usually be referred to a specialist:
- Gastroenterologists — specialists in the digestive system who perform colonoscopy, diagnose the cause of bleeding, and manage conditions such as inflammatory bowel disease, polyps and colorectal cancer.
Do not delay seeing a doctor in the hope the bleeding stops on its own. Early assessment is the best way to catch a serious cause when it is most treatable.
What to expect at the appointment
Your doctor will ask about the colour of the blood, whether it is on the paper, on the surface or mixed through the stool, how long it has been happening, and about any change in bowel habit, weight loss, tiredness or family history of bowel cancer. The examination usually includes feeling the abdomen and a digital rectal examination, where a gloved finger checks the back passage; this is quick and helps identify piles, fissures or other findings. Initial tests may include blood tests for anaemia and a stool test. If red-flag features are present, a colonoscopy is often arranged so the whole large bowel can be examined directly and polyps removed if found.
Screening and self-management
Because blood in the stool can be an early sign of colorectal cancer, screening matters. In Singapore, the Screen for Life programme recommends a yearly stool test (FIT), which detects hidden blood, for those aged 50 and above without symptoms, with subsidies available for eligible residents; ask your GP or polyclinic about your options. To ease piles and fissures, which are the commonest benign causes, increase dietary fibre and fluids, avoid straining and prolonged sitting on the toilet, and stay active. These measures help symptoms, but they are not a substitute for assessment if bleeding is persistent, recurrent or new for you.
Common questions
If I know I have piles, do I still need it checked?
Yes. Having piles does not protect you from also having a polyp or cancer, so unexplained or persistent bleeding should still be assessed rather than simply blamed on piles.
What does black, tarry stool mean?
It often signals bleeding higher in the gut, where blood has been partly digested. This is treated as more urgent and should be reviewed the same day.
Related guides
- Best Gastroenterology Clinics in Singapore — our editorial shortlist
- gastroenterology clinics directory
- Urology
- Oncology
- Oncology
Sources
- National Cancer Centre Singapore (NCCS) – Colorectal Cancer
- HealthHub (Singapore) – Colorectal Cancer
- NHS – Blood in stool
- Mayo Clinic – Rectal bleeding
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