Red blood in the faeces: when to worry?

By Cristiano Antonino On Feb 20, 2023

The presence of blood in the stool is an event that alarms us, sometimes even exaggeratedly, because often the first thing that comes to mind is cancer

Other times, however, we overlook the symptom because having a visit to that ‘area’ bothers us and because, after all (we think!), it will be trivial haemorrhoids.

Where does the blood in the stool come from?

Blood in the faeces can be visible to the naked eye (on toilet paper, inside the toilet or mixed with faeces, etc.) or it can be occult blood, i.e. not visible and only detected with a special laboratory test (detection of occult blood in faeces).

Blood in the stool is a sign of bleeding at a point in the digestive tract and its colour can give us an indication of where the bleeding is located

If the stool is tar-black in colour, it is a sign of what is called ‘melena’ and the cause of the bleeding is in the upper part of the digestive tract, i.e. the oesophagus, stomach, duodenum, small intestine or the right portion of the colon such as the cecum.

The black colour is determined by the presence of blood pigments resulting from the transformations undergone by haemoglobin as it passes through the gastrointestinal tract (‘digested’ blood).

The faeces, in addition to having a piceous black colour, give off a particularly fetid, nauseating odour.

If, on the other hand, the blood emitted, with or without faeces, is bright red or brownish red, one is in the presence of what is called haematochezia (from the Greek, ‘aima’, blood and ‘kezèin’, defecate) and the cause lies in the lower digestive tract (colon and rectum).

It should be noted, however, that in the presence of severe upper digestive bleeding, the blood emitted can quickly reach the rectum while maintaining a red colour.

Definitions of rectal bleeding

The emission of bright red blood from the anus is defined by the following terms:

Haematochezia. This is a generic term for bleeding that can occur from any part of the digestive tract, although it usually refers to the lower tract. The bleeding, which is minor, may accompany the faeces (as ‘streaking’, ‘varnishing’) or occur in isolation (at the end of defecation) as ‘dripping’.

Rectorrhagia. This indicates profuse, jet-like bleeding, often without faeces, of probable rectal origin.

Proctorrhagia. It is synonymous with rectorrhagia if the term is intended to indicate an anal cause (haemorrhoids, fissure) of bleeding (from Greek, ‘proctos’, anus).

Enterorrhagia. It is a generic term used to indicate profuse bleeding also with emission of clots whose origin is assumed to be higher than the rectum (proximal to the sigma).

Bright red blood in the stool: what to do?

If the colour is bright red, therefore, it generally indicates low, rectal bleeding, which could be a symptom of haemorrhoids, fissures, but also of polyps, a tumour form or an inflammatory or even vascular disease.

A doctor faced with a patient who reports red blood in the stool will make an immediate assessment considering age and any associated symptoms.

In the case of a young person who, after a defecatory effort, reports seeing red spots of blood on the toilet paper or in the bowl, it is easy to suspect haemorrhoidal bleeding.

On the other hand, if a patient over 50 (or even younger!) reports having noticed blood mixed with stools and if this is associated with the presence of mucus and a possible alteration of evacuation (constipation and/or diarrhoea), or even anaemia, then the thought becomes darker because there is really the suspicion of a tumour pathology.

The patient, when reporting to the doctor, must well indicate the characteristics and modalities of the bleeding (amount of blood emitted, associated symptoms, presence or absence of mucus, etc.) because on the basis of the characteristics of the blood emitted it is possible to formulate an initial diagnostic hypothesis.

It should be pointed out, however, that only a specialist examination (proctological examination, ano-rectoscopy, colonoscopy, etc.) can lead to a definitive diagnosis.

How does bleeding present itself?

Based on the presentation of rectal bleeding, the relevant diagnostic hypothesis is made.

Blood on toilet paper (paper bleeding)

If the faeces emitted are normal and blood is only visible on the toilet paper, during the cleaning phase, it can be assumed that the bleeding is a symptom of haemorrhoids.

Blood ‘dripping’

If the faeces emitted are normal and blood is visible at the end of defecation and you see it “dripping” into the bowl, it is most likely haemorrhoids.

Bleeding and pain

If bleeding is accompanied by anal pain, during and after the emission of stools, one may think of anal fissure complicated by bleeding.

Blood on stools

If the blood is bright red and streaks the stool, the cause is most likely haemorrhoids, but the suspicion of much more serious causes (tumours of the last intestinal tract) cannot be ruled out.

Blood in (mixed) stools

If the colour of the blood is dark red and it is mixed with stools, then the haemorrhage is in the large intestine (colon).

Diseases that can cause this type of problem are polyps, tumours, diverticula, inflammatory and vascular diseases.

Clotted blood

Indicates slow but significant bleeding from a pathology upstream of the rectum (diverticula, angiodysplasia, Dieulafoy lesions). The patient requires hospitalisation.

Bright red, abundant blood without stool

This is a serious cause of bleeding that soon leads to haemodynamic instability (drop in blood pressure, etc.).

Initially, the blood is accompanied by faeces, but after a few evacuations, only blood is discharged (usually a diverticular or vascular haemorrhage). The patient requires hospitalisation.

Blood, mucus and diarrhoeal stools

The emission of mucus with blood, possibly in association with diarrhoeal discharges, is typical of chronic inflammatory disease (CUP).

False bleeding

There are certain foods that can give a red colour to stools such that they simulate digestive bleeding.

This is a situation that, when it occurs, literally sends the patient into crisis.

It should be noted, however, that in the case of false bleeding, toilet paper does not become stained red, as it does in real bleeding.

However, it can occur that the toilet water takes on a reddish colour after consuming some of these foods (such as beets).

In addition to the false colour it is sometimes possible to see red food residues (tomatoes, peppers, etc.) in the faeces, but even then the ‘bits, dots or granules’ will not stain the toilet paper.

What to do if there is blood in the faeces?

If there is blood in the stool, one should always consult a doctor who will prescribe the appropriate means of diagnosis (rectoscopy, colonoscopy) after an appropriate clinical evaluation (which must include an anal inspection and digital exploration of the rectum).

The common error of the patient (and sometimes of doctors!) is to underestimate the presence of rectal bleeding because there is often a tendency to minimise it and think it is… trivial haemorrhoids.

In most cases it will be haemorrhoids (or some other benign cause) but we can only tell this after a specialist examination.