Rectal bleeding is defined as fresh or clotted blood in the faeces or in association with defecation.
The colour of the faeces may be otherwise normal, in contrast to melena Melena, which is defined as black, tar-like stools or the maroon stool often seen with caecal bleeding.
The site and cause of the bleeding must be identified, most importantly separating bleeding from the anal canal versus the proximal colon. The former can often be handled locally, whereas the latter requires a more global approach.
Patients in whome the bleeding is caused by a tumour, inflammatory bowel disease or other severe condition requiring specific treatment must be identified, examined and treated.
In patients with haemorrhoids, anal fissure, excoriation of anal skin or other mild condition the treatment is symptomatic.
History
Type of rectal bleeding
Does the bleeding occur only in association with defecation or also at other times?
Is the blood fresh (bright red), clotted or old (maroon)?
Is the blood seen
during cleansing (anal fissure or excoriation, external or prolapsed haemorrhoids)
dripping in the toilet bowl (internal haemorrhoids)
on the surface of the stools (tumour)?
What is the colour and consistency of the stools?
Are there other symptoms associated with the bleeding, like
anal pain (fissure)
abdominal pain or tenesmus (tumour, inflammation of the bowel)?
Other patient history
Ask about the duration, frequency, and eventual exacerbation of the symptoms.
Are the bowel movements normal? Have there been any changes in bowel habits?
Are there other symptoms (abdominal or systemic symptoms, weight loss)?
Does the patient have a history of liver or bowel disease?
Physical examination
Palpation and auscultation of the abdomen (tenderness?)
Inspection by spreading the anal margins: fissure, sentinel fold, rhagades, fistular orifices
Diagnose eventual mucosal or rectal prolapse by spreading the anal margins and asking the patient to bear down.
Digital rectal examination (DRE): tonus and strength of the anal sphincter, fissure, anal crypts, ampullar mucosa, prostate, colour of the stools
Proctoscopy: examination of the size, prolapse tendency and surface character of haemorrhoids by applying gentle compression on them while the patient is bearing down, and then pulling the proctoscope slowly outwards
Further investigations
Always identify the origin of rectal bleeding.
If an evident fissure is diagnosed in a young patient (under 50 years) it is sufficient to treat it and follow up. In other cases at least a sigmoidoscopy should be performed, even if it seems that the bleeding is only caused by haemorrhoids.
In all patients over 50 years of age, colonoscopy is recommended to rule out malignancies.
Colonoscopy should also be performed if an occult blood test used in colorectal cancer screening has been positive or if faecal calprotectin has been elevated and no gastrointestinal infection has been detected in the patient.