Key points
- Rectal bleeding is common, with an incidence of around 10% of adults per year. Most causes are benign but significant conditions can present this way
- Localised anorectal conditions such as haemorrhoids and anal fissures are the most likely cause
- In an acute bleed, hypotension (especially with a postural drop), tachycardia, acute confusion and collapse require an urgent response; patients on anticoagulants, and those with a history of alcoholic liver disease, chronic kidney disease or anaemia need careful assessment
- The presence of haemorrhoids does not rule out other pathology – careful questioning including any change in previous symptoms, weight loss, abdominal pain or bloating is essential
- In the absence of red-flag symptoms and no alternative cause, it is reasonable initially to treat a patient aged under 50 with visible haemorrhoids or an anal fissure symptomatically
Dr Kevin Barrett is a GPSI in gastroenterology in Hertfordshire and committee member of the Primary Care Society for Gastroenterology
Q: What are the commonest causes of rectal bleeding, by age, in adults?
A: Rectal bleeding is a common presenting symptom in general practice, with an incidence of around 10% of adults per year.1 Most causes are benign but there are significant conditions that can present in this way, and a structured and careful consultation is always required.
Because of the stigma that surrounds bowel symptoms it is hard to quantify the causes in order of likelihood, but NHS, public health and charity awareness campaigns such as #breakingthepootaboo have helped patients become more willing to discuss their concerns. The older the patient is, the more likely there is to be a malignant cause, and in younger adults inflammatory bowel disease is more likely. But all of the conditions listed can affect patients of any age.
Colorectal and anal cancers cause patients and clinicians alike the most concern. However, localised anorectal conditions are the most likely cause, with haemorrhoids and anal fissures at the top of the list. Next are conditions affecting the rectum and descending colon, including inflammatory bowel disease (more often ulcerative colitis than Crohn’s disease), polyps, diverticular disease (particularly with diverticulitis), perianal abscesses or fistulae. Occasionally the diarrhoea and irritation associated with irritable bowel syndrome, microscopic colitis or bile acid malabsorption can lead to rectal bleeding, although this may be more likely due to associated perianal irritation. Constipation and straining can cause damage and lead to tears and anal fissures.
One should always consider sexually transmitted infections, and also sexual abuse. Trauma from anal sex (including the use of toys) can damage the anus and it is important to discuss appropriate lubrication, preparation and consent with patients.
Any medication that increases the risk of bleeding (anticoagulants and antiplatelet agents) can exacerbate rectal bleeding. Portal hypertension secondary to liver disease can lead to rectal varices that can bleed quite dramatically. Other rarer causes include congenital vascular malformations such as angiodysplasia, and also radiation proctitis can follow treatment for prostate cancer.
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