Colorectal cancer is the 4th most common cancer in the UK and the 2nd most common cause of cancer death. NICE NG12 sets its referral thresholds at a positive predictive value of 3% or more, so most people referred will not have cancer — but the threshold is deliberately low. Critically, haemorrhoids are very common — the dangerous error is attributing bleeding to haemorrhoids without excluding more serious pathology. Upper GI bleeding presenting as melaena can be fatal — hospital risk-stratification (Glasgow-Blatchford score) drives urgency). Never assume bright red blood = haemorrhoids alone without appropriate assessment.

The colour and distribution of blood is the single most important clinical discriminator. Bright red blood on the paper or separate from stool (rather than mixed) usually indicates an anorectal source. However, some still have more proximal pathology. Melaena usually indicates an upper GI source but can arise from the small bowel or right colon, and a brisk upper GI bleed can present as fresh red blood — assess the whole patient rather than stool appearance alone. NSAIDs and antithrombotics increase the risk of diverticular bleeding. Always ask about medication.

Diverticular bleeding is the most common cause of significant lower GI haemorrhage in adults over 50. It is almost always painless and usually stops spontaneously — but requires hospital assessment and risk stratification (BSG 2019: shock index, Oakland score). Unstable or major ongoing bleeding → emergency admission with CT angiography to localise; stable → hospital investigation with colonoscopy on the next available list. The specialist team decides on transfusion and investigation. Aortoenteric fistula is rare but uniformly fatal without immediate surgery — any patient with prior AAA repair presenting with GI bleeding must be treated as this until excluded. IBD first presentation in primary care is frequently delayed — think of it in any young adult with bloody diarrhoea.

In a stable patient, with consent and a chaperone, PR examination can detect a low rectal or anal mass and should be done where clinically appropriate; never delay emergency transfer for it, and document if it was too painful and arrange specialist assessment. Internal haemorrhoids (the most common cause of bright PR bleeding) cannot be seen or felt on PR exam alone — they require proctoscopy. Postural drop (orthostatic hypotension) identifies occult haemodynamic compromise in patients appearing well supine — check it in any patient with significant rectal bleeding.

FIT (faecal immunochemical test) has replaced FOBT (faecal occult blood test) as the preferred primary care investigation. FIT is more sensitive and specific — it detects human haemoglobin, not animal blood in food. NICE HTG690 recommends FIT to guide colonoscopy need in symptomatic patients. Under the FIT-first pathway, people with rectal bleeding are offered FIT too; only a rectal mass, unexplained anal mass or unexplained anal ulceration skips FIT (NG12: consider a suspected cancer pathway referral directly) — and a negative FIT does NOT fully exclude CRC, so persistent symptoms still need safety-netting and review. Faecal calprotectin helps when IBD is suspected (interpret per local pathway; NICE HTG320).

NICE NG12 deliberately sets a low threshold for suspected cancer pathway referral in rectal bleeding — most people referred will have a benign cause. This is intentional: missing CRC carries far greater harm than an unnecessary colonoscopy. The Glasgow-Blatchford score is the hospital tool for risk-stratifying upper GI bleeds (the Oakland score applies to lower GI bleeds) and predicts need for intervention (endoscopy, blood, surgery); it is not a primary-care admission rule. Grade III haemorrhoids (require manual reduction) and grade IV (irreducible) almost always need surgical referral — topical treatment is ineffective at this stage.

GTN 0.4% ointment works by relaxing the internal anal sphincter (reducing hypertonia that impairs fissure healing) — it improves healing compared with lidocaine alone. Diltiazem 2% cream (unlicensed) has similar efficacy with fewer headaches. Rubber band ligation is an effective outpatient option for selected internal haemorrhoids. Topical steroids should not be used for more than 7 days continuously (atrophy, infection risk). Review NSAIDs and antithrombotics after a diverticular bleed, following local analgesia and gastroprotection guidance.

Adequate fibre and fluid, avoiding straining and managing constipation are practical measures, tailored to stool consistency and comorbidity. Physical activity is associated with lower colorectal cancer risk, without the bleeding risk. NHS Bowel Cancer Screening reduces bowel cancer mortality — ensuring eligible patients are enrolled and engaged is a primary care quality metric. Alcohol is a recognised WHO Group 1 carcinogen for colorectal cancer — clear, quantified advice should be given at every opportunity.

Patients with adenomas found on colonoscopy have an increased risk of future CRC — surveillance intervals (BSG/ACPGBI/PHE 2020 post-polypectomy guidelines) are evidence-based and must be communicated clearly and followed up. IBD patients with extensive colitis have a raised CRC risk that grows with disease duration — surveillance colonoscopy at risk-based intervals (1, 3 or 5 years; NICE CG118, BSG 2019) must be kept on track. Patients who do not receive their suspected cancer referral appointment confirmation within 14 days should be followed up proactively — system failures occur, and the patient cannot always advocate for themselves. A documented safety-net discussion is an RCGP SCA examination competency requirement.