Rectal Bleeding
Rectal bleeding is the passage of blood from the rectum, which may originate from any site along the gastrointestinal tract and ranges from minor anorectal conditions to life-threatening hemorrhage.
Murtagh Diagnostic Strategy
| Category | Diagnosis | Key Discriminator | Cantonese Question / Finding | Probability |
|---|---|---|---|---|
| Probability Diagnosis | Haemorrhoids | Painless bright red blood after/on stool, prolapsing perianal lump, a/w straining | 「去完大便之後有冇鮮血滴出嚟？有冇嘢凸咗出嚟？」 | ~45% |
| Anal fissure | Pain on defecation + fresh blood; history of constipation [3] | 「去大便開頭有冇好sharp嘅痛？」 | ~20% | |
| Serious Not To Miss | Colorectal carcinoma | Age > 50, change in bowel habit, weight loss, FHx, iron-deficiency anaemia | 「大便習慣有冇變？有冇輕咗磅？屋企人有冇腸癌？」 | ~5% |
| IBD (UC / Crohn's) | Bloody diarrhoea ± mucus, young adult, extraintestinal features (joints, eyes, skin) | 「有冇成日肚瀉帶血同黏液？關節有冇痛？」 | ~3% | |
| Ischaemic colitis | Elderly + CVS risk factors, sudden abdominal pain then bloody diarrhoea | 「有冇突然肚痛之後去血便？有冇心臟病？」 | ~1% | |
| Pitfalls | Diverticular disease | Painless profuse haematochezia, elderly, often self-limiting [2] | 「有冇試過突然間大量出血但冇乜痛？」 | ~5% |
| Colorectal polyp | Often asymptomatic; intermittent occult bleeding; found on screening | 「之前腸鏡有冇發現瘜肉？」 | ~3% | |
| Rectal STI proctitis | MSM, rectal discharge, tenesmus | 「有冇肛交？有冇分泌物？」 | ~2% | |
| Angiodysplasia | Elderly, a/w aortic stenosis (Heyde syndrome) [7], painless, right-sided | 「有冇心瓣膜問題？」 | ~2% | |
| Masquerades | Drugs (NSAIDs, anticoagulants) | Temporal relationship with medication | 「幾時開始食呢啲藥？」 | ~10% |
| Anaemia (iron-deficiency) | Fatigue, pallor, may be the only clue to occult CRC | Pallor on examination; conjunctival pallor | ~5% | |
| UGIB masquerading as PR bleed | 10–15% of severe haematochezia is from brisk UGIB [2] | 「有冇嘔過血或者嘔啡色嘢？」 | ~2% | |
| Trying to Tell Me Something? | Cancer anxiety / grief | Relative recently diagnosed with CRC; health anxiety | 「你最擔心嘅係咩？有冇屋企人最近唔舒服？」 | ~10% |
| Stress / functional | IBS-related symptoms, life stressor | 「最近壓力大唔大？」 | ~5% |
| Time | Task | Cantonese Key Phrases | Why It Scores Marks |
|---|---|---|---|
| 0:00–0:30 | Friendly opening, rapport | 「你好，我係X醫生，今日想同你傾下你嘅情況，方唔方便呀？」(Hello, I'm Dr X, I'd like to chat about your situation today, is that OK?) | Greeting + permission = interpersonal marks |
| 0:30–2:00 | Chief complaint & HPI – open question → SOCRATES for bleeding; relationship of blood to stool; colour; amount; bowel habit changes | 「可唔可以話我知你有咩唔舒服？」→「隻血係咩色？鮮紅定深色？」→「隻血係包住大便、混喺入面、定係自己流出嚟？」→「有冇去少咗或者去多咗大便？」 | Core symptom analysis; discriminates outlet bleeding vs proximal source |
| 2:00–2:30 | Red flags – weight loss, appetite, tenesmus, mucus, abdominal pain, anaemic symptoms | 「有冇輕咗磅？食嘢點呀？有冇覺得成日想去但去唔清？有冇頭暈、氣促？」 | Screens for colorectal cancer & IBD; "must not miss" |
| 2:30–3:30 | PMHx, DHx, FHx, SHx – previous colonoscopy, NSAID/anticoagulant/antiplatelet, family CRC/IBD/polyps, smoking, alcohol, occupation, diet, constipation | 「你之前有冇做過腸鏡？有冇食薄血藥或者止痛藥？屋企人有冇腸癌或者腸病？」 | Drug history & family history high-yield for CRC risk |
| 3:30–4:30 | ICE – uncover hidden agenda | 「你覺得自己有咩問題？」(Idea) →「你最擔心嘅係咩呢？」(Concern) →「你嚟睇醫生，最希望我哋可以點樣幫到你？」(Expectation) | Direct exam marks; the RFC often hides here – e.g. patient fears cancer |
| 4:30–5:15 | Signposting & summarise | 「我總結返，你有鮮血喺大便度已經X個禮拜，冇乜痛…我有冇講漏咗？」 | Shows active listening, scores communication marks |
| 5:15–6:00 | Explain plan, safety-net, close | 「我建議你做啲驗血同安排照腸，如果有大量出血、頭暈或者肚痛加重，要即刻返急症。你有冇嘢想問？」 | Safe closure + red-flag safety net |
Uncovering the hidden agenda: The RFC is often not the bleeding itself. Ask 「點解你揀今日嚟睇？」(Why did you come today specifically?) – the patient may have been triggered by a relative diagnosed with CRC, or has noticed weight loss, or read something online. This is where Concern lives.
| Domain | English Question | Cantonese Question | Why It Matters | If Positive Think Of |
|---|---|---|---|---|
| Onset/duration | When did the bleeding start? How often? | 「隻血幾時開始？幾密出一次？」 | Acute vs chronic guides urgency | Chronic intermittent → haemorrhoids, CRC; Acute massive → diverticular bleed |
| Colour | What colour is the blood? Bright red or dark? | 「血係鮮紅色定深色／暗紅色？」 | Fresh PR bleed: distal to splenic flexure; dark: proximal [1] | Bright red → anorectal; Dark/maroon → proximal colon; Black tarry → UGIB |
| Relationship to stool | Is the blood mixed in, on the surface, or dripping after? | 「血係混喺大便入面、包住外面、定係之後自己滴出嚟？」 | Mixed with stool → proximal to sigmoid; separate/after → outlet-type bleeding [2] | On paper/dripping → haemorrhoids, fissure; Mixed → CRC, IBD, diverticular |
| Amount | How much blood? Drops, streaks, or filling the bowl? | 「大概有幾多血？幾滴、幾條、定成個廁盤都係？」 | Quantifies severity | Large amount by itself → diverticular, angiodysplasia [2] |
| Pain on defecation | Do you have pain when you open your bowels? | 「去大便嗰陣有冇痛？」 | Fissure-in-ano: pain on defecation + fresh rectal bleeding [3] | Sharp pain at start → anal fissure; painless → haemorrhoids, CRC |
| Bowel habit change | Any change in frequency or consistency? | 「大便習慣有冇變？有冇時而肚瀉時而便秘？」 | Alternating diarrhoea and constipation → CRC [4] | CRC, IBD |
| Stool calibre | Are stools thinner than usual? | 「大便有冇變幼咗？」 | Pencil-thin stools → rectosigmoid CRC [4] | Left-sided / rectal CRC |
| Tenesmus | Do you feel you need to go but can't empty? | 「有冇覺得想去大便但去唔清？」 | Tenesmus: invariably present in lower rectal tumours [4] | Rectal cancer, proctitis |
| Mucus | Any mucus or slime in stool? | 「大便有冇黏液？」 | Bloody mucus → IBD or CRC | UC, rectal villous adenoma, CRC |
| Weight loss / appetite | Any unintentional weight loss? | 「有冇輕咗磅？食嘢有冇差咗？」 | Constitutional red flag for malignancy | CRC, IBD |
| Anaemic Sx | Dizziness, shortness of breath, fatigue? | 「有冇頭暈、氣促、成日覺得攰？」 | Chronic occult blood loss → Fe-deficiency anaemia | CRC (right-sided), angiodysplasia |
| Perianal Sx | Any perianal lump, itch, or prolapse? | 「有冇覺得肛門有嘢凸咗出嚟、痕癢？」 | Supports haemorrhoids | Haemorrhoids (prolapse), skin tag, perianal abscess |
| Drug Hx | Aspirin, NSAIDs, warfarin, DOACs? | 「有冇食阿士匹靈、薄血藥或者止痛藥？」 | Anticoagulants/antiplatelets worsen any GI bleed [5] | Drug-related bleeding, NSAID enteropathy |
| PMHx | Previous colonoscopy? IBD? Polyps? Liver disease? | 「之前有冇做過腸鏡、有冇腸炎、瘜肉？有冇肝病？」 | Prior polyps/IBD = higher CRC risk; liver disease → rectal varices | CRC surveillance, rectal varices |
| FHx | Any family history of bowel cancer, polyps, or IBD? | 「屋企人有冇人試過大腸癌、瘜肉或者腸炎？」 | Referral for colonoscopy if FHx CRC in 1st degree relative [6] | Hereditary CRC syndromes, FAP, Lynch |
| Social Hx | Smoking? Alcohol? Diet (fibre)? Occupation? | 「有冇食煙、飲酒？平時食多唔多菜？做咩工作？」 | Risk factors for CRC; functional impact | CRC risk, lifestyle counselling |
| Travel / sexual Hx | Recent travel? Receptive anal intercourse? | 「近排有冇去過旅行？」(If relevant:)「有冇肛交嘅習慣？」 | Infective colitis; STI-related proctitis | Amoebic dysentery, gonococcal/chlamydial proctitis |
| Constipation | Are you usually constipated? Straining? | 「平時有冇便秘？去大便使唔使好用力？」 | Straining → haemorrhoids & fissure risk | Haemorrhoids, fissure |
Case Report Form Answer Builder
Rectal bleeding × [duration].
High-yield points to capture:
- Onset, duration, frequency
- Colour (bright red / dark / mixed), amount
- Relationship to stool (on surface / mixed / after defecation / by itself)
- Associated Sx: pain on defecation, change in bowel habit, stool calibre, tenesmus, mucus
- Red flags: weight loss, appetite change, anaemic symptoms
- Relevant PMHx (previous colonoscopy, polyps, IBD), DHx (aspirin/NSAID/anticoagulant), FHx (CRC, polyps)
Likely RFC examples:
- "Patient concerned about the possibility of colorectal cancer"
- "Patient noticed increasing amount of rectal bleeding and is worried"
- "Prompted by a family member's recent diagnosis of bowel cancer"
Phrasing tip: The RFC is the patient's reason, not your diagnosis. Use patient-centred language. Often the hidden agenda IS the RFC.
| Example Wording | |
|---|---|
| Idea | "Patient thinks it might be haemorrhoids / is worried it could be cancer" |
| Concern | "Patient is worried about colorectal cancer, especially given family history of CRC" |
| Expectation | "Patient would like reassurance and investigation (e.g. colonoscopy) to rule out serious disease" |
In a primary care FM station with a middle-aged/young patient presenting with bright red painless outlet-type bleeding + straining/constipation history:
Most likely diagnosis: Haemorrhoids
Minimum supporting evidence: bright red blood separate from stool / on toilet paper, painless, history of constipation/straining, ± perianal lump/prolapse. Confirmed by proctoscopy.
If the stem features pain on defecation + fresh blood + constipation → consider Anal fissure as most likely.
If the stem has age > 50 + change in bowel habit + weight loss → consider Colorectal carcinoma.
| DDx | Key Discriminator |
|---|---|
| 1. Colorectal carcinoma | Age > 50, change in bowel habit, weight loss, iron-deficiency anaemia, FHx |
| 2. Anal fissure | Pain on defecation, history of constipation, visible fissure on inspection |
| 3. Inflammatory bowel disease (UC) | Young adult, bloody diarrhoea with mucus, extraintestinal manifestations |
(Alternatives depending on stem: diverticular disease in elderly, colorectal polyp, angiodysplasia)
| Domain | Problem |
|---|---|
| Biological | Rectal bleeding with risk of iron-deficiency anaemia; need to exclude colorectal malignancy |
| Psychological | Anxiety / fear of cancer (especially if FHx or media exposure) |
| Social | Impact on daily activities and work (e.g. embarrassment, frequent toilet visits, avoidance of social activities) |
| Diagnosis / DDx | Best Supporting Physical Sign | How to Elicit | Why It Supports This Diagnosis |
|---|---|---|---|
| Haemorrhoids (most likely) | Prolapsing haemorrhoidal cushions on proctoscopy / visible on inspection; bluish perianal swelling | DRE + proctoscopy; ask patient to bear down (Valsalva) – visible engorged vascular cushions at 3, 7, 11 o'clock positions [6] | Directly visualises the source; DRE to exclude other rectal lesions [6] |
| Anal fissure | Visible fissure on spreading the buttocks (usually posterior midline) [3] | Gently part the buttocks – look for linear tear; rectal examination and proctoscopy are painful and not indicated [3] | Pathognomonic finding; no instrumentation needed |
| Colorectal carcinoma | Palpable rectal mass on DRE; pallor (anaemia) [8] | Digital rectal examination – feel for fixed, irregular, hard mass; inspect conjunctivae for pallor | Low rectal tumours palpable on DRE; pallor from chronic occult blood loss |
| IBD (UC) | Tenderness over left iliac fossa; extraintestinal signs (erythema nodosum, oral ulcers, eye inflammation) | Abdominal palpation; general inspection | Supports colonic inflammation pattern |
| Diverticular disease | Usually no reliable physical sign in brief FM station | Abdominal exam may show LLQ tenderness if diverticulitis; often normal between episodes | Best exam clue: painless large-volume haematochezia in elderly → arrange colonoscopy |
Top Traps That Lose Marks
- Assuming all bright red PR blood = haemorrhoids – Always screen for CRC red flags (age, bowel habit change, weight loss, FHx). ALWAYS exclude other possible sources of PR bleeding [6].
- Forgetting to ask about drug history – Aspirin/NSAIDs/anticoagulants are high-yield.
- Missing the hidden agenda – The patient often fears cancer. If you don't ask ICE, you lose easy marks.
- Not asking about relationship of blood to stool – This is the single best discriminator between outlet and proximal bleeding [2].
- Forgetting UGIB can present as PR bleeding – 10–15% of severe haematochezia is from brisk UGIB [2]. Ask about haematemesis/coffee-ground vomiting.
- Performing DRE/proctoscopy on a patient with suspected fissure – Not indicated; diagnosis is by inspection (spreading buttocks) [3].
"Must Not Miss" Red Flags – Urgent Referral:
- Age > 50 with new PR bleeding + change in bowel habit → urgent colonoscopy referral [1]
- Unexplained iron-deficiency anaemia → colonoscopy
- Palpable rectal mass on DRE
- FHx of CRC in first-degree relative + PR bleeding → referral for colonoscopy [6]
- Haemodynamic instability (tachycardia, hypotension) → emergency
Minimal safe management / safety-net line for closing: 「我會安排你驗血睇下有冇貧血，同埋轉介你做腸鏡檢查排除其他問題。如果出血突然增多、頭暈企唔穩、或者肚好痛，要即刻去急症室。」 (I'll arrange blood tests for anaemia and refer you for colonoscopy. If bleeding suddenly increases, you feel faint, or have severe abdominal pain, go to A&E immediately.)
High Yield Summary
What to ASK: Colour, relationship of blood to stool, pain on defecation, bowel habit change, weight loss, drug history, family history of CRC, and ICE (especially cancer fear).
What to WRITE: Chief complaint with duration; relationship of blood to stool as key discriminator; RFC = usually cancer worry; most likely Dx usually haemorrhoids (unless red flags present); DDx must include CRC; biopsychosocial must include cancer anxiety and social impact.
What NOT to MISS: CRC red flags (age > 50 + change in bowel habit + weight loss + FHx); UGIB presenting as PR bleed; drug-related bleeding; fissure diagnosed by inspection only (no DRE).
Active Recall - Family Medicine Clinical Test
[1] Lecture slides: GC 186. Lower and diffuse abdominal painfresh blood in stool.pdf (p20 – intermittent PR bleeding investigation; CEA sensitivity ~30%) [2] Senior notes: Maksim Surgery Notes.pdf (p78 – LGIB history taking, relationship of blood to stool, DDx table); Ryan Ho Fundamentals.pdf (p282 – approach to LGIB, blood relationship to stool, 10-15% UGIB) [3] Lecture slides: GC 179. Anal pain perianal lesions and sepsis.pdf (p46 – fissure-in-ano: pain on defecation, diagnosis by inspection, DRE not indicated) [4] Senior notes: Ryan Ho GI.pdf (p165 – CRC clinical features: right side bleeds, left side blocks; tenesmus, pencil stools, alternating bowel habits) [5] Senior notes: Block A - Gastroenterology Interactive Tutorial.pdf (p1 – drug history importance, aspirin dilemma) [6] Senior notes: MBBS Final MB (Surgery) (Felix PY Lai).pdf (p748 – haemorrhoids: 4 degrees, ALWAYS exclude other sources, referral for colonoscopy indications; p691 – CRC diagnosis by DRE and pallor) [7] Senior notes: Block A - Coffee ground vomitus tarry stool upper GI bleeding.pdf (p8 – Heyde syndrome, angiodysplasia with aortic stenosis) [8] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (p894 – CRC physical exam: pallor, rectal mass on DRE; p653 – LGIB physical exam and biochemical tests)
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