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Lower Gastrointestinal Bleeding in Adults: History Taking and Differential Diagnoses

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Overview

Lower gastrointestinal bleeding (LGIB) describes bleeding occurring distal to the ileocaecal valve (i.e. the colon, rectum, and anus). It is common, and most cases are due to benign causes, however, there are many other possible causes, including malignancy.

Presentation

As a general rule of thumb, LGIB tends to present with bright or dark red blood. Upper gastrointestinal bleeding (UGIB) tends to present with melaena, which appears as black, tarry stools.

Blood generally accelerates intestinal transit time, meaning it is expelled sooner and before enzymatic digestion can take place, which would give it a melaena-like appearance.

History Taking

History of presenting complaint

With all presenting complaints, the following should be asked:

  • When did it start?
  • How long has this been going on?
  • Did it come on suddenly or gradually?
  • Is it continuous or intermittent?
  • Has this ever happened before?

Questions more specific to LGIB include:

  • How much blood is being passed?
  • Are any clots being passed?
  • Is it fresh (bright red) or old (dark red or black/tarry) blood?
  • The age of the patient may give some clues:

Associated symptoms

Other questions to ask are:

  • Is there any abdominal pain?
    • Use SOCRATES to assess this
  • Are they passing any mucus or discharge?
  • Do they experience fever?
  • Is there any weight loss?
    • Is this unexpected?
  • Is there any nausea or vomiting?
  • How is their appetite?
  • Are there any changes in bowel habits?
  • Do they experience tenesmus (the feeling of needing to pass stools even though the bowel is empty)?
  • Have they felt dizzy or experienced syncope?
    • These factors suggest that the patient has lost a significant amount of blood
  • If appropriate, have they experienced trauma or carried out any sexual activity?

Past medical history

  • Do they have any other medical conditions?
  • Do they take any regular medications?
  • Have they been prescribed antibiotics recently?

Other questions

  • Has there been any foreign travel?
  • Is there a family history of colorectal cancer?

Physical Examination

  • Measurement of vital signs:
    • The presence of tachycardia, hypotension, and/or tachypnoea may suggest haemodynamic instability secondary to blood loss
  • General assessment – may reveal:
    • Pallor or features of anaemia
    • Cachexia or signs of obvious weight loss
  • Abdominal examination – may reveal:
    • Pain
    • Masses – the presence of a mass suggests malignancy
    • Distention
    • Features of liver cirrhosis – this may predispose a patient to rectal varices
  • Rectal examination – must be performed in all patients with LGIB to rule out masses – may reveal:
    • Masses – suggests rectal cancer
    • Skin tags
    • Haemorrhoids
    • Fissures
    • Anal fissures
    • Gross blood

Investigations

Assessing severity

Initial investigations are aimed at assessing severity and may aid in identifying the underlying cause:

  • Full blood count (FBC):
    • May show anaemia
    • Increased white cell counts suggest infection
    • May show thrombocytopenia which can predispose to bleeding
  • Clotting studies:
    • May show clotting abnormalities such as increased INR, PT, or APTT
  • Group and save:
    • Determines patient blood group and screens for atypical antibodies
    • A crossmatch may be considered which is where red cell products are provided to the patient
  • Iron studies:
  • Urea and electrolytes:
    • May show elevated urea suggesting a UGIB
  • Liver function tests:
    • May be deranged suggesting liver cirrhosis
    • Low albumin may occur due to liver cirrhosis or protein-losing enteropathy
  • C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR):
    • May be elevated in inflammatory bowel disease
  • Faecal calprotectin:
    • Considered if inflammatory bowel disease is suspected
  • Stool culture tests:
    • If infective causes are suspected
  • Testing for sexually-transmitted infections:
    • May be considered

Haemodynamically unstable patients

Patients with haemodynamic instability (e.g. those with hypotension) should first be resuscitated. Investigations may then include:

  • Urgent CT angiogram (CTA) – before endoscopy
    • This can localise the bleeding site and therapies to stop bleeding (e.g. embolisation) can be performed to stabilise the patient
  • Upper GI endoscopy:
    • May be considered if the CTA cannot localise the bleed site
  • Emergency laparotomy:
    • If a CTA and endoscopy fail to locate the bleeding site

Haemodynamically stable patients

Blood transfusions may initially be considered. Following this, investigations may involve:

  • Colonoscopy:
    • May identify masses and allows for therapeutic intervention
  • Upper GI endoscopy:
    • If colonoscopy does not identify any causes

Differential Diagnoses: Common Causes

Haemorrhoids

  • Painless bright red bleeding post-defecation
  • Bleeding is generally self-limiting and not usually severe enough to cause anaemia
  • Patients may have a history of constipation and straining

Anal fissures

  • Painful bright red bleeding post-defecation
  • Patients may have a history of constipation
  • Fissures may be visible on examination, most commonly on the posterior midline
  • This may be a presenting feature of sexual abuse, particularly in children where constipation and Crohn’s disease have been ruled out

Diverticular disease

  • Patients are generally older (>50 years)
  • There may be a history of constipation, diarrhoea, and/or lower left abdominal pain
  • A lack of dietary fibre may be elicited from the history
  • Large volumes of bright red blood may be passed
  • Most cases of bleeding resolve spontaneously

Crohn’s disease

  • Patients are generally <50 years old
  • A history of chronic diarrhoea may be present
  • There may be associated fatigue, weight loss, and fever
  • An ileocaecal (right lower quadrant) mass may be present on examination
  • Oral ulcers and perianal disease (e.g. skin tags, fistulae, abscesses etc.) may be present
  • Anaemia may be seen
  • ESR/CRP may be elevated
  • Faecal calprotectin may be positive

Ulcerative colitis

  • Patients are generally <50 years old
  • A history of chronic diarrhoea may be present – more commonly bloody than in Crohn’s disease
  • Faecal urgency and tenesmus may be present
  • Extra-intestinal features (e.g. joint pain) may be present
  • Anaemia may be seen
  • ESR/CRP may be elevated
  • Faecal calprotectin may be positive

Colonic polyps

  • Patients tend to be >40 years old
  • Alongside bleeding, diarrhoea and constipation may be present
  • A positive family history of colonic polyps or colon cancer may be present
  • A rectal mass may be palpable, however, this is rare

Lower gastrointestinal tract cancer

  • Should be suspected in:
    • Patients ≥40 years with unexplained weight loss and abdominal pain
    • Patients ≥50 years with unexplained rectal bleeding
    • Patients ≥60 years with:
      • Iron deficiency anaemia (IDA) or
      • Changes in bowel habits or
      • Tests show occult blood in faeces
  • Patients with a rectal or abdominal mass
  • Patients <50 years with rectal bleeding and any unexplained:
    • Abdominal pain
    • Changes in bowel habit
    • Weight loss
    • IDA
  • Unexplained anal masses or anal ulceration
  • Associated symptoms including weight loss, bowel habit changes, abdominal pain, and tenesmus may be seen
  • Masses may be palpable on examination

Infectious gastroenteritis

  • Patients may have a history of travelling to or carrying out activities (e.g. eating street food) in a region that may predispose them to infection
  • There may be a history of acute diarrhoea and abdominal pain
  • Fever may be present
  • Abdominal pain may be present

Ischaemic colitis

  • Patients tend to be older (around >50 years) and may have an underlying cardiovascular disease (e.g. stable angina, atrial fibrillation etc.)
  • Sudden-onset and severe abdominal pain suggests acute mesenteric ischaemia
  • Less severe abdominal pain and chronic bloody diarrhoea suggest ischaemic colitis
  • Diffuse abdominal pain may suggest perforation and peritonitis
  • Anaemia may be seen
  • An increased white cell count may be seen
  • In acute mesenteric ischaemia, lactic acidosis may be seen

Differential Diagnoses: Less Common Causes

Meckel’s diverticulum

  • More common in children and young adults
  • Typically presents as painless massive bleeding
  • Abdominal masses may be present
  • Anaemia may be present

Angiodysplasia

  • Usually seen in older patients (around >50 years)
  • May have a history of intermittent painless bright red rectal bleeding which may be massive
  • Very few associated symptoms are seen

Rectal ulcer

  • A history of chronic straining and constipation is generally seen
  • There may be a sense of incomplete evacuation

Rectal varices

  • Usually presents as painless rectal bleeding in patients with portal hypertension
  • Signs of chronic liver disease may be seen (e.g. jaundice, ascites, hepatomegaly etc.)
  • Liver function tests may be deranged
  • Albumin may be low
  • Prothrombin time may be elevated

Dieulafoy’s lesion

  • Presents as painless bright red rectal bleeding that may be severe
  • Associated symptoms are generally uncommon
  • Anaemia may be seen
  • A colonoscopy shows the presence of the lesion

Trauma (e.g. sexual abuse)

  • Should be suspected if anal fissures are present when constipation and Crohn’s disease have been excluded, particularly in children

Sexually-transmitted infection

  • Ulcers may be present in the genital region that may be painful or painless
  • Inguinal lymphadenopathy may be present
  • Discharge may be present

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