Lower gastrointestinal bleeding
Updates to Article Attributes
Lower gastrointestinal bleeding (LGIB) is defined as that occurring distal to the ligament of Treitz (i.e. from the jejunum, ileum, colon, rectum or anus) and presenting as either haematochezia (bright red blood/clots or burgundy stools) or melaena.
Epidemiology
The incidence of LGIB is only one-fifth that of the upper gastrointestinal tract and is estimated to be ~24 per 100,000 adults per year. Male and older patients tend to suffer from more severe LGIB 3.
Clinical presentation
Acute bleeding is defined as bleeding of <3 days duration resulting in instability of vital signs, anaemia and/or the need for blood transfusion 3.
Chronic bleeding is defined as slow blood loss over a period of several days or longer, presenting with symptoms of occult faecal blood, intermittent melaena or scant hematochezia 3.
LGIB usually is chronic and the bleeding ceases spontaneously (80%) 3.
Pathology
Aetiology
Although LGIB can occur at any age, specific disease processes are distinctive for different age groups and familiarity with this can help tailor the diagnostic workup 2,6:
- adolescents and young adults
- older adults
- colonic diverticula (~40%)
- angiodysplasia (~25%)
- colorectal carcinoma (~12.5%)
- polyps (~7.5%)
- rectal trauma/fissure/haemorrhoids (~7.5%)
- upper gastrointestinal bleeding (e.g. peptic ulcer)
See article: lower gastrointestinal bleeding (differential diagnosis).
Risk factors
Risk factors include 1
- medications (e.g. NSAID, warfarin)
- recent colonoscopy with polypectomy (post polypectomy bleeding)
- prior abdominal/pelvic radiation (radiation proctitis/colitis)
- prior surgery
- history of alcoholism or chronic liver disease
- history of abdominal aortic aneurysm with or without surgical repair (i.e. causing an aortoenteric fistula)
Radiographic features
Colonoscopy is the first-line investigation of both diagnostic and therapeutic management. CT, nuclear medicine studies, and angiography can all be used to assess LGIB but have limited sensitivity when bleeding rates are intermittent or slow. Below are the estimated detectable rates of bleeding by modality 5,6:
- nuclear medicine: ≤0.1 mL/min
- CT angiography: ≥0.35 mL/min
- angiography: ≥0.5 mL/min
CT
CT angiography (CTA) provides a relatively non-invasive and effective way of localising the source of bleeding, especially in the patient with continued bleeding 5.
Studies have looked at the use of CTA in the localisation of GI haemorrhage report sensitivity of ~90% when there is active bleeding but are considerably lower when the bleeding is intermittent in nature with rates reported at ~45% 1.
Again, contraindications apply to patients with renal failure who are at risk of developing contrast-induced nephropathy 1.
Nuclear medicine
Erythrocytes are labelled with technetium-99m and then serial scintigraphy is performed (also known as a tagged red blood cell scan) to detect focal collections of radiolabelled material. It can be performed relatively quickly and may help localise the general area of active bleeding to guide subsequent endoscopy, angiography or surgery 1.
A false-positive result can be produced by a rapid transit of luminal blood so that labeled blood is detected in the colon even though it originated from a more proximal site in the GIT 1.
Angiography
In patients with lower GI bleedbleeding who are haemodynamically stable and do not have ongoing fresh per rectal bleedbleeding, an RBC-labeled Tc99m scan is recommended as a first line of investigation. Catheter angiogramangiography is recommended in patients with time to positive (TTP) of 9 min or less. If TTP is more than 9 min, the likelihood of detecting the bleeding site on angiogram will be markedly low.
Angiography can provide the opportunity for therapeutic intervention at the time of diagnosis 1, 2-2. However, the bleeding rate must be ≥0≥ 0.5 mL/min to detect extravasation into the gut, which is significantly higher than in nuclear medicine. Additionally, certain patient factors (e.g. contrast allergy, acute/chronic kidney disease) are potential contraindications to angiography 1.
See also
-</ul><h5>CT</h5><p>CT angiography (CTA) provides a relatively non-invasive and effective way of localising the source of bleeding, especially in the patient with continued bleeding <sup>5</sup>.</p><p>Studies have looked at the use of CTA in the localisation of GI haemorrhage report sensitivity of ~90% when there is active bleeding but are considerably lower when the bleeding is intermittent in nature with rates reported at ~45% <sup>1</sup>.</p><p>Again, contraindications apply to patients with renal failure who are at risk of developing <a href="/articles/contrast-induced-nephropathy">contrast-induced nephropathy</a> <sup>1</sup>.</p><h5>Nuclear medicine</h5><p>Erythrocytes are labelled with technetium-99m and then serial scintigraphy is performed (also known as a tagged red blood cell scan) to detect focal collections of radiolabelled material. It can be performed relatively quickly and may help localise the general area of active bleeding to guide subsequent endoscopy, angiography or surgery <sup>1</sup>. </p><p>A false-positive result can be produced by a rapid transit of luminal blood so that labeled blood is detected in the <a href="/articles/large-intestine-1">colon</a> even though it originated from a more proximal site in the GIT <sup>1</sup>. </p><h5>Angiography</h5><p>In patients with lower GI bleed who are haemodynamically stable and do not have ongoing fresh per rectal bleed, RBC-labeled Tc99m scan is recommended as a first line of investigation. Catheter angiogram is recommended in patients with time to positive (TTP) of 9 min or less. If TTP is more than 9 min, the likelihood of detecting the bleeding site on angiogram will be markedly low.</p><p>Angiography can provide the opportunity for therapeutic intervention at the time of diagnosis <sup>1, 2</sup>. However, the bleeding rate must be ≥0.5 mL/min to detect extravasation into the gut, which is significantly higher than in nuclear medicine. Additionally, certain patient factors (e.g. contrast allergy, acute/chronic kidney disease) are potential contraindications to angiography <sup>1</sup>. </p><h4>See also</h4><ul><li><a href="/articles/upper-gastrointestinal-bleeding">upper gastrointestinal bleeding (UGIB)</a></li></ul>- +</ul><h5>CT</h5><p>CT angiography (CTA) provides a relatively non-invasive and effective way of localising the source of bleeding, especially in the patient with continued bleeding <sup>5</sup>.</p><p>Studies have looked at the use of CTA in the localisation of GI haemorrhage report sensitivity of ~90% when there is active bleeding but are considerably lower when the bleeding is intermittent in nature with rates reported at ~45% <sup>1</sup>.</p><p>Again, contraindications apply to patients with renal failure who are at risk of developing <a href="/articles/contrast-induced-nephropathy">contrast-induced nephropathy</a> <sup>1</sup>.</p><h5>Nuclear medicine</h5><p>Erythrocytes are labelled with technetium-99m and then serial scintigraphy is performed (also known as a tagged red blood cell scan) to detect focal collections of radiolabelled material. It can be performed relatively quickly and may help localise the general area of active bleeding to guide subsequent endoscopy, angiography or surgery <sup>1</sup>. </p><p>A false-positive result can be produced by a rapid transit of luminal blood so that labeled blood is detected in the <a href="/articles/large-intestine-1">colon</a> even though it originated from a more proximal site in the GIT <sup>1</sup>. </p><h5>Angiography</h5><p>In patients with lower GI bleeding who are haemodynamically stable and do not have ongoing fresh per rectal bleeding, an RBC-labeled Tc99m scan is recommended as a first line of investigation. Catheter angiography is recommended in patients with time to positive (TTP) of 9 min or less. If TTP is more than 9 min, the likelihood of detecting the bleeding site on angiogram will be markedly low.</p><p>Angiography can provide the opportunity for therapeutic intervention at the time of diagnosis <sup>1-2</sup>. However, the bleeding rate must be ≥ 0.5 mL/min to detect extravasation into the gut, which is significantly higher than in nuclear medicine. Additionally, certain patient factors (e.g. contrast allergy, acute/chronic kidney disease) are potential contraindications to angiography <sup>1</sup>. </p><h4>See also</h4><ul><li><a href="/articles/upper-gastrointestinal-bleeding">upper gastrointestinal bleeding (UGIB)</a></li></ul>
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