Lower GI bleeding

INTRODUCTION

• Upper GI bleeds are the most common cause for lower GI blood
• More common in females and increases in the elderly
• 80% resolve spontaneously but cannot predict this
• Cause for bleeding found in <50% of cases
• Severe pain is more often small bowel in origin
• Embolic pain is acute onset vs. insidious if thrombotic, vasculitic or non-occlusive

DIFFERENTIAL DIAGNOSIS

• Diverticulosis
• Mesenteric ischaemia
• Ischaemic colitis
• Infectious colitis
• IBD
• Radiation colitis
• Pseudomembranous colitis
• Diverticulitis
• Colon carcinoma
• Meckel’s diverticulum
• Rectal ulcers
• Trauma
• IBD
• Polyps
  • Delayed haemorrhage can occur up to 3 weeks after polypectomy
• Carcinomas
• Haemorrhoids
• Anal fissures

PATHOPHYSIOLOGY

• 10% of haematochezia episodes are UGI in origin
• Melena is usually upper GI in origin or occasionally slow LGI bleeding
• Diverticulosis
  • Usually painless from erosion of penetrating artery
  • May be massive but 90% resolve spontaneously
  • Bleeding can recur in 50%
  • Most diverticulae on left colon but right-sided are more prone to bleeding
  • High risk patients are elderly with comorbidities, those with transfusion requirements and those on anticoagulants/NSAID’s
• Vascular ectasia
  • AV malformations and angiodysplasias
• Ischaemic colitis
  • Usually transient
  • 95% non-occlusive transient ischaemia
  • Occlusive embolic or thrombotic arterial occlusion normally involves small bowel as well
  • 15% suffer gangrenous necrosis with high mortality rate
  • Risk factors for ischaemic colitis include:
    • Aneurysmal rupture, vasculitis, hypercoagulable states, prolonged strenuous exercise, cardivascular insult, irritable bowel syndrome and vasoconstrictive medications
    • Most cases resolve on their own but 20% will require surgical intervention

• Mesenteric ischaemia
  • Thrombosis or embolism of SMA, mesenteric venous thrombosis and low-flow states
  • Diagnosis requires high index of suspicion
  • Mesenteric vein thrombosis rarely involves the colon
  • Must consider in age >60, AF, CCF, recent MI, post-prandial abdominal pain or unexplained weight loss
  • CT specificity 92% but sensitivity only 64%
  • Angiography is diagnostic study of choice
  • Mortality 50% if diagnosed within 24 hours

ISCHAEMIC COLITIS

• Most older patients will have at least one risk factor:
  • Aortoiliac instrumentation
  • CPB
  • MI
  • Haemodialysis
  • Thrombophilia
  • Constipating drugs
  • Extreme exercise
• Three clinical stages
  • Hyperactive phase – Severe pain, passage of bloody stool
  • Paralytic phase – Pain becomes contiuous and diffuse. Abdomen tender and distended without bowel sounds
  • Shock phase – Gangrenous MODS
• Treatment
  • Most patients resolve on their own with supportive care and bowel rest + IV fluids
  • Optimise cardiac fx, oxygenation, cease any vasoconstrictive drugs
  • No strong evidence for antibiotics but some authors advocate broad-spectrum Ab use to prevent bacterial translocation
  • Anticoagulation only if occlusive disease
  • Must monitor for progression to irreversible ischaemia

PROGNOSIS

• Risk factors for poor outcome
  • Male
  • SBP <90
  • HR >100
  • Hb <120
  • LDH >350
  • Na <136
  • WCC >15
• Oakland Score
  • <= 8 equates to low-risk and potentially suitable for outpatient management as predicts a >95% likelihood of safe discharge
  • Prospective study of 2336 patients and subsequently validated in 38 067 patients in the USA
  • Designed to predict ‘safe discharge’ using 7 variables
  • Composite outcome of absence of in-hospital bleeding, RBC transfusion, therapeutic intervention, in-hospital death and readmission with LGIB within 28 days
  • Variables
    • Age
    • Sex
    • Previous LGIB Admission
    • DRE blood
    • HR
    • SBP
    • Hb

PROGNOSIS

• High morbidity factors
  • Haemodynamic instability
  • Repeated haematochezia
  • Gross blood on initial PR
  • Initial Hct <35%
  • Syncope
  • Non-tender abdomen (predictive of severe bleeding)
  • Aspirin or NSAID use (predictive of diverticular bleeding)
  • >2 comorbidities

DIAGNOSIS

• History
  • This and prior episodes
  • Prior endoscopies
  • Weight loss/change in bowel habits = malignancy
  • Aortic graft = aortoenteric fistula
  • Medications – NSAID, anticoagulants, beta-blockers/CCB, iron/bismuth/beets
• Exam
  • Haemodynamics, abdo incl. liver, PR

IMAGING

• MDCT angiography is first-line
  • Sensitivity and specificity of 100 and 99% respectively
  • 93% accurate for diagnosing site of bleeding
  • Indicated in all haemodynamically unstable LGIB
• Angiographic diagnosis and therapy require brisk bleeding >0.5mL/min
  • Serious complications with invasive angiography in 10%
• Technetium-labelled red cell scintigraphy is more sensitive and can identify bleeding at >0.1mL/min but does require at least 3mL of blood to pool

TREATMENT

• NG tube
  • Haematochezia from upper GI source 10-14% of the time
  • 15% of patients with haematochezia have negative NG aspirate despite UGI source of bleeding
  • NG tube likely only beneficial in significant ongoing UGI bleeding in whom immediate intervention will occur
• Obtain early surgical consultation for severe bleeding
• Endoscopy
  • Unclear how rapidly this should be performed in stable patients
• Surgery
  • Continued bleeding and failure of endoscopic haemostasis
  • 5-25% rate of surgical intervention

Last Updated on June 23, 2021 by Andrew Crofton