Editing Lower GI bleeding (section)

== '''Aetiology''' (40% have two potential lesions) ==

=== '''Colonic     (95%)''' ===

** '''Anatomic      (painless, large-volume)'''
*** '''Diverticulosis       (30-40%)'''
**** As the dome of the        diverticulum forms, the vessel entering at that point becomes stretched        and can rupture
**** Bleeding usually occurs in        the absence of diverticulitis
**** Right colon is the source        of bleeding in >50% of patients (usual demographics)
**** Resolves spontaneously in        80% overall and 98.5% of those receiving <4 units pRBC per day. 10%        will rebleed within a year and nearly 50% within 10 years.
**** Intervention generally        considered necessary if >6U pRBC per day
***** IR - 85% success rate,         low rate of re-bleeding
***** Colonoscopy
****** Treat          if there are stigmata of recent haemorrhage - visualised bleeding,          exposed blood vessel, adherent clots
****** Dual          modality: can use adrenaline, coagulation, APC, and fibrin glue
****** Clipping          safer than bipolar (risk of perf), and also marks area
****** Tattoo          area?
***** OT (last resort)
**** Up to a third recur within        a year
*** '''Aorto-enteric       fistula'''
**** Suspect if previous aortic        surgery
** '''Vascular      (painless, large-volume)'''
*** '''Angiodysplasia       aka AVM/angiectasias/vascular ectasia (3%)'''
**** Acquired degenerative        lesions secondary to progressive dilatation of normal submucosal blood        vessels due to venous obstruction - distinct from true congenital AVMs
**** Can occur anywhere in the        GIT, but most commonly caecum
**** Painless/mild cramping.        Episodic venous bleeding. Increased prevalence in elderly. Often right        colonic/caecal.
**** 90% resolve spontaneously        - but can recur
**** Associated with aortic        stenosis, CCF, end-stage CKD, von Willebrand's disease, left        ventricular assist devices
**** Colonoscopy
***** APC is best, but can also         be treated with bipolar electrocoagulation or heater probe
***** Incidentally-discovered         lesions do not require any further treatment
**** IR 50% success rate
**** Thalidomide and octreotide        have demonstrated efficacy in treating chronic angiodysplastic bleeding
** '''Colitis/proctitis''' - most often associated      with pain and diarrhoea
*** '''IBD (3-4%)'''
**** Mostly UC
**** Bleeding almost always        from diffuse colitis with no discrete lesions amenable to treatment
**** Exclude infection as cause        of bleeding
**** Crohn disease can        sometimes produce discrete ulcers that have eroded into a vessel,        giving a good target for embolization
**** Very rare for major        bleeding to be the initial presentation of either Crohns or UC.
**** Schein recommends total        colectomy for major bleeding, as it signifies a failure of medical        management.
*** '''Infectious       (3-8%)''' -       separate topic
**** Especially CMV and C. diff
*** '''Radiation-induced       (1-3%)''' -       separate topic
*** '''Ischaemia       (5-10%)''' -       separate topic
** '''Neoplastic      (5-10%)'''
*** Responsible for 10% of       lower GI bleeding in pts >50
*** Bleeding tends to be minor       and sporadic
*** Iron deficiency anaemia
*** GISTs in particular can       erode into blood vessels
*** Resect colonic cancers if       causing massive bleeding
*** Rectal cancers: attempt to       avoid acute resection, which would be difficult and also spoil       neoadjuvant therapy. Reasonable to attempt endoscopic first. Then pack       the rectum with adrenaline-soaked gauze, which often works. Can then try       a few other things in OT via a trans-anal approach if possible. If all       else fails, have to resect and accept compromised oncologic outcomes.       Chronic bleeding can sometimes be treated with RTx.
** '''Miscellaneous      anorectal disorders (5-15%)'''
*** '''Haemorrhoids''' - most common cause in       young patients
**** External - painful,        sporadic, low-volume bleeds with red blood coating stool
**** Internal - painless        sporadic, low-volume bleeds with red blood coating stool
*** '''Anal       fissure'''
**** Tearing pain and bleeding        with defaecation
*** Temporise with a big Foley       catheter inflated in the rectal vault then tractioned against the anus
*** If operating, prone       jack-knife may be better - blood falls away and is easier to suction       clear
** '''Iatrogenic'''
*** '''Post-polypectomy       (3-7%)'''
**** Can usually be treated        endoscopically
*** '''Anastomotic'''
** '''Other/unknown      (11-30%)'''

=== '''Small bowel     (5%)''' ===

** '''Angiodysplasias'''
** '''Erosions or      ulcers'''
** '''Crohn      disease'''
** '''Radiation -'''      see separate      topic
** '''Meckel      diverticulum''' -      separate topic
** '''Neoplasia'''
** '''Aortoenteric      fistula'''