Editing Large bowel obstruction


Mechanical bowel obstruction distal to the ileocaecal valve.

== '''Epidemiology''' ==

* Comprises 24% of admissions     for mechanical bowel obstruction.
* Surgery required in 70% of     cases

== '''Aetiology:''' ==

=== '''Dynamic     (mechanical)''' ===

** '''Luminal'''
*** CRC (50% of LBO)
**** Most commonly descending        colon or rectosigmoid
*** Faecal impaction
*** Foreign body
*** Bezoar
** '''Mural'''
*** Diverticular stricture
**** Often seen in Hinchey II        disease, with an intramural or extramural abscess compressing bowel
**** If partial obstruction -        generally resolves with conservative management
**** If complete - may need        stenting/resection
*** Intussusception
**** In adults, almost always        associated with a pathologic lead point
**** 46% malignant in colon
*** IBD stricture
**** More likely to be Crohn's        (transmural)
*** Ischaemic/radiotherapy-induced       strictures
**** Fibrosis
**** Radiation Therapy Oncology        Group grading for radiation-induced bowel damage
*** Infection
**** Lymphogranuloma venereum
**** TB
**** Schistosomiasis
*** Hirschsprung disease
** '''Extraluminal'''
*** Extraluminal obstruction -       esp. ovarian cancer
*** Sigmoid Volvulus
**** See separate topic
*** Caecal volvulus
**** See separate topic
*** Hernia
*** Abdominal abscess
*** Retroperitoneal fibrosis
*** Adhesions (rare)

=== '''Adynamic     (functional - pseudo-obstruction)''' - Ogilvie Syndrome ===

** See separate topic      'Pseudo-obstruction
** Toxic megacolon
** Paralytic ileus

== '''Pathophysiology''' ==

* Distension of the colon     occurs as a result of gas and stool that gather proximal to the     obstruction
* Pressure within the bowel     wall can rise above the capillary pressure, diminishing adequate     oxygenation, leading to ischaemic necrosis and perforation
* Necrosis and perforation     usually occurs in the caecum due to Laplace's law (largest diameter - will     distend more under lower pressures and hence develop more wall stress)
* Venous ischaemia can also     develop due to mesenteric compression in strangulated hernias and volvulus

== '''Presentation:''' ==

* Increased peristalsis and     low-grade colicky pain
** Late obstruction may have      decreased bowel sounds
* Acute obstructions can be     dramatic rapid-onset pain, distension and tenderness
* Chronic progressive     obstructions may describe more of increasing constipation, pencil-thin     stools, and intermittent pain
* Functional obstructions     usually have distension, vague abdominal pain, and weak or absent bowel     sounds
* Ask about weight loss,     bleeding, bowel habits, night sweats. Check for hernias and incisions.     DRE.
* Classically, a mechanical     obstruction will give a collapsed rectum, while a pseudo-obstruction will     give a capacious rectum on DRE. Also need to exclude a synchronous rectal     cancer.

== '''Imaging''' ==

* Plain film - 'bent inner     sign' pointing to RUQ (sigmoid volvulus) and coffee bean sign pointing to     LUQ (caecal volvulus)
* CT with IV contrast.     According to Schein, no need for rectal or oral contrast
** Contrast enema can be useful      to evaluate distal causes of LBO (note use water soluble contrast, not      barium, so it can't be absorbed into peritoneum if there is a perf)
* Check for closed-loop     obstructions
** Competent ICV
** Hernia
** Volvulus

== '''Management''' - tailored to aetiology and patient factors ==

=== Medical management ===

** Fluid resus/electrolytes
** Consider IDC
** NGT for most patients
** Stoma marking

=== Indications for immediate     surgery ===

** Signs of perforation
** Ischaemia, including closed      loop (pneumatosis coli)
** Peritonitis
** Impending caecal perforation      (diameter >10cm)
** Tachycardia, hypotension,      lactic acidosis

=== If no immediate indication     for surgery - management by aetiology, the next day, once resuscitation     has occurred. ===

** '''Luminal'''
*** CRC
**** ''See        separate topic''
**** ''Proximal        to, and including, the splenic flexure - right hemicolectomy''
**** ''Sigmoid/left        colon - stenting as a bridge to surgery, or upfront surgery''
**** ''Low and        mid rectum - diversion to allow for neoadjuvant CRT''
*** Faecal impaction
**** ''Stool        softeners, manual disimpaction''
*** Foreign body
**** ''Remove        endoscopically''
*** Bezoar
**** ''Remove        endoscopically''
** '''Mural'''
*** Diverticular stricture
**** ''See        separate topic''
*** Intussusception
**** ''Surgery''
*** IBD stricture
**** ''See        separate topic - steroids''
*** Ischaemic/radiotherapy-induced       strictures
**** ''Low-residue        diet, antibiotics, endoscopic therapy such as argon beam coagulation        for colonic telangiectasias, balloon dilatation for strictures''
**** ''May        require intervention, most often for stricture''
*** Infection
**** Lymphogranuloma venereum
**** TB
**** Schistosomiasis
*** Hirschsprung disease
** '''Extraluminal'''
*** Extraluminal obstruction -       esp. ovarian cancer
**** ''Treat        the mass''
**** ''Consider        stent''
*** Sigmoid Volvulus
**** ''See        separate topic''
*** Caecal volvulus
**** ''See        separate topic''
*** Hernia
**** ''Usually        requires surgery''
*** Abdominal abscess
**** ''Drain        abscess''
*** Retroperitoneal fibrosis
*** Adhesions (rare)

== '''Choice of operation''' ==

* Right-sided obstructing     lesion - right hemicolectomy
** If perforation or      peritonitis, ischemia or necrosis, poor nutrition, sepsis,      immunosuppression or poor overall health, should have end ileostomy (70%      of these will never get reconnected)
** Self-expanding metal stent      is also an option as a bridge to hemicolectomy
* Left-sided obstructing     lesions are a bit more diverse in options/less clear-cut
** Hartmann's
** Subtotal colectomy (if      significant proximal colon dilatation or ischaemia)
** Proximal diversion
** Loop colostomy

== '''Operation''' ==

* If the large bowel is     severely distended and impeding view, decompress it with a 14G needle on a     syringe with the plunger removed, and attach to suction. Put that needle     through the tenia, ideally at a spot where you will make a hole anyway for     the anastomosis. If that fails due to fecal build-up, put a Poole sucker     through the hole.
* If in doubt, do an oncologic     resection
* If there is a large fixed     mass in the pelvis, don't try too hard to resect it
* Consider on-table colonic     lavage if doing an anastomosis, however UTD says not necessary
** Divide distally and place      the open distal end in a clean dish
** Pass a 16Fr Foley through      the base of appendix, run 4-6L of warm saline through until it comes out      clear, then close the appendicectomy

== '''Stenting''' ==

* Indications
** Poor candidates for surgery
** Locally advanced/metastatic      disease (neoadjuvant CTX)
* Technically possible in 90%     of patients
* Complications
** Migration
** Regrowth and re-obstruction
** Perforation
* Often used as a bridge to     surgery
* Surgery is still preferred if     there's no need to optimise oncologic outcomes

[[Category:Colorectal]]
[[Category:Intern education]]