14.10 (14.3) malignant bowel obstruction Flashcards
What is the formal definition of MBO
- Clinical evidence of BO = O
- BO beyond ligament of Treitz = B
- Incurable intra-abdo/intraperitoneal cancer = M
*Ligament of treitz = thin band of tissue that connects/supports end of duodenum + beginning of jejunum
List common causes of bowel obstruction
Adhesion
Buldge (hernia)
Cancer (especially ovarian and colon)
Anticancer treatment (e.g. radiation enteritis)
4 mechanisms by which cancer cause MBO
- Extrinsic compression (extra-mural tumor in mesentary or omentum)
- Intrinsic (intramural) compression (intra-mural invasion of bowel wall muscle)
- Intraluminal obstruction (e.g. polypoid lesions, bezoars, foreign body that occlude lumen)
- Functional dysmotility (e.g. diabetes, SCC, drugs like opioids/anti-cholinergic)
What is the overall progression of MBO?
- occlusion of lumen prevents or delays passage of contents
- Non absorbed fluids accumulate -> distension
- bowel continues to contract with increased non-coordinated peristalis even though no movement of contents
- bowel becomes distended stimulating intestinal fluid secretion -> vicious cycle of distension/secretion
FS:
Occlusion
Distension
Secretion -> distension
Differentiate how the following symptoms present in proximal vs distal MBO:
- Nausea/Vomiting
- Anorexia
- Abdo colicky pain
- Abdo distension
- Abdo bowel sounds
- Constipation/overflow diarrhea
Proximal (VS) Distal MBO (distal = distal SBO or large BO)
- Nausea/Vomiting - early and large volume (VS) late or absent, small volume, feculent odor
- Anorexia - often present (VS) late
- Abdo colicky pain - develops early and short intermittent cramps (VS) late and long interval between cramps
- Abdo distension - absent or late (VS) often present
- Abdo bowel sounds - often normal (VS) increased
- Constipation/overflow diarrhea - often late (VS) present early
List 4 options for intervention for malignant bowel obstruction
endoscopic - stents
surgery - intestinal resection
surgery - diversion (bypass or stoma)
surgery - adhesion lysis
interventional radiology - venting g tube
Beside plain AXR, CT and MRI - what other investigations can be ordered and why?
Barium contrast - shows stomach and proximal small bowel patency (may be limiting if pt vomits contrast)
Gastrograffin - visualization of proximal small bowel obstruction, helps to differentiate pseudo obstruction (outside book: also therapeutic due to osmotic effect - brings water into the gut, decrease intestinal wall edema)
List 5 factors that contribute to decisions about intervention in MBO
Age (biologic/physiologic) Performance status Malnutrition/cachexia Concurrent illness Prognosis Other: Stage of cancer: previous tx, current options Ascites
When is surgery more vs less beneficial (location wise)?
More beneficial in patients with LBO or partial SBO
Less beneficial in patients with complete SBO
How much small bowel does a patient require to maintain oral nutrition?
What happens if greater than this length is resected?
200cm
Poor nutrition/fluid absorption –> imbalance, high secretions from stomas
Ideal locations for stenting
Gastroduodenal and proximal jejunum (difficult in distal jejunum and ileum)
Colonic stenting (except for very low rectal tumors as it can cause incontinence)
FS: no no stent in distal jejunum + ileum + low rectal
List 5 complications of endoscopic stenting
pain
bleeding
fever
jaundice
stent failure - food or tumor growth
stent migration
perforation
fistula formation
Who is surgery best suited for? Name 2 of each:
Patient factor
Cancer factor
MBO factor
long life expectancy (>60d)
good performance status
slowly progressive disease
single site obstruction near gastric outlet
FS:
Patient factors (5) - age, nutrition, function, comorbidities, prognosis >60dYs
Cancer factors (2)
- slow progressing cancer
- Less than 2 of: high WBC, low, albumin, ascites, carcinomatosis
MBO factors (2)
- Single site
- LBO or partial SBO
Who is stenting best suited for?
median life expectancy >30d
intermediate to high performance status
short tumor length
obstruction near pylorus or prox 2/3 duodenum
FS: no stent in distal jejunum + ileum + low rectum
Who is symptom management only best suited for?
prognosis <30d
poor performance status
advanced cancer
ascites
multisite obstruction
