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Toronto Notes 2019 Small Bowel Obstruction General Surgery and Thoracic Surgery GS23
• Highriskforstrangulationbasedonclinicalsymptoms:urgentsurgerytopreventirreversible ischemia
■ early post-operative SBO: if bowel function does not return within 3-5 d after surgery; usually partial, extended conservative therapy (2-3 wk) with bowel rest, fluids, and TPN is appropriate
◆ surgery if presence of peritonitis or complete SBO demonstrated
Prognosis
• relatedtoetiology;mortality:non-strangulating<1%,strangulating8%(25%if>36h),ischemic=upto 50%
Prevention
• opensurgeryhasfourfoldincreaseinriskofSBOin5yrcomparedtolaparoscopicsurgery
Paralytic Ileus
Pathogenesis
• temporary,reversibleimpairmentofintestinalmotility;mostlyfrequentlycausedby:
■ abdominal operations, infections and inflammation, medications (opiates, anesthetics,
psychotropics), and electrolyte abnormalities ■ passing gas is the most useful indicator
• NOTthesameasintestinalpseudo-obstruction
■ chronic pseudo-obstruction refers to specific disorders that affect the smooth muscle and myenteric
plexus, leading to irreversible intestinal dysmotility
Clinical Features
• symptomsandsignsofintestinalobstructionwithoutmechanicalobstruction
■ bowel sounds are diminished or absent (in contrast to initial hyperactive bowel sounds in SBO)
Investigations
• routinepost-operativeileus:expected,noinvestigationneeded • ifileuspersistsoroccurswithoutabdominalsurgery
■ review patient medications (especially opiates)
■ measure serum electrolyte to monitor for electrolyte abnormalities (including extendedelectrolytes
like Mg, Calabour, PO4)
■ CT scan to rule out abscess or peritoneal sepsis, or to exclude complete mechanical obstruction
Treatment
• mostimportant:NPO+fluidresuscitation
• NGTdecompression,correctcausativeabnormalities(e.g.sepsis,medications,electrolytes),consider
TPN for prolonged ileus
• post-operative:gastricandsmallbowelmotilityreturnsby24-48h,colonicmotilityby3-5d
• currentinterestinnoveltherapiessuchasgumchewingandpharmacologictherapy(e.g.alvimopan,an
opioid antagonists)
Intestinal Ischemia
Etiology
• acute
■ arterio-occlusive mesenteric ischemia (AOMI)
◆ thrombotic, embolic, and extrinsic compression (e.g. strangulating hernia) ■ non-occlusive mesenteric ischemia (NOMI)
◆ mesenteric vasoconstriction secondary to systemic hypoperfusion (preserves supply to vital organs)
■ mesenteric venous thrombosis (MVT)
◆ consider hypercoagulable state (i.e. rule out malignancy), and DVT (prevents venous outflow)
• chronic:usuallyduetoatheroscleroticdisease–lookforCVDriskfactors
• canleadtoocclusioninvesselsthatsuppliesthesmallintestineandthelargeintestine
Clinical Features
• acute:severeabdominalpainoutofproportiontophysicalfindings,vomiting,bloodydiarrhea, bloating, minimal peritoneal signs early in course, hypotension, shock, and sepsis
• chronic:postprandialpain(frommesentericangina),fearofeating,andweightloss
• commonsites:SMAsuppliedterritory,“watershed”areasofcolon–splenicflexure,leftcolon,and
sigmoid colon
Psoas major muscle
Ileal/sub-ileal (<1%)
Inferior (1%) Paracolic (2%) Pelvic (32%)
Retrocecal (64%)
Iliacus muscle
Obturator internus muscle
© Natalie Cormier 2015, after Wensi Sheng 2010
Figure 11. Appendix anatomy
Pain“outofkeepingwithphysicalfindings”is the hallmark of early intestinal ischemia