NurseSavvy Cheat SheetDisease
Bowel Obstruction
Pathophysiology & Risk Factors
Bowel obstruction occurs when intestinal contents cannot pass through the lumen. Mechanical obstruction has a physical blockage (adhesions are the #1 cause of small bowel obstruction; tumors are #1 in large bowel). Functional obstruction (paralytic ileus) is absent peristalsis without a physical blockage, commonly after abdominal surgery or with opioid use.
Small bowel (SBO) vs large bowel (LBO) obstruction
Small bowel (SBO)Large bowel (LBO)
OnsetRapid, colickyGradual
VomitingEarly, profuse, biliousLate or feculent
DistensionMild to moderateMarked
Bowel soundsHigh-pitched, tinklingLow-pitched or absent
#1 causeAdhesionsTumor
Small bowel (SBO)
- Onset
- Rapid, colicky
- Vomiting
- Early, profuse, bilious
- Distension
- Mild to moderate
- Bowel sounds
- High-pitched, tinkling
- #1 cause
- Adhesions
Large bowel (LBO)
- Onset
- Gradual
- Vomiting
- Late or feculent
- Distension
- Marked
- Bowel sounds
- Low-pitched or absent
- #1 cause
- Tumor
Signs & Symptoms
EarlyProgresses →
colicky abdominal pain Hallmark
cramping, comes in waveshigh-pitched tinkling bowel sounds Hallmark
hyperactive, proximal to obstructionbilious vomiting
early/profuse in SBOLate / Severe
feculent vomiting
late finding, distal/LBOabsent bowel sounds
late bowel fatigue or ileusOther findings
abdominal distension
mild in SBO, marked in LBOno flatus or stool
obstipation; complete obstructionDiagnostics & Labs
Diagnostic
abdominal x-ray
distended loops with air-fluid levelsMonitor
metabolic alkalosis Hallmark
expected from NG loss of HClhypokalemia
complication of NG suction losseshyponatremia
from ongoing GI fluid lossesabdominal girth
decreasing girth = effective decompressionNG output trend
sudden drop = check tube patencyInterventions & Priorities
Confirmed obstruction — priority sequence
- NPOstop oral intake
- NG to low intermittent suctiondecompress
- Aggressive IV fluids + electrolytescounter third-spacing
- Reassess abdomen + outputgirth, NG trend, bowel sounds
Patient Teaching
report no flatus or stool
esp. post-opreport worsening or constant pain
NG tube remains until function returns
early ambulation post-op
promotes return of peristalsisComplications
bowel strangulation
compromised blood supplybowel necrosis
can occur within hoursperforation
rigid abdomen, peritonitishypovolemic shock
third-spacing and fluid lossesReport Nowescalate immediately
constant severe pain Hallmark
colicky shifting to constant = strangulationfever
ischemia/perforationrigid abdomen
peritoneal irritationrebound tenderness
peritonitis/perforationtachycardia
ischemia, shockno flatus and no stool
complete obstruction = surgical emergencyClinical Pearl
Post-op patient who stops passing flatus with crampy pain and bilious vomiting? Think obstruction. When colicky pain turns constant with fever and a rigid belly, it's strangulation — call surgery.