Small bowel obstructionMANAGEMENT

GASTROINTESTINAL PRESENTATIONS · 12 SECTIONS

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453 items

☷ Legend

01Approach to the Critical Patient/attcp42

Immediate priorities

›High risk small bowel obstruction triage

›Airway risk

›Persistent vomiting

›Reduced level of consciousness

›Aspiration risk

›Shock physiology

›Systolic blood pressure < 90 mmHg

›Heart rate > 120 beats/min

›Capillary refill delay

›Altered mental status

›Peritonitis concern

›Rebound tenderness

›Involuntary guarding

›Rigid abdomen

›Bowel ischemia concern

›Pain out of proportion

›Rising lactate

›Fever

›Leukocytosis

Early decision points

›Operative pathway triggers

›Immediate surgical consultation for suspected strangulation

›Peritonitis

›Free intraperitoneal air

›Closed loop obstruction on imaging

›Pneumatosis intestinalis on imaging

›Portal venous gas on imaging

›Resuscitation bay escalation criteria

›Persistent hypotension after initial fluids

›Ongoing severe pain requiring escalating opioids

›Progressive metabolic acidosis

Monitoring and access

›Monitoring set

›Cardiac monitor

›Continuous rhythm monitoring for electrolyte related dysrhythmia risk

›Pulse oximetry

›Target oxygen saturation per comorbidity

›Frequent vital signs

›15 minute intervals if unstable

›Urine output tracking

›Target 0.5 mL/kg/hour

›IV access plan

›Two large bore peripheral IVs for dehydrated patient

›Intraosseous access if no rapid peripheral access

02History/hx57

Focused features

›Symptom pattern

›Abdominal pain

›Colicky pain pattern

›Constant pain pattern

›Pain progression timeline

›Vomiting

›Bilious emesis

›Feculent emesis

›Inability to tolerate oral intake

›Bowel function

›Obstipation

›Last flatus

›Last stool

›Distension

›Progressive abdominal bloating

›Early satiety

Etiology risks

›Adhesive disease risk

›Prior abdominal surgery

›Appendectomy

›Colorectal surgery

›Gynecologic surgery

›Prior small bowel obstruction episodes

›Prior nonoperative management

›Prior operative lysis of adhesions

›Hernia risk

›Known abdominal wall hernia

›Inguinal hernia history

›Femoral hernia history

›Umbilical hernia history

›Malignancy risk

›Known intraabdominal cancer

›Colorectal cancer history

›Ovarian cancer history

›Peritoneal carcinomatosis history

›Inflammatory bowel disease risk

›Crohn disease history

›Prior strictures

›Prior bowel resection

›Other mechanical risk

›Prior abdominal radiation

›Radiation enteritis risk

›Foreign body ingestion

›Bezoar risk factors

Red flags for ischemia and perforation

›Ischemia and strangulation clues

›Severe continuous pain

›Pain out of proportion to exam

›Systemic toxicity

›Fever

›Rigors

›Bloody stool

›Hematochezia

›Melena

›Perforation clues

›Sudden pain change

›Abrupt pain relief followed by worsening diffuse pain

›Syncope

›Presyncope with abdominal pain

03Physical Exam/exam42

General and vitals

›Physiologic state

›Hydration status

›Dry mucous membranes

›Poor skin turgor

›Perfusion

›Cool extremities

›Mottling

›Temperature

›Fever

›Hypothermia

Abdominal exam

›Abdominal findings

›Distension

›Tympany

›Tenderness distribution

›Localized tenderness

›Diffuse tenderness

›Peritoneal signs

›Rebound tenderness

›Involuntary guarding

›Bowel sounds

›High pitched tinkling

›Minimal bowel sounds

Hernia and rectal exam

›Hernia examination

›Inguinal canals

›Tender irreducible mass

›Femoral region

›Tender mass below inguinal ligament

›Umbilicus and prior incision sites

›Incisional hernia

›Rectal exam indications

›Suspected gastrointestinal bleeding

›Gross blood

›Melena

›Suspected fecal impaction mimic

›Hard stool in rectal vault

PITFALLS

›Common misses

›Pain without major distension in early obstruction

›Early or proximal small bowel obstruction

›Normal initial lactate

›Lactate not sensitive for early strangulation

›Reduced pain after opioids

›Ongoing ischemia risk despite symptom blunting

04Differential Diagnosis/ddx40

Life threats and mimics

›Acute abdomen differentials

›Mesenteric ischemia ICD-10 K55.9

›Pain out of proportion

›Atrial fibrillation history

›Perforated viscus ICD-10 K63.1

›Free air

›Peritonitis

›Ruptured abdominal aortic aneurysm ICD-10 I71.4

›Hypotension

›Back pain

›Acute pancreatitis ICD-10 K85.9

›Epigastric pain radiating to back

›Elevated lipase

›Acute appendicitis ICD-10 K35.80

›Migratory pain

›Right lower quadrant tenderness

›Obstruction spectrum

›Large bowel obstruction ICD-10 K56.60

›Marked constipation

›Colonic dilation

›Ileus ICD-10 K56.0

›Diffuse bowel dilation including colon

›Recent surgery or opioids

›Gastric outlet obstruction ICD-10 K31.1

›Nonbilious vomiting

›Epigastric fullness

Etiologic differentials for small bowel obstruction

›Mechanical causes

›Adhesions ICD-10 K56.5

›Prior abdominal surgery

›Hernia ICD-10 K46.9

›Groin mass

›Incarceration

›Neoplasm ICD-10 C17.9

›Weight loss

›Anemia

›Crohn stricture ICD-10 K50.90

›Prior flares

›Perianal disease

›Volvulus of small bowel ICD-10 K56.2

›Closed loop signs on imaging

05Laboratory Tests/lt27

Core labs and interpretation

›Laboratory baseline

›Complete blood count for infection and ischemia signals

›Leukocytosis as stress or infection marker

›Hemoconcentration as dehydration marker

›Electrolytes and renal function for vomiting related derangements

›Sodium for hypovolemia pattern

›Potassium for arrhythmia risk

›Creatinine for contrast readiness and dehydration severity

›Glucose for metabolic stress and diabetes management

›Hyperglycemia in sepsis or dehydration

›Liver enzymes and bilirubin for alternate diagnosis

›Hepatobiliary disease mimic

Perfusion and acid base

›Ischemia screening labs

›Venous blood gas for pH and pCO2 mmHg

›Metabolic acidosis concern

›Lactate mmol/L for hypoperfusion tracking

›Rising lactate supporting ischemia concern

›Normal lactate not excluding strangulation

Additional labs by context

›Context dependent tests

›Lipase for pancreatitis mimic

›Elevated lipase supporting pancreatitis alternative

›C reactive protein for inflammatory signal

›Trend support for inflammatory bowel disease flare

›Type and screen for anticipated operation or bleeding

›Crossmatch if hemodynamic instability

›Pregnancy test for reproductive age

›Serum beta hCG for equivocal urine result

06Diagnostic Tests/dt51

Scoring Systems

›Risk stratification frameworks

›Strangulation risk assessment bundle

›Continuous severe pain

›Fever

›Tachycardia

›Peritoneal signs

›Leukocytosis

›Metabolic acidosis

›Elevated lactate mmol/L

›CT signs of ischemia

›Clinical rule limitations

›No single validated bedside score to exclude strangulation

›Imaging plus trajectory favored over isolated labs

MRI

›MRI role

›Pregnancy with nondiagnostic ultrasound and need to avoid ionizing radiation

›Noncontrast MRI abdomen where available

›Contrast considerations

›Avoid gadolinium in pregnancy unless essential

›Practical limitations

›Limited availability in time critical obstruction

›Motion artifact with vomiting

›CT abdomen pelvis evaluation

›Preferred study for suspected mechanical small bowel obstruction

›IV contrast for ischemia evaluation when renal function acceptable

›Key CT findings

›Transition point

›Closed loop configuration

›Mesenteric edema

›Reduced bowel wall enhancement

›Pneumatosis intestinalis

›Portal venous gas

›Free intraperitoneal air

›Contrast enhanced decision support

›If severe contrast allergy, noncontrast CT plus surgical discussion

›If severe renal impairment, risk benefit discussion for IV contrast

›Water soluble contrast challenge protocol

›Use in suspected adhesive partial obstruction without peritonitis

›Oral or nasogastric administration per local protocol

›Follow up imaging for contrast in colon within 24 hours supporting nonoperative success

Ultrasound

›Point of care ultrasound

›Small bowel obstruction sonographic features

›Dilated fluid filled small bowel loops

›Diameter > 2.5 cm supporting obstruction

›To and fro peristalsis

›Thickened bowel wall

›Complication screening

›Free intraperitoneal fluid

›Reduced peristalsis with severe illness

›Limits

›Operator dependency

›Reduced windows with marked distension

07Disposition/dispo18

Level of care

›Admission planning

›Surgical service admission for suspected mechanical obstruction

›Early consult for all confirmed small bowel obstruction

›ICU criteria

›Hemodynamic instability

›Rising lactate despite resuscitation

›Need for vasopressors

›Severe metabolic acidosis

›Floor appropriate criteria

›Hemodynamic stability after fluids

›No peritoneal signs

›Controlled pain and nausea with IV therapy

Discharge considerations

›Discharge rare scenarios

›Resolved symptoms with alternative diagnosis

›Gastroenteritis with normal imaging

›Partial obstruction resolved and tolerating oral intake after observation

›Clear return precautions

›Rapid outpatient follow up plan

08Treatment/t76

Supportive care

›Initial nonoperative management bundle

›Nil by mouth status

›Avoid oral intake until obstruction resolved

›IV fluids

›Balanced crystalloid bolus 10 to 20 mL/kg for hypovolemia

›Maintenance fluids adjusted to urine output and electrolytes

›Electrolyte correction

›Potassium replacement per institutional protocol

›Magnesium replacement per institutional protocol

›Nasogastric decompression

›Persistent vomiting

›Significant distension

›Respiratory compromise from gastric distension

Analgesia and antiemetics

›Symptom control medications

›Opioid analgesia options

›Fentanyl IV 25 to 50 micrograms

›Repeat every 5 to 10 minutes for severe pain

›Monitor respiratory rate and sedation

›Morphine IV 2 to 4 mg

›Repeat every 10 to 15 minutes as needed

›Avoid in severe hypotension

›Hydromorphone IV 0.2 to 0.5 mg

›Repeat every 10 to 15 minutes as needed

›Higher risk of oversedation in older adults

›Antiemetic options

›Ondansetron IV 4 mg

›Repeat once in 10 minutes for refractory nausea

›QT prolongation risk with repeated dosing

›Metoclopramide IV 10 mg

›Avoid if suspected mechanical complete obstruction with severe colic

›Extrapyramidal symptom risk

Antibiotics

›Antimicrobial indications

›Suspected strangulation

›Fever and leukocytosis with CT ischemia signs

›Suspected perforation

›Free air on imaging

›Suspected aspiration pneumonia from vomiting

›Hypoxia with infiltrate

›Empiric regimens for intraabdominal source

›Piperacillin tazobactam IV 4.5 g every 6 hours

›Renal dosing adjustment when eGFR reduced

›Broad gram negative and anaerobe coverage

›Ceftriaxone IV 2 g daily

›Add metronidazole IV 500 mg every 8 hours

›Alternative when lower pseudomonas risk

›Meropenem IV 1 g every 8 hours

›Reserve for high risk resistant organisms

›Renal dosing adjustment when eGFR reduced

Procedural and operative pathway

›Surgical management elements

›Immediate operative pathway

›Closed loop obstruction

›Peritonitis

›Bowel ischemia signs on CT

›Perforation

›Nonoperative trial conditions

›Suspected adhesive obstruction

›No peritonitis

›No CT ischemia signs

›Clinical improvement within 24 to 48 hours

›Water soluble contrast challenge integration

›Use for partial adhesive obstruction guidance

›Failure markers prompting surgery

›No contrast progression to colon within 24 hours

›Persistent high nasogastric output

›Worsening pain or vitals

VTE prophylaxis and adjuncts

›Hospital course risk reduction

›Venous thromboembolism prophylaxis

›Enoxaparin subcutaneous 40 mg daily

›Renal dosing adjustment when eGFR < 30 mL/min

›Avoid if active bleeding

›Unfractionated heparin subcutaneous 5000 units every 8 to 12 hours

›Use when severe renal impairment

›Stress ulcer prophylaxis indications

›ICU admission

›Mechanical ventilation

›Coagulopathy

09Special Populations/sp32

Pregnancy

›Pregnancy specific considerations

›Maternal fetal priorities

›Left lateral positioning to reduce aortocaval compression

›Early obstetrics consultation for viable gestation

›Diagnostic imaging approach

›Ultrasound first when feasible

›MRI preferred when further imaging needed and stable

›CT if life threatening concern and MRI unavailable

›Medication safety notes

›Avoid NSAIDs in later pregnancy

›Antiemetics with established pregnancy safety per local guidance

Geriatric

›Older adult considerations

›Atypical presentation risk

›Minimal pain despite serious pathology

›Delayed fever response

›Medication safety

›Lower initial opioid dosing

›Delirium monitoring with antiemetics

›Higher complication risk

›Earlier surgical consultation threshold

›Lower physiologic reserve for dehydration

Pediatrics

›Pediatric considerations

›Alternate etiologies by age

›Intussusception ICD-10 K56.1 in infants and toddlers

›Malrotation with volvulus ICD-10 Q43.3 in infants

›Incarcerated hernia

›Weight based resuscitation

›Isotonic crystalloid 20 mL/kg bolus for dehydration or shock

›Dextrose containing fluids when prolonged fasting risk

›Early pediatric surgery involvement

›Bilious vomiting in neonate as surgical emergency

›Suspected volvulus requiring urgent imaging and intervention

10Background/b35

Epidemiology

›Epidemiologic features

›Common causes distribution

›Adhesions as leading cause in high income settings

›Hernias prominent where unrepaired hernia prevalence high

›Recurrence considerations

›Prior adhesive obstruction increasing future risk

›Complication burden

›Strangulation and ischemia as primary mortality drivers

Pathophysiology

›Mechanistic overview

›Mechanical obstruction sequence

›Proximal dilation

›Fluid sequestration into bowel lumen

›Vomiting and dehydration

›Ischemia pathway

›Closed loop venous congestion

›Reduced arterial inflow

›Transmural necrosis

›Perforation pathway

›Increasing intraluminal pressure

›Wall compromise

›Bacterial translocation and peritonitis

Therapeutic Considerations

›Rationale for key therapies

›Nasogastric decompression benefits

›Reduced vomiting

›Reduced aspiration risk

›Reduced gastric and proximal bowel distension

›Fluid resuscitation benefits

›Correction of third spacing hypovolemia

›Improved renal perfusion for contrast imaging and anesthesia readiness

›Nonoperative management success profile

›Highest success in partial adhesive obstruction

›Failure risk increased with ischemia signs

›Antibiotics rationale

›Coverage for translocation in ischemia and perforation

›Early administration when operative course likely

11Patient Discharge Instructions/pdi18

Copy discharge instructions

›Small bowel obstruction discharge bundle

›Diet and activity

›Clear liquids then gradual advance as tolerated

›Avoid large high fiber meals for 48 to 72 hours

›Medications

›Use prescribed antiemetic as directed

›Avoid constipating medications when possible

›Follow up

›Primary care or surgery follow up within 48 to 72 hours if symptoms improving

›Earlier follow up for recurrent episodes history

›Return to emergency department immediately

›Worsening abdominal pain

›New persistent vomiting

›Inability to pass gas or stool

›Fever

›Blood in stool

›Fainting or severe weakness

›Increasing abdominal distension

12References/r15

Guidelines and high yield sources

›Professional guidance

›World Society of Emergency Surgery guidance for adhesive small bowel obstruction

›Water soluble contrast challenge as diagnostic and management adjunct in selected patients

›Early operative management for peritonitis and ischemia signs

›Surgical society recommendations for bowel obstruction evaluation

›CT abdomen pelvis with IV contrast for suspected mechanical obstruction and ischemia evaluation

Coding and terminology

›Coding references

›ICD-10 K56.6 other and unspecified intestinal obstruction

›Use when small bowel obstruction unspecified cause

›ICD-10 K56.5 intestinal adhesions with obstruction

›Use when adhesive obstruction documented

›ICD-10 K46.9 unspecified abdominal hernia with obstruction

›Use when hernia related obstruction documented

›SNOMED CT small bowel obstruction disorder

›Use for problem list standardization

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Reviewed by SymptomDx Medical Team · Last reviewed June 16, 2026

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