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gi.small-bowel-obstruction.core.v1PRODUCTION
gi.small-bowel-obstruction.core.v1

Small Bowel Obstruction

gastroenterologyacuteadult
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Care setting:

Encounter flow

12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Confirm SBO scope; distinguish from large-bowel obstruction, paralytic ileus, Ogilvie, mesenteric ischemia (WSES Bologna 2017; EAST 2012)

Inputs
1
Actions
0
Advance rule
Set
Advance when

mechanical SBO confirmed

Patient inputs (15)

Surgical risk; malignancy probability rises with age (WSES Bologna 2017)

Hypotension in strangulation / sepsis (EAST 2012; WSES Bologna 2017)

Tachycardia / SIRS / strangulation (WSES Bologna 2017)

Fever in strangulation / ischemia (WSES Bologna 2017)

Adhesive SBO is most common cause (~65-75%) (WSES Bologna 2017; EAST 2012)

Hernia-related SBO ~10-15% (WSES Bologna 2017)

Leukocytosis / left shift in strangulation (Zielinski 2017; WSES Bologna 2017)

Bowel ischemia marker; elevated → emergent OR (EAST 2012; Zielinski 2017)

Dehydration / contrast safety / abx dosing (NICE 2024)

Hypokalemia / metabolic alkalosis from emesis (WSES Bologna 2017)

First-line per ACR Appropriateness Criteria 2020; transition point + strangulation signs

Diagnostic + therapeutic for adhesive SBO; contrast in colon at 24h predicts resolution (Branco 2010; Abbas 2024 meta-analysis)

Malignant SBO — peritoneal carcinomatosis, palliative options (NICE 2024)

Crohn-related stricture — medical optimization first (WSES Bologna 2017)

Early postoperative SBO — prolonged NOM acceptable (EAST 2012; WSES Bologna 2017)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (7)

7 need judgement
  • informationallife_threateningstrangulation_signs_emergency
    Peritonitis, lactate >2, leukocytosis with left shift, or CT signs of strangulation (pneumatosis, portal venous gas, no wall enhancement, free fluid + mesenteric haziness) (Zielinski 2017; WSES Bologna 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningclosed_loop_obstruction
    CT shows two transition points or closed-loop pattern (ACR Appropriateness Criteria 2020; Zielinski 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningincarcerated_hernia
    Tender, non-reducible hernia with overlying skin changes (WSES Bologna 2017; EAST 2012)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverefailed_NOM_at_48_72h
    Persistent obstruction at 48-72h despite NGT, IVF, contrast challenge (WSES Bologna 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatecrohns_inflammatory_stricture
    Known Crohn disease with new SBO; CT suggests inflammatory rather than fibrotic stricture (ECCO 2020; WSES Bologna 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatemalignant_sbo_palliative
    Known peritoneal carcinomatosis, ineligible for OR (NICE 2024 palliative care)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildgastrografin_in_colon_at_24h
    Contrast reaches colon by 24h after gastrografin challenge (Branco 2010; Abbas 2024)
    Trigger could not be auto-evaluated — needs clinician judgement.

Workflow calculators

This dossier does not reference any calculators.

Recommended regimen

Small bowel obstruction — NOM with NGT decompression vs emergent OR (WSES Bologna 2017 + ACR 2020 + Abbas/Branco)
axis: sbo_pathwaystep 1 - Step 1 — Initial resuscitation and decompression (all SBO)
Selected step "Step 1 — Initial resuscitation and decompression (all SBO)" — Mechanical SBO confirmed by clinical or imaging
  • normal_saline_or_LR
    first line
    crystalloid
    1-2 L IV bolus then maintenance 75-125 mL/h • IV • continuous
    triggers: SBO_all_grades
    Aggressive volume resuscitation; correct hypovolemia and emesis-related contraction alkalosis (WSES Bologna 2017; EAST 2012)
    rxcui 9863
  • potassium_chloride
    first line
    electrolyte
    20-40 mEq IV/PO per dose; titrate to K 4.0 • IV/PO • PRN
    triggers: hypokalemia_from_emesis
    Replenish K+; check Mg simultaneously (WSES Bologna 2017)
    rxcui 8591
  • ondansetron
    first line
    antiemetic_5HT3
    4-8 mg IV q6h PRN • IV • PRN
    triggers: nausea_vomiting
    Symptom control; alternative metoclopramide avoided in mechanical obstruction (WSES Bologna 2017; NICE 2024)
    rxcui 26225
  • hydromorphone
    first line
    opioid
    0.5-1 mg IV q3-4h PRN • IV • PRN
    triggers: acute_pain
    Pain control; lower dose to avoid worsening ileus (EAST 2012)
    rxcui 3423

ed playbook — drug actions (6)

  1. 1. IV LR resuscitation
    1-2 L bolus then 75-125 mL/h maintenance • IV • continuous
    trigger: Hypovolemia/SBO
    Resuscitation (WSES Bologna 2017)
  2. 2. electrolyte repletion
    KCl 20-40 mEq titrated; Mg 2 g IV if low • IV/PO • PRN
    trigger: Hypokalemia/hypomagnesemia from emesis
    Correct contraction alkalosis (WSES Bologna 2017)
  3. 3. ondansetron
    4-8 mg IV q6h PRN • IV • PRN
    trigger: Nausea/vomiting
    Symptom control (NICE 2024)
  4. 4. hydromorphone
    0.5-1 mg IV q3-4h PRN • IV • PRN
    trigger: Pain
    Pain control; minimize to avoid worsening ileus (EAST 2012)
  5. 5. pre-op cefazolin
    2 g IV pre-incision • IV • one-time pre-op
    trigger: Planned OR
    SSI prophylaxis (ASHP/IDSA/SHEA 2013)
  6. 6. pip-tazo for strangulation/perforation
    4.5 g IV q6h • IV • q6h
    trigger: Strangulation/perforation suspected
    Broad coverage (SIS/IDSA cIAI 2010; WSES Bologna 2017)

Auto-drafted A&P note

ed

Subjective

- Possible entry pathways: Colicky abdominal pain + distension (WSES Bologna 2017); Vomiting (bilious/feculent) + obstipation (WSES Bologna 2017); CT/XR showing dilated small bowel + transition point (ACR Appropriateness Criteria 2020).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Small Bowel Obstruction** (gi.small-bowel-obstruction.core.v1).
Phenotype framing: Adhesive > hernia > malignant > Crohn stricture > volvulus > intussusception > gallstone ileus > radiation > paralytic ileus > LBO > acute mesenteric ischemia > Ogilvie (WSES Bologna 2017 frequency ranking)
Scope: Confirm SBO scope; distinguish from large-bowel obstruction, paralytic ileus, Ogilvie, mesenteric ischemia (WSES Bologna 2017; EAST 2012)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Small bowel obstruction — NOM with NGT decompression vs emergent OR (WSES Bologna 2017 + ACR 2020 + Abbas/Branco)** — step "Step 1 — Initial resuscitation and decompression (all SBO)".
1. normal_saline_or_LR 1-2 L IV bolus then maintenance 75-125 mL/h IV continuous (crystalloid, first line) — Aggressive volume resuscitation; correct hypovolemia and emesis-related contraction alkalosis (WSES Bologna 2017; EAST 2012)
2. potassium_chloride 20-40 mEq IV/PO per dose; titrate to K 4.0 IV/PO PRN (electrolyte, first line) — Replenish K+; check Mg simultaneously (WSES Bologna 2017)
3. ondansetron 4-8 mg IV q6h PRN IV PRN (antiemetic_5HT3, first line) — Symptom control; alternative metoclopramide avoided in mechanical obstruction (WSES Bologna 2017; NICE 2024)
4. hydromorphone 0.5-1 mg IV q3-4h PRN IV PRN (opioid, first line) — Pain control; lower dose to avoid worsening ileus (EAST 2012)

Setting playbook (ed) — Confirm SBO (clinical + CT), risk-stratify (partial vs complete; simple vs strangulated), initiate NPO + NGT + IV fluids + surgical consult, decide NOM vs OR (WSES Bologna 2017; EAST 2012)
5. IV LR resuscitation 1-2 L bolus then 75-125 mL/h maintenance IV continuous — Hypovolemia/SBO (Resuscitation (WSES Bologna 2017))
6. electrolyte repletion KCl 20-40 mEq titrated; Mg 2 g IV if low IV/PO PRN — Hypokalemia/hypomagnesemia from emesis (Correct contraction alkalosis (WSES Bologna 2017))
7. ondansetron 4-8 mg IV q6h PRN IV PRN — Nausea/vomiting (Symptom control (NICE 2024))
8. hydromorphone 0.5-1 mg IV q3-4h PRN IV PRN — Pain (Pain control; minimize to avoid worsening ileus (EAST 2012))
9. pre-op cefazolin 2 g IV pre-incision IV one-time pre-op — Planned OR (SSI prophylaxis (ASHP/IDSA/SHEA 2013))
10. pip-tazo for strangulation/perforation 4.5 g IV q6h IV q6h — Strangulation/perforation suspected (Broad coverage (SIS/IDSA cIAI 2010; WSES Bologna 2017))

Non-pharmacologic actions:
- NPO (WSES Bologna 2017)
- NGT decompression for vomiting / complete obstruction (relieves symptoms; consider in any moderate-severe SBO) (WSES Bologna 2017; EAST 2012)
- Foley if hemodynamic monitoring
- IV access × 2
- Surgical consult day 1 (WSES Bologna 2017)
- CT within 1-2h of presentation (ACR Appropriateness Criteria 2020)
- Avoid metoclopramide (mechanical obstruction) (WSES Bologna 2017)

AVOID / contraindication checks:
- NPO_for_full_obstruction (WSES Bologna 2017)
- No_metoclopramide_in_mechanical_obstruction (WSES Bologna 2017)
- No_low_residue_oral_feeding_until_resolution (EAST 2012)
- Caution_opioid_dosing_to_avoid_worsening_ileus (EAST 2012)
- Contrast_challenge_only_in_partial_adhesive_SBO (Branco 2010; Abbas 2024)

Monitoring

Regimen monitoring:
- serial abdominal exams q4 6h (WSES Bologna 2017)
- NGT output daily (WSES Bologna 2017)
- strict I O (WSES Bologna 2017)
- electrolytes daily (NICE 2024)
- serial lactate if ischemia concern (Zielinski 2017)
- passage of flatus BM (WSES Bologna 2017; EAST 2012)
- resolution or failure by 48 72h (WSES Bologna 2017)

Setting (ed) monitoring:
- Vitals q1-2h until stable (NICE 2024)
- NGT output (WSES Bologna 2017)
- Hourly UOP (NICE 2024)
- Serial abdominal exam (WSES Bologna 2017)
- Lactate q4-6h if ischemia concern (Zielinski 2017)

Follow-up plan: Surgery consult on admission, post-op diet advancement, discharge criteria for NOM, outpatient follow-up 2 weeks, recurrence education (WSES Bologna 2017; NICE 2024)
- Close-out criterion: follow-up scheduled

Monitoring phase: Serial abdominal exams q4-6h, NGT output, strict I&O, vitals q4h, electrolytes daily, serial lactate if ischemia concern, passage of flatus/BM (WSES Bologna 2017; NICE 2024)

Disposition

Current setting: ed — Confirm SBO (clinical + CT), risk-stratify (partial vs complete; simple vs strangulated), initiate NPO + NGT + IV fluids + surgical consult, decide NOM vs OR (WSES Bologna 2017; EAST 2012)

Disposition criteria:
- Admit ward: stable, partial adhesive SBO trial NOM (WSES Bologna 2017)
- Admit ICU: hemodynamic instability, septic, complete with strangulation suspected (EAST 2012)
- OR: strangulation, closed loop, incarcerated hernia, peritonitis, perforation, failed NOM (WSES Bologna 2017; EAST 2012)

Escalation triggers (move to higher acuity):
- Peritonitis → emergent OR (WSES Bologna 2017; EAST 2012)
- Closed loop on CT → emergent OR (ACR 2020; WSES Bologna 2017)
- Pneumatosis or portal venous gas → emergent OR (Zielinski 2017; WSES Bologna 2017)
- Incarcerated hernia → emergent OR (EAST 2012)
- Hemodynamic instability → ICU + emergent OR (WSES Bologna 2017)
- Lactate rising → ischemia → OR (Zielinski 2017; EAST 2012)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Peritonitis, lactate >2, leukocytosis with left shift, or CT signs of strangulation (pneumatosis, portal venous gas, no wall enhancement, free fluid + mesenteric haziness) (Zielinski 2017; WSES Bologna 2017)
- [LIFE_THREATENING] CT shows two transition points or closed-loop pattern (ACR Appropriateness Criteria 2020; Zielinski 2017)
- [LIFE_THREATENING] Tender, non-reducible hernia with overlying skin changes (WSES Bologna 2017; EAST 2012)

Citations

- WSES 2017 Bologna ASBO Guidelines + EAST 2012 SBO PMG + ACR Appropriateness Criteria 2020 + Branco 2010 / Abbas 2024 (water-soluble contrast meta-analyses) + Zielinski 2017 (CT predictors of surgery) + SnapSBO 2025 [PMID:29946347](https://pubmed.ncbi.nlm.nih.gov/29946347/)
- Cited evidence (PMID 23114494) [PMID:23114494](https://pubmed.ncbi.nlm.nih.gov/23114494/)
- Cited evidence (PMID 17380561) [PMID:17380561](https://pubmed.ncbi.nlm.nih.gov/17380561/)

Last reconciled with current guidelines: 2026-05-22.
References
  • WSES 2017 Bologna ASBO Guidelines + EAST 2012 SBO PMG + ACR Appropriateness Criteria 2020 + Branco 2010 / Abbas 2024 (water-soluble contrast meta-analyses) + Zielinski 2017 (CT predictors of surgery) + SnapSBO 2025 — PMID:29946347
  • Cited evidence (PMID 23114494) — PMID:23114494
  • Cited evidence (PMID 17380561) — PMID:17380561