12-phase flow (12)

1. 1FRAME
   Pain onset, location, quality; "worst-of-life" flag; hemodynamic state; pregnancy status anchor (Brun 2016)
   inputs: pain_onset_time, pain_location, pain_quality, pregnancy_status
   advance: pain characterized + life-threat screen run
2. 2ENTRY
   Migration, radiation, nausea/vomiting sequence, bowel function, urinary/gyn symptoms (Alvarado/RIPASA PMID 32468754)
   inputs: pain_migration, pain_radiation, associated_nausea_vomiting, bowel_function, urinary_symptoms, gynecologic_symptoms
   advance: entry presentation captured
3. 3CONTEXT
   Age, sex, prior surgery (SBO), ASCVD (mesenteric ischemia / AAA), liver disease (SBP / variceal), immunocompromised (typhlitis), anticoagulant (hematoma), vitals + temp (Brun 2016)
   inputs: age, sex, sbp, hr, rr, temp, spo2, prior_surgery, ascvd_risk_factors, liver_disease, immunocompromised, anticoagulant_use
   advance: context complete
4. 4RED_FLAGS
   Peritonitis / surgical abdomen; AAA leak; mesenteric ischemia; ruptured ectopic; ovarian/testicular torsion; perforated viscus; intra-abdominal septic shock; ACS-equivalent (Sakalihasan 2018; Kärkkäinen 2016; SSC 2026)
   inputs: sbp
   advance: no immediate life-threat OR routed to dedicated downstream engine
5. 5INITIAL_WORKUP
   CBC, BMP, lipase, LFT, lactate, UA, β-hCG (mandatory in reproductive-age female), hs-cTn if elderly/diabetic epigastric, ECG (Brun 2016; Atlanta 2012; Tokyo 2018)
   inputs: cbc_with_diff, bmp, lipase, lft, lactate, urinalysis, beta_hcg, troponin_hs, ecg_12_lead
   actions: panel.cbc, panel.renal, panel.lft
   advance: initial workup reviewed + quadrant-anchored next step decided
6. 6BRANCHING_WORKUP
   Pivot on quadrant + labs: RUQ → US abdomen; RLQ + female reproductive-age → TVUS + CT; RLQ male / non-pregnant → CT; LLQ / diffuse / flank → CT A/P with IV contrast; suspected AAA / mesenteric → CTA; suspected ectopic / torsion → TVUS (Brun 2016)
   inputs: us_abdomen_ruq, ct_abdomen_pelvis_iv, cta_aorta_mesenteric, us_pelvis_tv
   advance: branching workup pivots to disposition route
7. 7DIFFERENTIAL
   Quadrant-anchored ddx with pre-test priors: appendicitis (RLQ adults ~5-10%, kids 20-30%), cholecystitis (RUQ middle-aged ~20%), pancreatitis (epigastric ~15-20%), SBO (post-surgical diffuse ~10-15%), diverticulitis (LLQ >50 ~10-15%), mesenteric ischemia (>60 with AF ~5-10%), AAA (flank >65 ~1-3%), ectopic (pregnant pelvic ~5%), ovarian torsion (~1-5%), nonspecific (~30-40%) (Brun 2016)
   advance: differential ranked with pre-test priors documented
8. 8RISK_STRATIFICATION
   BISAP 0-2 mild / ≥3 severe pancreatitis (Atlanta PMID 23100216); Alvarado / RIPASA for appendicitis pretest (PMID 32468754); Tokyo 2018 cholangitis severity grade I/II/III (PMID 29032610); SSC 2026 qSOFA + lactate for sepsis (id.sepsis.core.v1); Glasgow-Blatchford if GI bleed overlay
   inputs: age
   advance: risk scores documented
9. 9TREATMENT
   Supportive at this layer: IVF resuscitation (LR > NS for sepsis/pancreatitis per SSC 2026); analgesia (early opioids appropriate — does NOT mask exam per Pines AAP 2007 PMID 17636812); antiemetics; empiric antibiotics if suspected septic source (Tokyo 2018 for cholangitis; piperacillin-tazobactam); NPO; surgical consult for peritonitis / surgical abdomen
   inputs: sbp
   advance: supportive Rx initiated; definitive Rx lives in downstream routed engine
10. 10DISPOSITION
    Surgical abdomen → OR; AAA leak → vascular OR; mesenteric ischemia → vascular surgery + IR; cholangitis → ERCP within 24-72 h (Tokyo 2018); pancreatitis BISAP ≥3 → ICU; cholecystitis → admit + early lap chole; appendicitis → OR appy; diverticulitis Hinchey I-II → admit/abx, III-IV → OR; ectopic ruptured → OR; torsion → OR; nonspecific abdominal pain stable → discharge with PCP follow-up + return precautions (Brun 2016)
    advance: disposition assigned + downstream handoff complete
11. 11MONITORING
    Serial abdominal exams q4-6h on observation; serial vitals + lactate trend for sepsis or ischemia; reassess pain after analgesia; repeat CBC + lipase if pancreatitis observation (Brun 2016)
    inputs: lactate, cbc_with_diff
    advance: evolution captures rule-in or rule-out
12. 12FOLLOWUP
    Discharged nonspecific abdominal pain: PCP within 48-72 h + return precautions (worsening pain, vomiting, fever, blood in stool, syncope); discharge bundle for diverticulitis (liquid diet → low-residue + outpatient colonoscopy 4-8 wks); cholecystitis post-op (lap chole 7-10 day follow-up); pancreatitis (alcohol/lipid counseling + outpatient MRCP if biliary)
    advance: discharge bundle prescribed + follow-up scheduled