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gi.diverticulitis.core.v1PRODUCTION
gi.diverticulitis.core.v1

Acute Colonic Diverticulitis (uncomplicated vs complicated — modified Hinchey) + post-recovery management

gastroenterologyacutesubacuteadult
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Encounter flow

12/12 authored

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

Current phase

Frame

Detailed

Establish scope — acute colonic diverticulitis episode vs subacute recovery/recurrence review; left-sided vs right-sided; exclude pregnancy/non-colonic mimics requiring divergent pathway (ASCRS 2020; WSES 2020)

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Advance rule
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episode vs recovery context set and pregnancy status known

Patient inputs (16)

Frailty / comorbidity-weighted disposition; colorectal-cancer pretest probability for interval colonoscopy; right-sided commoner in younger Asian patients (ASCRS 2020; WSES 2020)

Colovesical fistula commoner in men (no protective uterus); gynaecologic differentials in women (ASCRS 2020)

Fever component of severity; sepsis screen for perforation/peritonitis (WSES 2020)

Tachycardia → qSOFA/SIRS sepsis screen from perforation (WSES 2020)

Hypotension → septic-shock route (Hinchey III/IV peritonitis) (WSES 2020)

Renal function for IV-contrast CT and renal antibiotic dose adjustment (CKD-EPI 2021) (ASCRS 2020)

Leukocytosis supports diagnosis and severity stratification (ASCRS 2020)

CRP >150 mg/L raises probability of complicated disease (sens 85%, spec 65%, AUC 0.81 — Mäkelä Scand J Gastroenterol 2015 PMID 25665622); drives mandatory CT and trended for response (AGA CPU 2021)

Contrast-enhanced CT abdomen/pelvis is the diagnostic standard — sens ~94%, spec ~99%; confirms Dx, stages modified Hinchey, identifies abscess/free air/fistula/obstruction (ASCRS 2020; WSES 2020)

Pneumaturia / faecaluria / recurrent polymicrobial UTI → colovesical fistula (commonest diverticular fistula) (ASCRS 2020)

Transplant / chronic steroid / biologic → atypical presentation, higher perforation risk, lower threshold for antibiotics AND surgery (AGA CPU 2021; ASCRS 2020)

Recurrent / smouldering disease — drives individualised (NOT episode-count) elective-surgery shared decision (ASCRS 2020)

Imaging modality (US/MRI over CT) and surgical timing (WSES 2020)

Quality colonoscopy within ~1 yr obviates interval colonoscopy; otherwise scope 6-8 wk post-resolution to exclude malignancy (AGA CPU 2021)

Elevated lactate flags hypoperfusion / septic shock from faeculent peritonitis (WSES 2020)

US (first-line) / MRI alternative when CT contraindicated — pregnancy, radiation avoidance, iodine allergy (WSES 2020)

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

Severity triggers (8)

8 need judgement
  • informationallife_threateninggeneralised_peritonitis_free_air
    Generalised peritoneal signs + free intraperitoneal air on CT (Hinchey III/IV) (WSES 2020)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningseptic_shock_perforated_diverticulitis
    Hypotension despite adequate fluids + lactate >2 + suspected faeculent peritonitis (WSES 2020; SSC 2026)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereabscess_ge_4cm
    CT shows diverticular abscess ≥4 cm (Hinchey Ib/II) (ASCRS 2020)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereimmunocompromised_with_diverticulitis
    Diverticulitis in transplant / chronic steroid / biologic / cytotoxic-immunosuppressed host (AGA CPU 2021; ASCRS 2020)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereobstruction_from_diverticular_stricture
    Obstipation + bowel dilatation/transition point on CT from diverticular stricture (WSES 2020)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverelower_gi_bleed_distinct
    Painless hematochezia (diverticular bleeding) — DISTINCT from diverticulitis (ACG 2023)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatefailure_of_outpatient_management
    No improvement or clinical deterioration at 48–72 h of outpatient observation/oral antibiotics (AGA CPU 2021)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatecolovesical_fistula
    Pneumaturia / faecaluria / recurrent polymicrobial UTI (commonest diverticular fistula) (ASCRS 2020)
    Trigger could not be auto-evaluated — needs clinician judgement.

Workflow calculators

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RISK_STRATIFICATIONrequiredDrives risk stratification
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Recommended regimen

Diverticulitis antibiotic strategy — selective (uncomplicated) vs IV (complicated) (ASCRS 2020 + AGA CPU 2021 + WSES 2020 + AVOD/DIABOLO)
axis: diverticulitis_antibioticstep 1 - Step 1 — Uncomplicated, immunocompetent: NO routine antibiotics
Selected step "Step 1 — Uncomplicated, immunocompetent: NO routine antibiotics" — Modified Hinchey 0–Ia; immunocompetent; tolerating PO; no sepsis; no significant comorbidity/frailty; reliable follow-up
  • observation_clear_liquid_diet
    first line
    supportive
    Clear liquids → advance as tolerated • PO • continuous
    triggers: hinchey_0_or_Ia, immunocompetent, tolerating_PO
    AVOD (Chabok Br J Surg 2012 PMID 22290281; long-term PMID 31386199) + DIABOLO (Daniels Br J Surg 2017 PMID 29700480): antibiotics did NOT shorten recovery, prevent complications, or reduce recurrence — observation is equivalent
  • acetaminophen
    first line
    analgesic
    500–1000 mg PO q6h (max 3 g/day) • PO • q6h
    triggers: pain
    Preferred analgesic; AVOID NSAIDs/opioids — associated with perforation risk and constipation (AGA CPU 2021)
    rxcui 161

outpatient playbook — drug actions (3)

  1. 1. observation + clear liquids
    Clear liquids, advance as tolerated • PO • continuous
    trigger: Hinchey 0–Ia + immunocompetent + tolerating PO
    AVOD/DIABOLO — antibiotics not required (PMID 22290281; 29700480)
  2. 2. acetaminophen
    rxcui 161
    500–1000 mg PO q6h (max 3 g/day) • PO • q6h
    trigger: Pain
    Avoid NSAIDs/opioids — perforation/constipation risk (AGA CPU 2021)
  3. 3. amoxicillin-clavulanate (selective only)
    rxcui 19711
    875/125 mg PO BID × 7–10 days • PO • BID
    trigger: Immunocompromise / significant comorbidity / frailty / refractory — selective use only
    Selective antibiotics reserved for host-risk (ASCRS 2020)

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Left lower quadrant abdominal pain (classic left-sided diverticulitis) (ASCRS 2020); Right lower quadrant pain — right-sided / caecal diverticulitis (Asian, younger; appendicitis mimic) (WSES 2020); Change in bowel habit + low-grade fever ± nausea (AGA CPU 2021).

Objective

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

Assessment

**Acute Colonic Diverticulitis (uncomplicated vs complicated — modified Hinchey) + post-recovery management** (gi.diverticulitis.core.v1).
Phenotype framing: Confirm diverticulitis vs colorectal cancer mimicking diverticulitis (CRC prevalence ~1.9% overall, ~7.9% complicated, ~1.3% uncomplicated — colonoscopy after resolution), IBD, appendicitis (right-sided), ischaemic/infectious colitis, gynaecologic pathology, diverticular bleeding (painless — distinct entity) (AGA CPU 2021; Rottier CGH 2018)
Scope: Establish scope — acute colonic diverticulitis episode vs subacute recovery/recurrence review; left-sided vs right-sided; exclude pregnancy/non-colonic mimics requiring divergent pathway (ASCRS 2020; WSES 2020)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Diverticulitis antibiotic strategy — selective (uncomplicated) vs IV (complicated) (ASCRS 2020 + AGA CPU 2021 + WSES 2020 + AVOD/DIABOLO)** — step "Step 1 — Uncomplicated, immunocompetent: NO routine antibiotics".
1. observation_clear_liquid_diet Clear liquids → advance as tolerated PO continuous (supportive, first line) — AVOD (Chabok Br J Surg 2012 PMID 22290281; long-term PMID 31386199) + DIABOLO (Daniels Br J Surg 2017 PMID 29700480): antibiotics did NOT shorten recovery, prevent complications, or reduce recurrence — observation is equivalent
2. acetaminophen 500–1000 mg PO q6h (max 3 g/day) PO q6h (analgesic, first line) — Preferred analgesic; AVOID NSAIDs/opioids — associated with perforation risk and constipation (AGA CPU 2021)

Setting playbook (outpatient) — Uncomplicated (Hinchey 0–Ia) immunocompetent diverticulitis — observation + analgesia + clear liquids, NO routine antibiotics, 48–72 h re-check, recovery counselling, interval colonoscopy planning (AVOD PMID 22290281; DIABOLO PMID 29700480; AGA CPU 2021)
3. observation + clear liquids Clear liquids, advance as tolerated PO continuous — Hinchey 0–Ia + immunocompetent + tolerating PO (AVOD/DIABOLO — antibiotics not required (PMID 22290281; 29700480))
4. acetaminophen 500–1000 mg PO q6h (max 3 g/day) PO q6h — Pain (Avoid NSAIDs/opioids — perforation/constipation risk (AGA CPU 2021))
5. amoxicillin-clavulanate (selective only) 875/125 mg PO BID × 7–10 days PO BID — Immunocompromise / significant comorbidity / frailty / refractory — selective use only (Selective antibiotics reserved for host-risk (ASCRS 2020))

Non-pharmacologic actions:
- Return precautions: worsening pain, fever, vomiting, inability to tolerate PO → ED (ASCRS 2020)
- Clinical re-check in 48–72 h (AGA CPU 2021)
- Lifestyle counselling — high-fibre diet, physical activity, weight, smoking cessation; nuts/seeds NOT restricted (debunked myth) (AGA CPU 2021)
- Plan interval colonoscopy 6–8 wk if no quality colonoscopy within ~1 yr (AGA CPU 2021)
- No mesalamine/rifaximin/probiotics for prevention (AGA CPU 2021)

AVOID / contraindication checks:
- Uncomplicated_immunocompetent_antibiotics_NOT_routinely_required (AVOD PMID 22290281; DIABOLO PMID 29700480; AGA CPU 2021)
- Mesalamine_NOT_for_prevention_of_recurrence (AGA CPU 2021)
- Rifaximin_and_probiotics_NOT_for_prevention_of_recurrence (AGA CPU 2021)
- Avoid_NSAIDs_opioids_perforation_and_constipation_risk (AGA CPU 2021)
- Immunocompromise_lower_threshold_for_antibiotics_AND_surgery (ASCRS 2020; AGA CPU 2021)
- Renal_dose_adjust_ciprofloxacin_TMP_SMX_pip_tazo_ertapenem (CKD EPI 2021; ASCRS 2020)
- Fluoroquinolone_tendinopathy_QT_aortic_aneurysm_caution (ASCRS 2020)
- Carbapenem_reserved_for_ESBL_or_beta_lactam_allergy (WSES 2020)
- Antibiotic_duration_4_to_7_days_after_source_control (STOP IT principle; WSES 2020)

Monitoring

Regimen monitoring:
- clinical response at 48 to 72h (ASCRS 2020)
- CRP and WBC trend at 48 to 72h (Mäkelä PMID 25665622; AGA CPU 2021)
- repeat CT if no improvement or drain failure (WSES 2020)
- temperature q4h inpatient (WSES 2020)
- renal function during aminoglycoside free renal dosed abx (CKD-EPI 2021)
- interval colonoscopy 6 to 8 weeks post resolution (AGA CPU 2021)

Setting (outpatient) monitoring:
- Symptom diary; expect improvement <72 h (ASCRS 2020)
- Repeat CRP/WBC only if not improving (AGA CPU 2021)

Follow-up plan: Subacute recovery: interval colonoscopy 6–8 wk after resolution if no quality colonoscopy within ~1 yr (CRC yield ~1.9%, higher in complicated) — exclude malignancy/IBD; lifestyle (high-fibre diet, physical activity, weight, smoking cessation; nuts/seeds NOT restricted — debunked myth, counsel patient); individualised elective-surgery shared decision (NOT episode count) for smouldering/chronic, fistula, stricture, immunosuppressed, or inability to exclude cancer; chemoprophylaxis anti-pattern (no mesalamine/rifaximin/probiotics) (AGA CPU 2021; ASCRS 2020)
- Close-out criterion: interval colonoscopy decision made, lifestyle counselling delivered, elective-surgery decision documented, follow-up scheduled

Monitoring phase: Outpatient: clinical re-check 48–72 h, return precautions; expect improvement <72 h. Inpatient: vitals q4h, serial abdominal exam, CRP/WBC trend at 48–72 h, repeat imaging if no improvement (failure of drainage / new abscess); post-op recovery (ASCRS 2020; AGA CPU 2021)

Disposition

Current setting: outpatient — Uncomplicated (Hinchey 0–Ia) immunocompetent diverticulitis — observation + analgesia + clear liquids, NO routine antibiotics, 48–72 h re-check, recovery counselling, interval colonoscopy planning (AVOD PMID 22290281; DIABOLO PMID 29700480; AGA CPU 2021)

Disposition criteria:
- Continue outpatient observation if improving (AGA CPU 2021)
- Escalate to ED/inpatient if any escalation trigger met (ASCRS 2020)

Escalation triggers (move to higher acuity):
- No improvement / worsening at 48–72 h → ED + CT + IV antibiotics (ASCRS 2020)
- Fever, peritoneal signs, sepsis features → ED (WSES 2020)
- Inability to tolerate PO → ED for IV therapy (AGA CPU 2021)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Generalised peritoneal signs + free intraperitoneal air on CT (Hinchey III/IV) (WSES 2020)
- [LIFE_THREATENING] Hypotension despite adequate fluids + lactate >2 + suspected faeculent peritonitis (WSES 2020; SSC 2026)
- [SEVERE] CT shows diverticular abscess ≥4 cm (Hinchey Ib/II) (ASCRS 2020)

Citations

- ASCRS 2020 Treatment of Left-Sided Colonic Diverticulitis (Hall, Dis Colon Rectum) + AGA Clinical Practice Update on Medical Management of Colonic Diverticulitis 2021 (Peery/Shaukat/Strate) + WSES 2020 acute colonic diverticulitis (Sartelli) [PMID:22290281](https://pubmed.ncbi.nlm.nih.gov/22290281/)
- Cited evidence (PMID 31386199) [PMID:31386199](https://pubmed.ncbi.nlm.nih.gov/31386199/)
- Cited evidence (PMID 29700480) [PMID:29700480](https://pubmed.ncbi.nlm.nih.gov/29700480/)
- Cited evidence (PMID 32384404) [PMID:32384404](https://pubmed.ncbi.nlm.nih.gov/32384404/)
- Cited evidence (PMID 33279517) [PMID:33279517](https://pubmed.ncbi.nlm.nih.gov/33279517/)

Last reconciled with current guidelines: 2026-05-22.
References
  • ASCRS 2020 Treatment of Left-Sided Colonic Diverticulitis (Hall, Dis Colon Rectum) + AGA Clinical Practice Update on Medical Management of Colonic Diverticulitis 2021 (Peery/Shaukat/Strate) + WSES 2020 acute colonic diverticulitis (Sartelli) — PMID:22290281
  • Cited evidence (PMID 31386199) — PMID:31386199
  • Cited evidence (PMID 29700480) — PMID:29700480
  • Cited evidence (PMID 32384404) — PMID:32384404
  • Cited evidence (PMID 33279517) — PMID:33279517