12-phase flow (12)

1. 1FRAME
   Frame the suspected pediatric intussusception presentation: age band (< 3 mo / 3-6 mo / 6 mo - 3 y / > 3 y / > 6 y) drives pretest probability + pathologic-lead-point consideration; 6 mo - 3 y is classic high-pretest cohort with highest enema-success rates; < 3 mo or > 6 y atypical → high lead-point suspicion. Duration of symptoms drives ischemia / perforation risk; > 24 h higher failure rate; > 48 h relative surgical indication.
   inputs: age_in_months_or_years, duration_of_symptoms_in_hours
   advance: Age band + duration tagged; pretest probability + lead-point suspicion framing set
2. 2ENTRY
   Recognise via classic clinical features (paroxysmal pain + bloody / currant-jelly stool + abdominal mass — only ~ 15% have all three; partial presentations more common) OR atypical features (episodic lethargy + pallor without obvious abdominal complaints ~ 10%) OR imaging signature (target sign / pseudokidney sign on bedside US). HSP-associated and recurrent presentations have distinct management pivots.
   inputs: pain_pattern_paroxysmal_vs_constant, stool_character_currant_jelly_vs_bloody_vs_normal
   advance: Intussusception suspected by clinical features or US signature
3. 3CONTEXT
   Age + weight + recent viral illness (URI ~ 30% precede; adenovirus most associated) + rotavirus vaccine timing (transient 1-21 d post-vaccine risk window) + HSP history (raises ileoileal-surgical concern) + prior intussusception (recurrence ~ 10%; raises lead-point suspicion) + cystic fibrosis or other predisposing condition + hemodynamic + dehydration assessment.
   inputs: age_in_months_or_years, weight_kg, hr_pediatric, capillary_refill_pediatric, temperature_pediatric, recent_viral_illness_uri_within_2_weeks, rotavirus_vaccine_within_21_days, hsp_history_or_palpable_purpura, prior_intussusception_episodes
   advance: Risk-factor profile + dehydration status + age-band classification documented
4. 4RED_FLAGS
   Perforation / peritonitis (rigidity, guarding, rebound, free air on KUB) → emergent surgical management (enema CONTRAINDICATED); hemodynamic compromise / shock (hypotension by age-threshold, tachycardia + poor perfusion, capillary refill > 3 s, mottling) → ICU + IVF + pediatric surgery NOW; severe dehydration → pre-enema resuscitation REQUIRED before any enema attempt; persistent lethargy or altered mental status (atypical presentation) → expedite imaging + surgical readiness.
   inputs: sbp_pediatric, mental_status_lethargy_vs_alert, abdominal_exam_mass_distention_peritoneal_signs
   advance: Surgical-emergency criteria evaluated; resuscitation initiated if needed
5. 5INITIAL_WORKUP
   IV access + NPO + nasogastric decompression if vomiting / distention; CBC with diff + metabolic panel + lactate (if available); bedside abdominal US (target sign transverse / pseudokidney longitudinal — sensitivity > 97%); plain KUB (does NOT diagnose intussusception but rules out free air pre-enema, evaluates for obstruction pattern); pediatric surgery + interventional / pediatric radiology consult prior to enema attempt.
   inputs: cbc_with_diff_pediatric, metabolic_panel_pediatric, abdominal_ultrasound_target_pseudokidney, kub_xray_for_free_air_pre_enema
   actions: panel.cbc, panel.renal
   advance: IV access + NPO + NG if needed; US confirms intussusception OR rules it out; KUB rules out free air; consults engaged
6. 6BRANCHING_WORKUP
   Source-directed: type-and-screen if surgical management likely (failed enema, perforation, shock); abdominal CT or MR enterography only post-recovery for lead-point workup in recurrent or atypical-age cases (NOT acute); Meckel's scan (Tc-99m pertechnetate) for recurrence in age > 2 y with prior lead-point suspicion; rheumatology consult if HSP-associated.
   inputs: type_and_screen_pediatric
   advance: Pre-surgical workup ready if enema fails; lead-point workup queued if recurrent / atypical age
7. 7DIFFERENTIAL
   Acute gastroenteritis (vomiting + diarrhea + dehydration but lacks paroxysmal pain pattern + currant-jelly stool); volvulus (especially midgut — bilious emesis in younger infant; upper-GI series); incarcerated inguinal hernia (palpable groin mass; surgical emergency in its own right); Meckel's diverticulum bleed (painless bleeding distinct from intussusception's painful presentation); appendicitis (older child > 5 y; RLQ pain; Alvarado / PAS score); HSP without intussusception (purpura + abdominal pain but no target sign on US); psychogenic abdominal pain (older child; lacks paroxysmal pattern + objective findings).
   advance: Mimics excluded by US + clinical features; intussusception diagnosis confirmed or alternative pathway entered
8. 8RISK_STRATIFICATION
   Tier 1 (life-threatening — emergent surgery): perforation, peritonitis, shock, severe dehydration unresponsive to resuscitation. Tier 2 (high-risk — surgery preferred over enema): atypical age band (< 3 mo or > 6 y), HSP-associated (typically ileoileal), duration > 48 h, recurrent (≥ 2 episodes) with suspected lead point, ileoileal type. Tier 3 (standard enema candidate): age 6 mo - 3 y, ileocolic, duration < 24 h, hemodynamically stable, no perforation. Tier 4 (post-enema observation): inpatient × 24 h for recurrence-watch (~ 10% within 24-48 h).
   inputs: age_in_months_or_years, duration_of_symptoms_in_hours, sbp_pediatric, hsp_history_or_palpable_purpura, prior_intussusception_episodes
   advance: Tier assigned + medical-vs-surgical pathway chosen + admit vs observe decision documented
9. 9TREATMENT
   Pre-enema resuscitation: isotonic IV fluid (NS 20 mL/kg over 30-60 min, repeat × 1-2 PRN; max ~ 60 mL/kg total before reassessing for fluid overload) + NPO + NG decompression if distended / vomiting + analgesia (morphine 0.05-0.1 mg/kg IV titrated) + sedation per institutional protocol (often ketamine 1-2 mg/kg IV by pediatric sedation team OR dexmedetomidine). Pneumatic (air) enema preferred over hydrostatic — reduction success ~ 80-90% in classic-age uncomplicated cases; ≤ 3 attempts at maximum pressures per ACR Appropriateness Criteria (typically capped at 120 mmHg air or 1 m height of contrast column); pediatric surgery in attendance OR immediately available. Surgical reduction (laparoscopic preferred; open if unstable or large lead point) indicated for: failed enema after 3 attempts, perforation (any time), hemodynamic compromise / shock, peritonitis, severe dehydration pre-enema, atypical-age cohort with suspected pathologic lead point, HSP-associated ileoileal type.
   inputs: weight_kg, sbp_pediatric, abdominal_ultrasound_target_pseudokidney
   actions: panel.renal
   advance: Resuscitation complete; enema attempted with surgical backup OR direct surgical management if contraindicated; post-reduction monitoring plan in place
10. 10DISPOSITION
    Successful enema reduction → inpatient observation × 24 h (recurrence ~ 10% usually within 24-48 h) with serial abdominal exams + advancing diet from clear liquids; failed enema → operating room for surgical reduction; perforation / peritonitis / shock → ICU + emergent OR; recurrent intussusception → admit + lead-point workup queue. All discharge from inpatient requires tolerating diet + normal stool + family counseling on return precautions.
    inputs: sbp_pediatric, mental_status_lethargy_vs_alert
    advance: Disposition + level of care set; recurrence-watch plan in place if discharged from acute phase
11. 11MONITORING
    Post-enema: vitals q1-2h × first 6 h then q4h; serial abdominal exams q2-4h watching for recurrence (return of paroxysmal pain pattern) or post-procedure complication; advance diet from clear liquids → full liquids → soft → regular as tolerated; family at bedside + bedside instructions on recurrence signs (return of pain episodes, vomiting, bloody stool). Post-surgical: standard post-op care + early ambulation + diet advance per surgeon; ileus monitoring; wound infection surveillance.
    inputs: abdominal_exam_mass_distention_peritoneal_signs, pain_pattern_paroxysmal_vs_constant
    advance: Recurrence watch complete × 24 h; diet advanced; clinical status stable for discharge
12. 12FOLLOWUP
    Pediatrician follow-up within 1-2 weeks; return precautions reviewed with caregivers (recurrence signs: return of paroxysmal pain episodes, vomiting, bloody stool, lethargy — present to ED). Recurrent intussusception (≥ 2 episodes) → pediatric GI consult for lead-point workup: contrast study (upper-GI / small-bowel follow-through) + Meckel's scan (Tc-99m pertechnetate) + considered colonoscopy if age-appropriate; MR enterography for polyposis syndromes (Peutz-Jeghers). HSP-associated cases → rheumatology follow-up for HSP management beyond acute event. Rotavirus vaccine surveillance: report post-vaccine cases to VAERS (CDC surveillance) per AAP recommendation; family counseling that net benefit far exceeds individual case risk.
    advance: Follow-up scheduled + return precautions delivered + lead-point workup queued if recurrent