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peds.pyloric-stenosis.v1

Infantile hypertrophic pyloric stenosis (IHPS)

pediatricsacutepediatric
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12/12 authored

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

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Detailed

Frame the suspected IHPS presentation: age band (< 2 wk atypical-early / 2-3 wk / 3-5 wk / 5-8 wk classic peak 4-6 wk / > 8 wk atypical-late) drives pretest probability + atypical-presentation index. Sex + first-born + family history drive demographic priors (4:1 male predominance, first-born most over-represented). Duration of symptoms drives metabolic-derangement depth + dehydration severity. Macrolide exposure in first 2 wk drives pharmacologic association (erythromycin > azithromycin).

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Age + sex + duration + macrolide-exposure tagged; pretest probability + atypical-presentation framing set

Patient inputs (30)

Age band drives pretest probability + atypical-presentation index. Peak 4-6 wk; very early (< 2 wk) and late (> 8 wk) atypical bands require broader ddx workup. Preterm infants may present > 8 wk with blunted findings

Male predominance 4:1; first-born males most over-represented; raises pretest probability in age-appropriate cohort

Weight-based dosing for all fluids + electrolytes + analgesia + antibiotics; serial weights track recovery trajectory pre- and post-op

Preterm infants may present > 8 wk with blunted findings; lower threshold for imaging + ICU/NICU level of care given baseline frailty

Tachycardia + dehydration in prolonged duration; bradycardia raises concern for advanced dehydration / metabolic derangement

Capillary refill > 3 s + mottling = dehydration / shock — severe dehydration is OR contraindication until corrected

Dry mucous membranes + absent tear production = clinically meaningful dehydration; AAP DDC / Gorelick scoring

Projectile non-bilious is classic IHPS; bilious raises malrotation concern (urgent UGI series); bloody raises NEC or allergic enterocolitis concern

Hungry-after-vomit pattern is classic IHPS; lethargy raises sepsis / infection concern (route to id.sepsis.peds.v1 or peds.febrile-infant.core.v1 differential)

Weight loss or poor weight gain (vs natural growth curve) is classic IHPS; normal weight gain pattern supports GER differential

Erythromycin > azithromycin documented post-licensure surveillance association; relative risk ~ 8-10 (erythromycin) and ~ 2-3 (azithromycin) vs unexposed; CDC + AAP advisory

Maternal-side family history particularly noted; heritable association documented; raises pretest probability in age-appropriate cohort

First-born males most over-represented in IHPS cohorts; raises pretest probability

Cl < 100 mEq/L + K+ < 3.5 mEq/L + HCO3 > 30 mEq/L is the operational severe-alkalosis pattern; OR contraindicated until corrected

Hemoconcentration from dehydration; rules out sepsis differential; baseline pre-op

Hypoglycemia from prolonged poor feeding + dehydration is a concern; document baseline pre-op

First-line imaging — pyloric muscle thickness ≥ 3 mm AND channel length ≥ 14-17 mm; accessory signs target / antral nipple / failure of gastric emptying; sensitivity > 97%, specificity ~ 100% per Hernanz-Schulman 2003; ACR Appropriateness Criteria

Hypotension by age-appropriate threshold → severe dehydration / shock concern; IVF resuscitation 20 mL/kg NS bolus before any OR; routes to id.sepsis.peds.v1 if Phoenix-2024 criteria met

Duration > 7 d correlates with deeper metabolic derangement + severe dehydration; affects pre-op IVF correction duration

Pre-surgical type-and-screen routine; transfusion need rare for uncomplicated pyloromyotomy

Second-line — string sign + shoulder sign + mushroom sign in IHPS; corkscrew duodenum in malrotation; reserved for non-diagnostic US OR malrotation differential

Non-specific for IHPS itself; useful only for free air or massive distention; some centers obtain pre-op as baseline

LR+ ~ 25 when present; sensitivity ~ 50% in experienced operator hands; absent olive does NOT rule out IHPS (imaging is the anchor)

LR+ ~ 5 when present; supports IHPS in age-appropriate cohort

Modest risk elevation documented; not a deciding factor alone but raises pretest probability in age-appropriate cohort

Bottle feeding modestly raises risk vs breastfeeding; not a deciding factor but informs counseling

PGE1 used to maintain ductal patency in ductal-dependent congenital heart disease — documented IHPS association in neonates; relevant for the rare CHD-comorbid case

Paradoxical aciduria pattern (urine pH < 5.5 despite metabolic alkalosis); urine Cl low in volume-depletion + Cl-responsive alkalosis

Direct bilirubin > 2 mg/dL + persistent vomiting → urgent hepatology workup (biliary atresia < 60 d Kasai window); Gilbert-related hyperbilirubinemia is benign association in IHPS (~ 5% of cases)

Direct hyperbilirubinemia > 2 mg/dL + persistent vomiting MANDATES urgent hepatology workup (biliary atresia < 60 d Kasai window); also Gilbert, hemolytic anemia, breastfeeding jaundice

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

Severity triggers (9)

9 need judgement
  • informationalsevereihps_with_severe_metabolic_alkalosis
    IHPS with severe metabolic alkalosis (Cl < 100 mEq/L AND K+ < 3.5 mEq/L AND HCO3 > 30 mEq/L) — operating room CONTRAINDICATED until corrected; pre-op IVF correction over 12-48 h targeting Cl > 100, K+ > 3.5, HCO3 < 30; uncorrected alkalosis raises paradoxical aciduria + post-anesthesia apnea risk (blunted CO2 drive from CSF bicarbonate buffering) (APSA + pediatric anesthesia society)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveresevere_dehydration_in_infant
    Severe dehydration in IHPS infant (capillary refill > 3 s + dry mucous membranes + absent tear production + hypotension by age threshold + > 10% weight loss from baseline) — IVF resuscitation REQUIRED before any OR; bolus 20 mL/kg NS over 30-60 min, repeat × 1-2 PRN with reassessment for fluid overload (max ~ 60 mL/kg cumulative bolus); maintenance D5 1/2NS + 20 mEq/L KCl after first void documented (AAP pediatric resuscitation principles)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereprolonged_emesis_with_jaundice
    Prolonged emesis with jaundice (direct bilirubin > 2 mg/dL) in IHPS workup — broaden ddx aggressively; biliary atresia is CRITICAL (< 60 d Kasai portoenterostomy window; missed window → liver transplant); also Gilbert-related hyperbilirubinemia (benign association with IHPS in ~ 5% of cases), hemolytic anemia, breastfeeding jaundice; pediatric hepatology + GI consult MANDATORY (NASPGHAN + pediatric hepatology consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevererecurrent_or_persistent_emesis_postop
    Recurrent or persistent emesis post-pyloromyotomy beyond 48 h — concern for incomplete pyloromyotomy (~ 1-2% of cases) OR intraoperative mucosal perforation (occult); repeat US + UGI series + surgical re-evaluation; broader differential including GER + eosinophilic gastroenteritis + delayed gastric emptying (APSA pediatric surgical consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverepreterm_infant_with_atypical_presentation
    Preterm infant (gestational age < 37 wk at birth) with atypical IHPS presentation — may present > 8 wk corrected age with blunted clinical findings; lower threshold for bedside US imaging; PICU/NICU level of care given baseline frailty + comorbidities (chronic lung disease, anemia of prematurity, feeding intolerance from immaturity); pediatric surgery + NICU consultation (pediatric surgery + NICU consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatefailed_us_clinical_dx
    Failed initial US (pyloric muscle thickness < 3 mm OR channel length < 14-17 mm OR borderline measurements) with PERSISTENT clinical concern for IHPS — repeat US in 24-48 h (pyloric muscle may hypertrophy further with continued obstruction); consider upper-GI contrast study to evaluate malrotation differential; pediatric GI consult for GER ddx; do NOT operate on US-negative case without further workup (ACR Appropriateness Criteria + Hernanz-Schulman 2003)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateolder_infant_pyloric_dysfunction_atypical
    Older infant (> 8 weeks of life) with atypical IHPS-like presentation and borderline US measurements — broader differential including eosinophilic gastroenteritis (eosinophilia + endoscopic eosinophil infiltration), gastroparesis (gastric emptying study), pyloric muscle dysfunction without classical hypertrophy, GER, food protein-induced allergic enterocolitis; pediatric GI consult for differential workup (NASPGHAN + pediatric GI consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildpost_pyloromyotomy_emesis
    Post-pyloromyotomy emesis in the first 24-48 h — typically self-limited (residual edema; rates 50-80% reported); observe, advance feeds slowly, expect resolution; intervene only if persistent > 48 h or rising electrolyte derangements or worsening abdominal exam (APSA pediatric surgical consensus)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildmacrolide_associated_ihps
    IHPS associated with macrolide exposure within first 2 weeks of life (erythromycin > azithromycin) — strongest pharmacologic association; relative risk ~ 8-10 erythromycin, ~ 2-3 azithromycin in case-control studies; continue standard surgical pathway; counsel family on avoid-macrolides-in-neonates principle (CDC + AAP advisory); document exposure pattern; consider pharmacy notification for surveillance (CDC + AAP advisory)
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Pediatric IHPS pre-op IVF + electrolyte correction + perioperative antibiotics + analgesia (APSA + pediatric anesthesia society + Solomkin IDSA intra-abdominal 2010 peds-adapted)
axis: pediatric_ihps_preop_correction_and_perioperative
Selected axis "Pediatric IHPS pre-op IVF + electrolyte correction + perioperative antibiotics + analgesia (APSA + pediatric anesthesia society + Solomkin IDSA intra-abdominal 2010 peds-adapted)" by default fallback (first axis)
  • normal saline / lactated Ringer's
    first line
    crystalloid_isotonic
    20 mL/kg IV bolus over 30-60 min, repeat × 1-2 PRN; max ~ 60 mL/kg total before reassessing for fluid overload • IV • bolus PRN with reassessment
    triggers: ihps_with_severe_dehydration_or_shock, pre_op_resuscitation_required
    AAP pediatric resuscitation principles; only for shock physiology in IHPS (most cases require slower correction with D5 1/2NS + KCl maintenance, not boluses)
    rxcui 9863
  • D5 0.45% NaCl + 20 mEq/L KCl maintenance
    first line
    maintenance_fluid_with_potassium
    1.5 × maintenance rate with measured deficit replacement after first void documented • IV • continuous
    triggers: ihps_preop_metabolic_correction_phase
    Pre-op IVF posture for IHPS metabolic correction; targets Cl > 100, K+ > 3.5, HCO3 < 30 over 12-48 h before OR (APSA + pediatric anesthesia society)
    rxcui 9863
  • potassium_chloride
    first line
    electrolyte
    Add 20-40 mEq/L to maintenance IVF; titrate to serum K+ > 3.5; hold if K+ > 5.0 • IV • continuous
    triggers: ihps_preop_with_hypokalemia
    Replace hypokalemia (K+ < 3.5) targeting pre-op K+ > 3.5; do NOT exceed peripheral concentration 40 mEq/L without central access; OR contraindicated until corrected (pediatric anesthesia society)
    rxcui 8591
  • cefazolin
    first line
    first_gen_cephalosporin
    25-30 mg/kg IV single dose at induction • IV • pre-op single dose
    triggers: pyloromyotomy_pre_op_prophylaxis
    Pre-op single-dose antimicrobial prophylaxis for clean/clean-contaminated pyloromyotomy; no prolonged course for uncomplicated cases (Cantey SCOUT Lancet Infect Dis 2016 PMID 27452782 stewardship principles)
    rxcui 2180
  • ondansetron
    add on
    serotonin_5HT3_antagonist_antiemetic
    0.1-0.15 mg/kg IV single dose intraoperative or post-op PRN (sparingly in infant cohort) • IV • PRN
    triggers: ihps_post_op_persistent_emesis_above_baseline
    Sparingly used in infant cohort; post-op emesis is typically self-limited and resolves spontaneously; reserve for prolonged or severe; FDA pediatric label considerations
    rxcui 26225
  • acetaminophen
    first line
    analgesic_antipyretic
    10-15 mg/kg PO/PR q4-6h PRN (max 60 mg/kg/day in infants; lower than older pediatric ceiling) • PO/PR • q4-6h PRN
    triggers: ihps_post_op_analgesia
    First-line post-op analgesic in infants; avoid opioids in infant cohort when possible; safe at infant-appropriate dose
    rxcui 161
  • morphine
    rescue
    opioid_analgesic
    0.025-0.05 mg/kg IV PRN (HALVED infant doses vs older pediatric); monitor respiratory depression carefully • IV • PRN with monitoring
    triggers: ihps_post_op_severe_pain_unresponsive_to_acetaminophen
    Reserve for severe post-op pain; infant respiratory depression risk is elevated; use HALVED doses + capnography monitoring
    rxcui 7052
  • piperacillin-tazobactam
    rescue
    penicillin_BLI
    80-100 mg/kg IV q6-8h (piperacillin component) × 5-7 d for confirmed intraoperative mucosal perforation • IV • q6-8h
    triggers: intraoperative_mucosal_perforation_confirmed
    Broad Gram-positive + Gram-negative + anaerobe single-agent backbone for intra-abdominal contamination per Solomkin IDSA intra-abdominal 2010 (peds-adapted PMID 20583865); rare scenario (< 1% IHPS perforation rate)
    rxcui 74169
  • metronidazole
    rescue
    nitroimidazole
    10 mg/kg IV q8h (max 500 mg/dose); add to ceftriaxone (or cefotaxime if < 28 d) for anaerobic cover when pip-tazo not available • IV • q8h
    triggers: intraoperative_perforation_with_anaerobic_cover_when_pip_tazo_unavailable
    Anaerobic cover adjunct; alternative to single-agent pip-tazo (Solomkin IDSA 2010 peds-adapted)
    rxcui 6922

outpatient playbook — drug actions (4)

  1. 1. PO acetaminophen PRN
    10-15 mg/kg PO/PR q4-6h PRN (max 60 mg/kg/day in infants) • PO/PR • PRN
    trigger: Post-recovery mild discomfort
    Standard infant mild pain control
  2. 2. NO ongoing antibiotic prophylaxis
    N/A • N/A • N/A
    trigger: Uncomplicated post-recovery
    No prophylactic antibiotics post-pyloromyotomy (Cantey SCOUT 2016 stewardship)
  3. 3. NO macrolides in neonates < 6 wk going forward
    N/A — counsel family on avoidance • N/A • N/A
    trigger: Family education at every well-baby visit until 6 wk
    CDC + AAP advisory — erythromycin > azithromycin association with IHPS; avoid unless no alternative
  4. 4. continue routine vaccines per ACIP including infant immunization schedule
    per ACIP age-based schedule • per agent • per ACIP
    trigger: Routine well-baby care
    AAP — routine vaccination schedule maintained; post-pyloromyotomy is not a vaccination contraindication

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Infant 2-8 wk old with progressive non-bilious projectile vomiting, hungry-after-vomit, weight loss or poor weight gain — classic IHPS ENTRY signal (APSA + AAP infant-vomiting guidance; Hernanz-Schulman *Radiology* 2003 US criteria); Palpable "olive" in RUQ / epigastrium during/after a feed when the infant is relaxed — LR+ ~ 25 when present (sensitivity ~ 50% in experienced operator hands); Visible peristaltic waves moving left-to-right across the upper abdomen after a feed — LR+ ~ 5 for IHPS.

Objective

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

Assessment

**Infantile hypertrophic pyloric stenosis (IHPS)** (peds.pyloric-stenosis.v1).
Phenotype framing: GER (most common differential — non-projectile, infant well-appearing, growing along curve, normal labs, normal pyloric US); malrotation with midgut volvulus (bilious emesis at any age; UGI series with corkscrew duodenum); duodenal atresia (bilious emesis in first 24-48 h of life; double-bubble on KUB); sepsis-related ileus (febrile, lethargic; routes to peds.febrile-infant.core.v1 or id.neonatal-sepsis.early-late.v1); intussusception (different age band 6 mo - 3 y; target sign on US — `peds.intussusception.v1`); eosinophilic gastroenteritis (eosinophilia on CBC + endoscopy with eosinophil infiltration); food protein-induced allergic enterocolitis (bloody stool + atopic family); gastroparesis (rare in infants; gastric emptying study); biliary atresia (direct hyperbilirubinemia > 2 + acholic stool; < 60 d Kasai window); cow milk protein intolerance (bloody emesis; resolves with formula change).
Scope: Frame the suspected IHPS presentation: age band (< 2 wk atypical-early / 2-3 wk / 3-5 wk / 5-8 wk classic peak 4-6 wk / > 8 wk atypical-late) drives pretest probability + atypical-presentation index. Sex + first-born + family history drive demographic priors (4:1 male predominance, first-born most over-represented). Duration of symptoms drives metabolic-derangement depth + dehydration severity. Macrolide exposure in first 2 wk drives pharmacologic association (erythromycin > azithromycin).

No severity triggers fired against current inputs.

Plan

Regimen axis: **Pediatric IHPS pre-op IVF + electrolyte correction + perioperative antibiotics + analgesia (APSA + pediatric anesthesia society + Solomkin IDSA intra-abdominal 2010 peds-adapted)**.
1. normal saline / lactated Ringer's 20 mL/kg IV bolus over 30-60 min, repeat × 1-2 PRN; max ~ 60 mL/kg total before reassessing for fluid overload IV bolus PRN with reassessment (crystalloid_isotonic, first line) — AAP pediatric resuscitation principles; only for shock physiology in IHPS (most cases require slower correction with D5 1/2NS + KCl maintenance, not boluses)
2. D5 0.45% NaCl + 20 mEq/L KCl maintenance 1.5 × maintenance rate with measured deficit replacement after first void documented IV continuous (maintenance_fluid_with_potassium, first line) — Pre-op IVF posture for IHPS metabolic correction; targets Cl > 100, K+ > 3.5, HCO3 < 30 over 12-48 h before OR (APSA + pediatric anesthesia society)
3. potassium_chloride Add 20-40 mEq/L to maintenance IVF; titrate to serum K+ > 3.5; hold if K+ > 5.0 IV continuous (electrolyte, first line) — Replace hypokalemia (K+ < 3.5) targeting pre-op K+ > 3.5; do NOT exceed peripheral concentration 40 mEq/L without central access; OR contraindicated until corrected (pediatric anesthesia society)
4. cefazolin 25-30 mg/kg IV single dose at induction IV pre-op single dose (first_gen_cephalosporin, first line) — Pre-op single-dose antimicrobial prophylaxis for clean/clean-contaminated pyloromyotomy; no prolonged course for uncomplicated cases (Cantey SCOUT Lancet Infect Dis 2016 PMID 27452782 stewardship principles)
5. ondansetron 0.1-0.15 mg/kg IV single dose intraoperative or post-op PRN (sparingly in infant cohort) IV PRN (serotonin_5HT3_antagonist_antiemetic, add on) — Sparingly used in infant cohort; post-op emesis is typically self-limited and resolves spontaneously; reserve for prolonged or severe; FDA pediatric label considerations
6. acetaminophen 10-15 mg/kg PO/PR q4-6h PRN (max 60 mg/kg/day in infants; lower than older pediatric ceiling) PO/PR q4-6h PRN (analgesic_antipyretic, first line) — First-line post-op analgesic in infants; avoid opioids in infant cohort when possible; safe at infant-appropriate dose
7. morphine 0.025-0.05 mg/kg IV PRN (HALVED infant doses vs older pediatric); monitor respiratory depression carefully IV PRN with monitoring (opioid_analgesic, rescue) — Reserve for severe post-op pain; infant respiratory depression risk is elevated; use HALVED doses + capnography monitoring
8. piperacillin-tazobactam 80-100 mg/kg IV q6-8h (piperacillin component) × 5-7 d for confirmed intraoperative mucosal perforation IV q6-8h (penicillin_BLI, rescue) — Broad Gram-positive + Gram-negative + anaerobe single-agent backbone for intra-abdominal contamination per Solomkin IDSA intra-abdominal 2010 (peds-adapted PMID 20583865); rare scenario (< 1% IHPS perforation rate)
9. metronidazole 10 mg/kg IV q8h (max 500 mg/dose); add to ceftriaxone (or cefotaxime if < 28 d) for anaerobic cover when pip-tazo not available IV q8h (nitroimidazole, rescue) — Anaerobic cover adjunct; alternative to single-agent pip-tazo (Solomkin IDSA 2010 peds-adapted)

Setting playbook (outpatient) — Post-discharge pediatrician + pediatric surgery follow-up. Most IHPS cases recover completely with no long-term sequelae. Atypical / preterm / older infant cases require ongoing pediatric GI follow-up for differential broader workup if persistent symptoms.
10. PO acetaminophen PRN 10-15 mg/kg PO/PR q4-6h PRN (max 60 mg/kg/day in infants) PO/PR PRN — Post-recovery mild discomfort (Standard infant mild pain control)
11. NO ongoing antibiotic prophylaxis N/A N/A N/A — Uncomplicated post-recovery (No prophylactic antibiotics post-pyloromyotomy (Cantey SCOUT 2016 stewardship))
12. NO macrolides in neonates < 6 wk going forward N/A — counsel family on avoidance N/A N/A — Family education at every well-baby visit until 6 wk (CDC + AAP advisory — erythromycin > azithromycin association with IHPS; avoid unless no alternative)
13. continue routine vaccines per ACIP including infant immunization schedule per ACIP age-based schedule per agent per ACIP — Routine well-baby care (AAP — routine vaccination schedule maintained; post-pyloromyotomy is not a vaccination contraindication)

Non-pharmacologic actions:
- Family education reinforcement on return precautions (return of projectile vomiting, fever, wound issues → present to ED)
- Macrolide-avoidance counseling at every well-baby visit until 6 wk (CDC + AAP advisory)
- Lactation continuation support if breastfeeding
- Weight-gain trajectory tracking at every visit
- Routine well-baby care + ongoing vaccination per ACIP
- Pediatric GI consult queued if persistent symptoms post-discharge for broader ddx workup
- Pediatric hepatology consult if jaundice + direct bilirubin > 2 (biliary atresia < 60 d Kasai window)
- Family caregiver psychosocial check at follow-up (post-surgical infant illness can be traumatic for first-time parents)

AVOID / contraindication checks:
- Operate only on corrected metabolic state for IHPS (Cl > 100, K+ > 3.5, HCO3 < 30) (APSA + pediatric anesthesia society)
- Laparoscopic pyloromyotomy preferred over open at most centers (APSA pediatric surgical consensus)
- Pre op single dose cefazolin only for uncomplicated pyloromyotomy (Cantey SCOUT Lancet Infect Dis 2016 PMID 27452782)
- No prolonged antibiotic course for uncomplicated pyloromyotomy (Solomkin IDSA 2010 peds adapted PMID 20583865)
- 5 7 d course for confirmed intraoperative mucosal perforation only (Solomkin IDSA 2010 peds adapted)
- Avoid macrolides in neonates < 6 weeks (CDC + AAP advisory; erythromycin > azithromycin association with IHPS)
- Ceftriaxone avoid under 28 days bilirubin displacement (FDA 2009; AAP Puopolo 2018) — substitute cefotaxime in atypical early < 28 d presentation
- Fluid bolus 20 mL per kg with reassessment pediatric AAP DDC (AAP pediatric resuscitation principles); slower correction with D5 1/2NS + KCl maintenance is the IHPS norm
- KCl peripheral concentration max 40 mEq/L without central access
- Morphine respiratory depression in infants — HALVED doses + capnography monitoring
- Ondansetron QT prolongation minimal at single doses but cautious in infant cohort
- Gentamicin extended interval by gestational age neonate (AAP Puopolo 2018; Neofax) — applies if atypical early presentation < 28 d case requires aminoglycoside
- Vancomycin AUC target not trough (Rybak IDSA 2020 PMID 32191793) — applies if line source coinfection in rare perforation scenario

Monitoring

Regimen monitoring:
- pre-op metabolic correction tracked q6-8h (or q4h if severe alkalosis) — target Cl > 100, K+ > 3.5, HCO3 < 30
- serial weights pre- and post-op to track recovery trajectory
- continuous vitals during pre-op + intra-op + post-op
- capnography during intra-op anesthesia (pediatric anesthesia society)
- post-op vitals q4h × 24 h then per protocol
- serial abdominal exams q4h post-op for wound + bowel sounds + emesis pattern
- feed advance progression from clear liquids → formula/breastmilk as tolerated within 4-6 h post-op
- family-bedside-instruction documentation on return precautions for projectile vomiting recurrence + wound issues
- macrolide-avoidance counseling for neonates < 6 wk at discharge (CDC + AAP advisory)

Setting (outpatient) monitoring:
- Pediatrician visit at 1-2 weeks, 4-6 weeks, then routine well-baby care
- Pediatric surgery at 2-4 weeks post-op
- Pediatric GI at 4-6 weeks if persistent symptoms
- Pediatric hepatology if jaundice + direct bilirubin > 2
- Vaccination catch-up review at every well-baby visit

Follow-up plan: Post-op pediatric surgical follow-up at 2-4 weeks for wound check + scar inspection + weight-gain review; pediatrician follow-up within 1-2 weeks for routine well-baby care including weight-gain trajectory + feeding tolerance + family education on macrolide-avoidance principle in neonates < 6 weeks (CDC + AAP advisory); long-term outcomes excellent (most infants recover completely with no long-term sequelae); recurrence after pyloromyotomy < 1-2% (incomplete myotomy). Atypical / preterm / older infant cases: ongoing pediatric GI follow-up for differential broader workup if persistent symptoms (eosinophilic gastroenteritis, gastroparesis, pyloric dysfunction without classical hypertrophy). Jaundice cases: pediatric hepatology follow-up for biliary atresia workup if applicable (< 60 d Kasai window) OR Gilbert-related management.
- Close-out criterion: Follow-up scheduled + return precautions delivered + family education on macrolide-avoidance complete + atypical-case ddx workup queued if persistent symptoms

Monitoring phase: Post-op laparoscopic uncomplicated: vitals q4h × first 24 h then per protocol; serial abdominal exams q4h; feed advance from clear liquids → formula/breastmilk as tolerated within 4-6 h (early feeding well tolerated); first 24-48 h emesis common and typically self-limited (residual edema; rates 50-80% reported); transition to ad-lib feeding by 24 h; wound inspection daily; early ambulation. Post-op perforation case: as above + IV antibiotic course continuation × 5-7 d + serial labs (CBC + CMP) + watch for post-op abscess (rising CRP + persistent fever + worsening exam → CT for evaluation). Discharge planning: family education on feed advance + return precautions (return of projectile vomiting, fever, wound issues → ED) + surgical follow-up at 2-4 weeks.

Disposition

Current setting: outpatient — Post-discharge pediatrician + pediatric surgery follow-up. Most IHPS cases recover completely with no long-term sequelae. Atypical / preterm / older infant cases require ongoing pediatric GI follow-up for differential broader workup if persistent symptoms.

Disposition criteria:
- Sustained recovery — normal feeds + bowel function + weight-gain trajectory at age-appropriate baseline + no recurrent episodes in 4-6 wk + family demonstrating return-precaution + macrolide-avoidance knowledge

Escalation triggers (move to higher acuity):
- Recurrent projectile vomiting post-discharge → return to ED for repeat US + management (incomplete myotomy < 1-2%)
- Wound issues (drainage, fever, erythema) → urgent pediatric surgery + ED reassessment
- Failure to gain weight after expected post-op recovery → pediatric GI + surgery reassessment + broader ddx workup
- Family caregiver acute distress / PTSD symptoms after traumatic illness → mental-health referral
- Jaundice persistence or worsening → urgent hepatology + GI consult (biliary atresia < 60 d Kasai window if direct bilirubin > 2)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [SEVERE] IHPS with severe metabolic alkalosis (Cl < 100 mEq/L AND K+ < 3.5 mEq/L AND HCO3 > 30 mEq/L) — operating room CONTRAINDICATED until corrected; pre-op IVF correction over 12-48 h targeting Cl > 100, K+ > 3.5, HCO3 < 30; uncorrected alkalosis raises paradoxical aciduria + post-anesthesia apnea risk (blunted CO2 drive from CSF bicarbonate buffering) (APSA + pediatric anesthesia society)
- [SEVERE] Severe dehydration in IHPS infant (capillary refill > 3 s + dry mucous membranes + absent tear production + hypotension by age threshold + > 10% weight loss from baseline) — IVF resuscitation REQUIRED before any OR; bolus 20 mL/kg NS over 30-60 min, repeat × 1-2 PRN with reassessment for fluid overload (max ~ 60 mL/kg cumulative bolus); maintenance D5 1/2NS + 20 mEq/L KCl after first void documented (AAP pediatric resuscitation principles)
- [SEVERE] Prolonged emesis with jaundice (direct bilirubin > 2 mg/dL) in IHPS workup — broaden ddx aggressively; biliary atresia is CRITICAL (< 60 d Kasai portoenterostomy window; missed window → liver transplant); also Gilbert-related hyperbilirubinemia (benign association with IHPS in ~ 5% of cases), hemolytic anemia, breastfeeding jaundice; pediatric hepatology + GI consult MANDATORY (NASPGHAN + pediatric hepatology consensus)

Citations

- APSA (American Pediatric Surgical Association) pediatric surgical-emergency guidance for IHPS + AAP infant-vomiting guidance + macrolide-in-neonates advisory + NASPGHAN pediatric GI differential consensus for the persistently vomiting infant + ACR Appropriateness Criteria — Vomiting in Infants Up to 3 Months of Age + Hernanz-Schulman M *Radiology* 2003 (pyloric US diagnostic criteria — pyloric muscle thickness ≥ 3 mm + channel length ≥ 14-17 mm) + CDC + AAP macrolide-in-neonates advisory (erythromycin > azithromycin association with IHPS) + Pediatric anesthesia society consensus (operate only on corrected metabolic state) + Solomkin IDSA Complicated Intra-Abdominal Infection 2010 PMID 20583865 (peds-adapted for the < 1% intraoperative mucosal perforation) + SSC peds 2020 (for shock physiology if severe dehydration in IHPS precipitates sepsis) [PMID:20583865](https://pubmed.ncbi.nlm.nih.gov/20583865/)
- Cited evidence (PMID 32191793) [PMID:32191793](https://pubmed.ncbi.nlm.nih.gov/32191793/)
- Cited evidence (PMID 27452782) [PMID:27452782](https://pubmed.ncbi.nlm.nih.gov/27452782/)
- Cited evidence (PMID 30455342) [PMID:30455342](https://pubmed.ncbi.nlm.nih.gov/30455342/)

Last reconciled with current guidelines: 2026-05-15.
References
  • APSA (American Pediatric Surgical Association) pediatric surgical-emergency guidance for IHPS + AAP infant-vomiting guidance + macrolide-in-neonates advisory + NASPGHAN pediatric GI differential consensus for the persistently vomiting infant + ACR Appropriateness Criteria — Vomiting in Infants Up to 3 Months of Age + Hernanz-Schulman M *Radiology* 2003 (pyloric US diagnostic criteria — pyloric muscle thickness ≥ 3 mm + channel length ≥ 14-17 mm) + CDC + AAP macrolide-in-neonates advisory (erythromycin > azithromycin association with IHPS) + Pediatric anesthesia society consensus (operate only on corrected metabolic state) + Solomkin IDSA Complicated Intra-Abdominal Infection 2010 PMID 20583865 (peds-adapted for the < 1% intraoperative mucosal perforation) + SSC peds 2020 (for shock physiology if severe dehydration in IHPS precipitates sepsis) — PMID:20583865
  • Cited evidence (PMID 32191793) — PMID:32191793
  • Cited evidence (PMID 27452782) — PMID:27452782
  • Cited evidence (PMID 30455342) — PMID:30455342