Q40.0
BillableCongenital hypertrophic pyloric stenosis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Q40.0 an HCC code?
Yes. Q40.0 maps to Intestinal Obstruction/Perforation under the CMS-HCC V28 risk adjustment model.
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for Q40.0
For Q40.0 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed Q40.0 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Q40.0 is the ICD-10-CM diagnosis code for congenital hypertrophic pyloric stenosis. A birth defect where the muscle at the outlet of the stomach becomes thickened, preventing food from passing into the small intestine and causing severe vomiting in infants. Q40.0 sits in the ICD-10-CM chapter for congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (q00-qa0), within the section covering other congenital malformations of the digestive system (q38-q45).
Under the CMS-HCC V28 risk adjustment model, Q40.0 maps to Intestinal Obstruction/Perforation (HCC 78) with a community, non-dual, aged base RAF weight of 0.000. Q40.0 was not retained as a payment HCC under the older V24 model, so V28 introduced or recategorized it during the 2024–2026 phase-in. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
This condition typically presents in infants 2-8 weeks old; document the age of presentation. Because Q40.0 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for Q40.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This condition typically presents in infants 2-8 weeks old; document the age of presentation
- •Note whether the diagnosis was confirmed by ultrasound or other imaging
Clinical Significance
Congenital hypertrophic pyloric stenosis is a common surgical emergency in infants that can rapidly lead to dehydration, electrolyte imbalances, and failure to thrive if not promptly diagnosed and treated. Early recognition and surgical intervention (pyloromyotomy) typically result in excellent outcomes.
Documentation Requirements
- ✓Clinical presentation of projectile vomiting in infant
- ✓Physical examination findings (palpable pyloric mass)
- ✓Ultrasound confirmation of pyloric muscle thickening
- ✓Laboratory evidence of metabolic alkalosis and dehydration
- ✓Age at presentation and symptom onset
- ✓Surgical intervention details (laparoscopic vs open pyloromyotomy)
- ✓Post-operative recovery and feeding tolerance
- ✓Follow-up outcomes and complications if any