Key facts for DRG 818
- FY2027 relative weight
- 1.2940
- Higher than 35% of all MS-DRGs
- Change vs FY2026
- +11.7%
- FY2026 weight 1.1590
- Geometric mean LOS
- 3.0 days
- Arithmetic mean 3.8 days
- MDC
- 14
- Assignment of Diagnosis Codes
- Severity level
- with CC (complication or comorbidity)
- Transfer policy
- Not a transfer DRG
TL;DR
MS-DRG 818 is a surgical group in MDC 14 (Assignment of Diagnosis Codes) at the middle severity level of its family. CMS assigns it a FY2027 relative weight of 1.2940 with a geometric mean length of stay of 3.0 days and an arithmetic mean of 3.8. Its weight moved up 11.7% from FY2026 (1.1590). That weight is higher than 35% of all surgical and medical MS-DRGs. Its CC/MCC family (DRG 817, DRG 819) spans weights 0.7740 to 2.0530. The v44 Definitions Manual assigns it through 1964 principal diagnosis codes.
What changed from FY2026 to FY2027
CMS recalibrates every MS-DRG weight annually from the prior year's MedPAR claims. For DRG 818 the FY2027 relative weight is 1.2940 against 1.1590 in FY2026, a rise of 11.65%, which exceeds the 2% threshold worth re-checking in contract models.
| Metric | FY2026 | FY2027 | Change |
|---|---|---|---|
| Relative weight | 1.1590 | 1.2940 | +0.1350 |
| Geometric mean LOS (days) | 2.7 | 3.0 | +0.3 |
| Arithmetic mean LOS (days) | 3.4 | 3.8 | +0.4 |
CC and MCC family
DRG 818 shares its base definition with 2 other MS-DRGs split by severity. The family's weights span 0.7740 to 2.0530, a 2.65× spread, which is the payment effect of documenting qualifying complications and comorbidities.
Grouper logic (v44 Definitions Manual)
Principal Diagnosis: 1964 ICD-10 codes drive assignment to this group; the first 12 are shown.
| ICD-10 code | Description |
|---|---|
| O0000 | Abdominal pregnancy without intrauterine pregnancy |
| O0001 | Abdominal pregnancy with intrauterine pregnancy |
| O00101 | Right tubal pregnancy without intrauterine pregnancy |
| O00102 | Left tubal pregnancy without intrauterine pregnancy |
| O00109 | Unspecified tubal pregnancy without intrauterine pregnancy |
| O00111 | Right tubal pregnancy with intrauterine pregnancy |
| O00112 | Left tubal pregnancy with intrauterine pregnancy |
| O00119 | Unspecified tubal pregnancy with intrauterine pregnancy |
| O00121 | Right interstitial ectopic pregnancy without intrauterine pregnancy |
| O00122 | Left interstitial ectopic pregnancy without intrauterine pregnancy |
| O00129 | Unspecified interstitial ectopic pregnancy without intrauterine pregnancy |
| O00131 | Right interstitial ectopic pregnancy with intrauterine pregnancy |
Documentation and denial exposure
As a surgical DRG, assignment depends on a qualifying operating-room procedure being coded from the operative report; a missing or non-OR procedure code drops the stay into a medical DRG in MDC 14 with a lower weight. Because this family splits by severity, auditors target CC and MCC capture: each secondary diagnosis must be documented as present, monitored, evaluated or treated during the stay to survive a DRG-validation review. Typical inpatient denial codes for this group: CARC 16 (claim lacks information needed to group the stay), CARC 50 (the admission or procedure is judged not medically necessary), CARC 97 (a service is bundled into the DRG payment).
How QuickIntell uses DRG 818 data
QuickCode groups inpatient encounters against the current v44 logic, flags CC and MCC candidates that lack supporting documentation, and shows the weight difference across the family before the claim drops. QuickScribe captures the attending's language that supports severity, and QuickRCM works DRG-validation denials with the grouper evidence attached.
Frequently asked questions — DRG 818
What is MS-DRG 818?
MS-DRG 818 is "Other Antepartum Diagnoses with O.R. Procedures with CC", a surgical Medicare Severity Diagnosis-Related Group in MDC 14, Assignment of Diagnosis Codes. Medicare pays inpatient stays grouped here at the hospital's base rate multiplied by the DRG relative weight.
What is the FY2027 relative weight for DRG 818?
The FY2027 relative weight is 1.2940 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 1.1590, a change of +11.7%.
What is the average length of stay for DRG 818?
CMS reports a geometric mean length of stay of 3.0 days and an arithmetic mean of 3.8 days for FY2027. The geometric mean is used for transfer-payment calculations.
Which DRGs are in the same CC/MCC family as 818?
DRG 817 (Other Antepartum Diagnoses with O.R. Procedures with MCC, weight 2.0530); DRG 819 (Other Antepartum Diagnoses with O.R. Procedures without CC/MCC, weight 0.7740). The family's weights range from 0.7740 to 2.0530, so documented complications and comorbidities change payment materially.
What documentation supports the severity level of DRG 818?
DRG 818 is reached when the stay carries a secondary diagnosis from the CMS Complication or Comorbidity list but none from the MCC list. Common CC captures include chronic kidney disease stage 3 and above, uncontrolled diabetes with manifestations, malnutrition of specified severity and heart failure of a stated type. Each must be documented by the treating clinician and show clinical relevance in the record; a condition listed only in the problem list without assessment is the most frequent reason a CC is removed on audit and the stay drops to the base DRG.
Which codes group to DRG 818?
The v44 Definitions Manual lists 1964 principal diagnosis codes for this group. Examples from the principal diagnosis list: O0000 (Abdominal pregnancy without intrauterine pregnancy); O0001 (Abdominal pregnancy with intrauterine pregnancy); O00101 (Right tubal pregnancy without intrauterine pregnancy); O00102 (Left tubal pregnancy without intrauterine pregnancy).
Is DRG 818 a post-acute transfer DRG?
No. DRG 818 is not on the FY2027 post-acute care transfer list, so the transfer per-diem policy does not apply to it.
Sources
Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-01. Verify against the primary file before billing or contracting decisions.
- IPPS FY2027 Final Rule Table 5 (CMS-1849-F)Version v44 FY2027 · effective 2026-10-01 · file CMS-1849-F Table 5.txtSHA-256 01003dd571c1e2f5…
- IPPS FY2026 Final Rule Table 5 (CMS-1833-F)Version v43 FY2026 · effective 2025-10-01 · file CMS-1833-F Table 5.txtSHA-256 bf8c390d14b3cd3e…
- ICD-10 MS-DRG Definitions Manual v44 (text)Version v44 · effective 2026-10-01 · file fy2027-fr-icd10-ms-drg-definitions-manual-files-v44.zipSHA-256 ae4f6c11727fe91f…
Disclaimer
This page is an operational reference compiled from the CMS IPPS FY2027 final rule (Table 5) and the v44 ICD-10 MS-DRG Definitions Manual. Relative weights are national factors; actual payment depends on each hospital's wage-adjusted base rate, add-ons, outliers and transfer adjustments. Nothing here is legal, clinical or billing advice; verify grouping against your encoder and the published CMS files.