Key facts for DRG 601
- FY2027 relative weight
- 0.6010
- Higher than 2% of all MS-DRGs
- Change vs FY2026
- -0.7%
- FY2026 weight 0.6050
- Geometric mean LOS
- 2.3 days
- Arithmetic mean 2.9 days
- MDC
- 09
- Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast
- Severity level
- without CC or MCC
- Transfer policy
- Not a transfer DRG
TL;DR
MS-DRG 601 is a medical group in MDC 09 (Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast) at the base severity level of its family. CMS assigns it a FY2027 relative weight of 0.6010 with a geometric mean length of stay of 2.3 days and an arithmetic mean of 2.9. Its weight moved down 0.7% from FY2026 (0.6050). That weight is higher than 2% of all medical and surgical MS-DRGs. Its CC/MCC family (DRG 600) spans weights 0.6010 to 0.9970. The v44 Definitions Manual assigns it through 93 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 601 the FY2027 relative weight is 0.6010 against 0.6050 in FY2026, a fall of 0.66%.
| Metric | FY2026 | FY2027 | Change |
|---|---|---|---|
| Relative weight | 0.6050 | 0.6010 | -0.0040 |
| Geometric mean LOS (days) | 2.3 | 2.3 | +0.0 |
| Arithmetic mean LOS (days) | 2.6 | 2.9 | +0.3 |
CC and MCC family
DRG 601 shares its base definition with 1 other MS-DRG split by severity. The family's weights span 0.6010 to 0.9970, a 1.66× spread, which is the payment effect of documenting qualifying complications and comorbidities.
| DRG | Title | FY2027 weight | GMLOS |
|---|---|---|---|
| 600 | Non-Malignant Breast Disorders with CC/MCC | 0.9970 | 3.1 |
| 601 | Non-Malignant Breast Disorders without CC/MCC | 0.6010 | 2.3 |
Grouper logic (v44 Definitions Manual)
Principal Diagnosis: 93 ICD-10 codes drive assignment to this group; the first 12 are shown.
| ICD-10 code | Description |
|---|---|
| D493 | Neoplasm of unspecified behavior of breast |
| I972 | Postmastectomy lymphedema syndrome |
| N6001 | Solitary cyst of right breast |
| N6002 | Solitary cyst of left breast |
| N6009 | Solitary cyst of unspecified breast |
| N6011 | Diffuse cystic mastopathy of right breast |
| N6012 | Diffuse cystic mastopathy of left breast |
| N6019 | Diffuse cystic mastopathy of unspecified breast |
| N6021 | Fibroadenosis of right breast |
| N6022 | Fibroadenosis of left breast |
| N6029 | Fibroadenosis of unspecified breast |
| N6031 | Fibrosclerosis of right breast |
Documentation and denial exposure
As a medical DRG, assignment depends on the principal diagnosis sequenced from the attending's documentation; a secondary condition sequenced first, or a symptom code in place of the confirmed diagnosis, changes the MDC or the DRG. 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 601 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 601
What is MS-DRG 601?
MS-DRG 601 is "Non-Malignant Breast Disorders without CC/MCC", a medical Medicare Severity Diagnosis-Related Group in MDC 09, Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast. 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 601?
The FY2027 relative weight is 0.6010 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 0.6050, a change of -0.7%.
What is the average length of stay for DRG 601?
CMS reports a geometric mean length of stay of 2.3 days and an arithmetic mean of 2.9 days for FY2027. The geometric mean is used for transfer-payment calculations.
Which DRGs are in the same CC/MCC family as 601?
DRG 600 (Non-Malignant Breast Disorders with CC/MCC, weight 0.9970). The family's weights range from 0.6010 to 0.9970, so documented complications and comorbidities change payment materially.
What documentation supports the severity level of DRG 601?
DRG 601 is the base-severity assignment: no secondary diagnosis on the CC or MCC lists was coded, or the only ones present are excluded for this principal diagnosis. Revenue-integrity review here looks for undercapture, meaning conditions treated during the stay (electrolyte disorders, specified anemia, acute blood loss, pressure injuries present on admission) that were never documented to the specificity the lists require. A compliant query to the attending, not a coder assumption, is the only way to move a stay to the CC or MCC sibling.
Which codes group to DRG 601?
The v44 Definitions Manual lists 93 principal diagnosis codes for this group. Examples from the principal diagnosis list: D493 (Neoplasm of unspecified behavior of breast); I972 (Postmastectomy lymphedema syndrome); N6001 (Solitary cyst of right breast); N6002 (Solitary cyst of left breast).
Is DRG 601 a post-acute transfer DRG?
No. DRG 601 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.