Crystal's Coder Hub🧬 ICD-10 CM N13.30 — Unspecified Hydronephrosis
Billable Code Confirmed
ICD-10-CM N13.30 is a valid, billable 5-character ICD-10-CM code for FY2026. Characters 1-3 (N13) identify the category (obstructive and reflux uropathy); character 4 (3) specifies the “other and unspecified hydronephrosis” subcategory; character 5 (0) designates the unspecified subtype. No additional characters are available or required — this is a fully specified, terminal code at the 5th character level.
Non-Billable Parent Codes — Never Submit These
- ❌
N13— 3-character header — missing obstruction type, hydronephrosis status, and specificity- ❌
N13.3— 4-character subcategory — “other and unspecified hydronephrosis” — missing the 5th character distinguishing unspecified (N13.30) from other (N13.39)Always submit N13.30 (all 5 characters) when hydronephrosis is documented but the underlying etiology is unspecified or not yet determined. When etiology is known (e.g., UPJ obstruction → N13.0; ureteral stricture → N13.1; calculous obstruction → N13.2), the more specific code must be used.
Clinical Context: N13.30 Is a Default Code — Etiology Specificity Is Always Preferred
ICD-10-CM N13.30 is an “unspecified” code — it is appropriate only when the clinical documentation genuinely does not identify the cause of the hydronephrosis, or when the workup is still in progress at the time of coding. Per ICD-10-CM Official Guidelines, unspecified codes are acceptable when they most accurately reflect what is known, but the coder and CDI specialist should query the provider when imaging or clinical findings suggest a specific obstructive mechanism (e.g., crossing vessel, stricture, calculus, BPH) that would support a more precise code assignment.
Code Classification
ICD-10-CM Diagnosis Code — wRVU, global surgical period, and assistant-at-surgery fields are not applicable to this diagnosis code. For associated inpatient procedures, refer to the ICD-10-PCS Crosswalk section. For profee billing context, refer to the Commonly Associated CPT Codes section.
🔍 Code Description
ICD-10 CM N13.30 classifies unspecified hydronephrosis — the dilation of the renal pelvis and/or calyces (collecting system) due to obstruction, when the specific cause of the obstruction has not been documented or identified at the time of the encounter. Hydronephrosis represents a structural consequence of impaired urinary drainage at any level of the urinary tract (ureteropelvic junction, ureter, ureterovesical junction, or bladder outlet), resulting in increased pressure within the collecting system and, if prolonged, progressive renal parenchymal injury.
Pathophysiologically, obstruction causes retrograde pressure elevation that compresses renal tubules and vasculature, leading to tubular atrophy, interstitial fibrosis, and ultimately nephron loss if untreated. The “unspecified” designation (N13.30 vs. N13.39 — other hydronephrosis) reflects the absence of documented etiology at coding time, not a lesser clinical severity — significantly obstructive hydronephrosis coded as N13.30 may carry the same clinical urgency as a fully specified variant.
🌳 Code Tree / Hierarchy
N13 Obstructive and reflux uropathy ❌ Non-billable (3-char header)
│
├── N13.0 Hydronephrosis with ureteropelvic junction obstruction ✅ Billable
├── N13.1 Hydronephrosis with ureteral stricture, NEC ✅ Billable
├── N13.2 Hydronephrosis with renal and ureteral calculous obstruction ✅ Billable
│
├── N13.3 Other and unspecified hydronephrosis ❌ Non-billable (4-char subcategory)
│ │
│ ├── N13.30 Unspecified hydronephrosis ◀ THIS CODE ✅ Billable
│ └── N13.39 Other hydronephrosis ✅ Billable
│
├── N13.4 Hydroureter ✅ Billable
├── N13.5 Crossing vessel and stricture of ureter without hydronephrosis ✅ Billable
├── N13.6 Pyonephrosis ✅ Billable
│
├── N13.7 Vesicoureteral-reflux ❌ Non-billable (4-char subcategory)
│ └── (N13.70-N13.732 — billable 5th/6th character codes)
│
├── N13.8 Other obstructive and reflux uropathy ✅ Billable
└── N13.9 Obstructive and reflux uropathy, unspecified ✅ Billable
N13.30 vs. N13.39 — "Unspecified" vs. "Other"
N13.30 is used when the hydronephrosis has no documented cause or the etiology is unknown/pending workup. N13.39 (other hydronephrosis) is used when the hydronephrosis has a documented cause that doesn’t fit the more specific N13.0-N13.2 categories — for example, hydronephrosis due to an extrinsic pelvic mass, post-radiation fibrosis without stricture documentation, or pregnancy-related hydronephrosis. If the specific etiology is known and matches N13.0-N13.2, always use those more specific codes rather than N13.30 or N13.39.
✅ Includes
The following clinical terms and scenarios map to N13.30 when documented:
- Hydronephrosis NOS (not otherwise specified) — when provider documents “hydronephrosis” without specifying the cause
- Collecting system dilation of unspecified etiology confirmed on ultrasound, CT, or MRI without documented obstructive mechanism
- Hydronephrosis identified incidentally on imaging during workup for another condition, etiology unknown or pending
- Hydronephrosis, cause under investigation at time of encounter — appropriate to use N13.30 during initial diagnostic workup
- Renal pelvic dilation without documented cause (distinguished from Q62.0 congenital hydronephrosis)
❌ Excludes
Excludes 1 — Cannot Be Coded Simultaneously with N13.30
| Code | Description | Note |
|---|---|---|
| N13.6 | Pyonephrosis | When hydronephrosis is complicated by active infection/pus formation, N13.6 is the correct and exclusive code — N13.30 cannot be assigned simultaneously for the same anatomic site; N13.6 captures the infected hydronephrosis as a single clinical entity |
Excludes 1 Violation Risk
The most likely Excludes 1 violation with N13.30 is assigning it alongside N13.6 (pyonephrosis). Pyonephrosis represents hydronephrosis with superimposed infection creating a pus-filled, obstructed renal system. If both “hydronephrosis” and “pyonephrosis” appear in the documentation for the same kidney, assign only N13.6 — it is the more specific code and N13.30 is excluded. Do not code both simultaneously.
Excludes 2 — May Be Coded in Addition if Separately Present
| Code | Description | Note |
|---|---|---|
| N20.- | Calculus of kidney and ureter without hydronephrosis | If calculi are present but not causing hydronephrosis, N20 and N13.30 may coexist — but if calculi ARE the cause of the hydronephrosis, use N13.2 instead |
| Q62.0-Q62.3 | Congenital obstructive defects of renal pelvis and ureter | Congenital hydronephrosis (Q62.0) is separately codeable — N13.30 is for acquired hydronephrosis; assign the appropriate Q62 code when a congenital anomaly is the underlying etiology |
| Q62.11 | Hydronephrosis with UPJ obstruction, congenital | Use Q62.11 for congenital UPJ obstruction; N13.30 is not used when the cause is congenital in origin |
| N11.1 | Chronic obstructive pyelonephritis | May be separately coded if chronic infectious pyelonephritis is present concurrently with hydronephrosis |
📋 Clinical Overview
N13 Hydronephrosis Code Selection — Etiology-Driven Hierarchy
Selecting the correct N13 code requires the provider to document the mechanism of obstruction and presence/absence of hydronephrosis together. N13.30 is the code of last resort within the hydronephrosis group — always attempt to identify the more specific code first.
| Feature | N13.30 — Unspecified | N13.0 — UPJ Obstruction | N13.1 — Ureteral Stricture | N13.2 — Calculous |
|---|---|---|---|---|
| Hydronephrosis Present | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
| Obstructive Mechanism | Unknown / Not documented | UPJ obstruction (crossing vessel, intrinsic) | Ureteral stricture (non-calculous) | Renal or ureteral calculus |
| Imaging Expectation | Collecting system dilation, no identified cause | UPJ narrowing ± crossing vessel on CT | Focal ureteral narrowing on CTU/ureteroscopy | Calculus visible on CT or KUB |
| CDI Action | Query for etiology | No query needed — specific | No query needed — specific | No query needed — specific |
| DRG Group (PDx) | DRG 693/694 (Urinary Stones tier) | DRG 693/694 | DRG 693/694 | DRG 693/694 |
| Preferable Over N13.30? | N/A (last resort) | ✅ Always prefer if UPJ obstruction documented | ✅ Always prefer if stricture documented | ✅ Always prefer if calculus is the cause |
CDI Query Trigger — Unspecified Hydronephrosis with Imaging Findings
When imaging (CT urography, renal ultrasound, MAG-3) identifies a likely cause — crossing vessel, ureteral stricture, calculus, or extrinsic compression from a pelvic mass — but the provider’s documentation only states “hydronephrosis” without etiology, a CDI query should be generated. The goal is to upgrade from N13.30 to a more clinically accurate and specific code (N13.0, N13.1, N13.2, or N13.39 as appropriate). While DRG grouping in MDC 11 does not change between these codes (all group to DRG 693/694), specificity supports payer review, quality reporting, surgical authorization for pyeloplasty, and longitudinal clinical data integrity.
Manifestations & Symptom Burden
Common clinical presentations and associated conditions documented alongside N13.30:
- Flank or loin pain: Dull or colicky flank pain from distention of the renal capsule or collecting system — integral to the hydronephrosis, not separately codeable
- Acute kidney injury: AKI from obstructive nephropathy — code N17.9 or specify stage; functions as MCC, critical for DRG 693 tier
- Urinary tract infection: Ascending infection facilitated by urinary stasis — code N39.0 separately when documented; may elevate to N13.6 (pyonephrosis) if pus-forming
- Hematuria: Gross or microscopic — code R31.0 or R31.9 separately if documented as a distinct finding beyond the hydronephrosis
- CKD from chronic obstruction: If longstanding hydronephrosis has caused renal impairment — code N18.3, N18.4, or N18.5 as appropriate; CKD stages are HCC-mapped
Coding Manifestations
Maximize secondary diagnosis capture to fully reflect complexity and optimize DRG tier:
💰 HCC Risk Adjustment (CMS-HCC v28)
| Field | Detail |
|---|---|
| CMS-HCC Model Version | v28 (Fully implemented PY2026) |
| HCC Assignment | ❌ Not HCC-Mapped |
| HCC Category | N/A |
| RAF Coefficient | N/A |
N13.30 does not map to any HCC category under CMS-HCC v28 and does not independently contribute to RAF scoring.
Indirect HCC Relevance — Code the Downstream Complications
Although N13.30 is not HCC-mapped, obstructive nephropathy is a known cause of progressive renal function loss. When CKD has developed secondary to hydronephrosis, the CKD code (N18.1-N18.5) is HCC-mapped (HCC 137-138) and must be captured separately at every qualifying encounter for accurate RAF scoring. Similarly, if the underlying cause of the hydronephrosis is a malignancy (e.g., pelvic tumor compressing the ureter), the neoplasm code carries its own HCC assignment and must be coded concurrently.
🏥 MS-DRG Assignment
MDC 11 — Diseases and Disorders of the Kidney and Urinary Tract
| DRG | Title | Est. Relative Weight* |
|---|---|---|
| DRG 693 | Urinary Stones with MCC | ~1.00-1.30 |
| DRG 694 | Urinary Stones without MCC | ~0.65-0.85 |
| If a qualifying inpatient O.R. procedure is performed (e.g., pyeloplasty, nephrostomy): |
| DRG | Title | Est. Relative Weight* |
|---|---|---|
| DRG 673 | Other Kidney and Urinary Tract Procedures with MCC | ~3.50-4.50 |
| DRG 674 | Other Kidney and Urinary Tract Procedures with CC | ~2.00-2.80 |
| DRG 675 | Other Kidney and Urinary Tract Procedures without CC/MCC | ~1.40-1.80 |
| Approximate. Verify against IPPS FY2026 Final Rule Table 5 and your facility’s cost-to-charge ratios. |
Sequencing and DRG Tier Optimization
N13.30 as a principal diagnosis groups to the Urinary Stones DRG pair (693/694) per CMS MS-DRG v43.0/v43.1 MDC 11 logic — the DRG tier depends solely on whether a secondary diagnosis qualifies as an MCC. Acute kidney injury (N17.9) is the single most impactful secondary diagnosis to capture, as it functions as an MCC and shifts the case from DRG 694 → DRG 693. When a qualifying inpatient O.R. procedure is performed (pyeloplasty, nephrostomy, ureteroscopic treatment), the case re-groups entirely to the surgical DRG family (673-675), with significantly higher relative weights. Always verify POA (Present on Admission) status for secondary diagnoses — AKI coded as POA = “N” may trigger HAC review if it developed as a hospital-acquired complication.
🔗 Related ICD-10-CM Codes
N13 Hydronephrosis Group — Etiology-Specific Alternatives to N13.30
| Code | Description |
|---|---|
| N13.30 | Unspecified hydronephrosis ← This Code |
| N13.0 | Hydronephrosis with ureteropelvic junction obstruction |
| N13.1 | Hydronephrosis with ureteral stricture, not elsewhere classified |
| N13.2 | Hydronephrosis with renal and ureteral calculous obstruction |
| N13.39 | Other hydronephrosis (documented cause not fitting N13.0-N13.2) |
| N13.4 | Hydroureter |
| N13.5 | Crossing vessel and stricture of ureter without hydronephrosis |
| N13.6 | Pyonephrosis (Excludes 1 — cannot code simultaneously) |
Congenital Hydronephrosis (Separate Category — Not N13.30)
| Code | Description |
|---|---|
| Q62.0 | Congenital hydronephrosis |
| Q62.11 | Hydronephrosis with ureteropelvic junction obstruction, congenital |
| Q62.2 | Congenital obstruction of ureter |
Common Associated Secondary Diagnoses
| Code | Description |
|---|---|
| N17.9 | Acute kidney injury, unspecified (MCC — highest DRG impact) |
| N18.3 | Chronic kidney disease, stage 3 (CC — HCC-mapped) |
| N39.0 | Urinary tract infection, site not specified |
| R31.9 | Hematuria, unspecified |
🛠️ Commonly Associated CPT Codes (Urology)
Outpatient, Ambulatory Surgery, and Inpatient Setting Context
N13.30 is associated with both diagnostic workup CPT codes and interventional/surgical procedure codes depending on the setting. Diagnostic imaging (renal ultrasound, CT urography, MAG-3 nuclear scan) is used to characterize the hydronephrosis and identify etiology. Interventional procedures range from ureteral stent placement for temporary decompression to definitive surgical repair (pyeloplasty, nephrectomy for end-stage obstructed kidney).
| CPT Code | Description | Profee Coding Notes |
|---|---|---|
| 76770 | Ultrasound, retroperitoneal (kidneys, aorta, or complete) | Renal ultrasound — primary initial imaging for hydronephrosis; separately billable in profee setting with Modifier -26 in facility |
| 74178 | CT urography, with and without contrast | Comprehensive CT study for hydronephrosis workup — identifies etiology (calculus, stricture, mass); separately billable with Modifier -26 |
| 78708 | Kidney imaging morphology, with vascular flow and function | Nuclear MAG-3 diuretic renal scan — assesses differential function and drainage obstruction; critical when cause of hydronephrosis is unclear |
| 52332 | Cystourethroscopy, with insertion of indwelling ureteral stent | Ureteral stent insertion for temporary decompression of obstructed collecting system — commonly performed while awaiting definitive management |
| 52341 | Cystourethroscopy; with treatment of ureteral stricture | Endoscopic stricture treatment — relevant when hydronephrosis is found to be due to a stricture at the time of cystoscopy |
| 52344 | Cystourethroscopy with ureteroscopy; with treatment of ureteral stricture | Ureteroscopic stricture treatment — more comprehensive than 52341; includes ureteroscopic visualization and therapy |
| 50432 | Placement of nephrostomy catheter, percutaneous, including imaging guidance | Percutaneous nephrostomy — emergent decompression of obstructed, dilated collecting system; includes imaging guidance per CPT descriptor |
| 50544 | Laparoscopy, surgical; pyeloplasty | Definitive surgical repair when UPJ obstruction is confirmed as cause of hydronephrosis — once workup clarifies etiology, code shifts from N13.30 to N13.0 |
| 99213 | Office or other outpatient visit, established patient, low-to-moderate MDM | Outpatient follow-up for known/incidental hydronephrosis — commonly billed at moderate complexity with imaging review |
NCCI Bundling Considerations
- Diagnostic cystoscopy (52000) billed on the same day as any therapeutic cystourethroscopic procedure (e.g., 52332, 52341, 52344) is bundled — report only the therapeutic code; 52000 is a “separate procedure” descriptor and cannot be separately billed when a more comprehensive cystourethroscopic procedure is performed.
- Nephrostomy placement (50432) includes all imaging guidance per the CPT descriptor — do not separately bill fluoroscopy or ultrasound guidance codes when 50432 is reported.
- E/M (99213, 99214) billed on the same day as a procedure (e.g., 52332 stent insertion) in the office/outpatient setting requires Modifier -25 on the E/M to establish a separately identifiable and documented medical decision-making service beyond the pre-operative assessment for the procedure.
🔬 ICD-10-PCS Crosswalk (Inpatient Procedures)
When N13.30 is an inpatient diagnosis, these PCS codes are relevant for associated inpatient procedures.
| PCS Section | Body System | Root Operation | Clinical Application |
|---|---|---|---|
| 0 (Medical and Surgical) | T (Urinary System) | 9 (Drainage) | Percutaneous nephrostomy for emergent decompression — 0T930ZZ (Right Kidney) or 0T940ZZ (Left Kidney); route of drainage decompresses dilated collecting system |
| 0 (Medical and Surgical) | T (Urinary System) | H (Insertion) | Ureteral stent placement (antegrade or retrograde) — 0TH97DZ (Via Natural or Artificial Opening Endoscopic); stents relieve obstruction and allow drainage while awaiting definitive repair |
| 0 (Medical and Surgical) | T (Urinary System) | Q (Repair) | Pyeloplasty once etiology confirmed — 0TQ44ZZ (Right Kidney Pelvis, Percutaneous Endoscopic) or 0TQ54ZZ (Left); note: when pyeloplasty is performed, the ICD-10-CM principal diagnosis should be updated to N13.0 if UPJ obstruction is confirmed intraoperatively |
| 0 (Medical and Surgical) | T (Urinary System) | 7 (Dilation) | Ureteral stricture dilation — 0T747ZZ (Right Ureter, Endoscopic) or 0T757ZZ (Left Ureter); if stricture confirmed as cause, update principal DX to N13.1 |
💊 Coding Scenarios and Examples
Scenario 1 — Outpatient: Incidental Hydronephrosis, Etiology Pending Workup
Clinical Vignette: A 62-year-old male undergoes CT abdomen/pelvis for evaluation of abdominal pain. Radiology report identifies “moderate left-sided hydronephrosis without an identified obstructive lesion on this study.” The ordering internist’s assessment documents: “Left hydronephrosis — etiology undetermined, referring to urology for further evaluation.” No stone, stricture, or mass is identified on the CT. No prior urologic history.
ICD-10-CM (Outpatient — Code to Highest Degree of Certainty):
- N13.30 — Unspecified hydronephrosis (etiology unknown at time of encounter; appropriate to use unspecified code per outpatient guidelines — do not assign N13.0 or N13.1 until etiology is confirmed by urology workup)
Secondary Diagnoses:
- (Code the abdominal pain if separately documented as a co-reason for the encounter; otherwise, if CT finding is the primary finding being addressed, N13.30 stands alone)
Scenario 2 — Inpatient: Hydronephrosis with Acute Kidney Injury
Clinical Vignette: A 74-year-old female with a history of pelvic radiation for cervical cancer is admitted with right flank pain, oliguria, and creatinine 3.8 (baseline 1.1). CT pelvis shows right-sided moderate hydronephrosis with hydroureter; no stone visualized; ureteral narrowing is noted in the mid-ureter but the attending documents “hydronephrosis, etiology uncertain — possible radiation-related ureteral narrowing vs. recurrent malignancy — urology consulted for stent placement.” Urology performs emergent right ureteral stent placement.
Principal Diagnosis:
- N13.30 — Unspecified hydronephrosis (reason for admission; etiology not definitively confirmed at the time of coding — CDI query appropriate, see Scenario 3)
Secondary Diagnoses:
- N17.9 — Acute kidney injury, unspecified (MCC — shifts DRG 694 → DRG 693)
- Z85.41 — Personal history of malignant neoplasm of cervix uteri (relevant clinical context)
- Z92.3 — Personal history of irradiation (relevant for payer documentation)
MS-DRG Assignment: N13.30 (PDx) + N17.9 (MCC secondary) → DRG 693 (Urinary Stones with MCC). With a qualifying inpatient O.R. procedure (ureteral stent — depending on whether this meets the O.R. procedure threshold for inpatient DRG grouping), the case may shift to a surgical DRG. Verify stent procedure classification against your facility’s O.R. procedure list.
Scenario 3 — CDI Query: Hydronephrosis With Imaging Evidence of Likely Stricture
Clinical Vignette: A 55-year-old male is admitted with left flank pain. CT urography shows “moderate left hydronephrosis with focal narrowing of the left distal ureter.” The urologist’s H&P reads: “Left hydronephrosis, likely due to distal ureteral stricture vs. external compression — recommend ureteroscopy.” The final diagnosis line on the discharge summary reads only: “Left hydronephrosis.”
Action / Outcome: Imaging clearly shows focal ureteral narrowing and the urologist has documented a suspected stricture mechanism. The coding team should not assign N13.30 when a more specific code (N13.1 — hydronephrosis with ureteral stricture) appears to be supported clinically but is not explicitly confirmed in the final diagnosis. A CDI query is required before upgrading the code.
Query Response: The urologist responds: “Left hydronephrosis with ureteral stricture — confirmed on ureteroscopy performed during this admission; stricture treated with balloon dilation.”
Corrected ICD-10-CM Coding:
- N13.1 — Hydronephrosis with ureteral stricture, not elsewhere classified (upgraded from N13.30 after CDI clarification — more specific, clinically accurate)
- N17.9 — Acute kidney injury (if present and documented)
⚠️ Coding Pitfalls and Tips
| Pitfall or Tip | |
|---|---|
| ❌ | Defaulting to N13.30 When a Specific Code Is Supported by Documentation. N13.30 is a code of last resort within the N13 hydronephrosis family. If the provider documents — or if imaging clearly identifies — a UPJ obstruction, ureteral stricture, or calculous obstruction, the specific code (N13.0, N13.1, or N13.2) is required. Unspecified codes should not be used when specificity is available in the record. |
| ❌ | Assigning N13.30 Alongside N13.6 (Pyonephrosis). The Excludes 1 note under N13.3 prohibits coding N13.30 simultaneously with N13.6. When hydronephrosis has progressed to an infected, pus-filled system, assign only N13.6. |
| ❌ | Using N13.30 for Congenital Hydronephrosis. Congenital hydronephrosis belongs in the Q62 category (Q62.0, Q62.11). N13.30 is for acquired hydronephrosis. In pediatric patients especially, always verify the congenital vs. acquired distinction before assigning N13.30. |
| ❌ | Coding Flank Pain or Renal Colic Separately. Pain symptoms integral to the hydronephrosis (flank pain, loin pain, renal colic) are subsumed by N13.30 and are not separately reportable per Official Coding Guidelines. |
| ✅ | Always Query for Etiology When Imaging Suggests a Specific Mechanism. A CDI query asking the provider to specify the cause of hydronephrosis (UPJ obstruction, stricture, calculus, external compression) is always appropriate when imaging findings suggest a specific mechanism not reflected in the provider’s documentation. This improves data quality, supports prior authorization, and enables more clinically accurate code assignment. |
| ✅ | Capture AKI as MCC When Present. Acute kidney injury (N17.9) is among the most impactful secondary diagnoses for DRG optimization with N13.30 as PDx — it functions as an MCC and shifts from DRG 694 → DRG 693. Always scan the lab values (creatinine trend) and document AKI with POA status accurately. |
| ✅ | Update the Diagnosis Code When Workup Confirms Etiology Inpatient. If a patient is admitted with unspecified hydronephrosis (N13.30) and ureteroscopy during the same admission confirms the cause (e.g., stricture), the principal diagnosis should be updated to the more specific code (N13.1) before final billing per the Uniform Hospital Discharge Data Set (UHDDS) guidelines for principal diagnosis selection. |
| ✅ | Verify Laterality in O.R. and PCS Codes Even When ICD-10-CM Lacks It. N13.30 has no laterality character, but associated ICD-10-PCS codes (nephrostomy, stent, pyeloplasty) must reflect the correct laterality (Right vs. Left kidney/ureter). Ensure operative documentation clearly supports the PCS laterality selected. |
📚 Sources
-
CMS/NCHS. ICD-10-CM Official Guidelines for Coding and Reporting, FY2026. Section I.B — General coding guidelines (unspecified codes); Section I.C.14 — Diseases of the genitourinary system; Section II — Principal diagnosis selection. ^[1]
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CMS. IPPS Final Rule FY2026 — MS-DRG Definitions Manual v43.0/v43.1. MDC 11 logic tables — Urinary Stones DRG pair (693-694); DRG 673-675 surgical kidney/urinary tract procedures. ^[2]
-
CMS. ICD-10-CM/PCS MS-DRG v43.0 Definitions Manual — MDC 11 Principal Diagnosis List. Confirms N13.30 groups to Urinary Stones DRG (693/694) as principal diagnosis. Retrieved from CMS.gov. ^[3]
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AAPC Codify. ICD-10 Code N13.30 — Unspecified Hydronephrosis. Code description, Excludes 1/2 notes, valid FY2026 status. ^[4]
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icdlist.com. 2026 ICD-10-CM Diagnosis Code N13.30 — Unspecified Hydronephrosis. Billability confirmation, DRG assignment (DRG 693/694), MDC 11. ^[5]
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FindACode.com. N13.30 Unspecified Hydronephrosis — ICD-10-CM Diagnosis Codes. Code hierarchy and Excludes note documentation. ^[6]
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AAPC Urology Coding Alert. “Look for the Type of Obstruction for Hydronephrosis Diagnosis.” Published 2017-03-14. N13 code selection guidance based on obstruction type and documentation. ^[7]
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PROMBs Medical Billing. “ICD-10 Code for Hydronephrosis — N13.30 Billing & Compliance.” Published 2025-10-02. Associated CPT codes and billing notes for hydronephrosis. ^[8]
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Outsource Strategies International. “ICD-10 Codes for Reporting the Top Six Urologic Conditions.” Published 2020-02-25. Clinical context and coding guidance for N13 obstructive uropathy codes. ^[9]
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CMS. Revised CMS-HCC Model v28 Relative Factor Tables / CMS-HCC v28 Implementation PY2026. Confirms N13.30 is not HCC-mapped under CMS-HCC v28. ^[10]
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AAPC Urology Coding Alert / ACDIS. CPT Code Guidance — Percutaneous Nephrostomy (50432), Stent Insertion (52332), and Associated Imaging. NCCI bundling guidance and imaging inclusion rules for urologic procedures. ^[11]