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N23

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ICD-10 N23 — Unspecified renal colic

Short description

Unspecified renal colic — paroxysmal flank/inguinal pain consistent with renal or ureteric colic when documentation does not specify cause, site, or laterality.

Full description

Definition
ICD-10-CM N23 is the code for unspecified renal colic (also listed as nephralgia or ureteralgia) and is used when the clinical record documents renal/ureteric colic but lacks sufficient detail to assign a more specific code (for example, a urinary calculus with laterality). Typical presentation includes sudden severe flank pain radiating to the groin, often with nausea, vomiting, and hematuria.

Clinical features to document

  • Pain: onset, location (flank, groin), radiation, severity.
  • Associated symptoms: hematuria, nausea/vomiting, fever, urinary symptoms.
  • Objective findings: flank tenderness, positive urinalysis (RBCs), hydronephrosis on imaging.
  • Diagnostics: CT abdomen/pelvis without contrast (gold standard), renal ultrasound (pregnancy or hydronephrosis), urinalysis, serum creatinine.

Coding guidance

  • Use N23 when documentation supports renal colic but lacks specificity about cause, site, or laterality.
  • If imaging or clinician documents a stone and its site/laterality, use the appropriate N20.x code (e.g., N20.1 calculus of ureter; N20.0 calculus of kidney) instead of N23.

HCC, wRVU, and RVU information

HCC / risk-adjustment

  • N23 is not an HCC. It is an acute symptom/manifestation and does not map to chronic HCC categories used for prospective risk adjustment. Code chronic conditions (e.g., CKD) separately when present.

wRVU / RVU

  • Diagnosis codes do not carry wRVU or RVU values. Physician work RVUs and total RVUs are assigned to CPT procedure and evaluation codes (ED E/M, urology procedures, imaging interpretation). Select CPTs that reflect the documented service; those CPTs determine wRVU capture.

Primary related ICD-10 codes

  • N23 — Unspecified renal colic.
  • N20.0 — Calculus of kidney.
  • N20.1 — Calculus of ureter.
  • N20.2 — Calculus of kidney with calculus of ureter.
  • N20.9 — Urinary calculus, unspecified.
  • R31.- — Hematuria (when documented).
  • N17.- — Acute kidney injury (if obstruction causes renal impairment).

When to prefer other codes

  • If imaging confirms a stone and laterality/site, code the specific N20.x entry rather than N23. [

Sample CPT / HCPCS / procedure codes commonly used with N23

TypeCodeDescription
CPT99281-99285Emergency department visit levels
CPT52000Cystourethroscopy diagnostic
CPT50590Extracorporeal shock wave lithotripsy (ESWL)
CPT52332 / 52351Ureteroscopy with lithotripsy; with stone removal
HCPCSImaging revenue codesFacility billing for CT/US/XR imaging

Billing notes

  • Choose the ED E/M code that matches documented history, exam, and medical decision-making.
  • Imaging and urologic procedures drive facility and procedural reimbursement; physician CPTs determine wRVU.
  • Check NCCI edits and payer rules for bundling; use modifier 25 only when a separately identifiable E/M is documented on the same day as a procedure.

DRG and inpatient grouping

MS-DRG considerations

  • N23 is grouped within urinary stones/urinary tract DRG families and may appear as a principal or secondary diagnosis depending on the encounter. Typical MS-DRG groupings include urinary stones DRGs (e.g., DRG 693/694 in some groupers). Final DRG depends on principal diagnosis, procedures performed (ESWL, ureteroscopy), and presence of complications or comorbidities.

Documentation and sequencing checklist

  • Explicit diagnosis: document “renal colic,” “ureteric colic,” or the specific stone diagnosis (e.g., “left ureteral calculus”) when known.
  • Laterality and site: record left/right and kidney vs ureter when available.
  • Imaging results: include modality, findings (stone present, size, location, hydronephrosis).
  • Associated findings: hematuria, infection, obstruction, AKI—code these separately when present.
  • Treatment and procedures: document analgesia, antiemetics, IV fluids, urology consult, stent placement, lithotripsy, ureteroscopy; include indications and physician involvement.
  • ED documentation: ensure MDM supports chosen E/M level; document time and complexity for procedures.

Clinical pearls

  • Most likely cause: ureteral stone (urolithiasis).
  • Presentation: sudden severe flank pain radiating to groin, hematuria, nausea/vomiting.
  • Best test: noncontrast CT abdomen/pelvis for stone detection; ultrasound for pregnancy or to evaluate hydronephrosis.
  • Urology consult indications: obstructing stone with infection, solitary kidney, refractory pain, renal impairment, or large proximal stones.

Billing pitfalls to avoid

  • Using N23 when imaging documents a stone — use the specific N20.x code instead. ICD-10 Coded
  • Omitting laterality when known — laterality supports more specific coding.
  • Failing to code complications (hydronephrosis, AKI, UTI) when present.
  • Billing E/M and procedure without documentation of separate, identifiable service — support modifier 25 with clear documentation.

Example documentation template (copy into chart)

Assessment

  • Primary: Unspecified renal colic — ICD-10: N23.
  • Differential: Ureteral calculus; pyelonephritis; musculoskeletal flank pain.
  • Onset: [date/time].
  • Pain: Location [left/right flank], radiation to groin, severity [0-10].
  • Associated: Nausea/vomiting [yes/no]; hematuria [UA RBCs]; fever [T].
  • Labs: Creatinine [value]; UA [RBCs/WBCs]; pregnancy test if applicable.
  • Imaging: CT abdomen/pelvis ordered/performed — result: [e.g., 6 mm left distal ureteral stone with mild hydronephrosis]. Update diagnosis to N20.x if stone confirmed.
  • Plan: Analgesia, antiemetic, IV fluids, urology consult if obstructing stone or infection; update diagnosis and code procedures as performed.

Procedures

  • If performed: document procedure, indication, laterality, and CPT (e.g., 52351 ureteroscopy with stone removal).

Obsidian frontmatter patient template (YAML) for quick paste

patient: ""
mrn: ""
encounter_date: ""
chief_complaint: "Flank pain / suspected renal colic"
diagnosis_primary: "Unspecified renal colic (N23)"
diagnosis_specific: ""
laterality: ""
imaging_ordered: ""
imaging_result: ""
hematuria: ""
urine_rbc: ""
creatinine: ""
pregnancy_test: ""
urology_consult: false
procedures: []
tags: ["renal-colic","N23","urology","ED"]

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