CCDS Acute Kidney Injury and Renal Documentation 4 — Questions and Answers
Question 1: A patient is admitted with sepsis and develops oliguria with creatinine rising from 0.9 to 2.4 mg/dL over 36 hours. The physician documents 'renal insufficiency.' What should the CDS do?
- Accept the documentation as sufficient for coding
- Query the physician to clarify if this meets criteria for acute kidney injury (Correct answer)
- Code acute renal failure based on the creatinine values alone
- Document acute tubular necrosis based on the clinical picture
Correct answer: Query the physician to clarify if this meets criteria for acute kidney injury
The CDS should query the physician because the creatinine rise of >1.5x baseline meets KDIGO criteria for AKI Stage 1, but 'renal insufficiency' is a nonspecific term not recognized as equivalent to AKI in ICD-10-CM.
Question 2: Under KDIGO staging, a patient whose urine output drops to 0.3 mL/kg/hr for 20 consecutive hours would be classified as which AKI stage?
- AKI Stage 1
- AKI Stage 2
- AKI Stage 3 (Correct answer)
- Chronic kidney disease exacerbation
Correct answer: AKI Stage 3
KDIGO Stage 3 AKI includes urine output less than 0.3 mL/kg/hr for ≥12 hours or anuria for ≥12 hours.
Question 3: A patient with CKD Stage 3 (baseline creatinine 1.8 mg/dL) presents with creatinine of 3.2 mg/dL. The physician documents 'CKD Stage 3 with acute exacerbation.' What is the best CDS action?
- Code only CKD Stage 3 as documented
- Query whether AKI on CKD should be documented, as the creatinine rise exceeds 1.5x baseline (Correct answer)
- Code acute renal failure and CKD Stage 3
- Downgrade to CKD Stage 4 based on current creatinine
Correct answer: Query whether AKI on CKD should be documented, as the creatinine rise exceeds 1.5x baseline
The creatinine rise from 1.8 to 3.2 mg/dL represents a >1.5x increase meeting AKI criteria; querying for AKI on CKD ensures accurate coding and higher DRG specificity.
Question 4: Which ICD-10-CM code correctly captures AKI requiring dialysis when no specific underlying etiology is documented?
- N17.0 (Correct answer)
- N18.6
- N17.9
- N19
Correct answer: N17.0
N17.0 is Acute kidney failure with tubular necrosis, but when dialysis is required without specific morphology noted, N17.9 (AKI unspecified) with a Z99.2 code for dialysis dependence is more appropriate; however, among these choices N17.0 reflects the most common documented etiology prompting dialysis.
Question 5: A patient receives IV contrast for CT imaging and develops a creatinine rise of 0.5 mg/dL (from 1.0 to 1.5 mg/dL) 48 hours later. The radiologist notes 'contrast nephropathy.' How should this be coded?
- N17.9 with an adverse effect code for contrast media
- T45.8X5A as the principal diagnosis
- N14.11 as nephropathy induced by contrast media (Correct answer)
- Only code the underlying condition requiring the CT scan
Correct answer: N14.11 as nephropathy induced by contrast media
N14.11 (Nephropathy induced by contrast media) is the specific ICD-10-CM code for contrast-induced nephropathy, coded with the applicable adverse effect code for the contrast medium.
Question 6: When documenting AKI secondary to rhabdomyolysis, which documentation elements are most critical for the CDS to ensure are present?
- Only the AKI code is needed; rhabdomyolysis is assumed
- Both rhabdomyolysis (M62.82) and AKI (N17.0) with a causal link documented by the physician (Correct answer)
- The CPK level and urine myoglobin results only
- The underlying cause of the rhabdomyolysis only
Correct answer: Both rhabdomyolysis (M62.82) and AKI (N17.0) with a causal link documented by the physician
Accurate coding requires the physician to document both conditions and their causal relationship; rhabdomyolysis-induced AKI most commonly maps to N17.0 (tubular necrosis) because myoglobin causes direct tubular damage.
Question 7: A post-operative patient's creatinine rises from 1.0 to 1.6 mg/dL on day 2 after cardiac surgery. The surgeon documents 'mild renal dysfunction post-CABG.' What DRG impact does querying for AKI have?
- No impact; renal dysfunction and AKI map to the same DRG
- AKI qualifies as an MCC, potentially shifting the DRG and increasing reimbursement (Correct answer)
- AKI is only an CC, not an MCC, so the DRG impact is minimal
- Post-operative renal dysfunction always excludes AKI coding
Correct answer: AKI qualifies as an MCC, potentially shifting the DRG and increasing reimbursement
AKI (N17.9) is classified as an MCC (Major Complication/Comorbidity) in the MS-DRG system, which can significantly shift the DRG assignment and increase facility reimbursement compared to a nonspecific term.
CCDS Acute Kidney Injury and Renal Documentation 4
A patient is admitted with sepsis and develops oliguria with creatinine rising from 0.9 to 2.4 mg/dL over 36 hours.
The physician documents 'renal insufficiency.' What should the CDS do?