Radiology · Year 4 · from Radiology
Case 1: Contrast-Induced Nephropathy
Patient Demographics
- Age: 72 years
- Sex: Male
Chief Complaint
Routine follow-up for abdominal aortic aneurysm surveillance
Presenting Symptoms
The patient presents for scheduled CT angiography for surveillance of a known 4.5 cm infrarenal abdominal aortic aneurysm. He has a history of type 2 diabetes mellitus, hypertension, and mild chronic kidney disease with a baseline creatinine of 1.6 mg/dL (eGFR 42 mL/min/1.73m2). He reports no new symptoms but mentions he has been "a bit dehydrated" after recent gastrointestinal illness.
Physical Exam Findings
- Vital Signs: BP 148/86 mmHg, HR 78 bpm, RR 14/min, Temp 36.8C
- General: Alert, well-appearing elderly male
- Cardiovascular: Regular rate and rhythm, pulsatile abdominal mass palpable
- Extremities: Palpable dorsalis pedis pulses bilaterally
Imaging Findings and Interpretation
Pre-procedure Assessment: Laboratory values obtained reveal creatinine of 1.8 mg/dL (elevated from baseline), eGFR 38 mL/min/1.73m2. The patient's recent dehydration and underlying diabetic nephropathy place him at increased risk for contrast-induced nephropathy.
Risk Stratification: Using the Mehran Risk Score for contrast-induced nephropathy:
- Hypotension: 0 points
- IABP: 0 points
- CHF: 0 points
- Age >75: 0 points
- Anemia: 0 points
- Diabetes: 3 points
- Contrast volume (estimated 100mL): 1 point
- eGFR 38: 4 points
- Total: 8 points (moderate risk, approximately 14% risk of CIN)
Management Decision: Given the moderate risk profile and non-urgent indication, the procedure is postponed. The patient is instructed to ensure adequate oral hydration for 48 hours. Pre-hydration protocol with intravenous normal saline (1 mL/kg/hr for 6-12 hours before and after procedure) is planned. Metformin is held for 48 hours post-procedure due to risk of lactic acidosis if acute kidney injury develops.
Diagnosis
High-risk patient for contrast-induced nephropathy requiring pre-procedural optimization
Management
- Postpone non-urgent CT angiography for 48-72 hours
- Ensure adequate oral hydration
- Administer IV normal saline 1 mL/kg/hr starting 6 hours before and continuing 6-12 hours after contrast administration
- Use lowest necessary contrast volume with iso-osmolar or low-osmolar contrast agent
- Hold metformin for 48 hours post-procedure
- Repeat creatinine 48-72 hours post-procedure to assess for nephropathy
Radiological Image
Image Description: CT angiography demonstrating an infrarenal abdominal aortic aneurysm with mural thrombus. This type of contrast-enhanced study requires careful consideration of renal function and contrast-induced nephropathy risk.
Source: Wikimedia Commons - "Abdominal aortic aneurysm" by James Heilman, MD URL: https://commons.wikimedia.org/wiki/File:Aneurysem.png License: Creative Commons Attribution-Share Alike 3.0 Unported