From the Guidelines
The initial diagnostic step for suspected renal artery thrombosis is a renal ultrasound with Doppler, as it is a non-invasive and first-line tool in the evaluation of suspected renal artery stenosis (RAS) 1. This modality uses a combination of direct insonation of the anastomosis and main renal artery, as well as indirect intrarenal waveform morphology, to assess for the presence of RAS.
Key Points to Consider
- Peak systolic velocity (PSV) in the renal artery is commonly used as the parameter to assess for the presence of RAS on US, with cutoff values of 200 to 300 cm/s proposed in various studies 1.
- A tardus parvus waveform (small peak amplitude with delayed upstroke) can be seen within the transplanted kidney downstream to the stenosis, and this morphologic waveform change is reflected quantitatively by the acceleration time 1.
- The renal artery–to–iliac artery ratio can also be used, with a sensitivity of 90% and specificity of 96.7% using a cutoff value of 1.8 1.
Treatment Approach
Once diagnosed, treatment should focus on preventing further thrombosis and restoring renal perfusion.
- Immediate anticoagulation therapy with intravenous unfractionated heparin may be considered, followed by oral anticoagulation with warfarin 1.
- Catheter-directed thrombolysis using tissue plasminogen activator (tPA) may be considered in cases diagnosed within 24-48 hours of symptom onset 1.
- Supportive care, including blood pressure control, pain management, and monitoring of renal function, is essential to prevent permanent kidney damage 1.
From the Research
Initial Diagnostic Step
- The initial diagnostic step for suspected renal artery thrombosis is a renal ultrasound with Doppler 2, 3.
- This non-invasive imaging modality can help identify thrombosis or embolism in the renal artery and evaluate blood flow to the kidneys.
- Color Doppler sonography (CDS) is a useful tool in diagnosing large renal infarcts caused by thrombosis or embolism in the main renal artery 2.
Treatment
- Treatment for renal artery thrombosis may involve ultrasound-accelerated thrombolysis 4 or thrombectomy 5.
- Ultrasound-accelerated thrombolysis has been shown to be effective in achieving complete recovery of renal function, even after prolonged periods of ischemia 4.
- Thrombectomy, including aspiration thrombectomy and rheolytic thrombectomy, can also be effective in restoring blood flow to the kidney and improving renal function 5.
- In some cases, revascularization with stenting may be necessary to treat underlying stenosis or restenosis 5, 3.
Diagnostic Challenges
- While renal ultrasound with Doppler is a useful diagnostic tool, it may not always be sensitive or specific for detecting renal artery thrombosis or stenosis 6, 3.
- Other imaging modalities, such as CT angiography or digital subtraction angiography, may be necessary to confirm the diagnosis or evaluate the extent of thrombosis or stenosis 2, 5.
- Intrarenal arterial Doppler analysis may not be reliable for detecting renal vein thrombosis in native kidneys 6.