From the Guidelines
Renal ultrasound is a crucial diagnostic tool for chronic kidney disease (CKD) patients, and I strongly recommend obtaining it as part of the initial workup for newly diagnosed CKD patients or when there is an unexplained decline in kidney function. The primary goal of ordering a renal ultrasound for CKD patients is to evaluate kidney size, structure, and potential causes of kidney dysfunction, which can significantly impact morbidity, mortality, and quality of life. According to the most recent and highest quality study 1, renal ultrasound is usually appropriate for the initial imaging of CKD, and it can help identify structural abnormalities such as hydronephrosis, polycystic kidney disease, renal masses, stones, or scarring that may contribute to kidney damage.
Key Benefits of Renal Ultrasound in CKD Patients
- Helps assess kidney size, with small, echogenic kidneys typically indicating chronic, irreversible disease, while normal or enlarged kidneys may suggest acute or potentially reversible conditions 1
- Detects urinary tract obstruction, which requires prompt intervention to prevent further kidney damage and improve quality of life
- Provides a non-invasive imaging modality that avoids contrast exposure, which could further damage compromised kidneys and reduce morbidity and mortality
- Guides management decisions, including the need for additional diagnostic tests, specialist referrals, or specific treatments for underlying causes of CKD, ultimately improving patient outcomes and quality of life
Important Considerations
- Renal ultrasound may not be necessary for routine surveillance of CKD, but it is indicated when there is a prior history of stones or obstruction, renal artery stenosis, frequent urinary tract infections, or family history of autosomal dominant polycystic kidney disease 1
- The findings from a renal ultrasound can help differentiate AKI from CKD by determining renal size and volume, which is essential for developing an effective treatment plan and improving patient outcomes 1
- Color Doppler can be used to assess global perfusion and confirm arterial and venous patency, providing valuable information for managing CKD patients and reducing the risk of complications 1
By prioritizing the use of renal ultrasound in CKD patients, healthcare providers can improve patient outcomes, reduce morbidity and mortality, and enhance quality of life. Therefore, I strongly recommend ordering a renal ultrasound as part of the initial workup for newly diagnosed CKD patients or when there is an unexplained decline in kidney function, as supported by the most recent and highest quality study 1.
From the Research
Reasons for Ordering Renal Ultrasound for CKD Patients
- To evaluate morphological changes in the kidneys, such as longitudinal diameter and cortical thickness, which can indicate CKD progression 2
- To assess patterns of vascularization using color-Doppler and contrast-enhanced ultrasound, providing information on parenchymal perfusion and patency of veins and arteries 2
- To measure renal resistive indexes (RIs), which can reflect vascular compliance and are associated with different primary diseases, as well as CKD progression 2
- To screen patients at risk for CKD and evaluate CKD progression, as ultrasound is useful for monitoring changes in kidney structure and function over time 2, 3
- To detect hydronephrosis, with longitudinal views of the kidney showing good sensitivity and specificity, although a combination of longitudinal and transverse views may be warranted in high-risk patients or those with inadequate visualization of the upper pole of the kidney 4
Ultrasound Techniques and Interpretation
- Conventional ultrasound allows for measurement of longitudinal diameter and cortical thickness, evaluation of renal echogenicity, and assessment of urinary tract status 2
- Color Doppler and spectral Doppler provide important information on intrarenal microcirculation and diagnosis of renal artery stenosis 2
- Contrast-enhanced ultrasound and dynamic contrast-enhanced MRI may permit assessment of renal function in the near future 3
- Awareness of common and unusual sources of potential error in renal ultrasound technique and interpretation is essential to avoid pitfalls 5