From the Guidelines
The Urinary Tract Dilation (UTD) classification system is the recommended staging system for renal ectasia in neonates. This system incorporates prenatal and postnatal imaging findings based on several key factors, including anterior-posterior renal pelvic diameter (APRPD), calyceal dilation, renal parenchymal thickness, renal parenchymal appearance, and bladder abnormalities 1. The UTD system provides a comprehensive framework for evaluating and grading the severity of renal ectasia, which is essential for determining the need for additional testing, intervention, and monitoring disease progression over time.
When evaluating neonates with suspected renal ectasia, ultrasound is the primary imaging modality, and the UTD classification should be documented in reports to guide clinical management decisions regarding follow-up intervals and potential surgical intervention. The UTD system has been recommended by a consensus group from many separate organizations to increase standardization of reporting and care 1.
Key features of the UTD system include:
- Anterior-posterior renal pelvic diameter (APRPD)
- Calyceal dilation with distinction between central and peripheral calyceal dilation postnatally
- Renal parenchymal thickness
- Renal parenchymal appearance
- Bladder abnormalities
By using the UTD classification system, healthcare providers can ensure standardized terminology and communication, which is critical for providing optimal care for neonates with renal ectasia 1.
From the Research
Staging Systems for Renal Ectasia in Neonates
There are several staging systems for renal ectasia in neonates, including:
- The Society for Fetal Urology (SFU) grading system, which categorizes hydronephrosis into grades 0 to 4 2
- The Urinary Tract Dilatation (UTD) classification system, which categorizes urinary tract dilatation into grades normal, P1, P2, and P3 3
- The Onen grading system, which determines specific detailed findings of significant renal damage and suggests who can safely be followed conservatively from who will need surgical intervention for UPJHN 2
- A four-stage classification system based on anteroposterior pelvic diameter: I < 1 cm, II 1-1.5 cm, III 1.6-2 cm, and IV > 2 cm 4, 5
- An alternative grading system (AGS) that categorizes hydronephrosis into grades 0 to 4 based on the degree of renal pelvis dilatation, caliceal dilatation, and renal parenchymal loss 6
Characteristics of Each Staging System
Each staging system has its own characteristics and limitations, including:
- The SFU grading system is operator-dependent and may not accurately reflect the severity of hydronephrosis 2
- The UTD classification system has better inter-observer agreement than the SFU system, but may still have limitations in terms of accuracy and reliability 3
- The Onen grading system is an accurate and easily reproducible grading system that has high sensitivity and specificity, but may not be widely used or accepted 2
- The four-stage classification system based on anteroposterior pelvic diameter is a simple and straightforward system, but may not capture the full complexity of renal ectasia in neonates 4, 5
- The AGS is a comprehensive system that takes into account multiple factors, including renal pelvis dilatation, caliceal dilatation, and renal parenchymal loss, but may be more complex and difficult to use than other systems 6
Clinical Implications of Each Staging System
The choice of staging system can have significant clinical implications, including:
- Determining the need for surgical intervention versus conservative management 2, 6
- Monitoring the progression of renal ectasia and adjusting treatment accordingly 4, 5
- Evaluating the effectiveness of treatment and making adjustments as needed 3
- Communicating with patients and families about the severity of renal ectasia and the recommended course of treatment 2, 6