Sonographic differential diagnosis of duplex kidneys

Area of Science:

• Urology
• Pediatric Nephrology
• Medical Imaging

Background:

• Duplex kidneys possess two renal pelvises and ureters, with variations in their joining or bladder entry.
• Distinguishing normal from pathological duplex kidneys is crucial for appropriate clinical management.
• Pathological duplex kidneys occur in approximately 50% of cases, presenting with specific structural abnormalities.

Purpose of the Study:

• To delineate the differentiating features between normal and pathological duplex kidney anatomies.
• To highlight the common characteristics and potential complications associated with pathological duplex kidneys.
• To emphasize the importance of identifying associated conditions like megaureters, ureteroceles, and ectopic ureteral openings.

Main Methods:

• Review of anatomical variations in duplex kidneys.
• Clinical and imaging feature analysis to distinguish normal from pathological presentations.
• Differential diagnosis considerations for complex cases, including cystic alterations.

Main Results:

• Normal duplex kidneys exhibit normal-width pelves and ureters without dilation or cystic changes.
• Pathological duplex kidneys are identified by dilation of renal pelvises and/or ureters (megaureters), which can be obstructive or refluxive.
• Hypoplasia of one renal pole, especially the upper pole, is a strong indicator of a pathological duplex kidney, often linked to obstructive megaureter; lower pole hypoplasia is associated with vesicoureteral reflux.

Conclusions:

• Pathological duplex kidneys require differentiation from normal variants due to potential complications.
• Associated conditions such as megaureters, ureteroceles, and ectopic ureteral openings must be ruled out in pathological cases.
• Segmental multicystic dysplastic duplex kidney and segmental multicystic nephroma are important differential diagnoses in rare cases with cystic alterations.