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Unified criteria for ultrasonographic diagnosis of ADPKD
York Pei1, James Obaji, Annie Dupuis
1Division of Nephrology, University of Toronto, 8N838, 585 University Avenue, Toronto, Ontario, Canada. york.pei@uhn.on.ca
Insights
New ultrasound criteria improve autosomal dominant polycystic kidney disease (ADPKD) diagnosis, especially for PKD2 mutations. These guidelines enhance accuracy in at-risk individuals when genetic testing isn't available.
Area of Science:
- Nephrology
- Medical Genetics
- Diagnostic Imaging
Background:
- Autosomal dominant polycystic kidney disease (ADPKD) screening relies on ultrasound criteria.
- Current criteria, based on PKD1 mutations, may be suboptimal for PKD2 mutations, which cause milder disease.
- Accurate ADPKD diagnosis is crucial for at-risk individuals, particularly when genetic testing is not feasible.
Purpose of the Study:
- To evaluate and refine ultrasound diagnostic criteria for ADPKD.
- To develop unified criteria applicable to both PKD1 and PKD2 mutations.
- To improve diagnostic accuracy in at-risk populations undergoing routine screening.
Main Methods:
- Retrospective analysis of renal ultrasound and molecular genotyping data from 948 at-risk individuals across 97 families (58 PKD1, 39 PKD2).
- Comparison of various diagnostic criteria using sensitivity and specificity data from genetically confirmed affected and unaffected individuals.
- Simulation of expected PKD1/PKD2 case mix to assess criteria performance in families of unknown genotype.
Main Results:
- Existing diagnostic criteria showed reduced sensitivity for individuals with PKD2 mutations.
- Proposed unified criteria demonstrated improved performance across different age groups and genotypes.
- Specific cyst count thresholds were identified for diagnosis and exclusion in various age brackets (15-39, 40-59, ≥60 years).
Conclusions:
- Current ADPKD ultrasound screening criteria are suboptimal for PKD2 mutations.
- Unified diagnostic criteria incorporating age-specific cyst counts enhance diagnostic accuracy for ADPKD.
- These refined criteria are valuable for routine clinical screening of at-risk individuals, especially when genetic testing is unavailable.
Abstract:
Individuals who are at risk for autosomal dominant polycystic kidney disease are often screened by ultrasound using diagnostic criteria derived from individuals with mutations in PKD1. Families with mutations in PKD2 typically have less severe disease, suggesting a potential need for different diagnostic criteria. In this study, 577 and 371 at-risk individuals from 58 PKD1 and 39 PKD2 families, respectively, were assessed by renal ultrasound and molecular genotyping. Using sensitivity data derived from genetically affected individuals and specificity data derived from genetically unaffected individuals, various diagnostic criteria were compared. In addition, data sets were created to simulate the PKD1 and PKD2 case mix expected in practice to evaluate the performance of diagnostic criteria for families of unknown genotype. The diagnostic criteria currently in use performed suboptimally for individuals with mutations in PKD2 as a result of reduced test sensitivity. In families of unknown genotype, the presence of three or more (unilateral or bilateral) renal cysts is sufficient for establishing the diagnosis in individuals aged 15 to 39 y, two or more cysts in each kidney is sufficient for individuals aged 40 to 59 y, and four or more cysts in each kidney is required for individuals > or = 60 yr. Conversely, fewer than two renal cysts in at-risk individuals aged > or = 40 yr is sufficient to exclude the disease. These unified diagnostic criteria will be useful for testing individuals who are at risk for autosomal dominant polycystic kidney disease in the usual clinical setting in which molecular genotyping is seldom performed.
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