Why do undescended testes and posterior urethral valve occur together?

BACKGROUND/AIM: Undescended testis (UDT) occurs in ~2 % of newborn males, and occasionally these infants also have posterior urethral valve (PUV). The cause of this relationship is uncertain. We aimed to review the literature to identify publications documenting co-occurrence of UDT and PUV, and to summarise the theories of co-occurrence.

METHODS: A search of the literature (Embase, Medline, Pubmed; 1947-2015) was undertaken to identify publications describing the link between UDT in PUV patients, as well as PUV in UDT patients. Ten publications in English were found with both UDT and PUV: 9 articles describing the frequency of UDT in patients with PUV, and 1 article examining the frequency of PUV in infants with UDT.

RESULTS: UDT occurred in 12-17 % of PUV compared with 1-2 % in the control population, consistent with a 10-fold increase. PUV occurred in 1.2 % of UDT patients compared with 0.01 % in the control population, consistent with a 100-fold increase.

DISCUSSION: PUV leads to a 10-fold increase in occurrence of UDT, while the presence of UDT causes a 100-fold increase in occurrence of PUV. Four main theories of causation have been proposed, each of which have some merit but little supporting evidence, leaving the cause of simultaneous occurrence of PUV and UDT uncertain.