It involves a complex process comprising 3-pairs of embryogenic veins: posterior cardinal (iliac and confluent), subcardinal
(renal and hepatic) and supracardinal (prerenal).
The supra-renal segment develops from the right subcardinal
vein and the infra-renal segment develops from the right supracardinal vein.
During early embryogenesis, the posterior supracardinal and more anterior subcardinal
veins are formed.
Three paired venous channels that develop sequentially (posterior cardinal, subcardinal
, supracardinal) anastomose and regress (1).
7) It is postulated that the subcardinal
and supracardinal system form extensive anastomotic channels at the level of the renal vein and that the persistence of one of these midline anastomoses could result in pelviureteric junction obstruction; however, the occurrence of these anomalies in a case of CDH has not been reported before.