Complete unilateral ureteral obstruction in the fetal lamb. Part I: long-term outcomes of renal hemodynamics and anatomy.

Purpose: We evaluated the long-term consequences of complete fetal UUO on renal hemodynamics and anatomy.
Materials and Methods: A total of 26 fetal lambs underwent surgical UUO at 90 days of gestation and 14 twin matched animals served as controls. Synchronous bilateral ARBF was measured using mean transit time technology. Standard anatomical analysis, including evaluation of RPV, was performed in the kidneys. Measurements were done 10, 20 and 40 days following UUO in groups 1 to 3, respectively and in 1-month-old lambs in group 4.
Results: All obstructed kidneys underwent typical hydronephrotic transformations with a progressive decrease in parenchymal volume compared to that of contralateral and control kidneys. ARBF in obstructed kidneys was significantly decreased compared to their contralateral counterparts in all groups (p <0.01). Comparing ARBF to RPV showed that the decrease in ARBF was proportional to the loss of parenchymal volume in fetal obstructed kidneys but it remained significant in lambs (p <0.05).
Conclusions: Complete UUO alters ARBF, while vascularization of the remaining renal parenchyma is maintained in fetuses. Profound impairment of the renal arterial supply observed in lambs may be due to physiological changes linked to birth.