Fetal Renal Artery

The fetal renal artery can undergo Doppler interrogation in the same way that other fetal vessels are evaluated. It is unique in that it can reflect changes occurring in the peripheral circulation and differences in flow can be associated with fluctuations in the amniotic fluid volume. During the embryonic stage, a new renal artery develops with each new stage of renal development and also as the final kidney ascends from the pelvis into the renal fossa at the level of the lumbar spine. Although there can be more than one renal artery, there is usually one renal artery branching off the aorta on each side, which allows adequate assessment of total renal blood flow. The renal blood flow is a high resistance system which gradually decreases with advancing gestation. Evidence suggests that assessment of the renal artery reflects chronic redistribution of peripheral blood flow associated with fetal growth restriction and specificity may be improved by indexing velocity of flow to estimated fetal weight. Identification of the renal vascular pedicle is helpful in determining the presence and position of the kidneys in cases of oligo or anhydramnios. To date, renal artery flow and resistance to flow have had limited utility in clinical management. Most of its use is related to research of fetal physiology in health and disease. Further research regarding the variations in renal flow under various clinical circumstances may enhance its use in clinical practice.