NORMAL RENAL ARTERY PULSATILITY INDEX

• The flow velocity waveforms of the renal vessels are dependent on the vessel that is insonated (main trunk, lobar or arcuate branches).
• The PI must be used to assess the renal artery because the end-diastolic velocity is often absent in the second and early third trimester.

Week of gestation	5th percentile	50th percentile	95th percentile
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42	1.57 1.55 1.54 1.52 1.50 1.48 1.46 1.44 1.42 1.40 1.38 1.36 1.34 1.32 1.30 1.28 1.25 1.23 1.21 1.19 1.16	2.48 2.46 2.44 2.42 2.40 2.38 2.35 2.33 2.31 2.29 2.27 2.25 2.23 2.21 2.19 2.17 2.15 2.13 2.11 2.08 2.06	3.39 3.36 3.34 3.32 3.29 3.27 3.25 3.23 3.20 3.18 3.16 3.14 3.12 3.10 3.08 3.06 3.04 3.02 3.00 2.98 2.96