Small size-specific umbilical vein diameter in severe growth restricted fetuses that die in utero.

Background: To study changes in umbilical vein (UV) blood flow velocity, diameter and blood flow volume in intrauterine growth retardation (IUGR) fetuses who die in utero (IUD-IUGR).

Methods: Twelve singleton IUGR fetuses who died in utero below 600 g were included. All cases had abnormal uterine and umbilical arteries PI. UV diameter and velocity were measured at the time of diagnosis, and at the last exam, within 24 hours prior to intrauterine death. UV flow was calculated per unit weight (mL/min/kg) and abdominal circumference (AC) (mL/min/cm). UV diameter and velocity were normalized per unit AC. Findings were compared to 14 severe viable-IUGR and 22 normal gestational age-matched fetuses.

Results: UV flow (mL/min/kg) was significantly lower in IUD-IUGR compared to viable-IUGR (87 +/- 30 mL/min/kg) and control fetuses (131 +/- 33 mL/min/kg) both at the first (79 +/- 40 mL/min/kg) (P < 0.0001), and at the last exam (54 +/- 29 mL/min/kg) (P < 0.0001). No significant longitudinal flow changes were observed. UV velocity/AC was significantly reduced both in IUD-IUGR and viable-IUGR compared to normal fetuses. UV diameter/AC, was significantly reduced only in IUD-IUGR and not in viable-IUGR compared to normal fetuses.

Conclusions: UV flow (mL/min/kg) was significantly lower in IUD-IUGR fetuses both versus viable-IUGR and normal fetuses. A low flow was due to a decreased UV flow velocity, but also due to a reduced vessel size. This significantly smaller UV size observed in IUGR fetuses with the worst outcome could be considered a severe prognostic sign because of the diagnosis of severe growth restriction.