Background: Fetal death and neurologic damage have been observed after open fetal surgery for diaphragmatic hernia in human fetuses, and may be related to changes in fetoplacental blood flow in the early postoperative period. This study was designed to assess changes in fetoplacental blood flow after this procedure and the relationship to outcome.

Methods: Fifteen human fetuses (mean gestational age 25 wks, range 21-28 wks) were studied before and 1 day after open fetal surgery for diaphragmatic hernia, using 2-dimensional and pulsed-Doppler ultrasound. Hemodynamic variables measured or calculated were umbilical venous (UV) flow, UV flow velocity, diastolic umbilical arterial (UA) flow velocity, UA AB-ratio, and UA resistance index. Postoperative neurologic damage was assessed with prenatal head ultrasound and/or postnatal evaluation. Variables were analyzed for correlation with death and neurologic damage.

Results: There were no properative hemodynamic differences between fetuses that died (n=10) and survivors (n=5) or between patients that did (n=5) and did not (n=10) develop neurologic injury. On the day after surgery, UV flow was significantly lower in the 10 fetuses that died than in the 5 survivors(200±86 mL/min vs 347±86 mL/min; p=0.03), as was UV flow velocity (9.8±2.6 cm/sec vs 14.0±5.2 cm/sec; p=0.05). In addition, the diastolic UA flow velocity was significantly lower(4.5±1.7 cm/sec vs 7.7±2.4 cm/sec; p=0.03) and the UA resistance index higher (0.83±0.06 vs 0.72±0.07; p=0.03) in fetuses that suffered neurologic damage. Accordingly, there was also a strong tendency towards a higher AB-ratio in these fetuses (6.6±2.5 vs 4.2±0.07; p=0.06).

Conclusion: Fetal death and neurological damage are associated with low UV blood flow and increased placental resistance on the day after open fetal surgery for diaphragmatic hernia. Strategies to enhance fetoplacental blood flow and optimize fetal oxygen delivery may improve outcome.