Intravascular transfusion of fetuses with rhesus incompatibility: Prediction of fetal outcome by changes in umbilical venous pressure

Objective: We examined whether abnormal elevations in umbilical venous pressure during intravascular transfusion predict post-transfusion mortality. Methods: Umbilical venous pressures were measured during intravascular transfusion of human fetuses with Rhesus incompatibility. Five fetuses died within 24 hours after transfusion and nine fetuses survived the procedure. Results: Survivors and non-survivors were similar in demographic and clinical data, as well as in transfusion characteristics. The only difference between the groups was the change in umbilical venous pressure during the transfusion: 5.0 ± 6.3 mmHg for survivors versus 18.1 ± 10.4 mmHg for non-survivors (P = .01). An increase in the umbilical venous pressure of 10 mmHg or more predicted fetal death with a sensitivity of 80% and specificity of 89%. Conclusion: Based on these results, we have modified our transfusion technique. If the change in umbilical venous pressure during intravascular transfusion approaches 10 mmHg, we discontinue the procedure. If the change in pressure exceeds 10 mmHg during transfusion, we remove blood and replace it with an equal volume of saline.