Fetal blood gas changes in red-cell transfusion in alloimmunization

PURPOSE: the aim was to study Rh-alloimmunized pregnant women and describe the gasometric abnormalities and the fetal acid-base changes before and after intrauterine transfusion. METHODS: between June 2001 and October 2001, before and after intrauterine transfusion in the alloimunized fetuses, gasometric data and acid-base parameters were prospectively studied in the umbilical vein blood. The measurements were performed in 8 samples of 5 fetuses. The fetal blood was obtained by cordocentesis before and after the intrauterine transfusion. The results were compared to the volemic expansion, the gestational age at procedure, the estimated fetal weight and the hemoglobin values (g/dL). RESULTS: all the cases showed pH value reduction, mean of 0.09 (SD=0.02). The fetal hemoglobin value showed a mean improvement of 8.4 g/dL (SD=2.9 g/dL). The pO2 and HCO3- concentrations showed negative variation (mean deltapO2 = -1.28 mmHg, mean deltaHCO3- = -2.25 mEq/L). pCO2 showed improvement (mean deltapCO2 = 3.2 mmHg) and reduced values of base excess occurred (mean = -3.75). CONCLUSION: the gasometric analysis allows to conclude that intrauterine transfusion is followed by pH reduction in the umbilical vein, with relative fetal acidemia after the procedure.

Rh alloimunization; Intrauterine transfusion; Fetal gasometry

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