Fetal origin of amniotic fluid polymorphonuclear leukocytes.

OBJECTIVE: Although polymorphonuclear leukocytes are the inflammatory cells most frequently recovered from the amniotic cavity in cases of suspected intrauterine infection, the source of these cells has not been definitively determined. We took advantage of the gender difference between the mother and her male fetus, and we report four cases in which amniotic fluid polymorphonuclear leukocytes were identified as fetal by fluorescence in situ hybridization with probes specific for X and Y chromosomes. Fetal membranes were intact at the time amniotic fluid was obtained in all cases. STUDY DESIGN: Amniotic fluid was obtained from women with male fetuses in premature labor with clinical or laboratory evidence of infection. Cytospin preparations of amniotic fluid samples with polymorphonuclear leukocytes were prepared and sequentially stained with fluorescent reagents. To determine which cells were polymorphonuclear leukocytes, all replicate samples were stained with the fluorescent nuclear stain 4'-6-diamidino-2-phenyl-indole. This allowed definition of the characteristic multilobed polymorphonuclear leukocytes nuclear morphologic features. The sample was then probed with a rhodamine-labeled probe specific for the X chromosome and a fluorescein-labeled probe specific for the Y chromosome to assess whether the polymorphonuclear leukocytes were male or female. RESULTS: Ninety percent to 99% of polymorphonuclear leukocytes identified by normal multiple lobed nuclear morphologic study on 4'-6-diamidino-2-phenyl-indole staining had an X and Y chromosome and were therefore fetal cells. CONCLUSIONS: These data demonstrate a fetal response during intraamniotic infection. Further investigation of the roles for maternal and fetal polymorphonuclear leukocytes in chorioamnionitis may provide valuable information about the critical interaction of the two immune responses in this setting.

Routine umbilical cord blood gas determinations?

Between 1986 and 1988, 1924 term nulliparous patients with spontaneous onset of labor were studied to assess the importance of obtaining umbilical cord blood gas levels on all deliveries. The umbilical cord arterial and venous pH values (expressed as mean +/- 2 SD) were 7.24 +/- 0.14 (n = 1694) and 7.32 +/- 0.12 (n = 1820), respectively. The incidence of newborn depression (1- or 5-minute Apgar score less than 7) was 14.1%; of these depressed newborns, the incidence of normal umbilical cord arterial pH values (greater than or equal to -2 SD) was 77.8%. Of the vigorous newborns, there was a 2.1% incidence of umbilical cord arterial blood acidemia. Umbilical cord arterial blood acidemia in vigorous newborns was not highly predictive of specific morbidity in the immediate newborn period. Regression analysis demonstrated the umbilical cord arterial pH to correlate best with the Apgar scores when compared with all other arterial or venous blood gas measurements. We reached the following conclusions: (1) that obtaining cord arterial pH values in vigorous newborns should be considered since the values will provide objective documentation or normal fetal acid base balance in 98% of infants. (2) Only a cord arterial pH determination is recommended since it reflects fetal or newborn status more accurately than all other measurements. Additional measurements increase the likelihood of abnormal results and do not contribute to neonatal management. (3) An umbilical cord blood pH value is extremely useful in ruling out the diagnosis of birth asphyxia in the depressed newborn.