A COMPARISON OF UMBILICAL-CORD BLOOD-GAS VALUES BETWEEN NEWBORNS WITHAND WITHOUT TRUE KNOTS

Objective: To compare umbilical cord blood gas values in newborns with and without true knots, and to assess the potential impact of true kn ot formation on cord blood gases. Methods: Twelve newborn infants with true umbilical cord knots were identified and compared with a random control population of 104 newborn infants without true knots. The two groups were analyzed for 11 maternal-fetal variables to determine if t hey were comparable. Subsequently, the principal outcome variable of t he study was evaluated: a comparison between the umbilical arterial an d venous blood gas results of the true knot and control populations. R esults: The true knot and control populations were comparable with res pect to the maternal-fetal variables analyzed. The umbilical cord bloo d gas values did not differ between groups, except for a slightly lowe r umbilical artery bicarbonate value in the control group (22.0 mEq/L) versus the true knot group (24.5 mEq/L), P = .025. There was no signi ficant difference in the incidence of acidemia (umbilical artery pH le ss than 7.20) between the two groups. Conclusion: The presence of true umbilical cord knots does not alter the incidence of umbilical artery acidemia or change umbilical cord blood gas values. Review of the per tinent obstetric literature supports the hypothesis that true umbilica l cord knots lack clinical significance.