Hemolytic disease of the fetus: a comparison of the Queenan and extended Liley methods

Abstract

Objective: To compare the clinical utility of the Liley and Queenan methods to monitor the severity of fetal hemolytic disease. Methods: Amniotic fluid bilirubin was measured in specimens from 73 women sensitized to red blood cell antigens. Chloroform-extracted amniotic fluid was evaluated spectrophotometrically for bilirubin content by using the change-from-expected value of the optical density at 450 nm. Values in the four Queenan zones were compared with those of the four zones of the Liley graph (middle zone subdivided). Clinical utility and accuracy of the two methods were compared. Results: Treatment was based on interpretation of bilirubin values plotted on the Liley graph. Hydrops fetalis was not observed. The highest value for each patient was significantly more likely to be plotted in the highest zone using the Queenan method (23 of 73 compared with eight of 73 patients; P < .001). Overestimation of risk occurred with greater frequency when using the Queenan method (13 of 67 compared with seven of 67 patients; P = .031). Overestimation of risk by the Queenan method also was more likely at or before 28 weeks’ gestation (10 of 49 compared with four of 49 patients; P = .031). In nine cases (13%), the Queenan graph and method would have prompted unnecessary or premature umbilical vein sampling that was withheld using the Liley graph. Conclusion: The performance of the linearly extended Liley graph was superior to that of the Queenan graph, because the Queenan method frequently overestimated risk.