DEVIATION IN AMNIOTIC-FLUID OPTICAL-DENSITY AT A WAVELENGTH OF 450 NMIN RH-IMMUNIZED PREGNANCIES FROM 14 TO 40 WEEKS GESTATION - A PROPOSAL FOR CLINICAL MANAGEMENT

OBJECTIVES: Our purpose was to study deviations in values of amniotic fluid optical at 450 nm in Rh-immunized pregnancies in the second and third trimesters and to propose a clinical management plan. STUDY DESI GN: A total of 789 amniotic fluid single and serial values of deviatio ns in optical density at 450 nm were performed on Rh-immunized pregnan cies from 14 to 40 weeks' gestation. The relationship of the deviation s in amniotic fluid values of optical density at 450 nm to varying deg rees of fetal disease were examined. RESULTS: In Rh-negative fetuses ( unaffected) amniotic fluid values rise until 22 to 26 weeks before dec reasing to term. In fetuses at risk of dying in utero, values are high er and trends rise. A clinical management plan was devised on the basi s of the amniotic fluid findings of deviations in optical density at 4 50 nm. CONCLUSIONS: A clinical management scheme consisting of four zo nes is outlined. Rh-negative fetuses have minimal invasive procedures. Fetuses at risk of death undergo early cordocentesis for evaluation a nd therapy. Values that fall in between can be separated into two zone s on the basis of the degree of risk.