The peak height at 450 nm (? OD450) of amniotic fluid is obtained before the thirty-second week of pregnancy. This is divided into one of three decision groups based on the peak height.
Two or more determinations recommended for valid prognostication, since a single test result can be misleading.
continued observation, with vaginal delivery at or near term
0.07 - 0.17
delivery should be accomplished between the end of the 34th week and beginning of the 38th week
immediate therapy, either intrauterine exchange if under 34 weeks or premature delivery if over 34 weeks
The first group had 100% survival, with some requiring intrauterine transfusion.
The second group showed about 75% survival with many infants requiring intrauterine transfusions. If sequential determinations of the ?OD450 are performed
(1) Those with the ? OD450 decreasing by at least 0.01 units per week had the lowest mortality (11%)
(2) Those with the ? OD450 increasing by at least 0.01 units per week had the highest mortality rate (64%)
(3) Those with the ?OD450 stable (not decreasing or increasing by more than 0.01 unit per week) had an intermediate mortality rate (31%)
The third group can be further subdivided into 3 groups (0.18 - 0.30, 0.31- 0.40, > 0.40) with increasing fetal mortality and need for intrauterine transfusion.
• The mortality rates observed today (almost 30 years later) would be decreased due to better intrauterine and neonatal management. However, the relative severity of the different groups are still pertinent.
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Specialty: Obstetrics & Gynecology, Clinical Laboratory