How frequently should the amniotic fluid index be repeated?
OBJECTIVE
Our objective was to determine the most appropriate interval for assessing amniotic fluid volume with amniotic fluid index.


METHODS
In a retrospective analysis amniotic fluid indexes performed every 3 to 4 days in antepartum testing patients were compared with their follow-up values. Of 10,742 amniotic fluid indexes there were 7393 with follow-up values within 4 days. The results were stratified by current amniotic fluid index, gestational age, and concurrent nonstress test results. The groups were compared with chi 2 analysis.


RESULTS
Patients with normal amniotic fluid index (> or = 8 cm) had a 0.54% chance of oligohydramnios developing in the next 4 days. Those patients with low normal amniotic fluid indexes (5 to 8 cm) had a 5% chance of oligohydramnios developing within the next 4 days, and patients with low amniotic fluid indexes (< or = 5 cm) had a 59% chance of persistent oligohydramnios 4 days after the index examination. Subdividing by gestational age demonstrated that patients > or = 41 weeks' gestation had a 2.6% chance of oligohydramnios developing within 4 days if current amniotic fluid index was between 8 and 15 cm. Results of concurrent fetal heart rate findings did not appear to change the risk for development of oligohydramnios.


CONCLUSIONS
In patients < 41 weeks' gestation with normal amniotic fluid indexes, a repeat amniotic fluid index is not necessary for 7 days.
Lagrew
D C
DC
Division of Perinatal Medicine, Women's Hospital, Long Beach Memorial Medical Center, CA.
Pircon
R A
RA
Nageotte
M
M
Freeman
R K
RK
Dorchester
W
W
D000653:Amniotic Fluid / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006801:Humans; D016104:Oligohydramnios / Q000175:diagnosis; D011247:Pregnancy; D011295:Prenatal Care / Q000379:methods*; D011296:Prenatal Diagnosis; D012189:Retrospective Studies