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How frequently should the amniotic fluid index be repeated?
D C Lagrew1, R A Pircon, M Nageotte
1Division of Perinatal Medicine, Women's Hospital, Long Beach Memorial Medical Center, CA.
American Journal of Obstetrics and Gynecology
|October 1, 1992
Summary
For pregnant patients under 41 weeks with a normal amniotic fluid index (AFI), a repeat AFI measurement is not needed for 7 days. This interval helps optimize antepartum testing schedules.
Area of Science:
- Maternal-Fetal Medicine
- Obstetrics
- Fetal Monitoring
Background:
- Accurate assessment of amniotic fluid volume is crucial for fetal well-being.
- The amniotic fluid index (AFI) is a common method for assessing amniotic fluid volume.
- Optimal timing for repeat AFI measurements is debated, impacting antepartum testing protocols.
Purpose of the Study:
- To determine the most appropriate interval for repeat amniotic fluid index (AFI) assessments.
- To evaluate the risk of developing oligohydramnios based on AFI values and gestational age.
Main Methods:
- Retrospective analysis of 10,742 amniotic fluid indexes from antepartum testing patients.
- Comparison of AFI values with follow-up values within 4 days for 7393 patients.
- Stratification of results by AFI, gestational age, and nonstress test (NST) findings, with chi-squared analysis.
Main Results:
- Patients with normal AFI (≥8 cm) had a 0.54% risk of oligohydramnios within 4 days.
- Patients with low-normal AFI (5-8 cm) had a 5% risk, while those with low AFI (≤5 cm) had a 59% risk of persistent oligohydramnios.
- For patients ≥41 weeks with AFI 8-15 cm, the risk of oligohydramnios within 4 days was 2.6%; NST results did not significantly alter risk.
Conclusions:
- In patients under 41 weeks' gestation with normal AFI, a repeat AFI is not necessary for 7 days.
- This finding supports extending the interval for AFI re-evaluation in low-risk pregnancies.
- Optimized AFI assessment intervals can improve the efficiency of antepartum surveillance.