Never Neglect Amniotic Fluid Index During Prenatal Checkups – The Barometer of Fetal Health
- Elva Chen
- 2 minutes ago
- 1 min read
Amniotic fluid is known as life-sustaining liquid in pregnancy, serving as protective cushion and nutritional supply for the fetus. Nutrients pass through the placenta, and fetal urine is the main source of amniotic fluid.
The Amniotic Fluid Index (AFI) is a core ultrasound indicator to check amniotic volume, reflecting fetal intrauterine condition and warning hidden pregnancy risks.
Definition & Normal Range of AFI
AFI is calculated by summing the maximum vertical amniotic depth measured in four uterine quadrants via B-ultrasound, routinely tested after 28 weeks of gestation when amniotic volume is adequate.
Normal range: 8–25 cm; oligohydramnios (low fluid): below 5 cm; polyhydramnios (excess fluid): over 30 cm.
Why AFI screening matters
Abnormal AFI hints fetal malformations or gestational complications, helping doctors arrange pregnancy management and delivery plans.
Polyhydramnios (AFI＞30cm)
Causes: fetal neural tube/digestive tract defects, chromosomal anomalies; maternal gestational diabetes, hypertension, monozygotic multiple pregnancy.
Mild polyhydramnios (25–30cm): regular follow-up, limit sugar and water intake if fetus is healthy.
Severe polyhydramnios (＞35cm) with chest tightness or dyspnea: amniocentesis drainage for symptom relief. Pregnancy termination may be considered for severe fetal deformity based on gestational age and parental decision. Continuous fetal heart monitoring is required in labor to prevent premature membrane rupture and cord prolapse; C-section when necessary.
Oligohydramnios (AFI＜5cm, higher risk)
Causes: fetal urinary system malformation, chromosome disorders; maternal dehydration, hypertension, placental insufficiency; premature rupture of membranes, post-term pregnancy over 42 weeks.
Mild low fluid (5–8cm): increase oral fluid or intravenous hydration plus regular ultrasound review with normal fetus.
Expectant mothers need not panic with abnormal AFI. Regular prenatal visits help identify root causes for personalized clinical management.
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