Amniotic Fluid Index (AFI)

Amniotic Fluid Index (AFI) is measured by ultrasound summing the deepest vertical pocket in four uterine quadrants. A normal AFI is generally 5–25 cm. Values below 5 cm suggest oligohydramnios (low fluid) and values above 25 cm indicate polyhydramnios (excess fluid). Abnormal AFI prompts further monitoring and evaluation based on gestational age and cause.

An AFI of 20 cm is generally considered normal. It is well above oligohydramnios cutoffs (about <5 cm) and below common polyhydramnios thresholds (around 24–25 cm). Clinicians will interpret this with gestational age, clinical context and maternal health; routine follow-up ultrasounds or fetal surveillance are typically only advised if risk factors or symptoms are present.

Q1–Q4 refer to the four abdominal ultrasound quadrants. Q1: right upper quadrant (liver, gallbladder, right kidney); Q2: left upper quadrant (spleen, stomach, left kidney); Q3: left lower quadrant (descending/sigmoid colon, ovary, ureter); Q4: right lower quadrant (appendix, cecum, right ovary, ureter). Clinicians use these to localize pathology during scanning and reporting.

At 34 weeks, a normal amniotic fluid index (AFI) is about 8–18 cm. An AFI ≤5 cm indicates oligohydramnios; an AFI ≥24–25 cm suggests polyhydramnios. If your AFI is outside the normal range, your care team may repeat ultrasounds, monitor fetal well‑being, and discuss causes and treatment options. Contact your healthcare provider promptly for personalized guidance.

Yes, increasing maternal fluid intake can raise AFI temporarily. Oral or IV hydration has been shown to increase amniotic fluid volume within hours and is often used as initial management for mild oligohydramnios. Effects may be transient, so persistent low AFI requires obstetric evaluation and monitoring for underlying causes. Follow your healthcare provider’s guidance on hydration and treatment.

An AFI above about 24–25 cm is considered high (polyhydramnios). Mild polyhydramnios is usually 25–30 cm, while values over 30 cm indicate severe polyhydramnios. Elevated AFI warrants evaluation for maternal diabetes, fetal anomalies, infections, or multiple pregnancy, and close monitoring. Management may include ultrasound surveillance, maternal glucose testing, and interventions such as amnioreduction in severe cases.