Normal values for amniotic fluid index during uncomplicated twin pregnancy

Area of Science:

• Perinatology
• Maternal-Fetal Medicine
• Quantitative Ultrasound

Background:

• Amniotic fluid volume assessment is crucial in high-risk pregnancies.
• Twin pregnancies present unique challenges for monitoring fetal well-being.
• Standardized methods for assessing amniotic fluid index (AFI) in twins are needed.

Purpose of the Study:

• To establish normative gestational age trends for amniotic fluid index (AFI) in uncomplicated twin pregnancies.
• To provide a quantitative reference for AFI in twin gestations.
• To improve the diagnosis of oligohydramnios in twins.

Main Methods:

• Retrospective analysis of AFI measurements in 282 uncomplicated twin pregnancies (1985-1993).
• Amniotic fluid index measured via the four-quadrant deepest vertical pocket method.
• Linear regression analysis used to determine the relationship between gestational age and AFI.

Main Results:

• 1101 AFI measurements were analyzed between 25.5 and 40.5 weeks' gestation.
• Percentile values for AFI were established based on gestational age.
• The median AFI regression equation was determined: AFI = 19.4 - 0.12 x gestational age (P = .03).

Conclusions:

• Normative AFI trends for twin pregnancies have been established.
• These quantitative trends enhance the diagnosis of oligohydramnios in twins.
• The findings support a more reproducible assessment of amniotic fluid volume in twin gestations.