Vaginal fluid index - The fifth amniotic pocket

Area of Science:

• Obstetrics and Gynecology
• Fetal Medicine
• Diagnostic Ultrasound

Background:

• The forebag, an amniotic fluid pocket anterior to the presenting fetal part, plays a role in assessing fetal well-being.
• Standard methods for amniotic fluid volume assessment include the amniotic fluid index (AFI) and maximal vertical pocket (MVP).

Purpose of the Study:

• To evaluate the feasibility of transvaginal ultrasound measurements of the forebag.
• To assess the correlation between forebag measurements and established amniotic fluid assessment methods (AFI and MVP).

Main Methods:

• A prospective study involving women with singletons, vertex presentation, and normal AFI at term.
• Transvaginal ultrasound was used to measure the three orthogonal planes of the forebag, defining the vaginal fluid index (VFI).
• Correlation analysis was performed between VFI, forebag measurements, AFI, and MVP.

Main Results:

• The study enrolled 292 out of 305 women (95.7%), with successful visualization of the vaginal pocket in 266 (91.1%) cases.
• Significant correlations were found between vaginal pocket measurements and VFI with both AFI and MVP (R = 0.38, P < 0.001; R = 0.3, P < 0.001).

Conclusions:

• A novel ultrasound variable, the vaginal fluid index (VFI), demonstrated high feasibility in clinical practice.
• VFI measurements show significant correlation with AFI and MVP, suggesting its potential utility in clinical decision-making regarding delivery timing.