Assessment of Amniotic Fluid: SDP (DVP) or AFI — Choosing the Method for Oligohydramnios and Polyhydramnios
Methods for Assessing Amniotic Fluid Volume
According to ISUOG Practice Guidelines for conducting ultrasound in the third trimester (2024), amniotic fluid volume should be assessed using one of two methods:
- Subjectively — as 'normal' or 'abnormal' (decreased or increased).
- Semi-quantitatively — by measuring the maximum vertical pocket (DVP, deepest vertical pocket) or amniotic fluid index (AFI).
Amniotic Fluid Index (AFI)
AFI is a semi-quantitative assessment method representing the sum of vertical measurements of fluid pockets in four quadrants of the uterus. As defined in Ultrasound in Obstetrics & Gynecology (Vol. 63, No. 2, 2024), AFI is calculated as the sum of the deepest, unobstructed vertical fluid pockets measured in each of the four quadrants.
Maximum Vertical Pocket (DVP/SDP)
To measure DVP, the largest vertical pocket of amniotic fluid is identified, which is free from fetal parts and umbilical cord loops.
Choice of Method: DVP or AFI
| Clinical Situation | Preferred Method |
|---|---|
| Polyhydramnios assessment | AFI |
| Oligohydramnios assessment | DVP (maximum vertical pocket) |
This recommendation is consistently presented in the ISUOG Practice Guidelines (2024) and in Ultrasound in Obstetrics & Gynecology (Vol. 63, No. 1, 2024).
Threshold Values
Specific numerical thresholds for the diagnosis of oligohydramnios and polyhydramnios using AFI or DVP are not presented in the source fragments [to be clarified according to original guidelines].
Frequently asked questions
Which method should be preferred when polyhydramnios is suspected?
For polyhydramnios assessment, AFI is preferred (ISUOG, 2024).
Which method should be preferred when oligohydramnios is suspected?
For oligohydramnios assessment, DVP — maximum vertical pocket is preferred (ISUOG, 2024).
How is AFI calculated?
AFI is the sum of vertical measurements (deepest, unobstructed vertical pockets) of fluid in four quadrants of the uterus.
How is DVP correctly measured?
The largest vertical pocket of amniotic fluid is measured, which is free from fetal parts and umbilical cord loops.
What are the numerical thresholds for oligohydramnios and polyhydramnios?
Specific numerical thresholds are not provided in the source fragments — clarification is required according to original guidelines [to be clarified].