Amniotic fluid volume
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View The Radswiki's current disclosuresAt the time the article was last revised Tariq Walizai had no financial relationships to ineligible companies to disclose.
View Tariq Walizai's current disclosures- Amniotic fluid volume
- Amniotic fluid volumes
- Volume of amniotic fluid
- Amniotic fluid volume (AFV)
- Amniotic fluid volumes (AFV)
- Liquor volume
- Liquor volumes
Amniotic fluid volume (AFV) is a function both of the amount of water transferred to the gestation across the placental membrane, and the flux of water across the amnion.
On this page:
Physiology
Change in volume through gestation
The AFV undergoes characteristic changes with gestation. It progressively rises.
10 weeks gestation: ~10-20 mL
16 weeks gestation: ~250 mL
33 weeks gestation: ~800 mL
38-39 weeks: plateaus at ~1000 mL
finally decreases at 40 weeks to ~800 mL
Rate of change
At 8 weeks the volume increases by ~10 mL/week, at 13 weeks the AFV increases by 25 mL/week and reaches a maximum rate of 60 mL/week at 21 weeks gestation. The weekly volume increment then decreases and reaches zero at about 33 weeks of gestation at which point the mean AFV reaches its peak. After this point, the amniotic fluid volume declines at a rate of ~8% per week. During the first half of pregnancy, the amniotic fluid volume is closely correlated with fetal weight. The ratio of amniotic fluid to fetal volume increases until about 30 weeks of gestation and then appears to decline.
Radiographic features
Ultrasound
Ultrasound is the modality of choice of assessing amniotic fluid volumes. The AFV can be assessed by ultrasound by using three main indirect parameters:
See also
References
- 1. Gramellini D, Fieni S, Verrotti C, Piantelli G, Cavallotti D, Vadora E. Ultrasound Evaluation of Amniotic Fluid Volume: Methods and Clinical Accuracy. Acta Biomed. 2004;75 Suppl 1:40-4. - Pubmed
- 2. Brace R. Physiology of Amniotic Fluid Volume Regulation. Clinical Obstetrics and Gynecology. 1997;40(2):280-9. doi:10.1097/00003081-199706000-00005 - Pubmed
- 3. Beall M, van den Wijngaard J, van Gemert M, Ross M. Regulation of Amniotic Fluid Volume. Placenta. 2007;28(8-9):824-32. doi:10.1016/j.placenta.2006.12.004 - Pubmed
- 4. Ursula Knoll (Editor), Michael Entezami (Editor), Sanyukta Runkel (Translator). Ultrasound Diagnosis of Fetal Anomalies. (2003) ISBN: 1588902129 - Google Books
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