Amniotic fluid volume regulation

To better understand the mechanisms that regulate amniotic fluid (AF) volume, we measured AF volume and the rates of fetal swallowing and urination in 33 pregnant sheep at 124-142 days gestation. In four of five ewes over 9-18 days, the spontaneous changes in amniotic fluid volume correlated positively with urine flow rate and negatively with the rate of swallowing (R = 0.686, P less than 0.01), such that 47% of the AF volume changes could be attributed to changes in rates of urination and swallowing. Following infusion of one liter of isotonic amniotic saline (n = 12) or mannitol (n = 5), AF volume increased 110%, and after 24 h returned to the control value in the saline group but it remained elevated 59% above control in the mannitol group. AF sodium was unchanged following saline infusion but remained reduced following mannitol. Following withdrawal of 61% of AF over 20-40 min, AF volume averaged 51 and 71% of control at 24 and 48 h, respectively, whereas AF sodium was unchanged. Variations in rates of fetal swallowing or urine formation could not explain the entire changes in AF volume following either the volume infusion or withdrawal. These data suggest that AF volume is regulated within a relatively narrow range and fetal urine formation and swallowing together and transplacental fluid flux each appear to contribute equally to the regulation of AF volume.

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Amniotic fluid volume dynamics

Fetal and Maternal Medicine Review ◽

10.1017/s0965539500000486 ◽

1991 ◽

Vol 3 (2) ◽

pp. 89-104 ◽

Cited By ~ 23

Author(s):

William M Glibert ◽

Thomas R Moore ◽

Robert A Brace

Keyword(s):

Amniotic Fluid ◽

Fluid Volume ◽

Perinatal Morbidity ◽

Fluid Removal ◽

Embryonic Tissues ◽

Amniotic Fluid Volume ◽

Urine Production ◽

Fetal Urine ◽

Fluid Volume Regulation ◽

The Moment

From the moment of implantation until delivery some 37 weeks later, the human embryo or fetus is surrounded by fluid. Initially this fluid is a transudate from maternal and embryonic tissues which provides nutrients for the growing embryo. Starting in early pregnancy, the fetal kidneys begin to contribute substantial quantities of urine to the amniotic fluid volume. At mid pregnancy, when the skin becomes keratinized, the kidneys become the main source of amniotic fluid. Fetal swallowing is the main route of amniotic fluid removal. Although fetal urine production and swallowing have been studied in both human pregnancy and animal models, the knowledge from these investigations is not sufficiently extensive to explain overall amniotic fluid volume regulation. None the less, it is clear that the amniotic fluid is in a dynamic, ever-changing state. The production rate of the fetal urine in the human fetus at term (800–1200ml/day) is sufficient to replace completely the entire amniotic volume every 12–24 hours1. While the fetus is producing large volumes of urine, the volume of amniotic fluid is normally maintained within a very narrow range. Deviations from the normal range are often associated with significant perinatal morbidity and mortality.

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Sonographic Assessment of Amniotic Fluid Volume using Single Deepest Pocket (SDP) among Igbo Women with Uncomplicated Singleton Pregnancies.

10.33798/ajmas2019/00265. ◽

2019 ◽

Vol 2 (1) ◽

pp. 1-18

Author(s):

Chijioke Okeudo ◽

B.U. Ezem

Keyword(s):

Amniotic Fluid ◽

Gestational Age ◽

Cross Sectional Study ◽

Fluid Volume ◽

Singleton Pregnancy ◽

Cross Sectional ◽

South Eastern ◽

Amniotic Fluid Volume ◽

The Mean ◽

Singleton Pregnancies

Background: The amniotic fluid is fundamental for proper fetal development and growth. Ultrasound visualization of the amniotic fluid permits both subjective and objective estimates of the amniotic fluid. Objective: The objective of this study was to determine the reference values of normal single deepest pocket (SDP) – upper and lower limits, mean SDP and variation of the SDP with gestational age among Igbo women of South-Eastern Nigeria extraction carrying uncomplicated singleton pregnancy. Methodology: This was a prospective cross sectional study involving 400 women carrying uncomplicated singleton pregnancies and who were sure of the date of the first day of their last menstrual period. The single deepest pocket / maximum vertical pool were determined once at presentation at the hospital.. The study was conducted from January 1st to December 31st 2015. The second author carried out all the scanning. The SDP was obtained. Results: The womens’ mean and median ages were the same at 28 years. The gestational age range of the pregnancies was 14-41 weeks. The mean SDP was 5.8cm, while the 5th and 95th percentiles were 3.3cm and 8.5cm respectively. There was no difference in the mean SDP in both term and preterm. There was irregular but continuous rise of mean SDP to a peak of 6.8cm at gestational age of 39 weeks. In conclusion, the participants had a mean SDP of 5.8cm. There was also a positive correlation between SDP and Gestational age. We therefore recommend a longitudinal study to assess perinatal outcome and abnormal amniotic fluid volume among Igbo women of South-Eastern Nigeria. Key words: Single Deepest Pocket, Uncomplicated Singleton Pregnancy, Igbo Women.

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1129 How useful is assessment of amniotic fluid volume in antenatal surveillance of fetal growth restriction?

American Journal of Obstetrics and Gynecology ◽

10.1016/j.ajog.2020.12.1153 ◽

2021 ◽

Vol 224 (2) ◽

pp. S696

Author(s):

Lauren Sayres ◽

Camille Driver ◽

Xinyi Yang ◽

Mary Sammel ◽

Heather Straub ◽

...

Keyword(s):

Amniotic Fluid ◽

Fetal Growth ◽

Fetal Growth Restriction ◽

Fluid Volume ◽

Growth Restriction ◽

Amniotic Fluid Volume

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Fetal hyperechogenic kidney with normal amniotic fluid volume: a diagnostic dilemma

Prenatal Diagnosis ◽

10.1002/pd.1185 ◽

2005 ◽

Vol 25 (7) ◽

pp. 553-558 ◽

Cited By ~ 23

Author(s):

R. Mashiach ◽

M. Davidovits ◽

B. Eisenstein ◽

D. Kidron ◽

M. Kovo ◽

...

Keyword(s):

Amniotic Fluid ◽

Fluid Volume ◽

Diagnostic Dilemma ◽

Amniotic Fluid Volume

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