Biomaterial Database

Early amniocentesis: alphafetoprotein levels in amniotic fluid, extraembryonic coelomic fluid and maternal serum between 8 and 13 weeks. 1991

N C Wathen, and P L Cass, and D J Campbell, and M J Kitau, and T Chard

Department of Gynaecology, St Bartholomew's Hospital, West Smithfield, London, UK.

OBJECTIVE The aim was to establish a normal range of alphafetoprotein (AFP) concentrations in amniotic fluid from 8 to 12 weeks gestation, and to determine any difference between AFP levels in amniotic fluid and extraembryonic coelomic fluid. METHODS 150 women had a transvaginal ultrasound guided amniocentesis before termination of an apparently normal first trimester pregnancy. Separately identified samples of amniotic fluid and extraembryonic coelomic fluid were obtained and assayed by radioimmunoassay for AFP. RESULTS In amniotic fluid, very high levels of AFP were present at 8 weeks, levels falling rapidly up to 10 weeks after which there was a slight rise. Thus over the period 8 to 10 weeks, there was a significant inverse correlation between amniotic fluid AFP and gestational age (r = 0.67; P less than 0.001). In extraembryonic coelomic fluid, by contrast there was no trend in AFP relative to gestational age. CONCLUSIONS The rapidly changing levels of AFP from 8 to 10 weeks as well as the small volume of the amniotic cavity makes the use of amniocentesis impracticable before 11 weeks gestation. The lack of any relation between AFP levels in amniotic fluid and extraembryonic coelomic fluid emphasises the importance of identifying the site of amniocentesis in the first trimester.

UI	MeSH Term	Description	Entries
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011261	Pregnancy Trimester, First	The beginning third of a human PREGNANCY, from the first day of the last normal menstrual period (MENSTRUATION) through the completion of 14 weeks (98 days) of gestation.	Early Placental Phase,Pregnancy, First Trimester,Trimester, First,Early Placental Phases,First Pregnancy Trimester,First Pregnancy Trimesters,First Trimester,First Trimester Pregnancies,First Trimester Pregnancy,First Trimesters,Phase, Early Placental,Phases, Early Placental,Placental Phase, Early,Placental Phases, Early,Pregnancies, First Trimester,Pregnancy Trimesters, First,Trimesters, First
D011863	Radioimmunoassay	Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.	Radioimmunoassays
D012016	Reference Values	The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.	Normal Range,Normal Values,Reference Ranges,Normal Ranges,Normal Value,Range, Normal,Range, Reference,Ranges, Normal,Ranges, Reference,Reference Range,Reference Value,Value, Normal,Value, Reference,Values, Normal,Values, Reference
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000509	alpha-Fetoproteins	The first alpha-globulins to appear in mammalian sera during FETAL DEVELOPMENT and the dominant serum proteins in early embryonic life.	alpha-Fetoprotein,alpha Fetoprotein,alpha Fetoproteins
D000653	Amniotic Fluid	A clear, yellowish liquid that envelopes the FETUS inside the sac of AMNION. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (AMNIOCENTESIS).	Amniotic Fluid Index,Amniotic Fluid Indices,Amniotic Fluids,Fluid Index, Amniotic,Fluid Indices, Amniotic,Fluid, Amniotic,Fluids, Amniotic,Index, Amniotic Fluid,Indices, Amniotic Fluid
D016216	Ultrasonography, Prenatal	The visualization of tissues during pregnancy through recording of the echoes of ultrasonic waves directed into the body. The procedure may be applied with reference to the mother or the fetus and with reference to organs or the detection of maternal or fetal disease.	Fetal Ultrasonography,Prenatal Diagnosis, Ultrasonic,Ultrasonography, Fetal,Diagnosis, Prenatal Ultrasonic,Diagnosis, Ultrasonic Prenatal,Prenatal Ultrasonic Diagnosis,Prenatal Ultrasonography,Ultrasonic Diagnosis, Prenatal,Ultrasonic Prenatal Diagnosis,Diagnoses, Prenatal Ultrasonic,Diagnoses, Ultrasonic Prenatal,Prenatal Diagnoses, Ultrasonic,Prenatal Ultrasonic Diagnoses,Ultrasonic Diagnoses, Prenatal,Ultrasonic Prenatal Diagnoses