BGDA Practical Placenta - Diagnostic Techniques
Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities |
Chorionic Villus Sampling
Chorionic Villus Sampling test is done in the 10th to 12th week after the first day of the mother's last menstrual period. The test is done by looking at cells taken from the chorionic membrane or placenta. No anaesthetic is required, and a test result is usually available in two to three weeks.
When the test is carried out by an obstetrician experienced in the technique, the risk of miscarriage related to the test is about 2%. Potential disadvantages include maternal cell contamination, placental mosaicism and failure to obtain an adequate specimen. This may result in the need for a repeat procedure or amniocentesis.
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Amniocentesis
Amniocentesis is a prenatal diagnostic test carried out mainly between 14th to 18th week of pregnancy. Amniotic fluid is taken from the uterus, sent to a diagnostic laboratory and embryonic cells isolated from the amniotic fluid. No anaesthetic is required, and a result is usually obtained in about three to four weeks. When the test is carried out by an obstetrician experienced in the technique, the risk of a miscarriage related to the test is about 1 %.
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Placenta Term Parameters
Term placental composition, villous capillarization and the mean cross-sectional areas of peripheral villi and capillaries, data from a study sample of 15 normal placenta (mean placental volume, 652 ml). [1]
Variable | Unit | Placenta (mean, n = 15) |
Intervillous space | mL | 213 |
Stem villi | mL | 71.4 |
Peripheral villi | mL | 326 |
Trophoblast | mL | 95.5 |
Stroma | mL | 184 |
Fetal capillaries | mL | 46.9 |
Non-parenchyma | mL | 41.5 |
Peripheral villi | km | 89.2 |
Fetal capillaries | km | 310 |
TS area villi | µm2 | 3700 |
TS area capillary | µm2 | 150 |
Capillaries | mL mL-1 | 0.147 |
Length ratio | km km-1 | 3.6 |
- ↑ <pubmed>19141109</pubmed>
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Cite this page: Hill, M.A. (2024, June 16) Embryology BGDA Practical Placenta - Diagnostic Techniques. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDA_Practical_Placenta_-_Diagnostic_Techniques
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G