![]() ![]() Normal ranges for each substance tested are presented in relation to fetal gestational age in weeks. ![]() It should be noted that improper handling of specimens and contamination of the sample with blood or meconium may alter test results. Each of these categories, and the tests associated with them, are discussed individually. Tests of amniotic fluid are performed in order to screen for genetic and neural tube abnormalities, to identify hemolytic disease of newborns, and to assess fetal maturity. Surfactant is a lipoprotein that enables the exchange of gases at the alveolar level and contributes to the elasticity of lung tissue. A decreased amount of amniotic fluid can signify chronic fetal illness, placental insufficiency, and urinary tract abnormalities.Ĭhemical and microscopic analysis of amniotic fluid focuses on identification of proteins, chromosomal makeup, elevated bilirubin levels, and indications of surfactant production. Maternal disorders are diabetes and hypertensive disorders of pregnancy. Fetal disorders include anencephaly, esophageal atresia, fetal heart failure, and massive fetal edema. An excessive accumulation of fluid is associated with both fetal and maternal disorders. The quantity or volume of amniotic fluid present in the amniotic sac can also indicate various fetal disorders. ![]() Port wine staining generally indicates abruptio placentae. A yellow-brown opaque discoloration can indicate intrauterine death, and a simple yellow appearance may signal blood incompatibility. Fetal hypoxia is associated with the presence of meconium or meconium staining. Color changes that may indicate pathology include meconium staining (a green-tinged stain) or the actual presence of meconium, a material that collects in fetal intestines, in the amniotic fluid. This color change is normal and expected. As the pregnancy progresses, vernix caseosa, a cheeselike substance covering the skin of the fetus, and fetal urine can alter amniotic color. In early pregnancy, amniotic fluid is usually clear and colorless. Physical analysis of amniotic fluid includes assessment of the color and quantity of the fluid. Physical, chemical, and microscopic examination of amniotic fluid can assist in the diagnosis of conditions as varied as hypoxia, which is inadequate supply of oxygen at the cellular level, to hemolytic disease of the newborn, a condition in which fetal red blood cells are lysed. Since the risks to both fetus and mother can be life-threatening, amniocentesis is carried out utilizing strict aseptic techniques, and only when there is a high probability that a fetal disorder is present or imminent. Risks associated with amniocentesis include miscarriage, fetal injury, introduction of infectious agents from the mother's skin or the external environment in general, abortion, premature labor, and maternal hemorrhage. AmniocentesisĪmniocentesis is used to draw samples for both physical and microscopic analysis of amniotic fluid. Figure 8-1 illustrates this technique.Ĭhorionic Villi Figure 8-1. Amniocentesis is a needle puncture through the abdomen, uterine wall, and into the amniotic sac in order to withdraw fluid for analysis. Contraindications for this type of test include a history of premature labor or incompetent cervix and the presence of abruptio placentae or placentae previa.Īlthough amniotic fluid tests can identify fetal disorders, the sample collection method, amniocentesis, carries inherent risks. The need to determine fetal maturity is another indication for amniotic fluid tests. Advanced maternal age, at times defined as age 35 and older, may trigger routine chromosomal analysis. Indications for amniotic fluid tests are family or parental genetic disorders, mental retardation, chromosome or enzyme anomalies, or inherited blood disorders. Analysis of amniotic fluid provides diagnostic information about fetal well-being and fetal maturation. Amniotic fluid serves several purposes including protecting the fetus from shock, controlling embryonic and fetal body temperature, and allowing free movement of the developing fetus within the amniotic sac. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |