User:Hillenb3/sandbox

The Development of Amniocentesis

As early as 1877, researchers were already performing transabdominal amniocenteses. The original procedure was done during the third trimester and was meant to relieve pressure in pregnant women with hydramnios, or excess amniotic fluid. The procedure was done manually, with a fine needle being led into the uterus by touch in order to remove a volume of amniotic fluid.

The first people to preform an amniocentesis in order to obtain an amniography were Thomas Orville Menees, J. Duane Miller, and Leland E. Holly in 1930. To do this, dye was injected into the amniotic sac. This allowed the outline of the fetus and the placenta to be observed.

Several researchers worked on the development of amniocentesis for fetal sex determination in the 1950s.

Murray Lewellyn Barr, a Canadian anatomist, discovered that Barr bodies could be used to determine sex in addition to the sex chromosomes, with the help of his colleagues in 1949. By examining the cells of female and male mammals, Barr determined that typically females had Barr bodies— visible chromatin masses made up of inactivated X-chromosomes, which are typically found when two X-chromosomes are present— while males lacked them. His discovery was useful because sex chromosomes are not easy to see under a microscope. Furthermore, in 1956, Fritz Fuchs and Povl Riis used what Barr had discovered to realize that the presence of Barr bodies could be used to reveal the sex of fetuses born to mothers who were carriers of sex-linked diseases.

Between 1959 - 1967 Robert Lisle Gadd developed the new technique of amniocentesis for clinical assessment of fetal wellbeing in utero. He presented his results at the William Blair-Bell Memorial Lecture at the RCOG in London in 1965 and was awarded an MD from the University of Manchester for this work. He also described amniocentesis techniques, as well as other details about amniotic fluid in the chapter 'The Liquor Amnii' in the 1970 and 1977 editions of Scientific Foundations of Obstetrics and Gynaecology.

For the first time in 1966, Mark W. Steele and William Roy Breg successfully obtained fetal cells from amniotic fluid collected through amniocentesis. This led to the karyotyping of the chromosomes and the ability to diagnose aneuploidies such as Down Syndrome.

Up to mid 1970s amniocentesis procedures were done 'blind‘. Doctors Jens Bang and Allen Northeved from Denmark were the first to report amniocentesis done with the guide of an ultrasound in 1972. Chorionic Villus Sampling (CVS) was first performed by Italian biologist Giuseppe Simoni in 1983. Now real-time ultrasound is used during all invasive procedures because it provides for the safety of the fetus and accuracy of results.

Procedure

Before the start of the procedure, a local anesthetic can be given to the mother in order to relieve the pain felt during the insertion of the needle used to withdraw the fluid. After the local anesthetic is in effect, a needle is usually inserted through the mother's abdominal wall, then through the wall of the uterus, and finally into the amniotic sac. With the aid of ultrasound-guidance, a physician punctures the sac in an area away from the fetus and extracts approximately 20mL of amniotic fluid. If used for prenatal genetic diagnosis, fetal cells are separated from the extracted sample. The cells are grown in a culture medium, then fixed and stained. Under a microscope the chromosomes are examined for abnormalities. The most common abnormalities detected are Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Turner syndrome (monosomy X). In regard to the fetus, the puncture seals and the amniotic sac replenishes the liquid over the next 24–48 hours.