Percutaneous umbilical cord blood sampling
Encyclopedia
Percutaneous umbilical cord blood sampling (PUBS), also called cordocentesis, is a diagnostic genetic test
that examines blood from the fetal
umbilical cord
to detect fetal abnormalities. PUBS provides a means of rapid chromosome analysis and is useful when information cannot be obtained through amniocentesis
, CVS
, or ultrasound
(or if the results of these tests were inconclusive). This test carries a significant risk of complication and is typically reserved for pregnancies
determined to be at high risk for genetic defect.
which surrounds the fetus, PUBS examines fetal blood. An advanced imaging ultrasound determines the location for needle insertion into the placenta, and the needle is guided through the mother's abdomen and uterine wall
into the fetal vein of the umbilical cord, where a fetal blood sample is removed. The sample can then be sent for chromosomal analysis. The entire process lasts 45 minutes to an hour. Because the fetal vein is fragile early in pregnancy, PUBS is performed no earlier than 17 weeks into pregnancy.
PUBS testing has a turnaround time of about 72 hours and can detect chromosomal abnormalities, blood disorder, some metabolic disorders, infections, and some causes of structural problems. PUBS has largely replaced fetoscopy
, which has a much higher rate of miscarriage
.
It has been used with mothers with immune thrombocytopenic purpura.
at the puncture site, infection
, and premature rupture of membranes. During the procedure, the mother may feel discomfort similar to a menstrual cramp.
Genetic testing
Genetic testing is among the newest and most sophisticated of techniques used to test for genetic disorders which involves direct examination of the DNA molecule itself. Other genetic tests include biochemical tests for such gene products as enzymes and other proteins and for microscopic...
that examines blood from the fetal
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
umbilical cord
Umbilical cord
In placental mammals, the umbilical cord is the connecting cord from the developing embryo or fetus to the placenta...
to detect fetal abnormalities. PUBS provides a means of rapid chromosome analysis and is useful when information cannot be obtained through amniocentesis
Amniocentesis
Amniocentesis is a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections, in which a small amount of amniotic fluid, which contains fetal tissues, is sampled from the amnion or amniotic sac surrounding a developing fetus, and the fetal DNA is examined for...
, CVS
Chorionic villus sampling
Chorionic villus sampling , sometimes misspelled "chorionic villous sampling", is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus and testing it...
, or ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
(or if the results of these tests were inconclusive). This test carries a significant risk of complication and is typically reserved for pregnancies
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
determined to be at high risk for genetic defect.
Procedure
PUBS is similar to amniocentesis, but instead of sampling the amniotic fluidAmniotic fluid
Amniotic fluid or liquor amnii is the nourishing and protecting liquid contained by the amniotic sac of a pregnant woman.- Development of amniotic fluid :...
which surrounds the fetus, PUBS examines fetal blood. An advanced imaging ultrasound determines the location for needle insertion into the placenta, and the needle is guided through the mother's abdomen and uterine wall
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
into the fetal vein of the umbilical cord, where a fetal blood sample is removed. The sample can then be sent for chromosomal analysis. The entire process lasts 45 minutes to an hour. Because the fetal vein is fragile early in pregnancy, PUBS is performed no earlier than 17 weeks into pregnancy.
PUBS testing has a turnaround time of about 72 hours and can detect chromosomal abnormalities, blood disorder, some metabolic disorders, infections, and some causes of structural problems. PUBS has largely replaced fetoscopy
Fetoscopy
Fetoscopy is an endoscopic procedure during pregnancy to allow access to the fetus, the amniotic cavity, the umbilical cord, and the fetal side of the placenta. A small incision is made in the abdomen, and an endoscope is inserted through the abdominal wall and uterus into the amniotic cavity...
, which has a much higher rate of miscarriage
Miscarriage
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...
.
It has been used with mothers with immune thrombocytopenic purpura.
Risks
Miscarriage is the primary risk associated with PUBS and occurs in 1-2% of procedures. Additional possible complications are similar to those for amniocentesis and include blood lossBleeding
Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...
at the puncture site, infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
, and premature rupture of membranes. During the procedure, the mother may feel discomfort similar to a menstrual cramp.
See also
- Prenatal diagnosisPrenatal diagnosisPrenatal diagnosis or prenatal screening is testing for diseases or conditions in a fetus or embryo before it is born. The aim is to detect birth defects such as neural tube defects, Down syndrome, chromosome abnormalities, genetic diseases and other conditions, such as spina bifida, cleft palate,...
- Genetic testingGenetic testingGenetic testing is among the newest and most sophisticated of techniques used to test for genetic disorders which involves direct examination of the DNA molecule itself. Other genetic tests include biochemical tests for such gene products as enzymes and other proteins and for microscopic...
- AmniocentesisAmniocentesisAmniocentesis is a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections, in which a small amount of amniotic fluid, which contains fetal tissues, is sampled from the amnion or amniotic sac surrounding a developing fetus, and the fetal DNA is examined for...
- Chorionic villus samplingChorionic villus samplingChorionic villus sampling , sometimes misspelled "chorionic villous sampling", is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus and testing it...