Pregnancy Ultrasound Directed Placental Villus Sampling
Chorionic Villus Sampling
Pregnancy Ultrasound Directed Placental Villus Sampling
In Genetic Fetal Diagnosis
Ultrasound- guided chorionic villus sampling is a diagnostic modality done by getting a piece of the placental tissue for the purpose of genetic testing and well- being examination of the unborn baby.
Down Syndrome, Cystic Fibrosis, etc. May be diagnosed through the evaluation of the fetal chromosomal set up. CVS is best scheduled by the 10th-13th week of gestation.
CVS is best scheduled by the 10th-13th week of gestation.Ultrasound-guided chorionic villus sampling is a procedure best done by 11- 13 weeks of maternity.
Placental Villus Biopsy – How it is done
The placental tissue is sampled through a procedure known as chorionic villus sampling and this placental portion is evaluated for possible presence of possible chromosomal aberrations.The genetic make up of the fetus is assessed for abnormalities like Down Syndrome and Cystic Fibrosis.
CVS may be performed in two ways. These are
- Transabdominal – Across the abdomen.
- Transcervical – Across the cervix through the vagina.
A small portion of the placenta is then taken via aspiration into the needle.However, a thin plastic catheter is used in the transcervical approach.
Placental Biopsy – Infection has to be avoided
The initial procedure in CVS includes the application of antiseptic medications over the site of puncture in the abdomen.That area is then punctured with the aid of ultrasound viewing.
A gynecological examination position is the position of the woman undergoing the transcervical route.The cervix is viewed by inserting the speculum per vagina.
It is vital to ensure antisepsis during the procedure.The plastic catheter first enters the vagina.When the villi are reached, a syringe attached to the catheter is manipulated to suck away a small amount of the placental tissue.
Ultrasound Scan Guidance Reduces the Risk of CVS
In CVS, two attempts are only allowed to minimise the incidence of miscarriage.
CVS may be found difficult to perform in some women.Amniocentesis is a better option to this group of women. These situations include position of the uterus and the inaccessibility of the placental villi.
Transabdominal as well as trancervical routes are two options in doing the Chorionic Villus Sampling.A needle or catheter are utilized in these procedures– the catheter for the transcervical route and needle for the transabdominal route.
Placental Villus Biopsy Not Always Advisable
There are contraindications to CVS in some women.Chorionic villus sampling should be done to women with clear and definite indicatioins.
There are several reasons for being cautious:
A CVS is not constantly reliable.
- The placenta may not be clearly visible in some cases.
- May cause a miscarriage
- Is painful
- May cause bleeding
First off, this has to be a completely aseptic procedure – the abdomen in the former and the vagina in the latter.
The different CVS procedures utilize different equipments. Both are performed with aid of ultrasound scanning.
To get specimens from the placenta, the transabdominal procedures makes use of a needle while a catheter is used in a transcervical procedure.
The risk of Placental Biopsy
During the procedure, precautions are done to avoid any injury to the baby.The needle is delicately positioned in such a way that it outside of the gestational sa, aided by ultrasound scanning.
The possibility of miscarriage is increased by 1% when undergoing a CVS.This is most of the time due to infection after the procedure.
In order to protect against infection, an antiseptic is required at the beginning of each procedure.
A history of vaginal bleeding during the present pregnancy, abnormalities of the uterus like bicornuate uterus, and infections like a genital herpes are risk factors against the performance of CVS.
To avoid injury to the baby, the needle should be positioned away from the baby– preferably positioning it out of the gestational sac. Approximately 1% of patients who go through a CVS have a miscarriage. There are symptoms that the mother must be on the look out for complications after a CVS such as regular pain along with bleeding. These are the initial signs of a miscarriage. She should be advised to immediately contact her obstetrician or midwife.
Complications can still be seen up to 7 days following the procedure.
CVS Results – Processing the material
If the tissue specimen fails to grow in the laboratory, this may produce inaccurate results.There are newer techniques that now do not rely on grown cells from the tissue sample. However, the risk of contamination by maternal DNA is still a concern.
If for whatever reason chorionic villus sampling fails, Amniocentesis is the next option.
Amniocentesis by 15- 16 weeks of pregnancy is then suggested if this should happen.
A miscarriage after ultrasound guided amniocentesis or Chorionic Villus sampling may occur particularly if the mother experiences symptoms like menstrual-like pain with fresh blood.