Prenatal testing

[*Devon*]

Hello ladies!!

My mom is in Nursing school (at 52! Yay mom! :love )-- mainly interestd in L&D, which is the unit they're doing right now. Of course, she is learning all the very mainstream hospital ways of doing things, but don't get me started on that. Expect to see me popping up here occasionally to pick your wise brains on her behalf :innocent

I know many prenatal tests are invasive, possibly damaging to the baby, and unnecessary, but she is learning about them all and has a question - if chorionic villi sampling can be done earlier than amnio, why isn't it used more? If anyone has any info, thoughts, etc, we'd really appreciate it!!!

P.S. She was horrified when I pointed out to her how quickly they cut the cord in hospitals, so I'm making some progress with her... maybe by the time I ttc she'll be pro-homebirth :down

[Sagesgirl]

The short answer is that it carries greater risk.

As with amniocentesis, there is concern that having the test may cause a woman to miscarry. The likelihood of miscarriage due to CVS is not known with certainty. About 4% of women who have had CVS have had a miscarriage following the test. We do not know which of the miscarriages are actually due to the test, although it is believed that many of them are not due to the test but occur spontaneously. Several studies suggest that CVS has about a 0.5-1.0% greater risk than amniocentesis for causing a miscarriage. For some patients having the test done during the first three months of pregnancy, and knowing the results quickly is considered to such an advantage, that they are willing to assume a slightly higher risk rather than wait for amniocentesis. There is also a small but important risk of infection in the uterus following CVS. Although this is infrequent, the exact probability of the occurrence of infection has not yet been accurately determined. We believe that when we use the transabdominal method for CVS, the frequency of this complication may be the same as with amniocentesis. Following your CVS, you will be given an instruction sheet about how to watch for this and other complications of the test.

source (http://www.obgyn.upenn.edu/genetics/cvs.html)

[mwherbs]

beyond or added to risk is value systems- what are you going to do with the information?
this is a copy of the review I have which shows that even after the procedure you may still need further testing-- so it is alot to go through with the possibility of more testing
Cochrane Database Syst Rev. 2000;(2):CD000077.

Early amniocentesis versus transabdominal chorion villus sampling for prenatal
diagnosis.

Alfirevic Z.

Department of Obstetrics and Gynaecology, University of Liverpool, Liverpool,
UK, L69 3BX. zarko@liverpool.ac.uk

BACKGROUND: A major disadvantage of amniocentesis is that test results are
usually available only after 18 weeks gestation. Early amniocentesis can now be
done between 9 to 14 weeks gestation. OBJECTIVES: The objective was to assess
the safety and accuracy of early amniocentesis compared with chorion villus
sampling. SEARCH STRATEGY: The Cochrane Pregnancy and Childbirth Group trials
register and the Cochrane Controlled Trials Register were searched. Date of last
search: October 1998. SELECTION CRITERIA: Randomised trials comparing early
amniocentesis with transabdominal chorion villus sampling. DATA COLLECTION AND
ANALYSIS: One reviewer assessed eligibility and trial quality. MAIN RESULTS:
Three studies were included. Sampling failure was 0.4% in the early
amniocentesis group compared to 2% in the chorion villus group (relative risk
0.23, 95% confidence interval 0.08 to 0.65). Consequently, more women in the
chorion villus sampling group needed a second prenatal diagnostic test (relative
risk 0.43, 95% confidence interval 0.21 to 0.88). There were no statistically
significant differences in the laboratory failures (relative risk 0.43, 95%
confidence interval 0. 17 to 1.10) or number of women with various chromosomal
abnormalities (relative risk 0.51, 95% confidence interval 0.26 to 1. 04).
Combined total pregnancy loss in the early amniocentesis group was 6.2% (57/915)
compared with 5% (46/917) in the chorion villus sampling group (relative risk
1.24, 95% confidence interval 0.85 to 1.81). There were more spontaneous
miscarriages after early amniocentesis (4.4% versus 2.3%, relative risk 1.92,
95% confidence interval 1.14 to 3.23). There was no difference in the incidence
of neonatal respiratory distress and anomalies in the newborn infants. The
incidence of talipes was greater in the early amniocentesis group, although
haemangiomas were more common in the chorion villus sampling group. REVIEWER'S
CONCLUSIONS: Current data suggest that early amniocentesis is associated with a
greater risk of spontaneous miscarriage and neonatal talipes compared to
transabdominal chorion villus sampling. An increased risk of these complications
needs to be weighed against fewer technical difficulties and the possibility of
fewer neonatal haemangiomas.

[*Devon*]

Great! Thank you so much!!!