Instruments for chorionic villus sampling for prenatal diagnosis

Alfirevic Z, von Dadelszen P

Published Online:

January 20, 2010

More research is needed on the best surgical instruments to use for chorionic villus sampling testing during early pregnancy.

Chorionic villus sampling (CVS) is a test where a small piece of chorion (placental tissue) is removed from the woman's uterus and used for genetic testing. Chorion can be removed through the abdomen or through the cervix using fine needles, plastic or metal tubes or biopsy forceps. The woman's risk of miscarriage increases if several attempts are needed to get chorion, or the gestational sac is damaged. The review found some evidence that small forceps may be more effective and less painful than aspiration cannulae for transcervical CVS. There were no trials found on transabdominal CVS.

Abstract (click to read)

Background:

Chorionic villus sampling (CVS) is the method of choice for obtaining fetal tissue for prenatal diagnosis before 15 weeks of pregnancy. CVS can be performed using either transabdominal or transcervical approach. The type of instrument used could have a significant impact on the success rate of the procedure. An ability to manoeuvre the instrument within the uterine cavity without puncturing the gestational sac, and to see the tip of the instrument on ultrasound scanning are particularly important.

Objectives:

The objective of this review was to assess the effects of instruments used to obtain chorionic tissue in early pregnancy by transabdominal or transcervical route (chorionic villus sampling). The outcomes of interest were technical difficulties during the procedure, quality and quantity of obtained tissue, maternal adverse effects, pregnancy outcome and cost-effectiveness.

Search strategy:

The Cochrane Pregnancy and Childbirth Group's Trials Register (November 2002). We updated this search on 1 October 2009 and added the results to the awaiting classification section of the review.

Selection criteria:

Randomised trials comparing different instruments (forceps, cannula, needle) for chorionic villus sampling using either transabdominal or transcervical approach.

Data collection and analysis:

Eligibility and trial quality were assessed by two reviewers.

Main results:

There were no trials comparing instruments for transabdominal CVS. Forceps and cannula were evaluated in five transcervical CVS trials involving 472 women. When a cannula was used, operators obtained an inadequate sample (less than 5 mg) more often (relative risk (RR) 4.21, 95% confidence interval (CI) 2.15 to 8.25). Compared with forceps, cannulae had to be re-inserted more often (RR 2.98, 95% CI 1.62 to 5.47). Also, inserting a cannula was more painful (RR 1.93, 95% CI 1.11 to 3.37). One study reported the cost of the procedures and found CVS with cannula to be more expensive (weighted mean difference $183.7, 95% confidence interval 152.62 to 214.78).

When different types of cannulae were compared, Portex cannula was more likely to result in an inadequate sample and a difficult or painful procedure when compared with either the silver or aluminium cannula respectively.

Authors' conclusions:

Although there is some evidence to support the use of small forceps for transcervical chorionic villus sampling, the evidence is not strong enough to support change in practice for clinicians who have become familiar with aspiration cannulae.

[The three citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]

This record should be cited as:

Alfirevic Z, von Dadelszen P. Instruments for chorionic villus sampling for prenatal diagnosis. Cochrane Database of Systematic Reviews 2003, Issue 1. Art. No.: CD000114. DOI: 10.1002/14651858.CD000114

Assessed as up to date:

November 7, 2002

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Primary Review Group:

Pregnancy and Childbirth Group

Health topics:

Pregnancy & childbirth > Fetal assessment before labour > Prenatal diagnosis

Cochrane Summaries^beta

Independent high-quality evidence for health care decision making

Instruments for chorionic villus sampling for prenatal diagnosis

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