In 1994
published a report comparing early amniocentesis (EA) and chorionic villus sampling (CVS) performed at the same gestational age. They found a higher fetal loss rate among the EA group. In the discussion following this publication, reported similar results; that is an increased fetal loss rate after EA compared to CVS procedures. Eiben et al. (1994) wrote a letter questioning Nicolaides et al.'s results by assuming that the operators were inexperienced in performing EA. Our results (Cederholm and Axelsson, 1997) are in agreement with Nicolaides et al. and Vandenbussche et al. in that a higher fetal loss rate is found after EA than CVS. Again Eiben et al. (1997) assume that such results must be due to the operators being inexperienced in performing EA. The fact is that the participating operators (three senior doctors) have had a longstanding experience of invasive procedures, especially amniocenteses.
Thus, three reports from three different centres have found an increased fetal loss rate after EA compared to CVS performed in gestational weeks 10-13. We believe that these consistent results should be interpreted with greater respect and caution than is done by Dr Eiben and colleagues. Categorical statements and assumptions without scientific support will not add to our knowledge. Nor will it be of any help in choosing the safest method for performing invasive procedures in early pregnancy. Eiben and colleagues perform many EAs, but as long as they only present descriptive data, the scientific merit of their reports is limited, especially with such a low follow-up rate (Eiben et al., 1997). Hopefully, our German colleagues will embark on controlled comparative studies to test their hypothesis.