The Evaluation Of Serial Invasive Prenatal Diagnostic Techniques

BackgroundTo improve the birth quality and reduce the birth defects is the definite requirement and major developmental field announced by State Department of China. It has been reported that birth defect is the main reason for neonatal death in China. Aneuploidies for chromosomes 21,18,13, X and Y are the major causes in birth defects, which account for 65% to 80% of total cases, as well as 85% to 95% of neonatal cases. Aiming at such common aneuploidies, the research and development of screening and diagnostic technologies will play an important role in reducing birth defect and enhancing the birth quality.Prenatal diagnosis of chromosome abnormality depends mainly on cell culture and karyotyping of fetal cells, blood or chorionic tissues obtained from invasive techniques, which include amniocentesis, chorionic villus sampling(CVS), cordocentesis and fetoscopy. CVS and amniocentesis was widely used in many prenatal diagnostic centers, cordocentesis and fetoscopy are uncommonly used. To promote the widely use of these techniques is very important for prenatal diagnosis in China.ObjectiveTo evaluate the safety, effectiveness and complications of these invasive techniques.MethordsA retrospective study involved all cases from Jan 2005 to Dec 2009 who received amniocentesis, CVS, cordocentesis and fetoscopy in prenatal diagnosis center of Peking Union Medical College Hospital. The indication of the procedures, successful rates and complications were evaluated. Results1) Amniocentesis:5204 cases received amniocentesis in 5 years in a single center of Peking Union Medical College Hospital. Advanced maternal age and positive screening result of second trimester were the main indication of the procedure. The spontaneous abortion rate associated with the procedure was 1.35‰. Forty-six cases of common chromosomal aneuploidy and 17 cases of sex chromosome abnormalities were diagnosed.15 cases of structural chromosome abnormality were detected in younger women, among which 93.33% could be detected by FISH or QF-PCR theoretically.2) CVS:297 of 559 cases (53.31%) received CVS for molecular genetic analysis or enzymic analysis due to family history of genetic diseases, while 262 cases (46.9%) for cytogenetic analysis. Advanced maternal age was the main indication for CVS, accounting for 75.19%. Twelve cases of chromosome abnormalities were diagnosed. Positive diagnostic rate of CVS was 6.09%. Among the 12 cases,9 were aneuploidy (5 cases of T21 and 4 cases of T18). The aneuoploidy diagnostic positive rate of CVS was 4.57%, which was much higher than that of amniocentesis. Four cases of aneuploidy were diagnosed in 14 younger pregnant women with abnormal NT, with the positive diagnostic rate of 26.67%.3) Cordocentesis:Altogether 49 cases of cordocentesis were carried out during the past 5 years in our series, among which 26.53%(13/49) were due to the mosaic in cultured amniotic cells or as a repeat procedure when the cell culture was failed. It's noteworthy that 30.61%(15/49) of the cordocentesis were done as a remediation when the best chance of amniocentesis were missed among those women when they were transferred from other hospitals. Four of these cases were detected with abnormal kayrotype, with the positive diagnostic rate of 26.67%. Cordocentesis were all successfully done and got final diagnosis when amniotic fluid cell cultures were failed. The most common complication of cordocentesis was bleeding from the puncture site (44.9%), and the procedure was failed among 8.16% of the cases. 4) The value of fetoscope in the diagnosis of albinism:Eighty-seven women received fetoscopy procedure due to a history of delivering an affected child of albinism, among which 74 got successful procedure with definite diagnosis. The successful rate of the procedure was 85.1%, and the procedure related spontaneous abortion rate was 5.7%. Two women showed infection signs after the procedure, with the infection rate of 2.3%.Conclusions1. As a widely used invasive prenatal diagnosis procedure, amniocentesis is safe and effective.2. Rapid aneuploidy diagnosis methods should be thoroughly discussed with those younger women with positive screening test. Acceptance and widely use of those methods may dissolve the problem of rare resource of prenatal diagnosis center in our country.3. Chorionic villus sampling (CVS) after 11 weeks of gestation in first trimester and early second trimester is safe and effective. Screening test and prenatal diagnosis in first trimester should be promoted.4. The complications of cordocentesis are much higher than those of CVS and amniocentesis, thus not suitable to be a routine procedure for prenatal diagnosis of abnormal karyotype. Likewise, due to the higher rate of procedure related complications, the clinical use of fetoscope are limited and not applicable for widely use outside the tertiary centers.