Prenatal diagnoses with amniocentesis and cordocentesis: evaluation of 181 cases

Objective

 The aim of this study was to evaluate the results of invasive prenatal diagnostic procedures, amniocentesis and cordocentesis, performed in our clinic during 2002 and 2004

Methods

 Prenatal invasive diagnostic procedures were performed during 2002 and 2004 period of time due to high risk in triple
screening test (≥ 1/270), advanced maternal age (≥ 35), anomaly detection during obstetric ultrasonography, and other indications were evaluated. Retrospectively, 150 cases (16-21 weeks), 31 cases (19-21 weeks) that were evaluated by amniocentesis and cordocentesis, respectively.

Results

Tissue cultures were successful in 150 of 153 cases (%98) evaluated by amniocentesis and %100 successful in all of 31 cordocentesis. Chromosomal abnormality rate was 3.8% (7/181) in all cases with successful cultures. The largest group of indications was high risk in triple screening test (78/181) in which the percentage of chromosomal abnormalities was 3.8% (3/78). There was no chromosomal abnormality detected in 49 (%27) cases with the indication of only advanced maternal age. In the evaluation of 23 (%12) cases with ultrasound abnormalities, 3 cases (13%) were detected with chromosomal abnormalities. Pregnant women presented with other indications (%18) in whom only one of 31 cases (3.2%) was chromosomal anomaly.

Conclusion

The rate of producing a successful tissue culture was %98 in our first retrospective study on fetal karyotype. There
was no fetal loss in respect to the invasive procedure. Prenatal diagnosis must be performed in all cases with ultrasound abnormalities. Cases with low risk in triple screening test should be evaluated 

Keywords

Amniocentesis, cordocentesis, fetal karyotype, chromosomal abnormalities

Introduction

It is possible to get information about fetal karyotype by means of interferential processes used in prenatal diagnosis. Amniocentesis was first used in 1950 for sex determination and it was first included to clinical practice by making karyotype determination from fetal cells.1 In the last 30 years, most frequent indication for amniocentesis has been advanced age pregnancy. Except this indication, amniocentesis is being used for diagnosis of illnesses related with DNA analysis (like hemoglobinopathies), enzymatic analysis determination (diagnosis of metabolic illnesses) and for determination of congenital infections by PCR (Polymerase Chain Reaction). Multi-centered studies done up to
now showed the reliability of second trimester amniocentesis for mother and fetus.2-4 Widespread usage of scanning tests in the last decade and becoming widespread of determination by ultrasonography for diagnosis of chromosome anomalies increased demand for amniocentesis. Cordocentesis was first included to clinical practice by using for fetal blood, asphyxia, karyotype and infection determination in the end of 80s following the application with ultrasonography in 1984.(5,6 )Though it is known that fetal mortality related  with interferential procedure at pregnancies having problem may be higher; general average is accepted as 1-2%. (7,8 ) 
In this work, we evaluated the esultsfinterferential processes done for karyotype determination in between 2002 and 2004.

Methods

138 pregnants which had karyotype determination by amniocentesis and cordocentesis for the ~purpose of prenatal diagnosis in Obstetrics Clinic of Medical Faculty of Kahramanmaras Sutcu Imam University were determined retrospectively in terms of interference indications, fetal prognosis, cell culture success and genetic results. All cases and their spouses were informed orally about procedure technique and their possible complications before interference. Written consent forms were taken from couples before the application who accepted the interference. All patients were checked in terms of general blood biochemistry, hepatitis porter, Rh incompatibility. All interferential processes were
performed by one operator (M.A.G). ALOKA 4000 Prosound Model (Aloka Co., Ltd., Tokyo) 3.5 MHz transabdominal probe was used at interferences. After a detailed systematic ultrasonography determination and placenta localization; 1 ml amnion fluid was taken for each week from an area far from placenta by 20-21 G injector in between 16th – 21st gestational week by obeying classical amniocentesis rules.(9,10) Fetal loss occurred within two weeks following the interference was determined as a complication belonging to the process. Cordocentesis was done by taking 2 cc blood by 20-21 G needle to injector which 0.5 cc heparin existed from a free cordon concerning with localization of placenta or from 1-2 cm far from the point that cordon enters to placenta in between 19th-28th gestational week.(11 )
Triple test determination was done by measuring AFP, HCG, Ostriol levels in maternal blood in between 15th-20th gestational week. Biparietal diameter measurement was done in order to determine gestational week of the fetus. Interferential process with the purpose of karyotype determination related with gestational week and/or placental localization was applied to pregnants who had ≥1/270 risk of bearing baby with Down syndrome. 
The material was sent to Intergen-Ankara genetic laboratory in order to cytogenetic determination of amnion fluid and fetal blood. While amniotic fluids were worked by flask technique, cordocentesis were cultured by classical methods in RPMI medium. At least 20 metaphase plates were examined by using image analysis system in order to determine numeric and structural disorders in chromosome at all patients.

Results

Average gestational week of cases which had interferential process and indications of amniocentesis and cordocentesis cases are shown in Table 1. No result was obtained from three of 153 amniocentesis cases due to previous bleeding and infection related with it, thus 150 cases were taken into consideration. Karyotype resulting rate was found as 98% (150/153). Cell cultures succeeded in all cases (n:31) being applied cordocentesis. No complication (fetal loss) related to interference was found in cases which had interferential process. Chromosome anomaly rate was 3.8% (7/181) in our entire series. Four of cases (4/13, 12.9%) which were observed chromosome anomaly were found by cordocentesis and three of them (3/150, %2) were found by amniocentesis.
High risk at triple test was the most frequently seen indication within amniocentesis cases. Interferential process for the purpose of karyotype determination was applied to totally 78 (43%) cases after test and chromosome anomaly was observed in 3 cases (3.8%). There was age risk in addition to~high risk at triple test in 10 of 78 cases. No chromosome anomaly was observed in these 10 cases.
Interferential process was only applied to 49(27%) cases which were evaluated due to advanced maternal age (35-46). No chromosome disorder was seen in any case.  In the determination of 23 cases (12%) which were       und anomaly/anomalies in ultrasonography, 3 (13%) chromosome anomalies were found. Chromosome anomaly was observed only in 1 case (3.2%) within 31 cases which were applied interferential process for other reasons. Short femur, humerus and increased nuchal edema (6.1 mm) was found at 22nd gestational week of the case (trisomy 21) which was observed chromosome anomaly though high risk was not found (1/540) at triple test done in 17th gestational week.
Distribution of patients applied interferential process for other reason is shown in (Table 2). 
Cases found chromosome anomaly were ended by demand of families. Qualities of these cases are shown in (Table 3).

Discussion

Amniocentesis is the oldest well-known prenatal diagnosis method which is used most in the practice. Amniocentesis for the purpose of karyotype determination is frequently applied within 16th-20th gestational week. It was shown that
amniocentesis applied in this period and rate of fetal loss related with interference brought 1% additional
risk as to group which was not applied amniocentesis.(4 )No fetal loss related with interference in our work in which totally 150 amniocentesis cases and 31 cordocentesis cases were evaluated by only one operator. When all amniocentesis cases were evaluated, only 3 of 153 cases had culture failure. Culture success from fetal cells we obtained was 98%. Our success rate was similar to the result of 99% of Cengizoglu et al.12 Contamination of samples which was showed as the reason of low culture success in the studies of Yayla et al13 was also the most important reason for cases having no reproduction within our series. Chromosome anomaly rate of 3.2% (n:7) obtained from 181 cases which were performed by all interferential processes was compatible with the results that Yayla et al, Basaran et al (12,14 ) obtained. Four of chromosome anomalies observed in our series were obtained by cordocentesis (4/31, 12.9%) and three of them were obtained by amniocentesis (3/150, 2%). This chromosome failure rate we obtained in interferential processes was partially similar with rates of Yazicioglu et al15 which were 5.8% in amniocentesis group and 15.25% in cordocentesis group in their work performed in a near past. 
Diagnosis of fetal anomalies can be performed by a detailed ultrasonographic examination in second trimester. 3 of 23 cases we found fetal anomaly by ultrasonography were observed chromosome anomaly (13%). This rate was within the rates 8.7%-27.1% mentioned in literature.(13,16)
 Maternal serum biochemical scanning test (triple test)is kind of test which is done by basing on some biochemical determinants which are in maternal serum in between 15th-20th gestational weeks and secreted by mother-fetus unit and it is sensitive about 60% with 5% mistake rate for Down syndrome. 17 When interferential process with purpose of prenatal diagnosis are applied to pregnants older than thirty-five, 25-40% of cases with Down syndrome can be diagnosed.18 Singh et al stated the sensitivity of triple scanning test done in second trimester of advanced maternal age cases for Down syndrome as 92.3% with 0.8% mistake rate. (19 ) 
No chromosome anomaly was found in 49 cases within our series which were applied interferential process due to only advanced maternal age. Additionally, karyotype of 10 cases was normal which had high risk for Down syndrome in triple test and had age risk. Taner et al found Down syndrome risk as 1.11% and chromosome anomaly risk as 5.84% in their study in which they evaluated amniocentesis results in 359 advanced age gestation.  (20 ) In our work, the reason for not finding chromosome  abnormalities in cases including advanced maternal age + risked triple test which were in only advanced maternal age group can be explained by the minority of our case count.
Triple test risk was 1/540 of the case in 17th gestational week which was observed femoris, humerus and increased nuchal edema (6.1 mm) at 22nd gestational week within cases that we applied interferential process for other reasons even the cordocentesis result was found as Down syndrome, thus genetic ultrasonography to be done in the next periods of gestation is important.

Conclusion

Prenatal diagnosis should be applied to all cases which are found anomaly in ultrasonography. Detailed ultrasonography should be performed in next weeks to patients who are diagnosed low risk in triple test result and  terminant/determinants of chromosome anomaly should be searched.

References

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	File/Dsecription
	Table 1 Indications, average gestational weeks and ages of cases applied amniocentesis and cordocentesis.
	Table 2 Distribution of cases applied interferential process for other reasons.
	Table 3 Qualities of cases which were applied amniocentesis and cordocentesis and which were found chromosome anomaly.