Pure fetal blood samples obtained by cordocentesis: Technical aspects of 322 cases

Three hundred and twenty-two percutaneous umbilical blood samplings were performed over 4 years in our prenatal diagnostic centre. A 3·5 MHz sector ultrasound transducer was used to guide a 22·5-gauge needle under local anaesthesia. Sampling was performed fcir rapid fetal karyotyping (within 72 h) in 120 cases, for diagnosis of fetal toxoplasmosis in 133 cases, for determination of the severity of Rh immunization in 15 cases, and for diagnosis of congenital rubella in 4 cases. Pure fetal blood was obtained in 98·7 per cent of the cases after two attempts. The approach to the cord was either transamniotic or trans-piacental. Puncturing was preferentially done at the placental insertion of the cord (72·2 per cent of the cases) and the mean blood sample volume was 3·5 ml. The rate of fetal death in utero was 1 9 per cent, including two cases of amnionitis, one trisomy 18, and one severe bradycardia. The failures were due to sampling at an early stage of pregnancy (before gestation week 18), to maternal obesity, oligohydramnios, and the inexperience of the operator.     

Genetic diagnosis by chorionic villus sampling before 8 gestational weeks: Efficiency,reliability, and risks on 317 completed pregnancies

Transabdominal chorionic villus sampling (TA-CVS) was attempted in 328 high-risk pregnancies at 6–7 weeks of gestation. Sampling was feasible in 97.7 per cent of cases; chorionic tissue specimens of more than 10 mg were obtained in 94.4 per cent ofcases at the first needle insertion and in 100 per cent after a second attempt. Fetal karyotyping succeeded in 99.4 per cent of cases, while no diagnostic failures were reported in enzymatic and DNA analyses. Fetal loss rate in the first 4 weeks after CVS was significantly higher than in the later CVS series (7.2 vs. 2.5 per cent), but 50 per cent of losses were observed within 2 weeks in cases of inviable aneuploidies. A high incidence of severe limb abnormalities (1.6 per cent) was detected in pregnancies intended to continue, confirming the aetiological role of early CVS. Unclear visualization of the placental limits and poor control of the needle path are thought to be the main reasons for the vascular disruption of the chorionic plate, and thereby hypoxic embryo tissue damage. A better selection of cases, together with high-resolution vaginal ultrasound visualization, and analytical techniques requiring a minimal amount of tissue should avoid any teratogenic effect of early CVS.     

Chorionic villus sampling: An analysis of the obstetric experience of 1000 cases

Chorionic villus sampling was performed between 7 and 12 weeks gestation in 1000 patients, 935 of whom intended to continue after fetal diagnosis. Transcervical and Transabdominal aspiration techniques were used providing a sampling success rate of 99 per cent. Anatomical and clinical contraindications to transcervical aspiration were pointed out, and the complementary role of the transabdominal approach evaluated. In the 615 concluded pregnancies an overall abortion rate of 4.1 per cent was observed. A significant association between fetal loss and number of catheter insertions was demonstrated. Bacterial inoculation by catheter insertion and colonization of uterine cavity was suspected as the cause of chorionamnionitis diagnosed in two cases (0.2 per cent) after CVS. Bleeding was the most frequent early complication (12.0 per cent) following chorionic aspiration, but was not significantly related to pregnancy wastage. Late complications, i.e. premature rupture of membranes (0.8 per cent), preterm delivery (6.3 per cent), perinatal losses (1.2 per cent), placental disorders (1.6 per cent), and congenital defects (2.6 per cent) did not exceed the expected values. Normal intrauterine growth patterns were ultrasonically estimated by cross-sectional and longitudinal studies, while the weight at birth was normally distributed in the range of the general population.     

Prenatal diagnosis of thalassemia major by fetal blood analysis: Experience with 1000 cases

In this report we have summarized our experience with the prenatal diagnosis of β-thalassemia in 1000 pregnancies followed at least until 12 months after birth. In the majority of these cases, the thalassemia lesion was the nonsense mutation at the codon corresponding to amino acid 39, which produces the hematological phenotype of β-thalassemia. Fetal blood sampling was carried out by placental aspiration, by which a sufficient amount of fetal blood for analysis was obtained in the majority of cases (99 per cent). The fetal mortality associated with fetal blood sampling was 6·3 per cent. Those placental samples contaminated by maternal cells were successfully purified by Ørskov lysis. Fetal blood was analysed by globin chain synthesis on CM–52 columns, which gave reliable results. Two misdiagnoses (0·2 per cent) have been made of which one was due to a non-globin protein co-migrating with the β-chains while the other resulted from a misclassification of the type of thalassemia segregating in the family.     

The safety of fetoscopy: (I). Effect of umbilical vessel puncture on the fetal heart rate and cord histology

The fetal heart rate (FHR) was continuously monitored during 42 umbilical vessel punctures performed at the placental insertion of the cord in 24 diagnostic fetoscopies in which pure fetal blood was obtained. In only one patient did a deceleration first appear during puncture and aspiration of fetal blood. In two patients decelerations preceded fetoscopy and in two others they began during the fetoscopy but before puncture of an umbilical vessel. In 19 patients, the FHR did not change at all during the procedure. Fetal haemorrhage after sampling was either absent or minimal. Six pregnancies were terminated because a positive diagnosis had been made and 18 healthy babies were born. Umbilical cords were examined after 7 terminations of pregnancy and after 6 deliveries. In the former group the puncture could just be seen with the naked eye and the needle track was demonstrated histologically in 6. No traces of the puncture or other abnormalities were found in the cords after delivery. Fetal blood sampling from umbilical cord vessels, particularly at the placental insertion of the cord, is the technique of choice since pure fetal blood can be obtained without increasing the risk of fetoscopy.     

The significance of trisomy 7 mosaicism in chorionic villus cultures

Two cases of mosaic trisomy 7 confined to the cultured cells and not found in direct preparation were detected from 200 consecutive first-trimester chorionic villus samples (CVS) analysed. The mosaicism was similar in the two cases, but the pregnancy outcome was different. In both cases, the direct metaphases from the CVS were 46, XY. Culture metaphases were mos46,XY/47,XY, + 7; the trisomy 7 was seen in 34 per cent of cells from case 1 and 53 per cent from case 2. A sonogram at 15¹/₂ weeks revealed fetal death in utero in case 1, and the patient declined amniocentesis. The fetal tissue failed to grow in culture, but the placental cultured cells were 47,XY, + 7 in 28 (100 per cent) cells analysed. In the second case, all the amniotic fluid cells were 46,XY and the pregnancy resulted in a normal male with a 46,XY karyotype in the cord blood and foreskin fibroblast cultures. The term placenta was mosaic with 13/163 (8 per cent) trisomy 7 cells. Extensive cytogenetic studies on the placenta for the first time confirmed trisomy 7 mosaicism confined to the villus cultures.     

Cytogenetic analysis of 2928 CVS samples and 1075 amniocenteses from randomized studies

We report cytogenetic results from a randomized Danish chorionic villus sampling (CVS) and amniocentesis (AC) study including 2928 placental and 1075 amniotic fluid specimens processed in the same laboratory. The results are presented in groups comparing CVS with amniocentesis and transabdominal (TA) CVS with transcervical (TC) CVS as randomized. More abnormalities and more ambiguous diagnostic problems were found in placental tissues than in amniotic cells. There were no diagnostic errors and no incorrect sex predictions. Mosaicism was detected in 1 per cent of all cases of CVS (discordancies included). When confirmation studies were done, 90 per cent were found to be confined to the placenta. Eight cases (0.7 per cent) of mosaicism/pseudomosaicism were seen in amniotic fluid specimens, and two cases of five with confirmation studies were confirmed in the fetus. The rate of mosaicism/pseudomosaicism in CVS and AC specimens differed (P <0.05). The rate of pseudomosaicism in cultures of villi and amniotic fluid cells was 0.5 and 0.6 per cent, respectively. Single-cell aneuploidy was observed in 1.8 per cent of villi and 1.4 per cent of amniotic fluid cell specimens. Maternal cell contamination (MCC) was seen more often after TC sampling (4.5 per cent) compared with TA sampling (1.5 per cent), but posed no problems in interpretation. Compared with the processing of cultured specimens, the short-term method of preparation of villi in our laboratory doubled the technicians' workload. For practical and economic reasons we have ceased the routine use of short-term preparations.     

Transabdominal chorionic villus sampling for fetal genetic diagnosis. Technical and obstetrical evaluation of 100 cases

First trimester fetal diagnosis was established in 100 pregnancies at risk by transabdominal chorionic villus sampling (TA-CVS). Forty-eight per cent of the women were 35 years or more at the time of sampling. Using the double needle technique, both the aspiration and the diagnostic success rate were 100 per cent. The mean amount of villi aspirated was 28·2 mg (10–50 mg). The mean needle time was 3 min. Vaginal spotting appeared in 2 per cent of the women. Four women had therapeutic abortion due to abnormal findings and one for social reasons. Three fetuses with normal karyotypes were lost. Excluding the therapeutic abortions, the fetal loss rate was 3±2 per cent. The fetal loss rate in the amniocentesis control group (n = 200) was 3±6 per cent. The cytogenetic diagnosis was carried out by the direct preparation technique as well as by chorion villus cultivation. All karyotypes were confirmed by lymphocyte cultures from umbilical cord blood or heel blood from the newborn or from aborted fetal tissue. Transabdominal CVS is deemed a safe and easy tool for achieving chorionic villi in the first trimester.     

Fetal blood sampling via the umbilical cord using a needle guided by ultrasound report of 66 cases

Pure fetal blood has been aspirated in utero from the umbilical vein near the placental insertion of the cord using a twenty gauge needle under ultrasound guidance. Sixty-six samples were taken on 63 pregnancies between 17 and 32 weeks of gestation. One to two millilitres of blood can be obtained easily without amniotic fluid dilution or contamination by maternal blood, as confirmed by the measurements of the mean corpuscular volume, the histogram distribution of the red blood cells and the hematocrit. In all cases the Kleihauer test and isoelectrofocusing of the hemoglobins were performed. Coagulation factors were also studied in 60 cases. In 17 cases a medical abortion was voluntarily induced after the procedure, and the follow-up was normal during the observation period after sampling. In the other cases, pregnancies have continued normally and twelve healthy babies have already been born.     

Confined placental mosaicism in CVS and pregnancy outcome

The perinatal outcome of 26 patients with confined placental mosaicism (CPM) detected in chorionic villus sampling (CVS) who wished to continue their pregnancies was compared with that of two controls per patient matched for age and parity (n=52). There were no significant differences in birth weight or gestational age at delivery between patients with CPM and controls. There were no cases of intrauterine growth retardation (IUGR) in the CPM patients as compared with two (2/52, 3·8 per cent) in the control group (P>0·05). There was no significant increase in fetal loss between the study group (1/26, 3·6 per cent) and the controls (1/52, 1·9 per cent) (P>0·05).     

Chorionic mosaicism: Association with fetal loss but not with adverse perinatal outcome

Cytogenetic data from the United States NICHD collaborative study of chorionic villus sampling (CVS) were used to evaluate the clinical significance of chorionic mosaicism. The 10 754 patients with normal cytogenetic results were compared wtih 108 patients (1.0 per cent) with placental mosaicism and 181 patients (1.6 per cent) with pseudomosaicism. Of the pregnancies intended to continue, the pregnancy loss rate was significantly greater in patients with placental mosaicism than in the cytogenetically normal cohort (8.6 vs. 3.4 per cent, p <0.05). However, there was no difference in the frequencies of abruptio placenta, preterm labour or delivery, small-for-gestational-age newborns, pregnancy-induced hypertension, or neonates with Apgar scores less than 7.     

Umbilical cord haematoma as a complication of intrauterine intravascular blood transfusion

Between October 1985 and February 1989, 49 ultrasound-guided intravascular fetal blood transfusions were performed in 16 patients (14 with rhesus (Rh) isoimmunization, 2 with non-immunologic hydrops fetalis (NIHF)). As an intra-operative complication, perivascular haematoma of the cord occurred in three patients (7 per cent). In two cases, fetal bradycardia necessitated delivery by Caesarean section at 30 and 32 weeks' gestation, respectively. In the third case, fetal bradycardia developed during transfusion, at 31 weeks' gestation, but normalized within 3 min. The baby was delivered as planned at 36 weeks of gestation, after another transfusion at 34 weeks. Dislodgement of the needle tip into perivascular tissue, caused by sudden fetal or maternal movements, is the reason for this complication. The haematoma develops as a result of delayed recognition and continuous transfusion into Wharton' s jelly. Cord haematoma may be diagnosed in time by continuous ultrasound imaging, as illustrated in case 3. To minimize the risk of needle dislodgement during transfusion, sedation of the mother and complete immobilization of the fetus by injecting a short-acting muscle relaxant into the umbilical vessel are recommended.     

Transabdominal chorionic villus sampling and amniocentesis for prenatal diagnosis: 5 years' experience at a University Centre

The fetal loss rates and fetal congenital birth defects in 821 transabdominal (TA) chorionic villus sampling (CVS) and 771 amniocentesis (AC) cases were evaluated from a 5-year period (1987–1991) at the University Central Hospital of Turku. The parents were given the option of choosing between the two sampling procedures. CVS was performed, in most cases, at 11 weeks of gestation; and AC, at 15 weeks. The rate of total post-procedure loss was 6·7 per cent in the CVS group and 4·4 per cent in the AC group (p=0·08). The rate of spontaneous abortions was 1·9 per cent in the CVS group and 1·0 per cent in the AC group (p=0·10). The number of birth defects was low in both study groups. No limb reduction cases were observed. Mosaicism was noted in 14 CVS cases and in five AC cases. We conclude that TA-CVS is a safe and practical alternative to AC in prenatal fetal karyotyping.     

Fetal blood sampling and cytogenetic abnormalities

From September 1984 to April 1991, we performed cytogenetic analysis on fetal blood samples from 214 second-and third-trimester pregnancies. One hundred and thirty-four cases were referred to consider the possibility of chromosomal mosaicism following amniocyte studies. The confirmation rate of mosaicism is at 0 per cent (0/9), 1·4 per cent (1/70), and 40 per cent (22/55) for cases of level I, level II, and level III mosaicism, respectively. Four out of 17 cases were positive for the diagnosis of fragile X syndrome. Of 63 cases with abnormal ultrasound findings, blood disorders, or other genetically related clinical conditions, 11 were found to have a chromosome abnormality. Fetal blood sampling is a valuable adjunct to other methods in the prenatal diagnosis of chromosomal mosaicism or pseudomosaicism. It is also useful when rapid cytogenetic diagnosis is desired because of malformations detected in pregnancies at a late gestational age.     

Chorionic villus sampling by biopsy forceps. Results of 1580 procedures from a single centre

The results of a prospective series of 1580 chorionic villus sampling (CVS) procedures using biopsy forceps are presented. Most of the procedures (1442), including 11 sets of twins, were performed by the transcervical approach (TC-CVS), using a curved-shank thin forceps, and 138 by the transabdominal approach (TA-CVS), using a trocar-guided straight thin forceps. The mean gestational age for TC-CVS was 10.9 weeks, and in 233 cases (16 per cent) the procedure was carried out between the 12th and 14th weeks. The mean gestational age for TA-CVS was 16.7 weeks. The major indication for CVS was advanced maternal age (92.7 per cent in the TC and 91.8 per cent in the TA approach), and indications for abnormal ultrasound findings were more common in the TA approach (4.5 per cent) than in TC-CVS (0.07 per cent). Although sampling was apparently accomplished in all the procedures, in 3.1 per cent of the TC-CVS and 2.2 per cent of TA-CVS procedures, the samples were less than 1 mg after dissection. A cytogenic report was obtained in 96.1 per cent of the TC-CVS and 90.6 per cent of the TA-CVS. Maternal serum alpha-fetoprotein (MSAFP) was measured before and after TC-CVS and the post-CVS MSAFP was positively correlated with the sample weight. Second-trimester amniocentesis following CVS was required in 5.2 per cent (TC-CVS) and 6.5 per cent (TA-CVS), due to the failure to obtain a cytogenetic report or diagnostic confirmation. The follow-up to the 20th week was 100 per cent by ultrasound scan, and 88.6 per cent from the 21st week to 1 week after delivery. Fetal loss rates within 2 weeks of the procedure were 1.7 per cent (TC-CVS) and 0.8 per cent (TA-CVS) and total fetal loss accumulated to 1 week after delivery was 4.6 per cent (TC-CVS) and 5.9 per cent (TA-CVS). Factors found to increase significantly fetal loss in the TC-CVS series were maternal age and the collection of very small samples, but not the number of forceps insertions.     

Simultaneous placentacentesis and amniocentesis for prenatal karyotyping: Report on 250 cases

The efficacy and risks of simultaneous transabdominal chorionic villus biopsy (placentacentesis) and amniocentesis in the second and third trimesters were evaluated in 250 singleton pregnancies. The major indications were advanced maternal age (36·0 per cent), abnormal ultrasound findings (23·2 per cent), and low maternal AFP value (17·6 per cent). Nine abnormal karyotypes were found in placental tissue (3·6 per cent). The karyotypes of placental and amniotic cells were different in three cases, including two cases of false-positive mosaicism (08 per cent) and one case of a false-negative result (0·4 per cent) obtained by placental karyotyping. The problem of discrepant karyotypes in embryonic and extra-embryonic tissue does not seem to be restricted to the first trimester. The post-procedure fetal loss rate was estimated as approximately 1·8 per cent. We conclude that the procedure presented here combines the advantages of rapid karyotyping (placentacentesis) and high diagnostic reliability (amniocentesis). It does not seem to be necessary to restrict its use to late presentations and suspicious ultrasound findings.     

Prenatal diagnosis by chorionic villus sampling: Lessons of the first 600 cases

Chorionic villus sampling (CVS) has emerged as a first trimester alternative to amniocentesis for the prenatal detection of genetic disorders. We report our experience in 600 consecutive CVS procedures to better delineate the safety, efficacy and reliability of this new method of prenatal diagnosis. Adequate samples were obtained at the initial visit in 97 per cent of the cases, and successful cultures were established in 98.7 per cent of these patients. Chromosome abnormalities were detected in 5.9 per cent of those pregnancies tested because of advanced maternal age (≥ 35 years). A discrepancy between the villus karyotype and that of the fetus was found in 2.0 per cent of cases, and most commonly consisted of mosaicism in the villus sample for a chromosomal abnormality that was not found in fetal samples. The risk of spontaneous abortion following the procedure was 6.3 per cent. We conclude that chorionic villus sampling is an acceptably safe and reliable procedure, but further investigation is needed before it can become an established technique in prenatal diagnosis.     

Transabdominal villus sampling in early second trimester: A safe sampling method for women of advanced age

Transabdominal chorionic villus sampling (TA-CVS) was performed in 707 viable singleton pregnancies to exclude chromosomal abnormalities. Maternal age ranged between 36 and 49 years (mean 37·9 years); gestational age varied between 10·2 and 18·3 weeks (mean 13·3 weeks). In 639 women (90·4 per cent), a sufficient amount of chorionic tissue (⩾ 10 mg) was obtained after one needle insertion; in 66 women (9·3 per cent) two insertions were needed. An abnormal chromosome pattern was established in 19 cases (2·9 per cent). Vaginal bleeding or spotting within 28 days after TA-CVS occurred in 11 cases (1·5 per cent). The completed follow-up of 678 chromosomally normal pregnancies showed an overall fetal loss rate of 2·6 per cent before 28 weeks. The overall perinatal mortality was 0·9 per cent. When relating fetal loss to gestational age at TA-CVS, this was 6·6 per cent in women sampled before 12 weeks against only 1·8 per cent after 12 weeks. At the same time, the percentage of fetal loss occurring within 2 weeks following the procedure was 75 and 30 per cent, respectively. It is suggested that these data reflect the decline in spontaneous abortion rate during this particular period of pregnancy. It is concluded that TA-CVS is an effective procedure which, when performed after the natural decrease of fetal loss, appears to be a safe option for women of advanced maternal age.     

Prenatal diagnosis of trisomy 12 mosaicism: Physical and developmental follow-up

Follow-up evaluations were performed on a child at the ages of 2 years 8 months and also at 5 years who had been found on prenatal amniocentesis to be mosaic for trisomy 12. Eight of 36 colonies (22 per cent) were trisomy 12 at amniocentesis, with the remaining colonies showing a normal female karyotype. Cord blood, amnion, chorion, placental, and skin fibroblast chromosome studies failed to show any further evidence of a trisomy 12 cell line. At her evaluations, the child had normal physical and neurological findings. Psychomotor development was appropriate for age on screening.     

Cytogenetic analysis of 1375 amniotic fluid specimens from pregnancies with gestational age less than 14 weeks

Our laboratory has received 1375 early amniotic fluid (EA) specimens during the past 5-year period for cytogenetics analysis. The gestational ages of the EA specimens were less than 14 weeks as estimated by ultrasound. The average volume of specimen received was 16 ml. Specimens were typically received in two collection tubes and cultured in Chang A and in supplemented MEM media using the in situ technique. Of the 1375 EA specimens received, 1356 were successfully cultured and yielded results. Abnormal results were found in 67 (4.9 per cent) of the cases. Nineteen specimens (1.4 per cent) failed to yield a result. The mean turn-around time (TAT) for all EA specimens was 8.28 days. In 1991, the average TAT for the EA specimens was 8.00 days compared with a TAT of 6.59 days for all specimens received over 14 weeks gestational age. The number of EA specimens received has increased from 1.5 per month in 1986 to 57 per month in 1991. In summary, our experience with EA specimens for cytogenetic analysis has demonstrated that the success rate is 98.6 per cent and that an increasing number of obstetricians are performing early amniocentesis as they seek to provide their patients with earlier results and an alternative to chorionic villus sampling.