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The role of fetal blood sampling in prenatal diagnosis
Early Human Development, 29 (1992) 155-159 Elsevier Scientific Publishers Ireland Ltd.
155
EHD 01266
The role of fetal blood sampling in prenatal diagnosis K. Suzumori Department
of Obstetrics
and Gynecology,
Nagoya Nagoya
City University, 46 7 (Japan)
I-Kawasumi,
Mizuho-Cho.
Mizuho-Ku.
Summary Fetal blood sampling via cordocentesis is being used with increased frequency. In our clinic, 125 fetal blood samplings (109 patients) have been performed for evaluation of a variety of clinical situations. Our experience confirms the efficacy of the procedure and suggests that it may be an important tool for fetal assessment. Key words: fetal blood sampling; cordocentesis; fetal assessment
Introduction Many obstetrical techniques have come together to facilitate the diagnosis of genetic disorders prenatally. Fetal blood sampling is a relatively new addition to this field of study. Fetal blood can be obtained in the second trimester of pregnancy by fetoscopy or ultrasound-guided needling. Fetoscopy, although reliable for sampling of fetal blood, carries a relatively high risk of complications, including abortion, amniotic fluid leakage and preterm labor. More recently, improvements in imaging by ultrasonography have made fetoscopic guidance unnecessary; ultrasound-guided needling of the umbilical cord vein is the currently recommended method of fetal blood sampling [l-3]. Percutaneous umbilical blood sampling, or cordocentesis, has led to considerable optimism which appears justifiable. Technique In our clinic, cordocentesis is usually performed on an out-patient basis in a delivery room with surgical preparation of the abdomen. No maternal sedation is Correspondence to: K. Suumori, Department of Obstetrics and Gynecology, Nagoya City University, IKawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya 467, Japan.
0378-3782/9Z$O5.00 0 1992 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland
156
Fig.
I. Ultrasound-guided
cordocentesis.
administered. The site and direction of the umbilical cord at its insertion into the placenta are identified sonographically. The ultrasound device is a 5.0-MHz convex transducer (YOKOKAWA MED. SYSTEM U-Sonic RT2800) manipulated through a sterile bag. With the transducer in one hand, held parallel to the intended course of the needle (Fig. l), local anesthetic is infiltrated into the chosen site of entry of the maternal abdomen. We use a 23-gauge needle in order to reduce cord bleeding when the needle is withdrawn. A needle fixed syringe is introduced in the plane of the ultrasound section through the abdominal wall, the uterine wall, into the amniotic cavity and finally into the cord. If the placenta is anterior, a transplacental route is easiest and does not puncture the membranes. With a posterior placenta, a transamniotic approach may be necessary and is usually more difficult. Fetal injection of pancuronium is used in cases with posteriorly implanted placenta in which excessive fetal movement interferes with cord puncture or free loop cord is selected as the site of needle puncture (Fig. 2). Two hours after sampling, the patient is again examined ultrasonographically. To verify blood sample purity, the mean corpuscular volume is measured on a Coulter S Plus II. The risk of fetal death after cordocentesis depends upon the indication for sampling and the skill of the operator, but in our series, no procedure-related fetal loss was encountered.
Fig.
2. Varying
approach
to the cord.
157
Subjects
One hundred twenty-five samples were obtained during gestational weeks 18-39 in 109 patients who were referred to us for various prenatal diagnoses. Indications are summarized in Table I. The distribution of the samplings according to gestational age is shown in Table II. Nine patients had iterative sampling (from two to live) during the same pregnancy. Fetal karyotyping
The largest single group in our practice at present is karyotyping. A fetal karyotype can be obtained from lymphocytes within 48-72 h, compared with 7-10 days required for an amniocyte karyotype. This rapid karyotyping is beneficial for late presenting patients and for confident diagnosis of mosaicism in amniocytes or minute chromosomal rearrangement. When a fetal anomaly which is compatible with life and/or treatable is discovered by ultrasound, fetal karyotyping is also essential. The results obtained may be crucial to the further management of the pregnancy. Verification of amniocentesis results included amniocyte mosaicism (N = l), fragile X (N = 2) and parental carrier of minute chromosomal abnormality (N = 4). Fetal lymphocyte culture provides a quality of cytogenetic preparation comparable to that achieved at amniocentesis. The preparations are easy to band and would be suited for the detection of subtle chromosome anomalies, particularly small rearrangements detectable only by high resolution cytogenetics. The detection of fetal anomalies on ultrasound indicates the need for fetal karyotyping because of the common association with chromosomal abnormalities [4]. The clinical indications for cordocentesis and the number of abnormal karyotypes found in each group are listed in Table III. TARLE I Medical indications for fetal blood sampling during pregnancy. Indications of prenatal diagnosis Rapid karyotyping Reconfirmation of amniocentesis result Fetal anomaly on USG Viral infection Fukuyama muscular dystrophy Miscellaneous Hypophosphatasia Lesch-Nyhan syndrome Hemophilia A Others Total
No. of pregnancies
No. of samplings
7 49 18 15
7 62 18 18
3 1 1 15
3 I 1 15
109
125
158 TABLE 11 Number of procedures according to the duration of gestation. No. of samplings
Weeks of gestation at time of procedure
31
18-21
25 17 36 16
22-25 26-29 30-33 34-38
viralinfection Viral infection, especially rubella, in a pregnant woman is frequently transmitted to her fetus, resulting in fetal damage. We attempted to prenatally diagnose the existence of rubella infection by measuring the rubella specific IgM in fetal sera in 18 fetuses in whose mothers rubella infection had been confirmed during pregnancy. Specific IgM was detected in 9 fetuses and 8 of them were aborted. The fetal infection was confirmed by blood tests after abortion [5]. Recently, an alternative and complementary method of prenatal rubella infection detection with viral specific cDNA on villi was reported 161. This procedure will become our main tool in the near future and will be diagnostically applicable from early pregnancy. Fukuyama muscular dystrophy Fukuyama muscular dystrophy is characterized by clinical abnormalities suggestive of both myopathy and encephalopathy during the first few months of life and
TABLE III Indications and results of rapid karyotyping. Clinical indications
Total fetuses
Central nervous system Urinary tract abnormalities Nonimmune hydrops fetalis IUGR or oligohydramnios Cystic hygroma Abdominal-gastrointestinal Other Total
9 9
12 4 3
No. of abnormal karyotype (%) 1 (11.1) 2 (22.2) I (8.3) I (25.0) I (33.3)
6
0 (0.0)
6
0
49
(0.0)
6 (12.2)
159
is considered to be an autosomal recessive disease. We have described one affected fetus, who showed an elevated plasma creatine phosphokinase (CPK) activity. A 23week aborted fetus with associated brain malformation was confirmed to be affected [7]. Our subsequent experience (N = 14), however, indicates that not all diseased fetuses (N = 3) will have CPK elevations by 20 weeks gestation and that additional markers must be sought. Miscellaneous Recent developments in the study of genomic DNA using restriction enzymes, have already provided satisfactory results in the prenatal diagnosis of some genetic disorders, such as Duchenne muscular dystrophy, hemophilia A and B, hypophophatasia and Lesch-Nyhan disease. However, a small percentage of couples do not have any useful DNA polymorphisms and linkage analysis can not be established. For an accurate diagnosis of the disorders listed in Table I, procurement of pure fetal blood samples was necessary. Conclusions Fetal blood sampling is already sufficiently standardized and, although invasive and therefore involving some fetal risks, can be considered relatively safe. This technique need not be confined to the prenatal diagnosis of genetic disorders but may find wide application in the antenatal evaluation of the fetus and help elucidate the pathophysiology of a variety of pregnancy complications. Acknowledgement This work was supported by grant from the Ogyaa Donation JAMW. References 1 2 3 4 5 6 7
Daffos, F. et al. (1985): Am. J. Obstet. Gynecol., 153, 655-660. Weiner, C.P. (1987): Obstet. Gynecol., 70, 664-668. Hogge, W.A. et al. (1988): Am. J. Obstet. Gynecol., 158, 132-136. Shah, D.M. et al. (1990): Am. J. Obstet. Gynecol., 162, 1548-1550. Suzumori, K. et al. (1991): Asia-Oceania J. Obstet. Gynaecol., 17, 113-l 17. Terry, G.M. et al. (1986): Br. Med. J., 292, 930-933. Takada, K. et al. (1987): Acta Neuropathol. (Bed.), 74, 300-306.
Foundation
from
155
EHD 01266
The role of fetal blood sampling in prenatal diagnosis K. Suzumori Department
of Obstetrics
and Gynecology,
Nagoya Nagoya
City University, 46 7 (Japan)
I-Kawasumi,
Mizuho-Cho.
Mizuho-Ku.
Summary Fetal blood sampling via cordocentesis is being used with increased frequency. In our clinic, 125 fetal blood samplings (109 patients) have been performed for evaluation of a variety of clinical situations. Our experience confirms the efficacy of the procedure and suggests that it may be an important tool for fetal assessment. Key words: fetal blood sampling; cordocentesis; fetal assessment
Introduction Many obstetrical techniques have come together to facilitate the diagnosis of genetic disorders prenatally. Fetal blood sampling is a relatively new addition to this field of study. Fetal blood can be obtained in the second trimester of pregnancy by fetoscopy or ultrasound-guided needling. Fetoscopy, although reliable for sampling of fetal blood, carries a relatively high risk of complications, including abortion, amniotic fluid leakage and preterm labor. More recently, improvements in imaging by ultrasonography have made fetoscopic guidance unnecessary; ultrasound-guided needling of the umbilical cord vein is the currently recommended method of fetal blood sampling [l-3]. Percutaneous umbilical blood sampling, or cordocentesis, has led to considerable optimism which appears justifiable. Technique In our clinic, cordocentesis is usually performed on an out-patient basis in a delivery room with surgical preparation of the abdomen. No maternal sedation is Correspondence to: K. Suumori, Department of Obstetrics and Gynecology, Nagoya City University, IKawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya 467, Japan.
0378-3782/9Z$O5.00 0 1992 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland
156
Fig.
I. Ultrasound-guided
cordocentesis.
administered. The site and direction of the umbilical cord at its insertion into the placenta are identified sonographically. The ultrasound device is a 5.0-MHz convex transducer (YOKOKAWA MED. SYSTEM U-Sonic RT2800) manipulated through a sterile bag. With the transducer in one hand, held parallel to the intended course of the needle (Fig. l), local anesthetic is infiltrated into the chosen site of entry of the maternal abdomen. We use a 23-gauge needle in order to reduce cord bleeding when the needle is withdrawn. A needle fixed syringe is introduced in the plane of the ultrasound section through the abdominal wall, the uterine wall, into the amniotic cavity and finally into the cord. If the placenta is anterior, a transplacental route is easiest and does not puncture the membranes. With a posterior placenta, a transamniotic approach may be necessary and is usually more difficult. Fetal injection of pancuronium is used in cases with posteriorly implanted placenta in which excessive fetal movement interferes with cord puncture or free loop cord is selected as the site of needle puncture (Fig. 2). Two hours after sampling, the patient is again examined ultrasonographically. To verify blood sample purity, the mean corpuscular volume is measured on a Coulter S Plus II. The risk of fetal death after cordocentesis depends upon the indication for sampling and the skill of the operator, but in our series, no procedure-related fetal loss was encountered.
Fig.
2. Varying
approach
to the cord.
157
Subjects
One hundred twenty-five samples were obtained during gestational weeks 18-39 in 109 patients who were referred to us for various prenatal diagnoses. Indications are summarized in Table I. The distribution of the samplings according to gestational age is shown in Table II. Nine patients had iterative sampling (from two to live) during the same pregnancy. Fetal karyotyping
The largest single group in our practice at present is karyotyping. A fetal karyotype can be obtained from lymphocytes within 48-72 h, compared with 7-10 days required for an amniocyte karyotype. This rapid karyotyping is beneficial for late presenting patients and for confident diagnosis of mosaicism in amniocytes or minute chromosomal rearrangement. When a fetal anomaly which is compatible with life and/or treatable is discovered by ultrasound, fetal karyotyping is also essential. The results obtained may be crucial to the further management of the pregnancy. Verification of amniocentesis results included amniocyte mosaicism (N = l), fragile X (N = 2) and parental carrier of minute chromosomal abnormality (N = 4). Fetal lymphocyte culture provides a quality of cytogenetic preparation comparable to that achieved at amniocentesis. The preparations are easy to band and would be suited for the detection of subtle chromosome anomalies, particularly small rearrangements detectable only by high resolution cytogenetics. The detection of fetal anomalies on ultrasound indicates the need for fetal karyotyping because of the common association with chromosomal abnormalities [4]. The clinical indications for cordocentesis and the number of abnormal karyotypes found in each group are listed in Table III. TARLE I Medical indications for fetal blood sampling during pregnancy. Indications of prenatal diagnosis Rapid karyotyping Reconfirmation of amniocentesis result Fetal anomaly on USG Viral infection Fukuyama muscular dystrophy Miscellaneous Hypophosphatasia Lesch-Nyhan syndrome Hemophilia A Others Total
No. of pregnancies
No. of samplings
7 49 18 15
7 62 18 18
3 1 1 15
3 I 1 15
109
125
158 TABLE 11 Number of procedures according to the duration of gestation. No. of samplings
Weeks of gestation at time of procedure
31
18-21
25 17 36 16
22-25 26-29 30-33 34-38
viralinfection Viral infection, especially rubella, in a pregnant woman is frequently transmitted to her fetus, resulting in fetal damage. We attempted to prenatally diagnose the existence of rubella infection by measuring the rubella specific IgM in fetal sera in 18 fetuses in whose mothers rubella infection had been confirmed during pregnancy. Specific IgM was detected in 9 fetuses and 8 of them were aborted. The fetal infection was confirmed by blood tests after abortion [5]. Recently, an alternative and complementary method of prenatal rubella infection detection with viral specific cDNA on villi was reported 161. This procedure will become our main tool in the near future and will be diagnostically applicable from early pregnancy. Fukuyama muscular dystrophy Fukuyama muscular dystrophy is characterized by clinical abnormalities suggestive of both myopathy and encephalopathy during the first few months of life and
TABLE III Indications and results of rapid karyotyping. Clinical indications
Total fetuses
Central nervous system Urinary tract abnormalities Nonimmune hydrops fetalis IUGR or oligohydramnios Cystic hygroma Abdominal-gastrointestinal Other Total
9 9
12 4 3
No. of abnormal karyotype (%) 1 (11.1) 2 (22.2) I (8.3) I (25.0) I (33.3)
6
0 (0.0)
6
0
49
(0.0)
6 (12.2)
159
is considered to be an autosomal recessive disease. We have described one affected fetus, who showed an elevated plasma creatine phosphokinase (CPK) activity. A 23week aborted fetus with associated brain malformation was confirmed to be affected [7]. Our subsequent experience (N = 14), however, indicates that not all diseased fetuses (N = 3) will have CPK elevations by 20 weeks gestation and that additional markers must be sought. Miscellaneous Recent developments in the study of genomic DNA using restriction enzymes, have already provided satisfactory results in the prenatal diagnosis of some genetic disorders, such as Duchenne muscular dystrophy, hemophilia A and B, hypophophatasia and Lesch-Nyhan disease. However, a small percentage of couples do not have any useful DNA polymorphisms and linkage analysis can not be established. For an accurate diagnosis of the disorders listed in Table I, procurement of pure fetal blood samples was necessary. Conclusions Fetal blood sampling is already sufficiently standardized and, although invasive and therefore involving some fetal risks, can be considered relatively safe. This technique need not be confined to the prenatal diagnosis of genetic disorders but may find wide application in the antenatal evaluation of the fetus and help elucidate the pathophysiology of a variety of pregnancy complications. Acknowledgement This work was supported by grant from the Ogyaa Donation JAMW. References 1 2 3 4 5 6 7
Daffos, F. et al. (1985): Am. J. Obstet. Gynecol., 153, 655-660. Weiner, C.P. (1987): Obstet. Gynecol., 70, 664-668. Hogge, W.A. et al. (1988): Am. J. Obstet. Gynecol., 158, 132-136. Shah, D.M. et al. (1990): Am. J. Obstet. Gynecol., 162, 1548-1550. Suzumori, K. et al. (1991): Asia-Oceania J. Obstet. Gynaecol., 17, 113-l 17. Terry, G.M. et al. (1986): Br. Med. J., 292, 930-933. Takada, K. et al. (1987): Acta Neuropathol. (Bed.), 74, 300-306.
Foundation
from