•
Ultrasound
Ultrasound Assisted Amniocentesis in Prenatal Genetic Counseling 1 Peter H. Arger, M.D., David B. Freiman, M.D., Jeffry I. Komins, M.D., and Richard H. Schwarz, M.D. Pre-amniocentesis ultrasonic placental localization and fetal age determination have greatly facilitated genetic counseling by helping to reduce the morbidity of the procedure and by providing an accurate gestational age. The indications for amniocentesis, a technique to indicate the best site for the procedure, and results in 33 patients are discussed. INDEX TERMS: Amniotic fluid. Fetus, abnormalities • Fetus, ultrasound • Placenta, localization • Ultrasound, indications
Radiology 120:155-157, July 1976
Table I:
HE DIAGNOSIS of genetic diseases through amniocentesis and tissue cell culture analysis represents an important advance in the prevention of birth of infants with genetically determined biochemical defects and/or aberrations in the number or structure of chromosomes (10, 12). Genetic counseling may be based on in utero diagnosis, and not on a probability risk; this enables couples to selectively reproduce children free of the suspect problem. Transabdominal amniocentesis with ultrasonic placental and amniotic fluid localization (3, 9) can be accomplished with negligible untoward effects on the fetus or mother at 14- 18 weeks gestation.
T
METHOD AND MATERIALS
The criteria for patient selection are: (a) pregnancy is at high risk for a specific disease process; and (b) the specific disease process is demonstrable with a high degree of reliability by chromosomal or biochemical analysis. Most patients are over 35. The likelihood of having an abnormal baby increases with increasing age. Although women over the age of 35 constitute only 13.5 % of all pregnancies, they produce 50 % of all infants with mongolism (trisomy-21). Women over the age of 40 have a 1 % chance of having a mongoloid baby (10). Chromosomal number aberrations (trisomy-13, trisomy-21, and Turner's syndrome) are detected by our method, and represent the largest group of patients studied (TABLE 1). A second major group are those with previous offspring who had open neural tube defects. Alphafetoprotein analysis can demonstrate the presence of a fetus with such a problem. Couples who have produced a child with a neural tube defect that is multifactorial in origin have a 5 % chance for a subsequent similarly affected offspring (13). Though representing a minority of patients analyzed, many other disorders can be determined by this method, including (a) X-linked recessive disorders; (b) lipid metabolism disorders; (c) mucopolysaccharidosis; (d) amino acid disorders; and (e) carbohydrate metabolism disorders.
I ndications For Amniocentesis
Category
Number
Percentage
Advanced maternal age Prior open neural tube defect Prior biochemical or X-linked anomaly
22 of 33 10 of 33
66 30
3 of 33
9
The patient is scanned both longitudinally and transversely with a full bladder to determine fetal age and placental localization. If a head is not visualized amniocentesis is postponed, since the fetal head should be seen by 14 to 15 weeks. We use the Hellman-Kobayashi tables to determine fetal age (6, 7). Seeing the fetal head and determining the fetal age assures the proper age period for amniocentesis (14-18 weeks), so that the procedure is not inadvertently performed too late in gestation, when abortion cannot be offered should a defect be detected. It is likewise of value in preventing amniocentesis too early, when the amount of amniotic fluid is insufficient for sampling. If after two weeks a fetal head is still not visualized, amniocentesis is performed, since microcephaly and anencephaly may be diagnosed. If the placenta lies anteriorly, multiple transverse scans are obtained to determine the thinnest segment of placenta and the area with the most amniotic fluid below. A mark on the skin is placed over the selected area. Since our referring physicians do the amniocentesis immediately after voiding, the final transverse sections for placental localization, and marking of the amniocentesis site, are done after the patient voids. If the placenta is posterior (Fig. 1), a general area over the largest pool of amniotic fluid is selected. Polaroid views of the marked sites are sent with the patient to the referring physician so that he can evaluate the chosen area. We now use Gray scale (scan converter), but" leading edge" bi-stable B-scans can be used. The Gray scale scans determine the extent of the placenta (Fig. 2). The site selected and the angle of approach for amniocentesis
1 From the Departments of Radiology and Obstetrics & Gynecology, Hospital of the University of Pennsylvania, Philadelphia, Penn. Accepted for publication in December, 1975. ss
155
156
PETER H. ARGER AND OTHERS
can be shown on the polaroid by using the measuring markers (Fig. 3). When "leading edge" B-scan polaroids are used, the transducer can be placed on the selected site, so that the visualized light beam, representing the sound beam direction on the oscilloscope, can be seen (Fig. 4). Both of these methods allow the referring physician to estimate an angle of approach for amniocentesis, as well as locate a site relative to the placenta. The selected site can be cross-checked for fluid with high gain A-mode evaluation, in conjunction with both Gray scale and bistable B-scan methods (Fig. 5). Various other methods may be utilized to obtain the amniotic fluid. Ultrasonic A-mode and B-mode aspiration transducers may be used over the selected site to monitor the aspiration. The aspiration itself may be done in the ultrasound laboratory. We have discontinued this in our laboratory due to the combined logistical problems of coordinating patient appointments in a very busy laboratory with the schedules of a variety of busy referring physicians. In our experience, the B-scan aspiration transducer was somewhat difficult to use due to the proximity of the rigid scanning arm to the aspiration transducer and the angle of approach for amniocentesis. The advent of easily detachable B-scan aspiration transducers would most likely alleviate this problem. Our experience with the A-mode aspiration transducer was more satisfactory, though limited, since we have ceased to do the aspiration in the laboratory. Real-time scanners may also be used to locate the placenta, though we have no experience with this method. The advent of flexible aspiration real-time scanners would probably facilitate the speed and ease of this procedure. RESULTS
Thirty-three patients were selected for amniocentesis
July 1976
based on previously stated criteria. The overall number selected has increased due to the ease, accuracy and safety of the technique. When complete anterior placental location is shown and no thinner site can be found, benefit/risk ratios are discussed with patients. When the benefits barely outweigh the risks more patients decide not to undergo the procedure. When benefits clearly outweigh the risks, transplacental amniocentesis is done through the thinnest or most peripheral aspect of the placenta. All 33 patients had successful amniocentesis with cell tissue culture growth. In our experience, the use of ultrasound has shown no significant difference in cell tissue growth. Except for brief pain, none of our patients had any morbidity; no fetal complications have occurred. The number of taps necessary for successful amniotic fluid aspiration has decreased using this technique. The patients have tolerated the procedure better, and the number of bloody taps has decreased. Including the taps of several completely anterior placentas, we have had 7 bloody taps (including macro- and microscopic blood) in 33 patients (21 %); this is less than the percentages reported without ultrasound (5). Of the 33 patients analyzed by this method, 5 had an induced abortion due to the presence of an abnormal fetus. Three of the 5 abnormal fetuses were trisomy abnormalities, one a translocation, and one a neural tube defect (TABLE 2). DISCUSSION
The use of amniocentesis and tissue cell culture analysis has dramatically improved our ability to make a prenatal diagnosis of genetic disease. Pre-amniocentesis ultrasound placental localization and fetal age determination have contributed to this improvement. Though some authors (14)
Fig. 1. Longitudinal scan 3 cm to the left of the midline. Note the collection of echoes posteriorly, demonstrating a posterior placenta (closed white arrows). The circular collection of echoes superior to the placenta is the fetal head. Fig. 2. Gray scale abdominal cross section 8 cm below the umbilicus. Note the dense black echoes of a right anterior and lateral placenta just inside the myometrium (closed white arrows). Fig. 3. A gray scale cross section shows the dense black echoes of a posterior and lateral placenta (white arrows). The selected site and angle of approach are illustrated by the black dots of the measuring markers (black arrow).
157
AMNIOCENTESIS IN GENETIC COUNSELING
Vol. 120
have reported a decreased cell tissue culture growth with the use of ultrasound, most agree in reporting no significant change (4,8, 11). The success rate of cell tissue culture growth in noncontaminated amniotic fluid after amniocentesis has been reported to be greater than 90 % (15). We have had successful growth in all 33 of our patients. The short term complication rate of the procedure has been reported at less than 1 % (12, 13). Possible maternal morbidity includes abdominal pain (brief pain the only morbidity we've noted to date), peritonitis, maternal hemorrhage, and amnionitis. Though we have had none, possible fetal complications include the loss of the fetus due to abortion, placental abruption hemorrhage, and infection and needle puncture in a vital area which induces malformation. A large series of 350 amniocentesis procedures included two incidents of fetal morbitity (2). The pitfalls in this procedure are: (a) errors in diagnosis due to removal and culture of maternal urine; (b) maternal cell overgrowth; (c) multiple qestatlonrto) mosaicism; (e) laboratory error; and (I) failure of the culture to grow. Department of Radiology Hospital of University of Pennsylvania 3400 Spruce St. Philadelphia, Penn, 19104
Table II: Patient age 38
44 39
41 31
Ultrasound
Amniocentesis Tissue Culture Results Indications
Tissue culture
Age Age Age Age Previous neural tube defect
Mosaic trisomy-D Trisomy-18 C/G translocati on Trisomy-21 Positive alphafetoprotein
9. Kobayashi M, Hellman LM, Fillisti L: Placental localization by ultrasound. Am J Obstet Gynecol 106:279-285, 15 Jan 1970 10. Milunsky A, Littlefield JW, Kanvfer IN, et al: Prenatal genetic diagnosis. N Engl J Med 283: 1498-1504, 31 Dec 1970 11. Miskin M, Doran TA, Rudd N, et al: Use of ultrasound for placental localization in genetic amniocentesis. Obstet Gynecol 43: 872-877, Jun 1974 12. Nadler HL, Gerbie AB: Role of amniocentesis in the intrauterine detection of genetic disorders. N Engl J Med 282:596-599, 12 Mar 1970 13. Perno II ML, Prescott GH, Hecht F, et al: Prenatal diagnosis: Practice, pitfalls, and progress. Obst Gynecol 4:773-783, Nov 1974 14. Robinson A, Bowes W, Droegemueller W, et al: Intrauterine diagnosis: potential complications. Am J Obstet GynecoI116:937-941, 1 Aug 1973 15. Tutera G, Newman RL: Placental localization and diagnosis of antenatal hemorrhage by ultrasonography. Obstet Gynecol 42: 684-688, Nov 1973
REFERENCES 1. Bennett MJ: The technique and complications of amniocentesis. S Afr Med J 46:1545-1548,14 Oct 1972 2. Cook LN, Shott RJ, Andrews BF: Fetal complications of diagnostic amniocentesis: a review and report of a case with pneumothorax. Pediatrics 63:421-424, Mar 1974 3. Donald I, Abdulla U: Placentography by sonar. J Obstet Gynaecol Br Commonw 75:993-1006, Oct 1968 4. Fisher CC, Angell R, Garrett WJ, et al: Letter: Ultrasonic uterine examination prior to amniocentesis. Am J Obstet Gynecol 119:574-575,15 Jun 1974 5. Harrison R, Campbell S, Craft I: Risks of fetomaternal hemorrhage resulting from amniocentesis with and without ultrasound placental localization. Obstet Gynecol 46:389-391, Oct 1975 6. Hellman LM, Kobayashi M, Fillisti L, et aJ: Growth and development of the human fetus prior to the twentieth week of gestation. Am J Obstet Gynecol 103:789-800, 15 Mar 1969 7. Hellman LM, Kobayashi M, Fillisti L, et al: Sources of error in sonographic fetal mensuration and estimation of growth. Am J Obstet GynecoI99:662-670, 1 Nov 1967. 8. Hsu LYF, Dubin EC, Kerenyi T, et al: Results and pitfalls in prenatal cytogenetic diagnosis. J Med Genet 10: 112-119, Jun 1973
Fig. 4. High gain bi-stable B-mode abdominal cross section 8 em below the umbilicus, with the transducer on the selected site for amniocentesis, demonstrates the placenta (closed black arrows). The light beam represents the sound ,be~m direction (open black arrows). Fig. 5. High gain A-mode with transducer placed on the selected site shows the depth of fluid collection and its approximate size (closed white arrow).
Ultrasound
Ultrasound Assisted Amniocentesis in Prenatal Genetic Counseling 1 Peter H. Arger, M.D., David B. Freiman, M.D., Jeffry I. Komins, M.D., and Richard H. Schwarz, M.D. Pre-amniocentesis ultrasonic placental localization and fetal age determination have greatly facilitated genetic counseling by helping to reduce the morbidity of the procedure and by providing an accurate gestational age. The indications for amniocentesis, a technique to indicate the best site for the procedure, and results in 33 patients are discussed. INDEX TERMS: Amniotic fluid. Fetus, abnormalities • Fetus, ultrasound • Placenta, localization • Ultrasound, indications
Radiology 120:155-157, July 1976
Table I:
HE DIAGNOSIS of genetic diseases through amniocentesis and tissue cell culture analysis represents an important advance in the prevention of birth of infants with genetically determined biochemical defects and/or aberrations in the number or structure of chromosomes (10, 12). Genetic counseling may be based on in utero diagnosis, and not on a probability risk; this enables couples to selectively reproduce children free of the suspect problem. Transabdominal amniocentesis with ultrasonic placental and amniotic fluid localization (3, 9) can be accomplished with negligible untoward effects on the fetus or mother at 14- 18 weeks gestation.
T
METHOD AND MATERIALS
The criteria for patient selection are: (a) pregnancy is at high risk for a specific disease process; and (b) the specific disease process is demonstrable with a high degree of reliability by chromosomal or biochemical analysis. Most patients are over 35. The likelihood of having an abnormal baby increases with increasing age. Although women over the age of 35 constitute only 13.5 % of all pregnancies, they produce 50 % of all infants with mongolism (trisomy-21). Women over the age of 40 have a 1 % chance of having a mongoloid baby (10). Chromosomal number aberrations (trisomy-13, trisomy-21, and Turner's syndrome) are detected by our method, and represent the largest group of patients studied (TABLE 1). A second major group are those with previous offspring who had open neural tube defects. Alphafetoprotein analysis can demonstrate the presence of a fetus with such a problem. Couples who have produced a child with a neural tube defect that is multifactorial in origin have a 5 % chance for a subsequent similarly affected offspring (13). Though representing a minority of patients analyzed, many other disorders can be determined by this method, including (a) X-linked recessive disorders; (b) lipid metabolism disorders; (c) mucopolysaccharidosis; (d) amino acid disorders; and (e) carbohydrate metabolism disorders.
I ndications For Amniocentesis
Category
Number
Percentage
Advanced maternal age Prior open neural tube defect Prior biochemical or X-linked anomaly
22 of 33 10 of 33
66 30
3 of 33
9
The patient is scanned both longitudinally and transversely with a full bladder to determine fetal age and placental localization. If a head is not visualized amniocentesis is postponed, since the fetal head should be seen by 14 to 15 weeks. We use the Hellman-Kobayashi tables to determine fetal age (6, 7). Seeing the fetal head and determining the fetal age assures the proper age period for amniocentesis (14-18 weeks), so that the procedure is not inadvertently performed too late in gestation, when abortion cannot be offered should a defect be detected. It is likewise of value in preventing amniocentesis too early, when the amount of amniotic fluid is insufficient for sampling. If after two weeks a fetal head is still not visualized, amniocentesis is performed, since microcephaly and anencephaly may be diagnosed. If the placenta lies anteriorly, multiple transverse scans are obtained to determine the thinnest segment of placenta and the area with the most amniotic fluid below. A mark on the skin is placed over the selected area. Since our referring physicians do the amniocentesis immediately after voiding, the final transverse sections for placental localization, and marking of the amniocentesis site, are done after the patient voids. If the placenta is posterior (Fig. 1), a general area over the largest pool of amniotic fluid is selected. Polaroid views of the marked sites are sent with the patient to the referring physician so that he can evaluate the chosen area. We now use Gray scale (scan converter), but" leading edge" bi-stable B-scans can be used. The Gray scale scans determine the extent of the placenta (Fig. 2). The site selected and the angle of approach for amniocentesis
1 From the Departments of Radiology and Obstetrics & Gynecology, Hospital of the University of Pennsylvania, Philadelphia, Penn. Accepted for publication in December, 1975. ss
155
156
PETER H. ARGER AND OTHERS
can be shown on the polaroid by using the measuring markers (Fig. 3). When "leading edge" B-scan polaroids are used, the transducer can be placed on the selected site, so that the visualized light beam, representing the sound beam direction on the oscilloscope, can be seen (Fig. 4). Both of these methods allow the referring physician to estimate an angle of approach for amniocentesis, as well as locate a site relative to the placenta. The selected site can be cross-checked for fluid with high gain A-mode evaluation, in conjunction with both Gray scale and bistable B-scan methods (Fig. 5). Various other methods may be utilized to obtain the amniotic fluid. Ultrasonic A-mode and B-mode aspiration transducers may be used over the selected site to monitor the aspiration. The aspiration itself may be done in the ultrasound laboratory. We have discontinued this in our laboratory due to the combined logistical problems of coordinating patient appointments in a very busy laboratory with the schedules of a variety of busy referring physicians. In our experience, the B-scan aspiration transducer was somewhat difficult to use due to the proximity of the rigid scanning arm to the aspiration transducer and the angle of approach for amniocentesis. The advent of easily detachable B-scan aspiration transducers would most likely alleviate this problem. Our experience with the A-mode aspiration transducer was more satisfactory, though limited, since we have ceased to do the aspiration in the laboratory. Real-time scanners may also be used to locate the placenta, though we have no experience with this method. The advent of flexible aspiration real-time scanners would probably facilitate the speed and ease of this procedure. RESULTS
Thirty-three patients were selected for amniocentesis
July 1976
based on previously stated criteria. The overall number selected has increased due to the ease, accuracy and safety of the technique. When complete anterior placental location is shown and no thinner site can be found, benefit/risk ratios are discussed with patients. When the benefits barely outweigh the risks more patients decide not to undergo the procedure. When benefits clearly outweigh the risks, transplacental amniocentesis is done through the thinnest or most peripheral aspect of the placenta. All 33 patients had successful amniocentesis with cell tissue culture growth. In our experience, the use of ultrasound has shown no significant difference in cell tissue growth. Except for brief pain, none of our patients had any morbidity; no fetal complications have occurred. The number of taps necessary for successful amniotic fluid aspiration has decreased using this technique. The patients have tolerated the procedure better, and the number of bloody taps has decreased. Including the taps of several completely anterior placentas, we have had 7 bloody taps (including macro- and microscopic blood) in 33 patients (21 %); this is less than the percentages reported without ultrasound (5). Of the 33 patients analyzed by this method, 5 had an induced abortion due to the presence of an abnormal fetus. Three of the 5 abnormal fetuses were trisomy abnormalities, one a translocation, and one a neural tube defect (TABLE 2). DISCUSSION
The use of amniocentesis and tissue cell culture analysis has dramatically improved our ability to make a prenatal diagnosis of genetic disease. Pre-amniocentesis ultrasound placental localization and fetal age determination have contributed to this improvement. Though some authors (14)
Fig. 1. Longitudinal scan 3 cm to the left of the midline. Note the collection of echoes posteriorly, demonstrating a posterior placenta (closed white arrows). The circular collection of echoes superior to the placenta is the fetal head. Fig. 2. Gray scale abdominal cross section 8 cm below the umbilicus. Note the dense black echoes of a right anterior and lateral placenta just inside the myometrium (closed white arrows). Fig. 3. A gray scale cross section shows the dense black echoes of a posterior and lateral placenta (white arrows). The selected site and angle of approach are illustrated by the black dots of the measuring markers (black arrow).
157
AMNIOCENTESIS IN GENETIC COUNSELING
Vol. 120
have reported a decreased cell tissue culture growth with the use of ultrasound, most agree in reporting no significant change (4,8, 11). The success rate of cell tissue culture growth in noncontaminated amniotic fluid after amniocentesis has been reported to be greater than 90 % (15). We have had successful growth in all 33 of our patients. The short term complication rate of the procedure has been reported at less than 1 % (12, 13). Possible maternal morbidity includes abdominal pain (brief pain the only morbidity we've noted to date), peritonitis, maternal hemorrhage, and amnionitis. Though we have had none, possible fetal complications include the loss of the fetus due to abortion, placental abruption hemorrhage, and infection and needle puncture in a vital area which induces malformation. A large series of 350 amniocentesis procedures included two incidents of fetal morbitity (2). The pitfalls in this procedure are: (a) errors in diagnosis due to removal and culture of maternal urine; (b) maternal cell overgrowth; (c) multiple qestatlonrto) mosaicism; (e) laboratory error; and (I) failure of the culture to grow. Department of Radiology Hospital of University of Pennsylvania 3400 Spruce St. Philadelphia, Penn, 19104
Table II: Patient age 38
44 39
41 31
Ultrasound
Amniocentesis Tissue Culture Results Indications
Tissue culture
Age Age Age Age Previous neural tube defect
Mosaic trisomy-D Trisomy-18 C/G translocati on Trisomy-21 Positive alphafetoprotein
9. Kobayashi M, Hellman LM, Fillisti L: Placental localization by ultrasound. Am J Obstet Gynecol 106:279-285, 15 Jan 1970 10. Milunsky A, Littlefield JW, Kanvfer IN, et al: Prenatal genetic diagnosis. N Engl J Med 283: 1498-1504, 31 Dec 1970 11. Miskin M, Doran TA, Rudd N, et al: Use of ultrasound for placental localization in genetic amniocentesis. Obstet Gynecol 43: 872-877, Jun 1974 12. Nadler HL, Gerbie AB: Role of amniocentesis in the intrauterine detection of genetic disorders. N Engl J Med 282:596-599, 12 Mar 1970 13. Perno II ML, Prescott GH, Hecht F, et al: Prenatal diagnosis: Practice, pitfalls, and progress. Obst Gynecol 4:773-783, Nov 1974 14. Robinson A, Bowes W, Droegemueller W, et al: Intrauterine diagnosis: potential complications. Am J Obstet GynecoI116:937-941, 1 Aug 1973 15. Tutera G, Newman RL: Placental localization and diagnosis of antenatal hemorrhage by ultrasonography. Obstet Gynecol 42: 684-688, Nov 1973
REFERENCES 1. Bennett MJ: The technique and complications of amniocentesis. S Afr Med J 46:1545-1548,14 Oct 1972 2. Cook LN, Shott RJ, Andrews BF: Fetal complications of diagnostic amniocentesis: a review and report of a case with pneumothorax. Pediatrics 63:421-424, Mar 1974 3. Donald I, Abdulla U: Placentography by sonar. J Obstet Gynaecol Br Commonw 75:993-1006, Oct 1968 4. Fisher CC, Angell R, Garrett WJ, et al: Letter: Ultrasonic uterine examination prior to amniocentesis. Am J Obstet Gynecol 119:574-575,15 Jun 1974 5. Harrison R, Campbell S, Craft I: Risks of fetomaternal hemorrhage resulting from amniocentesis with and without ultrasound placental localization. Obstet Gynecol 46:389-391, Oct 1975 6. Hellman LM, Kobayashi M, Fillisti L, et aJ: Growth and development of the human fetus prior to the twentieth week of gestation. Am J Obstet Gynecol 103:789-800, 15 Mar 1969 7. Hellman LM, Kobayashi M, Fillisti L, et al: Sources of error in sonographic fetal mensuration and estimation of growth. Am J Obstet GynecoI99:662-670, 1 Nov 1967. 8. Hsu LYF, Dubin EC, Kerenyi T, et al: Results and pitfalls in prenatal cytogenetic diagnosis. J Med Genet 10: 112-119, Jun 1973
Fig. 4. High gain bi-stable B-mode abdominal cross section 8 em below the umbilicus, with the transducer on the selected site for amniocentesis, demonstrates the placenta (closed black arrows). The light beam represents the sound ,be~m direction (open black arrows). Fig. 5. High gain A-mode with transducer placed on the selected site shows the depth of fluid collection and its approximate size (closed white arrow).
