- Email: [email protected]
Choice of second-trimester genetic sonogram for detection of trisomy 21
Choice of Second-Trimester Genetic Sonogram for Detection of Trisomy 21 A N T H O N Y M. VINTZILEOS, MD, EDWIN R. GUZMAN, MD, JOHN C. SMULIAN, MD , MPH, DAVID A. MCLEAN, MD, A N D CANDE V. A N A N T H , PhD, M P H Objective: To determine the utilization rate of secondtrimester genetic sonogram and its role in influencing the decision for amniocentesis in women at increased risk for fetal trisomy 21. Methods: From November 1, 1993, to December 31, 1996, a second-trimester genetic sonogram or only genetic amniocentesis (as a first choice) were offered to pregnant women referred to our institution who were at increased risk for fetal trisomy 21. Results: During the study period, 2089 women were referred to our unit for genetic prenatal diagnosis; of these, 1426 (68%) chose only genetic amniocentesis, and 663 (32%) chose a genetic sonogram as their first option. The yearly utilization rates of genetic sonogram were two of 477 or 0.4% for 1993, 82 of 495 or 16.6% for 1994, 251 of 523 or 48.0% for 1995, and 328 of 594 or 55.2% for 1996. Adjusting for potential confounders, multivariable logistic regression analysis showed that the most important factors associated with the women's decision to undergo genetic amniocentesis were three or more ultrasound markers present (relative risk [RR] 189.5, 95% confidence interval [CI] 37.1, 980.0), two ultrasound markers present (RR 47.2, 95% CI 9.8, 267.8), one ultrasound marker present (RR 12.7, 95% CI 5.5, 29.7), and abnormal serum biochemistry (RR 3.0, 95% CI 1.0, 8.9). Conclusion: The increasing utilization trend, in conjunction with the fact that an abnormal sonogram was the most influential factor in women's decision to undergo genetic amniocentesis, suggests that genetic sonogram services for detection of trisomy 21 should be added to the armamentarium of all prenatal diagnostic centers. (Obstet Gynecol 1997;90:187-90. © 1997 by The American College of Obstetricians and Gynecologists.)
In recent years, m a n y studies have addressed the usefulness of various second-trimester ultrasound markers From the Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School/St. Peter's Medical Center, New Brunswick, New Jersey.
VOL. 90, NO. 2, AUGUST 1997
for the prenatal detection of fetal trisomy 21. By combining multiple ultrasound markers, some investigators have achieved detection rates of fetal trisomy 21 as high as 83-93%. 1-6 Because of these high detection rates, we have offered a comprehensive sonographic assessment by evaluating multiple ultrasound markers as an adjunct to maternal age and maternal serum biochemistry to adjust the risk status and modify clinical management. 6 However, this approach has not been evaluated in terms of use or h o w the results influence a w o m a n ' s decision to undergo amniocentesis. Therefore, we did a retrospective cohort study to determine the utilization rate of second-trimester genetic sonogram in patients at increased risk for fetal trisomy 21 and to evaluate its role in influencing w o m e n ' s decision to undergo genetic amniocentesis.
Materials and Methods From N o v e m b e r 1, 1993, to December 31, 1996, a second-trimester genetic sonogram or only genetic amniocentesis (as a first choice) were offered to each w o m a n referred in our antenatal testing unit who was at increased risk (at least 1:274) for trisomy 21 due to advanced maternal age (at least 35 years), abnormal serum biochemistry, or other (nonimaging) indication. Before referral to our unit, all patients were counseled b y genetic counselors w h o explained, in detail the risks and benefits of all diagnostic modalities for all possible fetal k a r y o t y p i c risks. Three h u n d r e d fifty-seven w o m e n of the present study were reported previously in an article 6 that focused on the clinical m a n a g e m e n t and the efficacy of a genetic sonogram to detect fetal trisomy 21. That report involved w o m e n from both antenatal testing units (in Connecticut and New Jersey), whereas the present study focuses only on w o m e n seen in our N e w Jersey unit.
0029-7844/97/$17.00 187 PII S0029-7844(97)00227-5
Table 1. Annual Utilization of Genetic Sonogram for Detection of Fetal Trisomy 21
Year
Candidates for prenatal diagnosis
Genetic sonogram No. (% [95% CII)
Amniocenteses after genetic sonogram No. (% [95% CI])
Total amniocenteses No. [95% CI]
1993" 1994 1995 1996 Total
477 495 523 594 2089
2/477 (0.4 [0.1, 0.7]) 82/495 (16.6 [15.3, 18.7]) 251/523 (48.0 [45.8, 50.2]) 328/594 (55.2 [53.2, 57.3]) 663/2089 (31.7 [30.7,32.8])
0/2 (--) 10/82 (12.2 [8.6, 15.8]) 20/251 (8.0 [6.3, 9.7]) 13/328 (4.0 [2.9, 5.11) 43/663 (6.5 [5.5, 7.5])
475/477 (99.6 [99.3, 99.9]) 423/495 (85.5 [83.9,87.11) 292/523 (55.8 [53.7, 58.1]) 279/594 (47.0 [44.9,49.0]) 1469/2089 (70.3 [69.3,71.4])
cI = confidence interval. Chi-square for trend, P ~ .01. * The genetic sonogram service was available only for 2 months in 1993 (November and December).
The genetic s o n o g r a m was p e r f o r m e d b y evaluating ten ultrasound markers according to m e t h o d s described previously. 6 If two or m o r e of the ultrasound markers were not visualized adequately, then a repeat ultras o u n d evaluation 1-2 weeks later was scheduled. A repeat examination was also scheduled if cardiac visualization was not adequate the first time. For the purpose of this study, only the results of the first examination were included. After the genetic sonogram, w o m e n were counseled accordingly, 6 and those w h o wished to have genetic amniocentesis h a d the procedure d o n e either immediately or within a few days. All w o m e n included h a d fetal o u t c o m e information available, w h i c h was obtained b y contacting the w o m a n or the pediatrician and also b y reviewing the results of genetic amniocentesis, if performed. Statistical analysis included descriptive statistics and multivariable logistic regression analyses, w h i c h used the decision for amniocentesis as the d e p e n d e n t variable and the following covariates as i n d e p e n d e n t variables: maternal age, gravidity, parity, individual risk before amniocentesis (under 1:100 versus at least 1:100), specific risk factor (three indicator variables were used: a d v a n c e d maternal age, abnormal s e r u m biochemistry, and "other" risk factor), gestational age, multiple gestation, inability to visualize all markers, n u m b e r of a b n o r m a l ultrasound markers, calendar year, a n d individual performing the examination. Results were expressed as relative risks (RR) and 95% confidence intervals (CI).
Results During the s t u d y period, 2089 w o m e n were referred to our unit for genetic prenatal diagnosis d u e to n o n i m aging indications. The p r i m a r y reasons for referral were a d v a n c e d maternal age (at least 35 years old) with or w i t h o u t a b n o r m a l s e r u m biochemistry (n = 1483 or 71%), a b n o r m a l s e r u m biochemistry in w o m e n y o u n g e r than 35 years old (n = 501 or 24%), or other (nonimaging) indications, ie, family history of a c h r o m o s o m e
188
V i n t z i l e o s et al
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abnormality (n = 105 or 5%). The m e a n (_+standard deviation) maternal age was 35.4 ± 4.3 years (range 15-47). A p p r o x i m a t e l y 80% of the w o m e n were white, 15% were Hispanic, and 5% were other (black or Asian). These d e m o g r a p h i c characteristics did not change during the years 1993-1996. Of the 2089 w o m e n , 1426 (68%) chose genetic amniocentesis, and 663 (32%) chose a genetic s o n o g r a m as a first option. The m e a n (_+standard deviation) gestational age of those choosing a genetic s o n o g r a m was 19.4 + 1.5 weeks (range 15-24). Table 1 shows the utilization rates of genetic son()gram, the n u m b e r of w o m e n receiving arnniocentesis after the genetic sonogram, and the total n u m b e r of amniocenteses for the years 1993-1996. O n l y two genetic s o n o g r a m s were p e r f o r m e d in the year 1993 because the service was not initiated until N o v e m b e r of that year. Therefore, the year 1993 could be considered as the "baseline year" because almost all w o m e n w h o were referred during 1993 received amniocentesis only (99.6%). In subsequent years, the p r o p o r t i o n of w o m e n w h o chose a genetic s o n o g r a m as a first option increased considerably; the n u m b e r and frequency of genetic amniocentesis after the genetic s o n o g r a m decreased; therefore, the total n u m b e r of amniocenteses also decreased. The rate of amniocentesis after genetic s o n o g r a p h y was decreased from 12.2% in 1994 to 4.0% in 1996, representing a 67% reduction (RR 0.33; 95% CI 0.14, 0.77). The total amniocentesis rate (sum of direct amniocenteses plus amniocenteses after genetic sonography) was decreased from 99.6% in 1993 to 47.0% in 1996. This is a 53% reduction rate in the total n u m b e r of genetic amniocenteses (RR 0.47; 95% CI 0.39, 0.57). The amniocentesis rate a m o n g the 663 w o m e n w h o chose genetic s o n o g r a m as a first option was as follows: n o r m a l genetic s o n o g r a m (absence of all ultrasound markers), 3.2% (19 of 597); only one ultrasound marker present, 24.5% (12 of 49); and two or m o r e ultrasound markers present, 70.6% (12 of 17). There was incomplete assessment of ultrasound markers in the first examination in only 63 (9.5%) of these 663 w o m e n , and they were given the option to return for a repeat examina-
Obstetrics & Gynecology
Table 2. Factors Associated with Women's Decision for
Amniocentesis Factor
Relative risk
95% Confidence interval
Three or more ultrasound markers present Two ultrasound markers present One ultrasound marker present Normal ultrasound (no markers) Abnormal serum biochemistry
189.5
37.1, 980.0
47.2
9.8, 267.8
12.7
5.5, 29.7
1.0
Referent
3.0
1.0, 8.9
tion. After adjusting for confounders, such as calendar year, individual p e r f o r m i n g the ultrasound examination, maternal age, gravidity, parity, individual risks before amniocentesis, gestational age, multiple gestation, a n d inability to visualize all markers, logistic multivariable regression analysis s h o w e d that the m o s t important factors associated with the w o m e n ' s decision to u n d e r g o amniocentesis were the presence of abnormal ultrasound markers and abnormal s e r u m biochemistry (Table 2).
Discussion A l t h o u g h the literature on ultrasound markers for fetal a n e u p l o i d y is almost 10 years old, there is limited information on the clinical impact of second-trimester genetic sonography. At the Robert W o o d Johnson Medical School-St. Peter's Medical Center, w e have offered genetic s o n o g r a p h y since N o v e m b e r 1, 1993. The detection rate of fetuses with trisomy 21 is evaluated continu o u s l y and prospectively in our unit, so that appropriate counseling can be p r o v i d e d to those interested in genetic sonography. At this time, w e have h a d a sensitivity of 87.5% and a false-positive rate of approximately 10% in detecting fetal trisomy 21. This s t u d y was u n d e r t a k e n to evaluate the utilization and clinical impact of second-trimester genetic sonogr a p h y in influencing the decision to u n d e r g o amniocentesis. O u r data suggest that there is an ever-increasing p r o p o r t i o n of w o m e n w h o prefer to have a genetic s o n o g r a m as a first option rather than amniocentesis. D u r i n g the last year of the s t u d y (1996), the p r o p o r t i o n of w o m e n choosing the genetic s o n o g r a m as a first option w a s 55.2%. This increasing trend of utilization was associated with the finding that the results of the genetic s o n o g r a m w a s the most important determining factor in deciding about genetic amniocentesis. According to our data, the use of second-trimester genetic s o n o g r a p h y resulted in a dramatic reduction in
VOL. 90, NO. 2, AUGUST 1997
amniocentesis rates a m o n g w o m e n w h o were at increased risk for aneuploidy. Because genetic amniocentesis is associated with procedure-related fetal losses, it w o u l d a p p e a r that the use of second-trimester genetic s o n o g r a p h y m a y save fetal lives. In the present series, there were 620 w o m e n w h o were evaluated b y genetic s o n o g r a m and did not have amniocentesis. Because fetal loss d u e to amniocentesis is at least one in 250, two to three fetal losses were possibly avoided. In addition to reducing the loss of n o r m a l fetuses, second-trimester genetic s o n o g r a p h y has the potential for e n o r m o u s cost savings. If we assume that the average charge is $300 for p e r f o r m i n g an amniocentesis and $700 for karyotyping, then the cost savings for each w o m a n w h o has a genetic s o n o g r a m instead of amniocentesis is approximately $1000. The charge for a genetic s o n o g r a m is about the same as the charge for the s o n o g r a m (fetal b i o m e t r y plus u l t r a s o u n d guidance) before the amniocentesis, and the cost of counseling is about the same regardless of w h e t h e r or not the w o m a n chooses only genetic a m n i o c e n t e s i s or genetic s o n o g r a m . Because 620 w o m e n received genetic s o n o g r a m s instead of genetic amniocentesis in the years 1993-1996, this potentially could reflect estimated cost savings of m o r e than $600,000 for health care payers. In our experience, offering genetic s o n o g r a m s to w o m e n at increased risk for fetal trisomy 21 is associated with a high utilization rate. The increasing utilization trend in conjunction with the cost-effectiveness and the fact that an a b n o r m a l s o n o g r a m w a s the m o s t influential factor in a w o m a n ' s decision to u n d e r g o genetic amniocentesis suggests that, given adequate quality control, genetic s o n o g r a m services for detection of trisomy 21 should be a d d e d to the a r m a m e n t a r i u m of all prenatal diagnostic centers.
References 1. Benacerraf BR, Neuberg D, Bromley B, Frigoletto FD. Sonographic scoring index for prenatal detection of chromosomal abnormalities. J Ultrasound Med 1992;11:449-58. 2. BenacerrafBR, Harlow BL, Frigoletto FD. Hypoplasia of the middle phalanx of the fifth digit. J Ultrasound Med 1990;9:389-94. 3. Nadel AS, Bromley B, Frigoletto FD, Benacerraf BR. Can the presumed risk of autosomal trisomy be decreased in fetuses of older women following a normal sonogram? J Ultrasound Med 1995;14: 297-302. 4. DeVore GR, Alfi O. The use of color Doppler ultrasound to identify fetuses at increased risk for trisomy 21: An alternative for high-risk patients who decline genetic amniocentesis. Obstet Gynecol 1995; 85:378-86. 5. Vintzileos AM, Egan JFX. Adjusting the risk for trisomy 21 on the basis of second trimester ultrasonography. Am J Obstet Gynecol 1995;172:837-44. 6. Vintzileos AM, Campbell WA, Rodis JF, Guzman ER, Smulian JC, Knuppel RA. The use of second-trimester genetic sonogram in
V i n t z i l e o s et al
Use of Genetic Sonogram 189
guiding clinical management of patients at increased risk for fetal trisomy 21. Obstet Gynecol 1996;87:948-52.
Address reprint requests to: Anthony M. Vintzileos, MD Director, Maternal-Fetal Medicine and Obstetrics Robert Wood Johnson Medical Schoolfl_IMDNJ St. Peter's Medical Center 254 Easton Avenue, MOB 4th Floor New Brunswick, N] 08903 E-mail: [email protected]
Received January 29, 1997. Received in revisedform March 26, 1997. Accepted April 6, 1997.
Copyright © 1997 by The American College of Obstetricians and Gynecologists. Published by Elsevier Science Inc.
N O T I C E OF R E D U N D A N T PUBLICATION The editors and Editorial Board have determined that an article published in the (Part 2) October 1996 issue (da Silva OP, Ramanan R, Romano W, Bocking A, Evans M. N o n i m m u n e hydrops fetalis, preliminary sequestration, and favorable neonatal outcome. Obstet Gynecol 1996;88:681-3) represented redundant publication of one appearing in the June 1996 issue of the Journal of Pediatric Surgery (Evans MG. H y d r o p s fetalis and p u l m o n a r y sequestration. J Pediatr Surg 1996;31:761-4). The two articles describe the same three cases. Readers are hereby advised that only three cases have been reported in these two articles. The editors and Editorial Board have determined further that the redundant publication occurred without the knowledge of Drs. da Silva, Ramanan, Romano, and Bocking.
190 Vintzileos et al
Use of Genetic Sonogram
Obstetrics & Gynecology
In recent years, m a n y studies have addressed the usefulness of various second-trimester ultrasound markers From the Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School/St. Peter's Medical Center, New Brunswick, New Jersey.
VOL. 90, NO. 2, AUGUST 1997
for the prenatal detection of fetal trisomy 21. By combining multiple ultrasound markers, some investigators have achieved detection rates of fetal trisomy 21 as high as 83-93%. 1-6 Because of these high detection rates, we have offered a comprehensive sonographic assessment by evaluating multiple ultrasound markers as an adjunct to maternal age and maternal serum biochemistry to adjust the risk status and modify clinical management. 6 However, this approach has not been evaluated in terms of use or h o w the results influence a w o m a n ' s decision to undergo amniocentesis. Therefore, we did a retrospective cohort study to determine the utilization rate of second-trimester genetic sonogram in patients at increased risk for fetal trisomy 21 and to evaluate its role in influencing w o m e n ' s decision to undergo genetic amniocentesis.
Materials and Methods From N o v e m b e r 1, 1993, to December 31, 1996, a second-trimester genetic sonogram or only genetic amniocentesis (as a first choice) were offered to each w o m a n referred in our antenatal testing unit who was at increased risk (at least 1:274) for trisomy 21 due to advanced maternal age (at least 35 years), abnormal serum biochemistry, or other (nonimaging) indication. Before referral to our unit, all patients were counseled b y genetic counselors w h o explained, in detail the risks and benefits of all diagnostic modalities for all possible fetal k a r y o t y p i c risks. Three h u n d r e d fifty-seven w o m e n of the present study were reported previously in an article 6 that focused on the clinical m a n a g e m e n t and the efficacy of a genetic sonogram to detect fetal trisomy 21. That report involved w o m e n from both antenatal testing units (in Connecticut and New Jersey), whereas the present study focuses only on w o m e n seen in our N e w Jersey unit.
0029-7844/97/$17.00 187 PII S0029-7844(97)00227-5
Table 1. Annual Utilization of Genetic Sonogram for Detection of Fetal Trisomy 21
Year
Candidates for prenatal diagnosis
Genetic sonogram No. (% [95% CII)
Amniocenteses after genetic sonogram No. (% [95% CI])
Total amniocenteses No. [95% CI]
1993" 1994 1995 1996 Total
477 495 523 594 2089
2/477 (0.4 [0.1, 0.7]) 82/495 (16.6 [15.3, 18.7]) 251/523 (48.0 [45.8, 50.2]) 328/594 (55.2 [53.2, 57.3]) 663/2089 (31.7 [30.7,32.8])
0/2 (--) 10/82 (12.2 [8.6, 15.8]) 20/251 (8.0 [6.3, 9.7]) 13/328 (4.0 [2.9, 5.11) 43/663 (6.5 [5.5, 7.5])
475/477 (99.6 [99.3, 99.9]) 423/495 (85.5 [83.9,87.11) 292/523 (55.8 [53.7, 58.1]) 279/594 (47.0 [44.9,49.0]) 1469/2089 (70.3 [69.3,71.4])
cI = confidence interval. Chi-square for trend, P ~ .01. * The genetic sonogram service was available only for 2 months in 1993 (November and December).
The genetic s o n o g r a m was p e r f o r m e d b y evaluating ten ultrasound markers according to m e t h o d s described previously. 6 If two or m o r e of the ultrasound markers were not visualized adequately, then a repeat ultras o u n d evaluation 1-2 weeks later was scheduled. A repeat examination was also scheduled if cardiac visualization was not adequate the first time. For the purpose of this study, only the results of the first examination were included. After the genetic sonogram, w o m e n were counseled accordingly, 6 and those w h o wished to have genetic amniocentesis h a d the procedure d o n e either immediately or within a few days. All w o m e n included h a d fetal o u t c o m e information available, w h i c h was obtained b y contacting the w o m a n or the pediatrician and also b y reviewing the results of genetic amniocentesis, if performed. Statistical analysis included descriptive statistics and multivariable logistic regression analyses, w h i c h used the decision for amniocentesis as the d e p e n d e n t variable and the following covariates as i n d e p e n d e n t variables: maternal age, gravidity, parity, individual risk before amniocentesis (under 1:100 versus at least 1:100), specific risk factor (three indicator variables were used: a d v a n c e d maternal age, abnormal s e r u m biochemistry, and "other" risk factor), gestational age, multiple gestation, inability to visualize all markers, n u m b e r of a b n o r m a l ultrasound markers, calendar year, a n d individual performing the examination. Results were expressed as relative risks (RR) and 95% confidence intervals (CI).
Results During the s t u d y period, 2089 w o m e n were referred to our unit for genetic prenatal diagnosis d u e to n o n i m aging indications. The p r i m a r y reasons for referral were a d v a n c e d maternal age (at least 35 years old) with or w i t h o u t a b n o r m a l s e r u m biochemistry (n = 1483 or 71%), a b n o r m a l s e r u m biochemistry in w o m e n y o u n g e r than 35 years old (n = 501 or 24%), or other (nonimaging) indications, ie, family history of a c h r o m o s o m e
188
V i n t z i l e o s et al
Use of Genetic Sonogram
abnormality (n = 105 or 5%). The m e a n (_+standard deviation) maternal age was 35.4 ± 4.3 years (range 15-47). A p p r o x i m a t e l y 80% of the w o m e n were white, 15% were Hispanic, and 5% were other (black or Asian). These d e m o g r a p h i c characteristics did not change during the years 1993-1996. Of the 2089 w o m e n , 1426 (68%) chose genetic amniocentesis, and 663 (32%) chose a genetic s o n o g r a m as a first option. The m e a n (_+standard deviation) gestational age of those choosing a genetic s o n o g r a m was 19.4 + 1.5 weeks (range 15-24). Table 1 shows the utilization rates of genetic son()gram, the n u m b e r of w o m e n receiving arnniocentesis after the genetic sonogram, and the total n u m b e r of amniocenteses for the years 1993-1996. O n l y two genetic s o n o g r a m s were p e r f o r m e d in the year 1993 because the service was not initiated until N o v e m b e r of that year. Therefore, the year 1993 could be considered as the "baseline year" because almost all w o m e n w h o were referred during 1993 received amniocentesis only (99.6%). In subsequent years, the p r o p o r t i o n of w o m e n w h o chose a genetic s o n o g r a m as a first option increased considerably; the n u m b e r and frequency of genetic amniocentesis after the genetic s o n o g r a m decreased; therefore, the total n u m b e r of amniocenteses also decreased. The rate of amniocentesis after genetic s o n o g r a p h y was decreased from 12.2% in 1994 to 4.0% in 1996, representing a 67% reduction (RR 0.33; 95% CI 0.14, 0.77). The total amniocentesis rate (sum of direct amniocenteses plus amniocenteses after genetic sonography) was decreased from 99.6% in 1993 to 47.0% in 1996. This is a 53% reduction rate in the total n u m b e r of genetic amniocenteses (RR 0.47; 95% CI 0.39, 0.57). The amniocentesis rate a m o n g the 663 w o m e n w h o chose genetic s o n o g r a m as a first option was as follows: n o r m a l genetic s o n o g r a m (absence of all ultrasound markers), 3.2% (19 of 597); only one ultrasound marker present, 24.5% (12 of 49); and two or m o r e ultrasound markers present, 70.6% (12 of 17). There was incomplete assessment of ultrasound markers in the first examination in only 63 (9.5%) of these 663 w o m e n , and they were given the option to return for a repeat examina-
Obstetrics & Gynecology
Table 2. Factors Associated with Women's Decision for
Amniocentesis Factor
Relative risk
95% Confidence interval
Three or more ultrasound markers present Two ultrasound markers present One ultrasound marker present Normal ultrasound (no markers) Abnormal serum biochemistry
189.5
37.1, 980.0
47.2
9.8, 267.8
12.7
5.5, 29.7
1.0
Referent
3.0
1.0, 8.9
tion. After adjusting for confounders, such as calendar year, individual p e r f o r m i n g the ultrasound examination, maternal age, gravidity, parity, individual risks before amniocentesis, gestational age, multiple gestation, a n d inability to visualize all markers, logistic multivariable regression analysis s h o w e d that the m o s t important factors associated with the w o m e n ' s decision to u n d e r g o amniocentesis were the presence of abnormal ultrasound markers and abnormal s e r u m biochemistry (Table 2).
Discussion A l t h o u g h the literature on ultrasound markers for fetal a n e u p l o i d y is almost 10 years old, there is limited information on the clinical impact of second-trimester genetic sonography. At the Robert W o o d Johnson Medical School-St. Peter's Medical Center, w e have offered genetic s o n o g r a p h y since N o v e m b e r 1, 1993. The detection rate of fetuses with trisomy 21 is evaluated continu o u s l y and prospectively in our unit, so that appropriate counseling can be p r o v i d e d to those interested in genetic sonography. At this time, w e have h a d a sensitivity of 87.5% and a false-positive rate of approximately 10% in detecting fetal trisomy 21. This s t u d y was u n d e r t a k e n to evaluate the utilization and clinical impact of second-trimester genetic sonogr a p h y in influencing the decision to u n d e r g o amniocentesis. O u r data suggest that there is an ever-increasing p r o p o r t i o n of w o m e n w h o prefer to have a genetic s o n o g r a m as a first option rather than amniocentesis. D u r i n g the last year of the s t u d y (1996), the p r o p o r t i o n of w o m e n choosing the genetic s o n o g r a m as a first option w a s 55.2%. This increasing trend of utilization was associated with the finding that the results of the genetic s o n o g r a m w a s the most important determining factor in deciding about genetic amniocentesis. According to our data, the use of second-trimester genetic s o n o g r a p h y resulted in a dramatic reduction in
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amniocentesis rates a m o n g w o m e n w h o were at increased risk for aneuploidy. Because genetic amniocentesis is associated with procedure-related fetal losses, it w o u l d a p p e a r that the use of second-trimester genetic s o n o g r a p h y m a y save fetal lives. In the present series, there were 620 w o m e n w h o were evaluated b y genetic s o n o g r a m and did not have amniocentesis. Because fetal loss d u e to amniocentesis is at least one in 250, two to three fetal losses were possibly avoided. In addition to reducing the loss of n o r m a l fetuses, second-trimester genetic s o n o g r a p h y has the potential for e n o r m o u s cost savings. If we assume that the average charge is $300 for p e r f o r m i n g an amniocentesis and $700 for karyotyping, then the cost savings for each w o m a n w h o has a genetic s o n o g r a m instead of amniocentesis is approximately $1000. The charge for a genetic s o n o g r a m is about the same as the charge for the s o n o g r a m (fetal b i o m e t r y plus u l t r a s o u n d guidance) before the amniocentesis, and the cost of counseling is about the same regardless of w h e t h e r or not the w o m a n chooses only genetic a m n i o c e n t e s i s or genetic s o n o g r a m . Because 620 w o m e n received genetic s o n o g r a m s instead of genetic amniocentesis in the years 1993-1996, this potentially could reflect estimated cost savings of m o r e than $600,000 for health care payers. In our experience, offering genetic s o n o g r a m s to w o m e n at increased risk for fetal trisomy 21 is associated with a high utilization rate. The increasing utilization trend in conjunction with the cost-effectiveness and the fact that an a b n o r m a l s o n o g r a m w a s the m o s t influential factor in a w o m a n ' s decision to u n d e r g o genetic amniocentesis suggests that, given adequate quality control, genetic s o n o g r a m services for detection of trisomy 21 should be a d d e d to the a r m a m e n t a r i u m of all prenatal diagnostic centers.
References 1. Benacerraf BR, Neuberg D, Bromley B, Frigoletto FD. Sonographic scoring index for prenatal detection of chromosomal abnormalities. J Ultrasound Med 1992;11:449-58. 2. BenacerrafBR, Harlow BL, Frigoletto FD. Hypoplasia of the middle phalanx of the fifth digit. J Ultrasound Med 1990;9:389-94. 3. Nadel AS, Bromley B, Frigoletto FD, Benacerraf BR. Can the presumed risk of autosomal trisomy be decreased in fetuses of older women following a normal sonogram? J Ultrasound Med 1995;14: 297-302. 4. DeVore GR, Alfi O. The use of color Doppler ultrasound to identify fetuses at increased risk for trisomy 21: An alternative for high-risk patients who decline genetic amniocentesis. Obstet Gynecol 1995; 85:378-86. 5. Vintzileos AM, Egan JFX. Adjusting the risk for trisomy 21 on the basis of second trimester ultrasonography. Am J Obstet Gynecol 1995;172:837-44. 6. Vintzileos AM, Campbell WA, Rodis JF, Guzman ER, Smulian JC, Knuppel RA. The use of second-trimester genetic sonogram in
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guiding clinical management of patients at increased risk for fetal trisomy 21. Obstet Gynecol 1996;87:948-52.
Address reprint requests to: Anthony M. Vintzileos, MD Director, Maternal-Fetal Medicine and Obstetrics Robert Wood Johnson Medical Schoolfl_IMDNJ St. Peter's Medical Center 254 Easton Avenue, MOB 4th Floor New Brunswick, N] 08903 E-mail: [email protected]
Received January 29, 1997. Received in revisedform March 26, 1997. Accepted April 6, 1997.
Copyright © 1997 by The American College of Obstetricians and Gynecologists. Published by Elsevier Science Inc.
N O T I C E OF R E D U N D A N T PUBLICATION The editors and Editorial Board have determined that an article published in the (Part 2) October 1996 issue (da Silva OP, Ramanan R, Romano W, Bocking A, Evans M. N o n i m m u n e hydrops fetalis, preliminary sequestration, and favorable neonatal outcome. Obstet Gynecol 1996;88:681-3) represented redundant publication of one appearing in the June 1996 issue of the Journal of Pediatric Surgery (Evans MG. H y d r o p s fetalis and p u l m o n a r y sequestration. J Pediatr Surg 1996;31:761-4). The two articles describe the same three cases. Readers are hereby advised that only three cases have been reported in these two articles. The editors and Editorial Board have determined further that the redundant publication occurred without the knowledge of Drs. da Silva, Ramanan, Romano, and Bocking.
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