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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy.
Address reprint requests to: Lorenzo Guariglia, MD Department of Obstetrics and Gynecology Catholic University of the Sacred Heart Largo A. Gemelli, 8 00168 Rome Italy
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Abstract |
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Methods: We prospectively analyzed records of 3592 sequential pregnant women at 10–16 weeks’ (singleton) gestation (mean 13 weeks and 2 days). After exclusion of 114 women, there were 3478 women in the study. Each woman underwent a transvaginal sonographic survey for fetal anomalies as well as biometric measurements. Fetuses diagnosed with malformations were followed to delivery, and those without underwent transabdominal sonography at 18–24 weeks’ gestation.
Results: The anomaly detection rate by transvaginal ultrasound was 51.6% (33 of 64; 95% confidence interval [CI] 38.7, 64.2) in early pregnancy, and the detection rate by transvaginal ultrasound combined with second-trimester transabdominal ultrasound was 84.4% (54 of 64; 95% CI 73.1, 92.2). Cystic hygroma and fetal hydrops were the anomalies detected most frequently by transvaginal ultrasound. Low detection rates for abnormalities of the face and of the cardiac, skeletal, and urinary systems were found even when both methods were used.
Conclusion: Transvaginal sonography appears to be an effective way to identify many congenital fetal anomalies in early pregnancy. There is a good probability of diagnosing cystic hygroma and fetal hydrops, although other abnormalities, particularly heart defects, are associated with lower detection rates.
One of the most important purposes of prenatal sonography is early ultrasound identification of fetal malformations.1,2 The ability of ultrasound to detect fetal abnormalities accurately is debated in the literature.3,4 In the last few years, a new ultrasound technique that uses transvaginal probes has been developed to identify in detail anatomic structures and improve detection of congenital anomalies in early pregnancy.2,5–8
As use of transvaginal sonography during early pregnancy increases,1 more major and minor anomalies are diagnosed.2 Most reports concern high-risk women9–13 or specific anomalies14,15 and there are few data on unselected populations.8,16–18 Further study is needed on transvaginal sonography as the sole method of detecting congenital anomalies.13 We report our experience using transvaginal ultrasound in early pregnancy to detect fetal anomalies.
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Materials and Methods |
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The purpose of the transvaginal ultrasound was to date the pregnancy and confirm viability of the fetus. Subjects gave verbal informed consent.
Gestational age was estimated on the basis of the first day of the last menstrual period, a history of regular cycles lasting 24–32 days, and an early positive pregnancy test. If menstrual dating was uncertain, gestational age estimated by sonography was used.
Study ultrasound equipment included Toshiba Sonolayer SSA-270 A and SSA-340 A (Toshiba Corp., Tokyo, Japan) equipped with 5.0- and 6.0-MHz endovaginal convex probes, with angles of vision of 86° and 121°, respectively. For transabdominal scanning, a 3.5-MHz convex probe was used. Echocardiographic examinations were done with a commercially available color-coded Doppler ultrasonic system (AU 570 A; Esaote Biomedica, Genoa, Italy) equipped with a 3.5-MHz convex probe. The Doppler carrier frequency ranged from 2.5 to 5 MHz and the high-pass filter was set at 100 MHz. All examinations were done by the authors.
Careful sonographic searches for malformations or anatomic abnormalities were conducted in all cases. Fetal biometric measurements were part of the routine examination. Minor anomalies and minor sonographic markers such as transitory defects were not considered.
Pregnant women with abnormal fetuses detected by transvaginal ultrasound were informed of appropriate management and prospectively rescanned by transabdominal ultrasound until delivery. If transvaginal scan results were normal, routine transabdominal sonographic examinations were offered at 18–24 weeks’ gestation.
Fetal karyotyping was offered in all cases of cystic hygroma, hydrops, heart defects, and left diaphragmatic hernia and in three of five cases of central nervous system (CNS) defects detected by transvaginal sonography. It was offered in two cases of heart defects and one case of spina bifida and ventriculomegaly diagnosed later by transabdominal sonography. The other fetuses were followed up without amniocentesis.
Study fetuses underwent pathologic examination or autopsy after spontaneous or elective abortion; all other infants were examined at birth by a pediatrician and clinically followed up for 6 months to assess developmental, physical, and growth characteristics.
Binomial exact 95% confidence intervals (CIs) were calculated using Stata 6.0 software (Stata Corp., College Station, TX).
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Results |
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Sixty-four structural anomalies were present in our study population with an overall rate of 1.8% (64 of 3478; 95% CI 1.4, 2.3). Thirty-three anomalies were revealed in 26 fetuses by first transvaginal scans. Sonographic findings and outcomes of the pregnancies are listed in Table 1
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Seven fetal hydrops, isolated or associated with other malformations, were diagnosed early in pregnancy, and six cases resulted in spontaneous abortion. An additional 11 malformations were detected by transvaginal scans: five CNS anomalies, two heart defects, one left diaphragmatic hernia, one abdominal cyst, one unilateral renal agenesis, and one clubfoot.
Karyotyping after transvaginal sonography revealed abnormal karyotypes for eight fetuses with cystic hygroma (four trisomy 21, three 45,XO, and one trisomy 18). Transabdominal sonography later revealed associated heart defects in two of those cases (one with trisomy 21 and one with a 45,XO) karyotype. Trisomy 21 was diagnosed in a case of isolated fetal hydrops and a case of severe ventriculomegaly.
In addition to the three missed heart defects, transabdominal scans in the middle of the second trimester revealed 18 structural anomalies not identified by early scans, for a total of 21 malformations (Table 2). In only three cases did women elect to have karyotyping performed after transabdominal sonography (one of the three fetuses had a ventricular septal defect, one had a large right atrium and ventricle, and one had spina bifida and ventriculomegaly). No karyotypic abnormalities were found.
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Detection rates for fetal anomalies by all sonographic examinations and by transvaginal scan only were 84.4% (54 of 64; 95% CI 73.1, 92.2) and 51.6% (33 of 64; 95% CI 38.7, 64.2), respectively. The detection rates for anomalies of different organs and systems are reported in Table 3. Anomalies of the neck, CNS, thoracoabdominal region, urinary system, and face and fetal hydrops were the abnormalities most readily identified by ultrasound during pregnancy, whereas heart and skeletal abnormalities were more difficult to determine, and eye abnormalities were missed.
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Discussion |
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There are few data available on detection of fetal structural anomalies by transvaginal scans in early pregnancy in unselected populations. Detection rates reported in the literature range from 41% to 65%.8,17,18 This range is probably due to differences in gestational ages at the time of scanning, incidences of particular abnormal findings in study populations, and abilities of sonographers. Sonographic recognition of congenital anomalies depends on knowledge of normal fetal anatomy, ultrasound resolution, and natural histories of the particular disorders.5 Scans during the first stage of pregnancy will miss some fetal anomalies because they appear later in pregnancy or might be undetectable at that stage.11
Even if many major congenital anomalies can be detected by transvaginal scan at the beginning of the second trimester, an early transvaginal ultrasound screening for fetal abnormalities always will be burdened by the risk of false-negative cases. In our study, the diagnostic accuracy of early transvaginal sonographic examination in detecting congenital anomalies was relatively high; 61.1% of the malformations diagnosed prenatally and 51.6% of all malformations revealed were accurately diagnosed. Most abnormalities detected during pregnancy were severe, and 57.4% (27 of 47) of those pregnancies were terminated or ended with miscarriage or neonatal death.
The diagnostic feasibility of this technique is influenced by the fetal abnormality and the time of the scan. Detection of cystic hygroma and fetal hydrops was particularly good. In all cases, these abnormalities were diagnosed at the end of the first trimester or early in the second trimester. Central nervous system defects, heart anomalies, skeletal and limb defects, renal defects, diaphragmatic hernia, and facial defects were more difficult to detect, and that could be true even for scans performed in the second trimester. In accordance reports that in most cases ventriculomegaly develops at later stages of pregnancy,12,13 we detected that defect by transvaginal sonography only in one of five cases. With regard to the fetal heart, an early transvaginal survey of the four chambers should not be conducted earlier than the 13th week of gestation,7 and it has been suggested that it be routine after that.19 In most cases, images of the heart are inadequate for detection of most cardiac anomalies8 (although the four chambers are clearly defined), probably because of the heart’s small size16 and lack of development. In particular, alterations in fetal chamber size, ventricular septal defects, and differences in size among various vessels might not be apparent until later in pregnancy or after delivery. There also is growing evidence that for some cardiac anomalies diagnosis by ultrasound is feasible only later in pregnancy or after birth.19,20 That is one of the most important issues associated with detectability of fetal cardiac anomalies by transvaginal sonography and is evidenced by the high variability in detection rates. Cullen et al10 reported poor rates of detection of heart abnormalities in the first trimester, and Hernadi and Torocsick8 stated that in most cases, heart images were inadequate at that point in pregnancy and detected only large ventricular septal defects. Whitlow et al18 reported a rate of detection of cardiac abnormalities of 40% in an unselected population in the first trimester. Yagel et al19 reported a rate of 64% and Bronshtein et al21 a rate of 77% in high-risk and low-risk populations. In our series, only 18% of the cardiac anomalies were diagnosed by transvaginal sonography in early pregnancy. When a second-trimester transabdominal scan was done, in association with, in most cases, an echocardiographic examination, that percentage increased to 56%. Our data and data reported by others suggest that first-trimester cardiac scanning should be confined to high-risk pregnancies and always be followed by second-trimester transabdominal echocardiographic scanning.15,19
Fetal limbs can be seen consistently from 11 weeks on; however, difficulty in diagnosing limb defects in early pregnancy has been reported.22 Only one case of skeletal and limb anomalies in our series was detected prenatally by transvaginal scan, and two cases of club-foot were detected later by transabdominal scans, owing to the fact that, even if single cases of skeletal defects are detected in early pregnancy by transvaginal scan,23,24 skeletal malformations are rare.25 Many skeletal anomalies develop by midpregnancy, making ultrasound detection of them possible only later in pregnancy.22 Other anatomic features, such as hydronephrosis, diaphragmatic hernia, and facial defects, are rare and evident only at midpregnancy.
By combining the two examinations in our series, we were able to detect 84.4% of structural congenital abnormalities. Even if further clinical work is necessary better to define its role in early ultrasonographic diagnosis of individual congenital anomalies, in our experience transvaginal sonography is a good method for scanning fetuses and effectively identifies many congenital anomalies in early pregnancy.
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Footnotes |
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Received December 9, 1999. Received in revised form April 19, 2000. Accepted May 11, 2000.
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References |
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2. Chitty LS, Pandya PP. Ultrasound screening for fetal abnormalities in the first trimester. Prenat Diagn 1997;17:1269–81.[Medline]
3. Timor-Tritsch IE, Monteagudo A, Peisner DB. High-frequency transvaginal sonographic examination for the potential malformation assessment of the 9-week to 14-week fetus. J Clin Ultrasound 1992;20:231–8.[Medline]
4. D’Ottavio G, Meir YJ, Rustico MA, Conoscenti G, Maieron A, Fischer-Tamaro L, et al. Pilot screening for fetal malformations: Possibilities and limits of transvaginal sonography. J Ultrasound Med 1995;14:575–80.[Abstract]
5. Timor-Tritsch IE, Peisner DB, Raju S. Sonoembryology: An organ-oriented approach using a high-frequency vaginal probe. J Clin Ultrasound 1990;18:286–98.[Medline]
6. Braithwaite JM, Armstrong MA, Economides DL. Assessment of fetal anatomy at 12 to 13 weeks of gestation by transabdominal and transvaginal sonography. Br J Obstet Gynaecol 1996;103:82–5.[Medline]
7. Rosati P, Guariglia L. Transvaginal fetal biometry in early pregnancy. Early Hum Dev 1997;49:91–6.[Medline]
8. Hernadi L, Torocsick M. Screening for fetal anomalies in the 12th week of pregnancy by transvaginal sonography in an unselected population. Prenat Diagn 1997;17:753–6.[Medline]
9. Sabbagha RE, Sheikh Z, Tamura RK. Predictive value, sensitivity and specificity of ultrasonic targeted imaging for fetal anomalies in gravid women at high risk for birth defects. Am J Obstet Gynecol 1985;152:822–7.[Medline]
10. Cullen MT, Green J, Whetham J, Salafia C, Gabrielli S, Hobbins JC. Transvaginal sonographic detection of congenital anomalies in the first trimester. Am J Obstet Gynecol 1990;163:466–76.[Medline]
11. Rottem S, Bronshtein M. Transvaginal sonographic diagnosis of congenital anomalies between 9 weeks and 16 weeks, menstrual age. J Clin Ultrasound 1990;18:307–14.[Medline]
12. Achiron R, Tadmore O. Screening for fetal anomalies during the first trimester of pregnancy: Transvaginal versus transabdominal sonography. Ultrasound Obstet Gynecol 1991;1:186–91.[Medline]
13. Yagel S, Achiron R, Ron M, Revel A, Anteby E. Transvaginal ultrasonography at early pregnancy cannot be used alone for targeted organ ultrasonographic examination in a high-risk population. Am J Obstet Gynecol 1995;172:971–5.[Medline]
14. Bronshtein M, Zimmer E, Blumenfeld Z. Transvaginal sonography (TVS) of the fetal urinary tract. Eur J Ultrasound 1996;3:1–7.
15. Gembruch U. Prenatal diagnosis of congenital heart disease. Prenat Diagn 1997;17:1283–98.[Medline]
16. Achiron R, Weissman A, Rotstein Z, Lipitz S, Mashiach S, Hegesh J. Transvaginal echocardiographic examination of the fetal heart between 13 and 15 weeks’ gestation in a low-risk population. J Ultrasound Med 1994;13:783–9.[Abstract]
17. Economides DL, Braithwaite JM. First trimester ultrasonographic diagnosis of fetal abnormalities in a low-risk population. Br J Obstet Gynaecol 1998;105:53–7.[Medline]
18. Whitlow BJ, Chatzipapas IK, Lazanakis ML, Kadir RA, Economides DL. The value of sonography in early pregnancy for the detection of fetal abnormalities in an unselected population. Br J Obstet Gynaecol 1999;106:929–36.[Medline]
19. Yagel S, Weissman A, Rotstein Z, Manor M, Hegesh J, Anteby E, et al. Congenital heart defects: Natural course and in utero development. Circulation 1997;96:550–5.
20. Marasini M, DeCaro E, Pongiglione G, Ribaldone D, Caponetto S. Left heart obstructive disease: Changes in the echocardiographic appearance during pregnancy. J Clin Ultrasound 1993;21:65–8.[Medline]
21. Bronshtein M, Zimmer EZ, Gerlis LM, Lorber A, Drugan A. Early ultrasound diagnosis of fetal congenital heart defects in high-risk and low-risk pregnancies. Obstet Gynecol 1993;82:225–9.
22. Gaffney G, Manning N, Boyd PA, Rai V, Gould S, Chamberlain P. Prenatal sonographic diagnosis of skeletal dysplasias: A report of the diagnostic and prognostic accuracy in 35 cases. Prenat Diagn 1998;18:357–62.[Medline]
23. D’Ottavio G, Tamaro LF, Mandruzzato G. Early prenatal ultrasonographic diagnosis of osteogenesis imperfecta: A case report. Am J Obstet Gynecol 1993;169:384–5.[Medline]
24. Soothill PW, Vuthiwong C, Rees H. Achondrogenesis type 2 diagnosed by transvaginal ultrasound at 12 weeks’ gestation. Prenat Diagn 1993;13:523–8.[Medline]
25. Bernasheck G, Stuemplen I, Deutinger J. The value of sonographic diagnosis of fetal malformations: Different results between indication-based and screening-based investigations. Prenat Diagn 1994; 14:807–12.[Medline]
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