| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
ORIGINAL RESEARCH |
From the Division of Maternal-Fetal Medicine, Department of Gynecology and Obstetrics, The Johns Hopkins University School of Medicine, Baltimore, Mary-land.
 |
ABSTRACT |
|---|
TOP
 ABSTRACT MATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
METHODS: A retrospective analysis of fetuses diagnosed with single umbilical artery by sonography was conducted between January 1995 and June 2000 (n = 127). In the 103 patients who had fetal echocardiograms, we examined the frequency of abnormal echocardiographic findings when the initial sonogram demonstrated a normal four-chamber view and cardiac outflow tracts.
RESULTS: Approximately 1% of fetal anomaly screens had a diagnosis of single umbilical artery. Of these, 72% were isolated (no other anomalies identified). No fetus in this group had an abnormal echocardiogram. There was one postnatal diagnosis of cardiac disease in this group; it was not predicted by either the four-chamber and outflow tract views or the echocardiogram. Among the group with other anomalies, the four-chamber view predicted every abnormal echocardiogram but one.
CONCLUSION: Fetal echocardiography does not appear to add further diagnostic information to the antenatal evaluation of the fetus with isolated single umbilical artery when normal four-chamber and outflow tract views of the heart have already been obtained.
Single umbilical artery is the most common of human umbilical pathologies, occurring in 0.08% to 1.90% of all pregnancies.1 Previous investigators have reported that single umbilical artery is associated with a variety of structural abnormalities of the genitourinary, central nervous, cardiovascular, and musculoskeletal systems, as well as with aneuploidy.2–10 Because of the reported association with cardiovascular malformations, since 1995 we have recommended fetal echocardiography for all women whose fetuses have a single umbilical artery. We undertook a retrospective cohort study to evaluate the contribution of fetal echocardiography to the evaluation and management of these pregnancies. We were particularly interested in whether the echocardiogram added useful clinical information in the otherwise apparently normal fetus (isolated single umbilical artery).
|
MATERIALS AND METHODS |
|---|
|
TOP
ABSTRACTMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Registered sonographers performed all ultrasound examinations in a center where their practice was limited to obstetric sonography, and attending perinatologists confirmed the findings. We followed a standard scanning protocol that included images of the central nervous system, spine, heart, diaphragm, stomach, kidneys, bladder, umbilical cord and cord insertion, and extremities. Early in the study period, cardiac outflow tracts were not routinely imaged as part of the anatomic survey, but these were added to the protocol and imaged when possible for the majority of the study period. We employed the following ultrasound units during the study period: Advanced Technology Laboratories Ultramark 9 (ATL, Bothell, WA); Acuson 128XP10 (Acuson, Mountain View, CA); Corometrics Aloka 650 or Aloka ProSound 5500 (Aloka, Wallingford, CT); or Siemens Elegra Basic or Advanced (Siemens Ultrasound, Issaquah, WA). We diagnosed single umbilical artery when a cross-sectional image of the umbilical cord demonstrated only two vessels and when a transverse view of the fetal pelvis showed only one umbilical artery coursing around the fetal bladder. We routinely used color or power Doppler sonography to confirm the diagnosis of single umbilical artery. Either a perinatologist or a pediatric cardiologist with specialized training in fetal echocardiography performed the fetal echocardiograms. The fetal echocardiogram consisted of an evaluation of the cardiac axis and situs, the four-chamber view including pulmonary veins, left and right ventricular outflow tracts, inferior vena cava, superior vena cava, the aortic arch, and ductus arteriosus. Using spectral and color Doppler imaging, transvalvular velocities were measured and the presence or absence of regurgitation was determined. An M-mode recording was made to rule out fetal arrhythmias. Two of the authors (DG, CC) reviewed each sonogram to confirm the diagnosis of two-vessel cord and to evaluate the adequacy of imaging the four-chamber view and outflow tracts at the time of the anatomic survey.
|
RESULTS |
|---|
|
TOP
ABSTRACTMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
We separated into two groups the 103 fetuses with single umbilical artery that had undergone fetal echocardiography. Group 1 was composed of 74 fetuses with apparently isolated single umbilical artery (71.8%), and Group 2 was composed of 29 fetuses with other anomalies identified by sonography (28.2%). For all pregnancies where delivery data were available, we confirmed that infants had been appropriately classified; in Group 1 no baby had additional noncardiac structural defects detected at birth (true isolated single umbilical artery).
All 74 fetuses from Group 1 had a normal fetal echocardiogram. Of these, 68 had had a normal, adequate four-chamber view of the heart prior to referral for echocardiography; 41 also had adequate images of one or both outflow tracts. In those for whom the cardiac anatomy could not be imaged at the time of the initial anatomic survey, the most frequent reason was unfavorable fetal position. Delivery data were available on 42 (56.7%) of the patients in Group 1. The remaining patients were referred to our center for ultrasound evaluation only and returned to their primary obstetricians for antenatal care and delivery, and outcome data are not available. We found documentation of the presence of a two-vessel cord, either by clinical inspection, histopathologic examination, or both, in 27 (64.2%) of the cases for whom delivery data were available. We could not locate, either in delivery records or surgical pathology reports, documentation of the number of cord vessels for 12 patients (28.6%). Three patients were noted to have a three-vessel cord at delivery (7.1%). Of the fetuses classified into Group 1 on sonography, none of those for whom follow-up was available had a noncardiac abnormality detected at birth.
All 29 fetuses in Group 2 underwent echocardiography; 17 (58.6%) were normal, and 12 (41.4%) were abnormal. Sixteen of the 17 fetuses with normal echocardiograms also had normal, adequate four-chamber views of the heart at the time of the anatomic survey; in the remaining case, a normal four-chamber view was obtained at a subsequent study. In 11 of the 12 fetuses with an abnormal echocardiogram, the four-chamber view was also abnormal at the time of the anatomic survey. Delivery data were available on 23 (79.3%) of Group 2 patients. Of these, a two-vessel cord was documented in 17 (73.9%) cases, three (13.6%) had no documentation, and three (13.6%) were found to have a three-vessel cord. In sum, of the 23 fetuses from Group 2 for whom delivery data were available, 17 had cardiac disease diagnosed at birth; the results of their antenatal sonograms and fetal echocardiograms are summarized in Table 1
.
|
). Eleven of these patients had abnormalities noted during fetal echocardiography, and seven had normal fetal echocardiograms. All but one of these 18 had other (extracardiac) anomalies noted at the time of the anatomic survey. In other words, only one of these fetuses with confirmed cardiac disease was originally classified into Group 1 (isolated single umbilical artery), and the abnormalities in this case were not identified during either the anatomic survey or the fetal echocardiogram, which was performed at 18 weeks’ gestation (Table 1, Case 17). At the birth of this infant, a heart murmur was auscultated. The infant was discharged from the newborn nursery on day of life 2. The murmur persisted on day 5 of life and the baby was referred to pediatric cardiology. The postnatal echocardiogram showed a small-to-moderate apical muscular ventricular septal defect, a small perimembranous ventricular septal defect, a small secundum atrial septal defect, and borderline aortic arch hypoplasia. In this case, the more detailed fetal cardiac examination performed at the fetal echocardiogram did not diagnose the anomalies. |
DISCUSSION |
|---|
|
TOP
ABSTRACTMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
The antenatal sonographic diagnosis of single umbilical artery was first reported in the late 1980s.12 Reports of association between single umbilical artery and other anomalies have created an imperative to identify or exclude the presence of such anomalies, and detailed sonography is advised for all fetuses with single umbilical artery.1–5,9–14 (See also Csescei K et al. Incidence and association of single umbilical artery: Response to Drs. Leung and Robson [letter – reply]. Am J Med Genet 1993;46:248–9.) Estimates of the frequency of aneuploidy range widely, between 4% and 50% in cases with single umbilical artery and other anomalies.1,3,6,8,12,15 With isolated single umbilical artery, the rate of aneuploidy is not known; however, most authors do not recommend routine karyotype.1,3,6,8,12,15
Several reports explicitly address the issue of fetal echocardiography in the setting of single umbilical artery. Abuhamad et al recommend fetal echocardiography in all cases of single umbilical artery.1 Ulm et al recommend that umbilical artery Doppler velocimetry be performed and that a complete evaluation (karyotype, echocardiogram, and detailed sonogram) is only indicated when the systolic/diastolic ratio is elevated.16 In this series, none of the fetuses with elevated systolic/ diastolic ratios and isolated single umbilical artery had cardiac anomalies identified by echocardiogram. Budorick et al17 report a series of 65 fetuses with a single umbilical artery. They identified one congenital heart defect among 21 fetuses with apparently isolated single umbilical artery, and concluded that a 5% incidence of congenital heart disease among fetuses with isolated single umbilical artery warrants fetal echocardiography in all such cases.
The cardiac abnormalities identified by fetal echocardiography in our series were first suspected on the four-chamber and outflow tract views at the time of the anatomic survey, with one exception (sensitivity = 94.1%). In Case 14, there was a normal four-chamber view at the anatomic survey. A subsequent echocardiogram at 18 weeks showed a borderline small aortic valve (0.23 cm, normal range 0.23–0.39 cm) with peak velocity across the aortic valve at the upper limit of normal. The patient failed to follow up at 32 weeks’ gestation as recommended. This fetus had other anomalies. In another fetus (Case 13) with single umbilical artery and dilated cerebral ventricles, the four-chamber view and fetal echocardiogram at 21 weeks’ gestation were both normal. However, on day of life 2, this infant was diagnosed with critical aortic stenosis and underwent aortic valvuloplasty and closure of a patent ductus arteriosus. These cases, as well as the single case of a fetus with isolated single umbilical artery and postnatally diagnosed cardiac disease (Case 17), illustrate the difficulty in diagnosing some congenital heart defects in the antenatal period, even when fetal echocardiography is performed. Ott18 reported a sensitivity of 62.5% for fetal echocardiography in a group considered high risk for congenital heart disease. Bromley et al19 reported a sensitivity of 82% for fetal echocardiography in fetuses at risk for congenital heart defects. The most commonly missed lesions in this series were septal defects and valvular stenosis, similar to our experience with fetal echocardiography for single umbilical artery.
Other investigators have studied the role of fetal echocardiography in screening for structural heart defects in selected populations. Smith et al20 found that among 223 women with insulin-dependent diabetes, there were 11 congenital heart defects in the offspring. When the four-chamber view and outflow tracts were normal, additional views did not detect cardiac anomalies. They reported a sensitivity of 82% for the four-chamber and aortic outflow tract views for diagnosing congenital heart disease.
Fetuses with isolated single umbilical artery appear to have a low incidence of congenital heart disease compared to those with other abnormalities. In our population, no case of congenital heart disease was detected at the time of fetal echocardiography when the four-chamber and outflow tract views were normal in fetuses with isolated single umbilical artery. In other words, the findings on four-chamber view and outflow tracts corresponded with the findings on echocardiography in all cases of isolated single umbilical artery. Based on these findings, fetal echocardiography may not be indicated as a routine part of the evaluation of the fetus with an isolated single umbilical artery, unless the four-chamber view and outflow tracts are abnormal or cannot be obtained. Our findings are at odds with those of other investigators; further prospective studies may help to clarify this question.
There are several potential limitations to the conclusions of our study. First, the study population was relatively small. It is possible that with a larger series, there would be fetuses with cardiac disease that would be missed by the four-chamber and outflow tract views, yet which would be identified on echocardiogram. In our study population, the incidence of cardiac abnormalities among fetuses with isolated single umbilical artery was 2.4% (1 of 42 for whom the anatomic survey showed normal four-chamber and outflow tract views). To show that this incidence is different than the rate of cardiac malformations in a general obstetric population (approximately 1%) would require a sample size of 2560, assuming an 
of .05 and 1-ß of .80. If one assumes a 5% rate of congenital heart disease among fetuses with isolated single umbilical artery as described by Budorick,17 the necessary sample size would be 500. Because the detection rate for both the four-chamber/outflow tract assessment and the fetal echocardiogram have been reported as 60–80%, it is difficult to assess the necessary sample size for a study to determine whether fetal echocardiography adds useful information after normal four-chamber and outflow tract views have been obtained. Second, approximately half of our study population was scanned for indications other than routine anatomic assessment, thus potentially limiting the ability to generalize the results. Lastly, we do not have postnatal follow-up on 35% of the patients. Many of those with normal structural surveys and fetal echocardiograms returned to the care of their referring obstetricians and delivered elsewhere. It is possible that some of these infants were diagnosed postnatally with cardiac disease that was missed by our antenatal studies.
There were six subjects who were found at birth to have a three-vessel cord (5.9%). One was described as having a two-vessel cord by the examining pediatrician; however, histologic section identified a third vessel. One was described on ultrasound as a three-vessel cord on cross-section of the cord itself, but Doppler identified only one artery coursing around the fetal bladder; clinical examination revealed a three-vessel cord. Jones et al14 reported that the sensitivity and positive predictive value of ultrasound for diagnosis of single umbilical artery were 65%. In the same report, the diagnostic accuracy of clinical examination by both pediatricians and obstetricians was compared to histologic diagnosis; obstetricians missed 24% of the diagnoses of single umbilical artery, and pediatricians missed 16%. Hill et al reported recently that in a cohort of 1027 fetuses who were examined by ultrasound after 15 weeks’ gestation and for whom placental pathology examinations were routinely performed, the sensitivity and specificity for the detection of a two-vessel umbilical cord were 85% and 99.7%, respectively.21 As we do not have complete follow-up on our cohort of fetuses with two-vessel cords, we are not able to estimate the sensitivity or specificity of ultrasound. Of note, neither of these reports employed color Doppler to identify the number of cord vessels, and Hill additionally excluded assessment of the number of umbilical vessels adjacent to the fetal bladder. Awaiting further study is an assessment of how the three potential methods of identifying the number of cord vessels by ultrasound (examination of a free loop, determination of the number of vessels adjacent to the fetal bladder, and utilization of color or power Doppler to determine flow) compare to the gold standard of histologic examination.
|
Footnotes |
|---|
Received February 2, 2002. Received in revised form April 29, 2002. Accepted May 2, 2002.
|
REFERENCES |
|---|
|
TOP
ABSTRACTMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
2. Catanzarite VA. The clinical significance of a single umbilical artery as an isolated finding of prenatal ultrasound. Obstet Gynecol 1995;86:155–6.[Medline]
3. Chow JS, Benson CB, Doubilet PM. Frequency and nature of structural anomalies in fetuses with single umbilical arteries. J. Ultrasound Med 1998;17:765–8.[Abstract]
4. Csecsei K, Kovacs T, Hinchcliffe SA, Papp Z. Incidence and associations of single umbilical artery in prenatally diagnosed malformed, midtrimester fetuses: A review of 62 cases. Am J Med Genet 1992;43:524–30.[Medline]
5. Hermann UJ, Sidiropoulos D. Single umbilical artery: prenatal findings. Prenat Diagn 1987;8:275–80.
6. Khong TY, George K. Chromosomal abnormalities associated with a single umbilical artery. Prenat Diagn 1992; 12:965–8.[Medline]
7. Leung AK. Robson WL. Single umbilical artery: A report of 159 cases. Am J Dis Child 1989;143:108–11.[Abstract]
8. Saller DN, Keene CL, Sun CJ, Schwartz S. The association of single umbilical artery with cytogenetically abnormal pregnancies. Am J Obstet Gynecol 1990;163:922–5.[Medline]
9. Sener T, Ozalp S, Hassa H, Zeytinoglu S, Basaran N, Durak B. Ultrasonographic detection of single umbilical artery: A simple marker of fetal anomaly. Int J Gynecol Obstet 1997;58:217–22.[Medline]
10. Thummala MR, Raju TN, Langenberg P. Isolated single umbilical artery and the risk for congenital malformations: a meta-analysis. J Pediatr Surg 1998;33:580–5.[Medline]
11. Tortora M, Chervenak FA, Mayden K, Hobbins JC. Antenatal sonographic diagnosis of single umbilical artery. Obstet Gynecol 1984;63:693–6.
12. Nyberg DA, Mahony BS, Luthy D, Kapur R. Single umbilical artery: Prenatal detection of concurrent anomalies. J Ultrasound Med 1991;10:247–53.[Abstract]
13. Deka D, Buckshee K. Single umbilical artery: Prenatal diagnosis. Indian J Pediatr 1992;59:137–8.[Medline]
14. Jones TB, Sorokin Y, Bhatia R, Zador IE, Bottoms SF. Single umbilical artery: Accurate diagnosis? Am J Obstet Gynecol 1993;169:538–40.[Medline]
15. Parilla BV, Tamoura RK, MacGregor SN, Geibel LJ, Sabbagha RE. The clinical significance of a single umbilical artery as an isolated finding on prenatal ultrasound. Obstet Gynecol 1995;85:570–2.[Abstract]
16. Ulm B, Ulm M, Deutinger J, Bernaschek G. Umbilical artery Doppler velocimetry in fetuses with a single umbilical artery. Obstet Gynecol 1997;90:205–9.[Abstract]
17. Budorick NE, Kelly TF, Dunn JA, Scioscia AL. The single umbilical artery in a high-risk patient population. What should be offered? J Ultrasound Med 2001;20:619–27.
18. Ott WJ. The accuracy of antenatal fetal echocardiography in high- and low-risk patients. Am J Obstet Gynecol 1995; 172:1741–9.[Medline]
19. Bromley B, Estroff JA, Sanders SP, Parad R, Roberts D, Frigoletto FD, et al. Fetal echocardiography: Accuracy and limitations in a population at high and low risk for heart defects. Am J Obstet Gynecol 1992;166:1473–81.[Medline]
20. Smith RS, Comstock CH, Lorenz RP, Kirk JS, Lee W. Maternal diabetes mellitus: Which views are essential for fetal echocardiography? Obstet Gynecol 1997;90:575–9.[Abstract]
21. Hill LM, Wibner D, Gonzales P, Chenevy P. Validity of transabdominal sonography in the detection of a two-vessel umbilical cord. Obstet Gynecol 2001;98:837–42.
This article has been cited by other articles:
|
|
 |
|
  R. Hershkovitz, E. Sheiner, and M. Mazor Middle cerebral artery blood flow velocimetry among healthy fetuses with a single umbilical artery. J. Ultrasound Med., November 1, 2006; 25(11): 1405 - 1408. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
