The clinical significance of a single umbilical artery as an isolated finding on prenatal ultrasound

Changes in Artery Diameters and Fetal Growth in Cases of Isolated Single Umbilical Artery

Background-There are conflicting data in the international literature on the risks of abnormal fetal growth in fetuses presenting an isolated single umbilical artery (SUA), and the pathophysiology of this complication is poorly understood. Objective-To evaluate if changes in diameter of the remaining umbilical artery in fetuses presenting an isolated SUA are associated with different fetal growth patterns. Study design-This was a two-center prospective longitudinal observational study including 164 fetuses diagnosed with a SUA at the 20-22-week detailed ultrasound examination and 200 control fetuses with a three-vessel cord. In all cases, the diameters of the cord vessels were measured in a transverse view of the central portion of the umbilical cord, and the number of cord vessels was confirmed at delivery. Logistic regression and nonparametric receiver operating characteristic (ROC) analysis were carried out to evaluate the association of the umbilical artery diameter in a single artery with small for-gestational age (SGA) and with fetal growth restriction (FGR). The impact of artery dimension was adjusted for maternal BMI, parity, ethnicity, side of the remaining umbilical artery and umbilical resistance index (RI) in the regression model. Results-A significantly (p < 0.001) larger mean diameter was found for the remaining artery in fetuses with SUA compared with controls (3.0 ± 0.9 vs. 2.5 ± 0.6 mm). After controlling for BMI and parity, we found no difference in umbilical resistance and side of the remaining umbilical artery between the SUA and control groups. A remaining umbilical artery diameter of >3.1 mm was found to be associated with a lower risk of FGR, but this association failed to be statistical significant (OR = 0.60, 95% CI = 0.33-1.09, p value = 0.089). We also found that the mean vein-to-artery area ratio was significantly (p < 0.001) increased in the SUA group as compared with the controls (2.4 ± 1.8 vs. 1.8 ± 0.9; mean difference = 0.6; Cohen's d = 0.46). Conclusion-In most fetuses with isolate SUA, the remaining artery diameter at 20-22 weeks is significantly larger than in controls. When there are no changes in the diameter and, in particular, if it remains <3.1 mm, the risk of abnormal fetal growth is higher, and measurements of the diameter of the remaining artery could be used to identify fetuses at risk of FGR later in pregnancy.

Differences in perinatal outcomes according to forming period of single umbilical cord in singleton pregnancy

OBJECTIVES

The aim of this study was to establish the frequency and associations of single umbilical artery (SUA) diagnosed until the first vs second or third trimester.

METHODS

A retrospective cohort study was conducted on singleton pregnancies at a tertiary perinatal center. All women underwent both the first and second trimester scans in which the number of arteries in the umbilical cord was routinely documented. SUA was classified as aplastic type when the diagnosis was made in the first trimester and as occlusion type when diagnosed in the second or third trimester. Adverse perinatal outcome was calculated as occurrence of fetal death, birthweight centile < 10^th , or Apgar score at 5 minutes < 7.

RESULTS

A total of 8675 women underwent ultrasound examinations during the study period. Of the 32 SUA cases, 17 (0.2%) were of the aplastic type and 15 (0.2%) of the occlusion type. Congenital anomalies were more in aplastic than in occlusive SUA (58.8% vs 20%, .043). The occlusive SUA had higher postnatal coiling index (0.3 vs 0.2, .034) and diagnosis of hypercoiled cord (46.7% vs 5.9%, .013) than the aplastic type.

CONCLUSIONS

The different gestational age at diagnosis and coiling characteristics suggest two types of SUA, namely, aplastic and occlusion types, which are associated with differences in perinatal outcomes.

Reference charts for umbilical Doppler pulsatility index in fetuses with isolated two-vessel cord

PURPOSE

To determine reference values for umbilical Doppler pulsatility index in fetuses with isolated two-vessel cord and to compare these values with standard umbilical Doppler pulsatility index curves from 23 to 40 gestational weeks.

METHODS

A retrospective longitudinal cohort study was conducted between January 2014 and December 2017 in a tertiary referral hospital and included 62 pregnant women with isolated single umbilical artery (two-vessel cord) and 174 measurements. Only uncomplicated term pregnancies were included. A reference curve for umbilical Doppler pulsatility index was built up and compared with a standard curve commonly used for fetuses with three-vessel cord.

RESULTS

Umbilical Doppler pulsatility index values were much lower than expected in cases with two-vessel cord compared to 3-vessel cord: mean of the regression equations was 1.02 ± 0.23 vs. 0.86 ± 0.19, respectively (p value < 0.001). This difference was quite constant across the gestational weeks considered, showing that the slopes of the two regressions were very similar.

CONCLUSION

Reference curves for umbilical Doppler pulsatility index in two-vessel cord pregnancies were determined. Pulsatility index values were significantly different compared with those commonly used for three-vessel cord. Using lower reference values for umbilical pulsatility index in cases with two-vessel cord may allow a better identification of fetuses affected with intrauterine growth restriction, thus improving fetal surveillance.

Isolated Single Umbilical Artery and Fetal Echocardiography: A 25-Year Experience at a Tertiary Care City Hospital

OBJECTIVES

To review our 25-year experience with a single umbilical artery and fetal echocardiography to estimate the need for this test in cases of an isolated single umbilical artery.

METHODS

We conducted a retrospective review of 436 patients with a diagnosis of a single umbilical artery at our institution between 1990 and 2015. Two hundred eighty-eight women had both an anatomic survey and a fetal echocardiogram. Pregnancies with concurrent extracardiac anomalies or aneuploidy were excluded. The study population was divided into 3 groups based on cardiac views on the anatomic survey: normal, incomplete, and suspicious. Echocardiographic results were compared among the 3 groups. The primary outcome measure was the incidence of cardiac anomalies in the normal group at fetal echocardiography. The data were analyzed by the χ² test or Fisher exact test.

RESULTS

The mean maternal age ± SD of the group was 29.2 ± 6.2 years; 44.1% were primiparas. The mean gestational age at diagnosis was 22.6 ± 5.2 weeks, and the mean gestational age at fetal echocardiography was 25.1 ± 3.6 weeks. In the normal group, 99.1% (230 of 232) of women had a normal fetal echocardiogram; the 2 abnormal cases were ventricular septal defects. Normal echocardiograms were obtained in 81.8% (36 of 44) and 25.0% (3 of 12) of the "incomplete" and "suspicious" groups, respectively.

CONCLUSIONS

Fetuses with a single umbilical artery, in the absence of structural abnormalities, and with normal cardiac views at the time of the anatomic survey do not warrant an echocardiogram.

Association of isolated single umbilical artery with perinatal outcomes: Systemic review and meta-analysis

Objective

The aim of this study was to evaluate the association between prenatally diagnosed isolated single umbilical artery (iSUA) and perinatal outcomes.

Methods

We searched Medline, Embase, the Cochrane Library, and KoreaMed from inception to January 2016, with no language or regional restrictions, for cohort and case-control studies reporting on the relationship of iSUA and perinatal outcomes. We assessed the odds ratios (ORs) and 95% confidence intervals (CIs) for the occurrence of small for gestational age, preterm birth, pregnancy-induced hypertension, neonatal intensive care unit admission, and perinatal mortality in fetuses with iSUA compared with those in fetuses with three vessel cord.

Results

Eleven articles totaling 1,731 pregnancies with iSUA met the selection criteria. Studies varied in design, quality, outcome definition, and results. Meta-analysis carried out within predefined groups showed that the presence of an iSUA was associated with small for gestational age (OR, 2.75; 95% CI, 1.97 to 3.83; P<0.00001), preterm birth (OR, 2.10; 95% CI, 1.72 to 2.57; P<0.00001), pregnancy-induced hypertension (OR, 1.62; 95% CI, 1.00 to 2.63; P=0.05), neonatal intensive care unit admission (OR, 2.06; 95% CI, 1.33 to 3.19; P=0.001), and perinatal mortality (OR, 2.29; 95% CI, 1.32 to 3.98; P=0.003).

Conclusion

Pregnancies complicated by iSUA are at increased risk for small for gestational age, preterm birth, pregnancy-induced hypertension, neonatal intensive care unit admission and perinatal mortality. Further, large prospective cohort studies are required to improve the quality of prenatal counseling and the neonatal care for pregnancies with iSUA.

Association Between Isolated Single Umbilical Artery and Perinatal Outcomes: A Meta-Analysis

Background

To evaluate the association between the isolated single umbilical artery (iSUA) and perinatal outcomes, including pregnancy outcomes and perinatal complications.

Material/Methods

We performed a meta-analysis of 15 eligible studies regarding the relationship between the iSUA and perinatal outcomes, including gestational age at delivery, nuchal cord, placental weight, small for gestational age (SGA), oligohydramnios, polyhydramnios, pregnancy-induced hypertension (PIH), gestational diabetes mellitus (GDM), preeclampsia, and perinatal mortality. The overall odds ratios (OR) or standardized mean difference (SMD) were calculated.

Results

The occurrence of nuchal cord was not found to be different between an iSUA and a three-vessel cord (TVC) fetus. For perinatal complications, the SGA, oligohydramnios, polyhydramnios, GDM, and perinatal mortality showed dramatic difference between women with an iSUA and women with a TVC fetus, which implied that the presence of iSUA significantly increased the risk of perinatal complications. For other perinatal complications, such as PIH and preeclampsia, no significant association was detected.

Conclusions

Our meta-analysis suggests that the presence of iSUA would increase the risk of perinatal complications such as SGA, oligohydramnios, polyhydramnios, GDM, and perinatal mortality. Therefore, pregnant women with an iSUA fetus have poorer perinatal outcomes and more attention should be given to the management of their pregnancy compared to women with a TVC fetus.

Isolated single umbilical artery is an independent risk factor for perinatal mortality and adverse outcomes in term neonates

OBJECTIVE

To determine whether an isolated single umbilical artery (iSUA) is an independent risk factor for perinatal mortality in term neonates with normal estimated fetal weight (EFW) prior to delivery.

METHOD

A population-based study was conducted, including all deliveries occurring between 1993 and 2013, in a tertiary medical center. Pregnancies with and without iSUA were compared. Multiple gestations, chromosomal, and structural abnormalities were excluded from the cohort. Only pregnancies delivered at term with normal EFW evaluated prior to delivery were included. Stratified analysis was performed using multiple logistic regression models to evaluate the risk of adverse outcomes and perinatal mortality for iSUA fetuses.

RESULTS

During the study period, 233,123 deliveries occurred at "Soroka" University Medical Center, out of which 786 (0.3 %) were diagnosed with iSUA. Different pregnancy complications were more common with iSUA fetuses including: placental abruption (OR = 3.4), true knot of cord (OR = 3.5) and cord prolapse (OR = 2.8). Induction of labor and cesarean delivery were also more common in these pregnancies (OR = 1.5 and OR = 1.9, respectively). iSUA neonates had lower Apgar scores at 1 and 5 min (OR = 1.8, OR = 1.9, respectively) compared to the control group and perinatal mortality rates were higher both antenatally (IUFD, OR = 8.1) and postnatally (PPD, OR = 6.1).

CONCLUSION

iSUA appears to be an independent predictor of adverse perinatal outcomes in term neonates.

Should fetal growth be a matter of concern in isolated single umbilical artery?

OBJECTIVE

To examine birth weight in pregnancies with isolated single umbilical artery (ISUA).

METHODS

Case control study with retrospective review of 131 singleton pregnancies with isolated single umbilical artery diagnosed before birth. Control group consisted of 730 singleton pregnancies recruited prospectively, that had histological confirmation of a 3 vessels cord. Pregnancies were classified as uncomplicated or high-risk according to the presence of diseases that increase the risk of placental insufficiency during pregnancy. Mean birth weight and frequency of low birth weight (< 2.500 g), very low birth weight (< 1.500 g) and fetal growth restriction below the 5th and 10th centiles were compared between groups.

RESULTS

Mean birth weight difference between ISUA (n=131, 2840±701g) and control (n=730, 2.983 ± 671g) pregnancies was 143g (95% CI= 17-269; p=0.04) and birth weight below the 5thcentile was significantly more common in ISUA group [28/131 (21.4%) versus 99/730 (13.6%), p=0.02]. When only uncomplicated pregnancies were considered in both groups, no birth weight differences were observed. Amongst high-risk subgroups, birth weight below the 5th centile remained significantly more common in ISUA compared to control pregnancies [10/35 (28.6%) versus 53/377 (14.1%), p=0.04].

CONCLUSION

Isolated single umbilical artery does not increase the risk of fetal growth restriction in uncomplicated singleton pregnancies.

Determination of risk factors and perinatal outcomes of singleton pregnancies complicated by isolated single umbilical artery in Turkish population

OBJECTIVE

To address the possible risk factors, eventual pregnancy outcomes, and probable troubles in follow-ups of pregnancies complicated by an isolated single umbilical artery and to provide data on Turkish cases in such an aspect that ethnic divergences may have influence.

MATERIAL AND METHODS

A total of 16568 singleton pregnancies that were delivered between May 2006 and May 2013 were retrospectively screened. Ninety-three fetuses were found to have an isolated single umbilical artery. One-hundred pregnancies that did not show any structural or chromosomal abnormalities were randomly selected from the rest of the cases to establish the control group. IBM SPSS Statistics 20.0 software was utilized for statistical analysis. Non-parametric data were analyzed with Mann-Whitney U test and were presented as means±standard deviations. P values less than 0.05 were statistically significant. For the adjustment of confounding factors, odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by multiple logistic regression analysis.

RESULTS

The incidence of small for gestational age (SGA) fetuses and hypertensive disorders in pregnancy was found to be significantly higher in cases with an isolated single umbilical artery (p<0.001 and p=0.022, respectively). Maternal smoking was found to be independently associated with the occurrence of an isolated single umbilical artery (OR: 3.556; 95% CI: 1.104-11.45). The risk of preterm birth was not higher in the study group (OR: 0.538; 95% CI: 0.576-2.873). The incidence of cases who underwent cesarean delivery because of non-reassuring fetal heart trace was similar in the study and control groups (p=0.499).

CONCLUSION

Attention should be paid to the development of hypertensive disorders in cases with a diagnosis of an isolated single umbilical artery, and parents should be counseled properly, including the information on increased risk of SGA. Strict follow-up of pregnancies complicated with an isolated single umbilical artery in terms of preterm birth seems unfeasible except in cases with accompanying risk factors for preterm labor.

Umbilical artery blood flows among pregnancies with single umbilical artery: a prospective case-control study

OBJECTIVES

To evaluate peak systolic velocity (PSV) in the umbilical artery (UA) among patients with single umbilical artery (SUA) as compared with patients with three vessel cords.

METHODS

A prospective case-control study was performed. UA blood flow velocimetry was obtained from fetuses with SUA and from a control group with three vessel cord. PSV and pulsatility index (PI) were measured. Patients' characteristics were compared for statistical differences and a linear regression model was constructed for the different groups.

RESULTS

UA Doppler velocimetry measurements were obtained from 29 patients with SUA and from 29 controls matched for gestational age. The differences between UA PI with and without SUA were significant (F = 3.471; p = 0.0379) showing a lower PI in the SUA group. However, no significant statistical difference was found in PSV between these two groups (F = 0.149; p = 0.86).

CONCLUSIONS

While the impedance in the UA of patients with a SUA was lower compared with patients with a normal umbilical cord, the PSV did not differ.

The impact of isolated single umbilical artery on labor and delivery outcome

OBJECTIVE

Data regarding the association between isolated single umbilical artery (SUA) and pregnancy outcome are inconsistent and mainly address the risk of pregnancy complications. Thus, we aimed to focus on the association between isolated SUA, and labor and delivery.

METHODS

We conducted a case-control study of all singleton pregnancies diagnosed with isolated SUA (no known chromosomal/structural anomalies/fetal growth restriction) attempting vaginal delivery. Obstetric and neonatal outcome was compared with that of a control group of pregnancies with a three-vessel cord in a 1:2 ratio matched by parity. Composite adverse outcome included the following: Cesarean section (CS) and/or operative delivery due to non-reassuring fetal heart rate (NRFHR), prolonged neonatal admission, low Apgar score and umbilical artery pH < 7.2.

RESULTS

Out of 34 196 deliveries, 162 (0.5%) were diagnosed with SUA, and 91 (0.27%) were diagnosed with isolated SUA. Isolated SUA was associated with a higher rate of CS due to NRFHR (5.5% vs 1%, p = 0.02), small for gestational age (SGA) (14.3% vs 4.9%, p = 0.009), lower birth weight, and a higher rate of composite adverse outcome (20.9% vs 8.8%, p = 0.005). On multivariable analysis, isolated SUA was independently associated with an increased risk for composite adverse outcome (OR 2.34, 95% CI 1.05-5.21).

CONCLUSION

Isolated SUA is associated with increased risk for CS due to NRFHR and increased rate of SGA.

Relationship of isolated single umbilical artery to fetal growth, aneuploidy and perinatal mortality: systematic review and meta-analysis

OBJECTIVE

To review the available literature on outcome of pregnancy when an isolated single umbilical artery (iSUA) is diagnosed at the time of the mid-trimester anomaly scan.

METHODS

We searched MEDLINE (1948-2012), EMBASE (1980-2012) and the Cochrane Library (until 2012) for relevant citations reporting on outcome of pregnancy with iSUA seen on ultrasound. Data were extracted by two reviewers. Where appropriate, we pooled odds ratios (ORs) for the dichotomous outcome measures: small for gestational age (SGA), perinatal mortality and aneuploidy. For birth weight we determined the mean difference with 95% CI.

RESULTS

We identified three cohort studies and four case-control studies reporting on 928 pregnancies with iSUA. There was significant heterogeneity between cohort and case-control studies. Compared to fetuses with a three-vessel cord, fetuses with an iSUA were more likely to be SGA (OR 1.6 (95% CI, 0.97-2.6); n = 489) or suffer perinatal mortality (OR 2.0 (95% CI, 0.9-4.2); n = 686), although for neither of the outcomes was statistical significance reached. The difference in mean birth weight was 51 g (95% CI, -154.7 to 52.6 g): n = 407), but again this difference was not statistically significant. We found no evidence that fetuses with iSUA have an increased risk for aneuploidy.

CONCLUSION

In view of the non-significant association between iSUA and fetal growth and perinatal mortality, and in view of the heterogeneity in studies on aneuploidy, we feel that large-scale, prospective cohort studies are needed to reach definitive conclusions on the appropriate work-up in iSUA pregnancies. At present, targeted growth assessment after diagnosis of iSUA should not be routine practice.

Outcomes of an isolated single umbilical artery in singleton pregnancy: a large study from the Middle East and Gulf region

OBJECTIVE

To assess the frequency and accuracy of prenatal diagnosis of a single umbilical artery (SUA) and to compare the fetal and neonatal outcome of isolated SUA to that of a normal three-vessel umbilical cord in a population from the Middle East and Gulf region.

STUDY DESIGN

Data were collected from 37,500 singleton pregnancies that were scheduled for antenatal care and delivered at Security Forces Hospital in Riyadh, Saudi Arabia, between May 2004 and December 2012. Comparisons between the groups were performed using a chi-square test or a Fisher exact test for the categorical variables, and Student's t test or Wilcoxon's rank-sum test were used for continuous variables. The Kappa statistic was used to study the agreement between the antenatal and final neonatal diagnosis of SUA. A univariable analysis was used to calculate the unadjusted and adjusted ORs and the 95% CIs expressing the relationship of the normal three-vessel umbilical cord, the isolated SUA, and each outcome.

RESULTS

A total of 35,249 cases completed the study, including 35,026 cases with normal neonatal three-vessel umbilical cords (Group B). SUA was present in 223 (0.63%) neonates (0.45% isolated SUA (Group A) and 0.18% non-isolated SUA). The sensitivity, specificity, positive predictive value and negative predictive value of using prenatal ultrasound for the diagnosis of SUA were 90.58%, 99.9%, 98.5% and 99.94%, respectively. Neonatal anomaly was present in 2.6% of the fetuses with isolated SUA. A pregnancy with isolated SUA was more likely to be complicated with polyhydramnios (OR 3.32; CI 1.22-9.04), preterm delivery <34 weeks (OR 4.662; CI 2.346-9.195), birth weight <10th percentile (OR 2.1; CI 1.44-2.93), cesarean delivery for fetal distress (OR 2.72; CI 1.53-4.81), perinatal death (OR 3.31; CI 1.34-8.12), admission to NICU (OR 2.71; CI 1.87-3.91), and placental abnormalities (OR 3.25; CI 2.14-4.93; p value 0.0001) compared to a pregnancy with a fetal and neonatal three-vessel cord.

CONCLUSION

Isolated SUA is associated with anomalies at birth and with an increased risk of adverse pregnancy outcomes even in the absence of other anomalies. A pregnancy with this complication should receive close fetal monitoring for growth and fetal wellbeing.

A case of a four-vessel umbilical cord: don’t stop counting at three!

There are various numerical abnormalities of umbilical cord vessels known in the literature, the single umbilical artery being the most prevalent. A four-vessel umbilical cord is found less frequently, and moreover, is less well-known in daily practice. A persistent right umbilical vein, however, can be associated with potentially serious congenital defects. A case of a four-vessel umbilical cord containing two arteries and two veins is presented. The literature on this subject reports both a differentiation between the two variants, intrahepatic and extrahepatic, which can be distinguished during antenatal ultrasound screening, and a possible association with congenital abnormalities, some of which can carry substantial morbidity and mortality. Although the incidence of a four-vessel umbilical cord is low, its presence should be considered both during routine antenatal ultrasound screening and on physical examination of any neonate.

Single umbilical artery: Does side matter?

INTRODUCTION

The aim of this study was to determine if laterality of an absent umbilical artery (AUA) is associated with specific sonographic findings, chromosomal defects or postpartum birth defects.

MATERIALS AND METHODS

In this retrospective cohort study, ultrasound reports and medical records of patients who received an obstetric ultrasound at the University of Iowa Hospitals and Clinics with an identified laterality of the AUA from 1989 to 2007 (n = 405) were reviewed. Rates of sonographic abnormalities between fetuses with a right versus left AUA were compared using Fisher's exact test. Adjustments for confounding were made using logistic regression modeling. The significance level was set at 0.05.

RESULTS

Right AUAs on ultrasound demonstrate higher unadjusted rates of ultrasound abnormalities with a higher percentage of fetuses with >1 additional abnormality (51.1 vs. 37.0%; p = 0.0043). The left AUA group had a significantly higher percentage of isolated AUA (63.0 vs. 48.8%; p = 0.004). In a multivariate analysis, a sonographic right AUA was significantly associated with gastrointestinal (GI) and genitourinary (GU) abnormalities. No other ultrasonographic and umbilical artery Doppler abnormalities, chromosomal defects or postpartum birth defects were significantly associated with a specific laterality of the AUA.

DISCUSSION

Our study identified a significant association between a right AUA and concomitant fetal GI and GU abnormalities. Contrary to previous reports, we conclude that laterality of the AUA may prove to be an easily identified early marker of fetal abnormalities.

Isolated single umbilical artery and fetal karyotype

OBJECTIVE

To determine the need for fetal karyotyping in cases of an isolated single umbilical artery (SUA) identified during the second-trimester routine anomaly scan.

METHODS

All patients booked for antenatal care and delivery in our hospital are offered two ultrasound scans in pregnancy, one at 11-13 weeks' gestation as part of screening for chromosomal defects and another at 20-23 weeks for detailed fetal examination. In addition we examine patients referred from other hospitals because of suspected fetal abnormalities during their routine second-trimester scan. We performed a search of the database to retrieve all cases with an SUA and reviewed the ultrasound findings, fetal karyotype and pregnancy outcome.

RESULTS

There were 643 cases with SUA, including 424 (65.9%) where the condition was isolated, 133 (20.7%) with one major fetal defect and 86 (13.4%) with multiple defects. The incidence of chromosomal abnormalities was 0% in the isolated SUA group, 3.7% in those with one defect and 50.7% in those with multiple defects. The commonest chromosomal abnormalities were trisomy 18, trisomy 13 and triploidy, which together accounted for 82.9% of cases.

CONCLUSION

The finding of an SUA should prompt the sonographer to search for fetal defects and if these are found the risk for chromosomal abnormalities is increased. In cases of apparently isolated SUA there is no evidence of increased risk of chromosomal abnormalities.

Indications for fetal echocardiography high referral, low yield?

An excellent imaging tool in the prenatal diagnosis and ongoing evaluation of congenital heart defects, fetal echocardiography is indicated in a selected population at increased risk compared with the general population. For certain "soft markers" of fetal congenital heart defects, ambiguity in the indications for fetal echo may result in a high referral rate, but low yield of congenital heart disease. Here, we critically examine 4 conditions, 2 maternal and 2 fetal: maternal gestational diabetes, advanced maternal age, isolated echogenic focus, and single umbilical artery. This critical review reveals that more prospective population-based studies with higher power and minimal bias need to be performed to establish the absolute risk of congenital heart defects in a selected population compared with that of the general population. Nonetheless, our analysis indicates that the absolute risk of congenital heart defects associated with each of these markers is low.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader should be able to define which patients should be referred for fetal echocardiography based on known risks, distinguish between relative and absolute risks for fetal congenital heart disease, and summarize fetal anomaly risks for women with altered glucose metabolism.

Single umbilical artery in fetopathological investigations

Single umbilical artery (SUA) is a relatively common malformation that may call attention to the possibility of associated malformations (often chromosome aberrations). The current study aimed at surveying malformations associated with SUA on the basis of fetopathological investigations, analyzing the role of history, summarizing the clinically important factors emerging together with this malformation. In this study, we processed the details of 204 cases in which SUA was confirmed fetopathologically after miscarriage or induced abortion between 1990 and 2007. In our sample, SUA occurred in 7.38% of the cases. The history was positive in almost 30% of the cases. The majority of the cases had a positive obstetric and the minority of them a positive genetic history. The highest association of SUA with other malformations was found for craniospinal ones, but an association with cardiovascular malformations should also be mentioned. Regarding the individual types of malformation, SUA was most commonly associated with hydrocephalus, but Potter's sequence, trisomy 21, and atrioventricular septal defect also reached a higher rate in associated SUA. Previously published articles dealing with associated malformations found that urogenital malformations were most commonly associated with SUA. 'Itemizing' the different non-chromosomal malformations in association with SUA, we found that hydrocephalus, Potter's sequence, and atrioventricular septal defect were the most frequent malformations, while in earlier studies, the association with non-chromosomal malformations such as vertebral malformations, imperforated anus, cheilognathopalatoschisis, and renal agenesis occurred more frequently than usual.

The value of single umbilical artery in the prediction of fetal aneuploidy: findings in 12,672 pregnant women

OBJECTIVES

To assess the risk of the association of single umbilical artery and aneuploidies.

METHODS

In a general unselected obstetric population of 12,672 singleton pregnant women from January 1998 to December 2002, we detected 61 fetuses (prevalence, 0.48%) with single umbilical artery (SUA) on prenatal ultrasound at 16 to 23 menstrual weeks.

RESULTS

Among the 61 fetuses with 2-vessel cord, 39 (64%) had SUA as an isolated finding, and 22 (36%) had additional findings, either minor or major. One (2.56%) of the 39 fetuses with SUA as an isolated finding had aneuploidy (trisomy 21 at maternal age of 32 years), whereas 5 (41.6%) of the 12 fetuses with SUA concomitant with major anomalies were aneuploid. None of the 10 fetuses with SUA and minor anomalies had aneuploidy. Among the 12,611 women with 3-vessel cord, we instead found 8 cases of trisomy 21 (0.06%), 1 case of translocation 14-21 (0.007%), 5 cases of trisomy 18 (0.04%), 1 case of trisomy 13 (0.007%), 1 case of 47,XXX (0.007%), and 2 cases of monosomy X (0.01%).

CONCLUSIONS

In an unselected population, second trimester sonographic detection of SUA and major fetal anomalies indicate increased risk for fetal aneuploidy. However, even if this study is based on a large population, the only 1 case of trisomy 21 among the fetuses with SUA as an isolated finding is not sufficient to draw a conclusion, and larger studies are needed to confirm or infirm this single case.

Single umbilical artery and its siding in the second trimester of pregnancy: relation to chromosomal defects

OBJECTIVES

To determine the possible association between single umbilical artery (SUA) in the second trimester of pregnancy and the incidence of chromosomal abnormalities. To determine whether the presence of chromosomal defects in fetuses with SUA is related to the side of the missing artery.

METHODS

Color flow imaging of the fetal pelvis was used to determine the number of umbilical arteries in 2147 fetuses immediately before amniocentesis for karyotyping in the second trimester of pregnancy.

RESULTS

SUA was diagnosed in 102/2147 (4.8%) cases. The left umbilical artery was absent in 60/102 (58.8%) fetuses, compared with the 42/102 (41.2%) for the right artery. The rate of chromosome abnormalities was significantly higher among fetuses with SUA than among those with 2 umbilical arteries (19/102 or 18.6% versus 109/2045 or 5.3%; OR = 4.1, 95% CI 2.3-7.1, p < 0.0001). Among fetuses with SUA, there was no significant difference in the rate of chromosome abnormalities between those with absence of the left versus the right artery (11/60 or 18.3% versus 8/42 or 19.0%, p = 0.93). There was an SUA in 5/39 (12.8%) cases with trisomy 21, 8/16 (50%) with trisomy 18, 1/4 (25%) with trisomy 13 and 5/69 (7.2%) with other chromosomal defects. There were no chromosome abnormalities in fetuses where a single umbilical artery was an isolated sonographic finding. All fetuses with SUA and chromosomal defects had associated abnormalities detected by ultrasound.

CONCLUSION

A single umbilical artery (SUA) in the second trimester of pregnancy has a high association with trisomy 18, 13, 21 and other chromosomal defects, but all chromosomally abnormal fetuses had associated malformations detected by ultrasound. The absence of the left artery is more frequent than the absence of the right artery. The association with chromosomal abnormalities seems to be equal on each side.

Características de los neonatos con y sin arteria umbilical única. Análisis de dos series consecutivas de recién nacidos con y sin defectos congénitos

BACKGROUND AND OBJECTIVE

The implications of the presence of a single umbilical artery (SUA) are unknown. Although most articles are based on selected samples, they suggest a relationship between SUA and malformations. Consequently, prenatal detection of SUA causes concern, since there are no definitive guidelines that can be followed after identification of this abnormality. The objective of this study was to comparatively analyze SUA in two series of consecutive births, with and without congenital defects.

PATIENTS AND METHODS

A total of 19,909 cases and 19,148 controls from the Registry of the Spanish Collaborative Study on Congenital Malformations were studied. The variables analyzed were sex, birth weight, length, occipito-frontal circumference, gestational age, prematurity, delivery by caesarean section, umbilical cord length, placental weight, survival at 72 hours, primiparity, oligohydramnios, and polyhydramnios. Calculations included relative frequency, odds ratios (OR) and 95 % confidence intervals, the chi-square test, Fisher's p-value, and Student's t-test.

RESULTS

SUA was found in 2.29 % of cases and in 1.03 % of controls (p = 0.0000001). These figures showed secular variation due to improvements in prenatal diagnosis and interruption of some pregnancies. When cases with and without SUA were compared, those with SUA had lower values of somatometry at birth, umbilical cord length and gestational age and had a higher risk for oligohydramnios, polyhydramnios, caesarean section, and death in the first 72 hours. Among controls, the only differences were a shorter umbilical cord and a higher frequency of oligohydramnios among infants with SUA.

CONCLUSIONS

The results suggest that certain malformations associated with SUA could cause some of the differences among cases. Shortening of the umbilical cord and oligohydramnios could be related to SUA, as these abnormalities were found in both cases and controls. Comparison of cases and controls suggests that the etiopathogenesis of SUA could differ in the two groups.

Perinatal results following the prenatal ultrasound diagnosis of single umbilical artery

OBJECTIVE

To study the perinatal results in our population, following the prenatal ultrasound diagnosis of a single umbilical artery (SUA), as this alteration is associated with fetal malformations, chromosomal abnormality, and poor perinatal results.

MATERIALS AND METHODS

A retrospective review of all obstetric ultrasounds carried out between October 2000 and December 2003 in our service, obtaining the postnatal results of the fetuses diagnosed with an SUA.

RESULTS

From a total of 5,987 pregnant patients examined by ultrasound scan at 20th week, an SUA was found in 40 cases, representing an incidence of 0.7%. Of these, 84.6% were normal pregnancies at birth and 15.4% presented other malformations and/or chromosomal abnormalities. No aneuploidy was found in pregnancies where there were no other associated findings in the ultrasound scan at 20 weeks. All cases with serious congenital malformations accompanying the SUA were diagnosed prenatally. There was a 5% of perinatal mortality rate among our fetuses with SUA, which represents a mortality rate 10 times greater than the overall rate among our patients.

CONCLUSIONS

The ultrasound discovery of an SUA implies the meticulous search for other associated malformations, and in the absence of these, the risk of a chromosomal abnormality is very low, unless it is a high-risk patient. However, the growth and wellbeing of the fetus must be carefully monitored in the last 3 months, although the ultrasound scan does not show any other associated alterations.

Controversial ultrasound findings

This article has reviewed a few of the more controversial findings in the field of obstetric ultrasound. For each one evidence-based strategies for the management of affected pregnancies have been suggested, derived from what the authors believe is the best information available. In some cases, this information is very limited, which can make counseling these patients extremely difficult. Some physicians find using specific likelihood ratios helpful in these complex discussions. An example of the relative likelihood ratios for several markers of trisomy 21 is illustrated in Table 10. Although the management of each of the findings discussed in this article is different, a few generalizations can be made. To begin with, the detection of any abnormal finding on ultrasound should prompt an immediate detailed ultrasound evaluation of the fetus by someone experienced in the diagnosis of fetal anomalies. If there is more than one abnormal finding on ultrasound, if the patient is over the age of 35, or if the multiple marker screen is abnormal, an amniocentesis to rule out aneuploidy should be recommended. Of the six ultrasound findings reviewed here, the authors believe that only echogenic bowel as an isolated finding confers a high enough risk of aneuploidy to recommend an amniocentesis in a low-risk patient. The other findings in isolation in a low-risk patient seem to confer only a modest increased risk of aneuploidy, if any, and this risk is certainly less than the risk of unintended loss from amniocentesis. Wherever possible, modifiers of this risk, such as maternal age, history, and first and second multiple marker screening, should be used to define more clearly the true risk of aneuploidy. As obstetric ultrasound moves forward, particularly into the uncharted waters of clinical use of three- and four-dimensional ultrasound, one can expect a whole new crop of ultrasound findings with uncertain clinical significance. Clinicians are well advised to await well-designed studies to determine the clinical significance of these findings before altering clinical care.

Single umbilical artery: What does it mean for the fetus? A case-control analysis of pathologically ascertained cases

PURPOSE

To ascertain the frequency of chromosomal and other anomalies in fetuses with single umbilical artery.

METHODS

Placentas with single umbilical artery were identified from hospital pathology laboratory records. For each identified case, the next consecutive placenta with two umbilical arteries served as a control. Pathology records, maternal histories, and prenatal ultrasounds when available were reviewed for congenital anomalies, pregnancy complications, and maternal characteristics. When indicated, placental specimens, amniocytes, or neonatal bloods were karyotyped.

RESULTS

Single umbilical artery existed in 2.0% (97/4846) of pathological specimens. Fetuses with single umbilical artery had significantly more chromosomal (10.3% vs. 1.0%) and other congenital anomalies (27% vs. 8%).

CONCLUSIONS

The high incidence of major chromosomal and congenital anomalies justifies detailed fetal ultrasonography, echocardiography, and amniocentesis for karyotype when single umbilical artery is discovered during routine ultrasound.

Single umbilical artery at 11-14 weeks' gestation: relation to chromosomal defects

OBJECTIVE

To determine the possible association between single umbilical artery (SUA) at 11-14 weeks of gestation and the incidence of chromosomal abnormalities.

METHODS

Color flow imaging of the fetal pelvis was used to determine the number of umbilical arteries in 717 fetuses immediately before chorionic villus sampling for karyotyping at 11-14 weeks' gestation.

RESULTS

Single umbilical artery (SUA) was diagnosed in 21/634 (3.3%) chromosomally normal fetuses, in 5/44 (11.4%) with trisomy 21, 14/18 (77.8%) with trisomy 18 and 2/21 (9.5%) with other chromosomal defects. In the chromosomally normal group there was no significant difference in median fetal crown-rump length or nuchal translucency (NT) between those with a single and those with two umbilical arteries. In the 42 fetuses with SUA the expected number of cases of trisomy 21, estimated on the basis of maternal age, gestational age and fetal NT, was 4.7, which was not significantly different from the observed 5. The corresponding numbers for trisomy 18 were 2.0 for expected and 14 for observed (Fisher's exact test P = 0.0016).

CONCLUSION

A SUA at 11-14 weeks' gestation has a high association with trisomy 18 and other chromosomal defects.

Antenatal detection of a single umbilical artery: does it matter?

The presence of a single umbilical artery is recognised as a soft marker for congenital anomalies, aneuploidy, earlier delivery and low birthweight. Most of the available data are derived from case series or highly selected populations and are therefore likely to be unrepresentative. In this retrospective case-comparison study, we firstly aimed to determine the incidence of a single umbilical artery in an unselected population and secondly to examine the clinical significance of this soft marker. Over a 40-month period, 107 cases were identified from a cohort of 35 066 births giving an incidence of 3.1 per 1000 total births and late pregnancy losses. The antenatal detection rate was only 30%. Compared to fetuses with normal cord vasculature, fetuses with a single umbilical artery were more likely to be delivered at an earlier gestation and to weigh less, were 1.7 times more likely to be delivered by a Caesarean section and 19% of the cases had a congenital anomaly. The perinatal mortality was 49.0 per 1000 total births, which was 6 times higher than the background hospital rate. The presence of a single umbilical artery is associated with a poorer perinatal outcome compared to that in fetuses with three vessels in the cord. Unfortunately, the antenatal detection rate is poor. Recognising the importance of this soft marker in counselling and management of pregnancies should provide the stimulus to improve detection rates.

Antenatal diagnosis of single umbilical artery: is fetal echocardiography warranted?

OBJECTIVE

To estimate the utility of fetal echocardiography in the evaluation of the fetus with isolated single umbilical artery.

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.

Prenatal diagnosis of single umbilical artery: determination of the absent side, associated anomalies, Doppler findings and perinatal outcome

OBJECTIVE

To determine the absent side of a single umbilical artery and its association with malformations and abnormal karyotypes.

METHODS

We prospectively studied 102 fetuses from 13 to 39 weeks of gestational age with a prenatally identified single umbilical artery. The absent side, pregnancy data, Doppler findings and the perinatal outcome were reviewed.

RESULTS

(1) The left umbilical artery was absent in 71 (69.6%) and the right in 31 (30.4%) fetuses; (2) Single umbilical artery as an isolated finding occurred in 59 (57.8%) pregnancies and was not associated with aneuploidy. The mean gestational age at delivery in this group was 38.4 weeks and the mean birth weight was 3047 g. Six (10.2%) fetuses were small for gestational age, all of them with normal umbilical and uterine Doppler findings; and (3) Chromosomal abnormalities were diagnosed in 10 of 43 fetuses with single umbilical artery and congenital malformations. In nine of 10 fetuses with aneuploidy the left umbilical artery was not developed. Absence of the left artery occurred in 21 of 33 fetuses with sonographic anomalies and normal karyotype. Pathologic Doppler measurements of the umbilical artery were found in only one case of nonchromosomal abnormality.

CONCLUSION

Our data suggest that in fetuses with single umbilical artery the absence of the left artery is more frequent than the absence of the right artery. The association with additional malformations seems to be equal on each side.

Ultrasonographic detection of single umbilical artery: a simple marker of fetal anomaly

OBJECTIVE

To detect associated anomalies, karyotypes and perinatal prognosis of fetuses with single umbilical artery.

METHOD

Fifteen fetuses who have single umbilical artery were evaluated in the obstetrical ultrasonography and medical genetics departments of Osmangazi University.

RESULTS

Fifteen fetuses with single umbilical artery were detected during antenatal ultrasonographic examinations. Associated sonographic abnormalities include oligohydramnios (two), intrauterine growth retardation (one), renal agenesis (one), fetal ascites (one), diaphragmatic hernia (one), hydrocephalus (two), and meningomyelocele (one). Complications related to the pregnancy were pre-eclampsia in one case and abruptio placenta in another. Karyotype analysis was available in 11 cases and the only cytogenetic abnormality detected was trisomy 18 in one case. Two cases with hydrocephalus and single umbilical artery were delivered by cesarean section at 34 and 38 weeks, but both died (on the first and fifth days after birth). Five pregnancies were terminated because of intrauterine death (one), severe pre-eclampsia (one), cytogenetic abnormality (one), and multiple congenital anomalies associated with single umbilical artery (two) at 36, 27, 22, 26 and 29 weeks, respectively. Eight of the neonates who had no additional congenital or cytogenetic abnormality were completely normal at birth and during the neonatal period. Diagnoses were confirmed pathologically in all cases.

CONCLUSION

Scanning the umbilical cord should be one of the essential parts of ultrasonographic examination. When single umbilical artery is detected, a detailed ultrasonographic examination is necessary to rule out associated abnormalities. We advise fetal karyotyping even when no additional pathology can be detected on ultrasonographic examination.