Chromosomal abnormalities associated with a single umbilical artery

A single umbilical artery was seen in 10 out of 117 cytogenetically abnormal pregnancies. The abnormal karyotypes found to be associated with a single umbilical artery were trisomy 18 (n = 5), monosomy X (n = 2), triploidy (n = 1), sex chromosome (47,XYY; n = 1) and translocation (46t(X,5)(q13p15); n = 1). With the exception of the translocation case, all cases with a single umbilical artery had anatomical defects which were detectable ultrasonographically. This suggests that a single umbilical artery alone is not an indication for prenatal fetal karyotyping.     

Single umbilical artery: Prenatal findings

In 450 patients with pregnancy at high risk for fetal malformation and/or intrauterine growth retardation, the umbilical cord was investigated sonographically for the presence of a single umbilical artery. A single umbilical artery was diagnosed in four fetuses between 23 and 33 weeks of gestation and suspected in two. Three cases were overlooked at sonography. All seven surviving fetuses had growth retardation at delivery and four also showed severe malformations. Whenever a single umbilical artery is found at sonography, further work-up is required to rule out associated anomalies, intrauterine growth retardation, or chromosomal abnormality.     

Type II single umbilical artery (persistent vitelline artery) in an otherwise normal fetus

A single umbilical artery resulting from absence of the umbilical arteries and persistence of the vitelline artery that arises directly from the abdominal aorta has been described only in malformed fetuses with sirenomelia or caudal regression. Such an aberrant artery was suggested to be the etiology of sirenomelia caused by a ‘steal’ mechanism of blood flow from the caudal end of the embryo. We present a case in which prenatal ultrasound showed a similar aberrant single artery arising from the abdominal aorta in an otherwise normal fetus with a normal course of pregnancy. This vessel, a continuation of the superior mesenteric artery (SMA), corresponds to a persistent vitelline artery assuming the function of the umbilical arteries. The etiology of such a finding and its possible consequences are discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

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. Copyright © 2003 John Wiley & Sons, Ltd.     

Single umbilical artery stenosis associated with intrauterine fetal death post-transfusion

Single umbilical artery is among the most common funicular vascular anomalies. In contrast, umbilical artery stenosis is rare, and has only been reported in three-vessel cords. We describe a case of single umbilical artery stenosis in a fetus with no associated malformations. Intrauterine fetal death occurred at 28weeks' gestation following cordocentesis and intravascular transfusion for Rhesus alloimmunization. Single umbilical artery stenosis may place the fetus at increased risk, particularly in cases requiring interventions involving cord manipulation. Copyright © 2002 John Wiley & Sons, Ltd.     

Ultrasound demonstration of masses in a 15 week fetus: Hydrops in a fetus with umbilical cord occlusion

A fetal abnormality detected at 15 weeks by ultrasound consisted of cystic appearing masses in the neck and back region. The differential diagnosis included gonadal dysgenesis (Turner's syndrome) with cystic hygroma, neural tube defect, e.g. encephalocele or meningomyelocele, and fetal hydrops. Intrauterine fetal demise occurred at 17 weeks. The fetus had marked edema possibly related to umbilical cord occlusion.     

Prenatal diagnosis of chromosomal abnormalities from chorionic biopsy samples: Improved success rate using a modified direct method

Several methods for fetal chromosome analysis using chorionic biopsy samples were compared. A modified direct method for culturing villi was considered to be the method of choice and details are presented of 186 pregnancies tested prenatally. The success rate in obtaining a fetal karyotype with the direct method was 93 per cent. The fetal loss rate in the prenatal series was 4.3 per cent and congenital abnormalities in the babies already born did not differ from the expected incidence.