Single umbilical artery
As Singular umbilical artery ( SUA), also singular umbilical artery ( SNSA ), refers to a variant or anomaly of the umbilical cord in the human fetus. For ultrasonic observation in cross section, in particular for the Doppler ultrasound to detect only an umbilical vein and an umbilical artery, instead of the normal two umbilical arteries.
Dissemination
The SUA takes an average of one in front of 100 pregnancies and is the most common abnormality of the umbilical cord. In about 70 % of fetuses the right, at 30 %, the left umbilical artery absent.
Before the introduction of ultrasound technology the SUA was found most in the study after giving birth of the placenta. Since the vast majority of expectant mothers are not investigated worldwide today with the advanced technologies that are needed to confirm the presence of SUA in utero, it can be assumed that most cases are recognized today after birth.
Clinical manifestations
Isolated finding
The incidence of SUA represents a risk factor for other complications, still have the vast majority of babies neither problems during pregnancy or after birth. Is especially the case if no other soft markers for malformations are visible in sonography. In a study at the University of Lübeck, the SUA was 57.8 % of 102 examined fetuses an isolated finding and not associated with aneuploidy, an average of four studies, the figure was even at 68.1 %, with a study in the U.S. 2010 with 643 cases, 65.9 %. In the study of Lübeck all children in this group ( 59) were phenotypically healthy at birth. The average gestational age was 38.4 weeks and the children were thus " born on schedule ." The average birth weight of newborns in this group was 3047 grams and was thus normal. 10.2% of these neonates were relatively small ( " small for gestational age ").
Soft markers for complications
In the study, the University of Lübeck of fetuses with SUA various congenital anomalies were observed in 43 out of 102.
Damage in the chromosomes were found in 10 of the 102. All 10 cases were diagnosed due to significant malformations already in ultrasound. The authors recommend that the study " in accordance with most authors," above all the sonography as a diagnostic tool, to 13 and 18 to exclude other anomalies, particularly trisomy. They recommend an amniocentesis and karyotyping analysis only if already in the sonography further abnormalities were found.
The rate of miscarriage was 25.5 % of diagnosed suas, with only fetuses with other anomalies were severely affected for SUA.
A single artery in the umbilical cord is considered Sonographic soft markers for:
- Edwards syndrome ( trisomy 18) / 5 cases in the study by the University of Lübeck with 102 suas
- Patau syndrome ( trisomy 13) / 2 cases in the study at the University of Lübeck with 102 suas
- Trisomy 9
- Pallister - Killian syndrome
- VACTERL
- Heart failure ( in 6.25 %)
- Congenital defects in the urogenital tract, especially the kidneys, and renal agenesis (about 6.48% of cases)
A study by the Free University of Berlin, in the 362 fetuses were included with a single umbilical artery, revealed that can be associated malformations and chromosomal abnormalities at a single umbilical artery with great certainty prenatally diagnosed, and that the risk of overlooked malformations is low unremarkable findings in the qualified ultrasound examination.
Methods of investigation
In Germany, regular repeat examinations are recommended to monitor the growth of the fetus during pregnancy and to detect possible malformations after discovery of a SUA in ultrasound. Also postnatally, the children are carefully examined to rule out possible anomalies. An amniocentesis for chromosome analysis is recommended only when a large safety needs of pregnant women.