See all in Pregnancy. See all in Preschooler. See all in Life as a Parent. See all in Video. You might also like You might also like. Nuchal translucency NT scan. Pregnant with twins: what to expect. Pregnancy ultrasound scans: an overview. What is a chorionicity scan? Can we find out the sex of our baby?
Are ultrasound scans safe? Get the BabyCentre app. Brazil Canada Germany India. We are able to see the individual vessels of the umbilical cord in most pregnancies after 18 weeks gestation, and often as early as weeks. Single umbilical artery occurs in 0. This condition is associated with increased risks of birth defects and of pregnancy complications. We have published articles regarding the recognition and management of pregnancies with a single umbilical artery, and have developed a separate information sheet about single umbilical artery.
This can be seen on most ultrasound scans between 15 and 30 weeks gestation. It is a significant birth defect, carries associations with chromosomal and other abnormalities, and requires surgery after birth to repair. Very early in embryonic development, there are two umbilical veins as well as two arteries.
Usually, the right umbilical vein disappears, and the left vein persists. There may be an association between persistent right umbilical vein and increased rates of fetal abnormalities. When we see a persistent right umbilical vein, we recommend:.
Umbilical vein varix is a condition in which the umbilical vein is dilated wider than normal as it runs through the abdomen. There is controversy in the literature as to the best way to manage pregnancies when an umbilical vein varix is diagnosed. There may be associations between umbilical vein varices and certain fetal abnormalities, and therefore we recommend a comprehensive review of fetal anatomy when an umbilical cord varix is seen. There may be an association with an increase in the rate of stillbirth.
If we identify an umbilical vein varix for your baby, we will develop an individualized management plan, which will typically include:. After delivery, flow within the umbilical vein stops, and therefore umbilical vein varices do not cause problems for the baby after delivery. Our center was one of the first to attempt routine imaging of the cord insertion into the placenta. As the pregnancy progresses, it becomes more difficult to see the entry of the cord into the placenta, especially if the placenta is on the back wall of the uterus and the baby is in front of it.
Marginal cord insertions may be associated with increased chances of premature birth and of growth problems for the fetus. Therefore, if we see a marginal cord insertion at the time of an ultrasound scan, we recommend:.
Membranous cord insertion is associated with increased rates of single umbilical artery, of fetal growth problems, of preterm birth, and also with heart rate abnormalities during labor which result in an increase in the rate of forceps or vacuum delivery, but not of cesarean section.
Membranous cord insertions are common in multiple gestations. For example, in over half op triplet pregnancies, at least one of the babies has a membranous cord. When we identify a membranous cord insertion, we recommend:. What is Vasa Previa? Sometimes, vessels within the membranes will be seen to run close to or over the cervix. This is a very uncommon condition — about pregnancies, but carries tremendous risk to the baby, since during labor the vessels can rupture, causing bleeding from the umbilical cord.
We pioneered techniques for detection of vasa previa, and have published one of the largest series on the subject. If a vasa previa is detected during your sonogram, we will give detailed recommendations for pregnancy care for you. Cord knots are present in between. Most knots are believed to form between 13 and 26 weeks gestation, when the fetus tends to be most mobile within the uterus. Umbilical cord knots are notoriously difficult to detect by sonography, and have been rarely diagnosed in utero.
There is no unanimity of opinion regarding management of pregnancy once a cord knot has been diagnosed. If we suspect that a cord knot is present, we recommend:. One author has suggested that less than 2 cm between turns of the umbilical vein places the pregnancy at increased risk. We rely upon the cord appearance as much as the measured distance. Hypercoiled cords are rare; when we identify one on ultrasound, management recommendations are individualized.
There's one vein and two arteries. But sometimes the cord has one vein and just one artery. In that case, it's called a single umbilical artery. It's sometimes called a two-vessel cord. The placenta sends nutrients and oxygen to your baby through the vein.
The artery takes waste to the placenta. Most babies with one artery grow and develop normally. But sometimes whatever caused it can affect the baby's growth. The cord, placenta, or other organs might also have problems.
Birth in some babies with a single artery may be induced early. Doctors aren't sure what causes it. The cord forms early as the baby develops. In most cases, a single artery is found with an ultrasound. The test is done in the second trimester. It uses sound waves to make pictures of the baby fetus inside the uterus.
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