Velamentous cord insertion
Encyclopedia
Velamentous cord insertion is an abnormal condition during pregnancy
. Normally, the umbilical cord
inserts into the middle of the placenta
as it develops. In velamentous cord insertion, the umbilical cord inserts into the fetal membranes
(choriamniotic membranes), then travels within the membranes to the placenta (between the amnion
and the chorion
). The exposed vessels are not protected by Wharton's jelly
and hence are vulnerable to rupture. Rupture is especially likely if the vessels are near the cervix
, in which case they may rupture in early labor
, likely resulting in a stillbirth
. This is a serious condition called vasa previa. Not every pregnancy with a velamentous cord insertion results in vasa previa, only those in which the blood vessels are near the cervix.
When a velamentous cord insertion is discovered, the obstetrician will monitor the pregnancy closely for the presence of vasa previa. If the blood vessels are near the cervix, the baby will be delivered via cesarean section as early as 35 weeks to prevent the mom from going into labor, which will likely kill the baby. Early detection can reduce the need for emergency cesarean sections.
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
. Normally, the umbilical cord
Umbilical cord
In placental mammals, the umbilical cord is the connecting cord from the developing embryo or fetus to the placenta...
inserts into the middle of the placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
as it develops. In velamentous cord insertion, the umbilical cord inserts into the fetal membranes
Fetal membranes
The fetal membranes, or chorioamniotic membranes, are the amnion and chorion which surround and protect a developing fetus....
(choriamniotic membranes), then travels within the membranes to the placenta (between the amnion
Amnion
The amnion is a membrane building the amniotic sac that surrounds and protects an embryo. It is developed in reptiles, birds, and mammals, which are hence called “Amniota”; but not in amphibians and fish , which are consequently termed “Anamniota”. The primary role of this is the protection of the...
and the chorion
Chorion
The chorion is one of the membranes that exist during pregnancy between the developing fetus and mother. It is formed by extraembryonic mesoderm and the two layers of trophoblast and surrounds the embryo and other membranes...
). The exposed vessels are not protected by Wharton's jelly
Wharton's jelly
Wharton's jelly is a gelatinous substance within the umbilical cord, largely made up of mucopolysaccharides . It also contains some fibroblasts and macrophages...
and hence are vulnerable to rupture. Rupture is especially likely if the vessels are near the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
, in which case they may rupture in early labor
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
, likely resulting in a stillbirth
Stillbirth
A stillbirth occurs when a fetus has died in the uterus. The Australian definition specifies that fetal death is termed a stillbirth after 20 weeks gestation or the fetus weighs more than . Once the fetus has died the mother still has contractions and remains undelivered. The term is often used in...
. This is a serious condition called vasa previa. Not every pregnancy with a velamentous cord insertion results in vasa previa, only those in which the blood vessels are near the cervix.
When a velamentous cord insertion is discovered, the obstetrician will monitor the pregnancy closely for the presence of vasa previa. If the blood vessels are near the cervix, the baby will be delivered via cesarean section as early as 35 weeks to prevent the mom from going into labor, which will likely kill the baby. Early detection can reduce the need for emergency cesarean sections.
External links
- http://www.askanob.com/umbilicalcordfindings/cordandvasaprevia.html
- http://www.nature.com/jp/journal/v27/n7/fig_tab/7211757f1.html