The placenta is an organ that develops in the uterus during pregnancy, serving as the interface between the mother and the developing fetus. It facilitates the exchange of nutrients, oxygen, and waste products, playing a role in supporting fetal growth and well-being. Chorangiosis is a finding related to changes within this organ.
Understanding Chorangiosis
Tiny, finger-like projections called chorionic villi extend from the placenta into the mother’s uterine wall. These villi are where the exchange of substances between the mother and baby takes place.
Chorangiosis is a placental pathology characterized by an abundance of blood vessels within these chorionic villi. In a typical third-trimester pregnancy, a microscopic examination of the terminal chorionic villi usually shows five or fewer cross-sections of fetal capillaries. However, in areas affected by chorangiosis, the number of capillaries can increase significantly, often significantly more.
Chorangiosis is considered a vascular change involving the terminal chorionic villi, often resulting from longstanding, low-grade hypoxia, which means a reduced oxygen supply to the placental tissue. The placenta may respond to this reduced oxygen by growing new blood vessels in the chorionic villi, a process that leads to chorangiosis. The reported incidence of placental chorangiosis is around 5% to 7%.
Factors Linked to Chorangiosis
Several conditions and factors are associated with the presence of chorangiosis.
Gestational diabetes, a type of diabetes that develops during pregnancy, is one such association. In pregnancies complicated by gestational diabetes, placental histopathological findings can include an increased incidence of chorangiosis. This suggests glucose metabolism issues may influence placental vascular development.
Maternal smoking is another factor linked to chorangiosis. Studies have indicated that vascular changes in the placenta, including chorangiosis, are more frequently found in placentas from mothers who smoke. Smoking may contribute to changes in placental blood vessel structure, possibly due to its effects on oxygen levels.
Living at high altitudes is also associated with chorangiosis. Reduced oxygen availability at higher elevations can lead to chronic low-grade hypoxia in the placental tissue. The placenta may adapt to this environment by increasing its vascularity, resulting in the changes seen in chorangiosis. Other potential links include pregnancy-induced hypertension and preeclampsia, which also involve issues with blood pressure and placental function.
How Chorangiosis is Identified
The diagnosis of chorangiosis occurs after birth, through a detailed microscopic examination of the placenta.
Following delivery, the placenta is sent to a pathology laboratory where multiple sections are taken, embedded in paraffin, and stained with hematoxylin-eosin. This allows a pathologist to view the tissue under a microscope.
During the microscopic examination, the pathologist looks for specific changes in the chorionic villi, particularly an increase in the number of blood vessels. The diagnostic criteria for chorangiosis involve observing a certain density of capillaries within the villi across multiple areas of the placenta. Specifically, it is defined by the presence of at least 10 villi, each containing 10 or more vascular channels, in 10 or more areas when viewed microscopically.
Implications of Chorangiosis for Pregnancy
The finding of chorangiosis in a placenta can carry varying clinical significance for both the mother and the baby.
It was once thought that chorangiosis did not occur in normal placentas. However, more recent studies have reported its presence in some placentas without associated maternal disorders or fetal complications. This indicates that while it is a pathological finding, it is not always indicative of a serious problem.
Despite instances where chorangiosis appears benign, it is often considered a sign of placental injury associated with reduced oxygen supply in the uterus. It has been linked to higher rates of certain adverse pregnancy outcomes, including an increased risk of abortion, intrauterine fetal death, and lower Apgar scores at 5 minutes after birth. Some studies have also shown associations with stillbirths, fetal growth restriction, and congenital malformations. Its presence may prompt further investigation into potential underlying maternal or fetal conditions.