The umbilical cord connects the placenta to a developing fetus, delivering oxygen and nutrients and removing waste. An umbilical cord blood clot forms within one of its blood vessels, obstructing blood flow.
Prevalence of Umbilical Cord Blood Clots
Umbilical cord blood clots are rare. The estimated incidence is approximately 1 in 1,300 deliveries, though some studies indicate a higher incidence in high-risk pregnancies, around 1 in 250 gestations.
Umbilical vein thrombosis occurs more frequently than umbilical artery thrombosis, affecting the vein in 71-85% of cases. However, umbilical artery thrombosis, though less common, is more often associated with adverse pregnancy outcomes. Incidence can reach about 0.05% to 0.19% in specific study populations.
Causes and Risk Factors
The exact cause of umbilical cord blood clots is often unknown, but several factors can contribute to their formation. These include issues specific to the umbilical cord itself, such as true knots, strictures, excessive coiling, or abnormal insertions where the cord attaches to the placenta.
Maternal conditions can also play a role. These include pre-existing or gestational diabetes, pre-eclampsia, and maternal thrombophilia, a condition that increases the likelihood of blood clot formation. Fetal conditions, such as anomalies or intrauterine growth restriction, can also be associated with umbilical cord clots. Additionally, procedures like cordocentesis or intrauterine transfusions may sometimes lead to clot formation.
Potential Effects on Mother and Baby
An umbilical cord blood clot can affect the fetus due to compromised blood flow. This can lead to reduced oxygen and nutrient supply, potentially causing fetal distress or intrauterine growth restriction, where the baby does not grow as expected. In severe instances, it can result in stillbirth.
While the direct impact is primarily on the fetus, complications during delivery, such as excessive bleeding, may occur. Long-term effects on babies who survive can include neurological injury. The severity of consequences often depends on the clot’s size, location, and the degree of blood flow obstruction.
Diagnosis and Medical Approach
Umbilical cord blood clots are detected through prenatal ultrasound examinations, particularly using Doppler studies that assess blood flow. These clots are often incidental findings during routine scans. A suspicious sign might be the detection of only one umbilical artery when two were previously seen, which can indicate a thrombotic event.
Upon diagnosis, medical management focuses on monitoring the pregnancy closely. This may involve frequent checks of fetal movement and electronic fetal monitoring to assess the baby’s well-being. Depending on the clot’s impact and gestational age, early delivery, often by emergency cesarean section, might be recommended to improve outcomes.