What are the other Names for this Condition? (Also known as/Synonyms)

• PRUV (Persistent Right Umbilical Vein)

What is Persistent Right Umbilical Vein? (Definition/Background Information)

• The umbilical cord contains two umbilical arteries and one umbilical vein, providing a connection between maternal and fetal blood circulation. However, during early pregnancy, there are two umbilical veins, namely the right and left umbilical vein
• During the course of normal fetal development, the right umbilical vein disappears, while the left umbilical vein persists. However, infrequently, it is the right vein that remains, while the left vein disappears
• In other words, Persistent Right Umbilical Vein (PRUV) is a condition in which the right umbilical vein remains open or persists, whereas the left vein regresses, during the embryonic stage of life in pregnancy
• In a normally developing embryo, obliteration of the right umbilical vein happens between 4 to 7 weeks of gestation. The left umbilical vein then transports all the blood. It is connected to the portal vein. The right umbilical vein remains as an intrahepatic supernumerary structure
• There are two types of Persistent Right Umbilical Vein - type 1 and type 2
  • Type 1 Persistent Right Umbilical Vein: It is also known as intrahepatic PRUV. It is the most common form accounting for 95% of the cases. It is usually associated with ductus venosus and does not interfere with the hemodynamics (blood flow). This type has a relatively good prognosis
  • Type 2 Persistent Right Umbilical Vein: It is also known as extrahepatic PRUV. The PRUV is in direct connection with right atrium or the inferior vena cava (IVC). In this type, there is agenesis (failure to develop) of the ductus venosus portraying a poorer prognosis. The absence of ductus venosus causes heavy hemodynamic burden. Fetal hydrops also develops in affected fetuses from volume overload
• Persistent Right Umbilical Vein may occur as the only anomaly (isolated condition) or can form part of complex anomalies in fetuses along with situs inversus visceralis and situs ambiguous. The condition may also be associated with the congenital absence of the ductus venosus (DV) and other, typically severe fetal malformations

Who gets Persistent Right Umbilical Vein? (Age and Sex Distribution)

• Persistent Right Umbilical Vein occurs in between 1 in 250 to 1 in 1,250 pregnancies
• Women who are pregnant with both male and female fetuses can be affected
• All racial and ethnic groups may be affected, but a higher incidence rate is observed among Caucasian women over Afro-American or Asian women

What are the Risk Factors for Persistent Right Umbilical Vein? (Predisposing Factors)

• There are no known risk factors for Persistent Right Umbilical Vein as it is commonly an isolated finding
• However, a few cases are known to be associated with certain congenital cardiac defects

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Persistent Right Umbilical Vein? (Etiology)

The exact cause of development of Persistent Right Umbilical Vein (PRUV) remains unknown. However, a few possible etiologies (sets of causes) are thought to be associated with PRUV including:

• Deficiency of folic acid in early trimester
• Use of retinoic acid or retinoic acid containing products; these are classified as teratogens (agents causing cancers)
• Obstruction of left umbilical vein in early trimester can lead to PRUV

What are the Signs and Symptoms of Persistent Right Umbilical Vein?

• Persistent Intrahepatic Right Umbilical Vein: Generally, there are no signs and symptoms as the hemodynamics are usually normal in type 1 PRUV (intrahepatic type), particularly when these are isolated cases where the ductus venosus is normal
• Persistent Extrahepatic Right Umbilical Vein: There may be signs of hemodynamic decompensation in the absence of ductus venosus with type 2 PRUV (extrahepatic type)

How is Persistent Right Umbilical Vein Diagnosed?

The diagnosis of Persistent Right Umbilical Vein may involve the following tests and exams:

• Physical examination along with an evaluation of one’s medical history: The healthcare provider may check for any signs of fetal distress such as non-reassuring fetal heart rate
• Prenatal abdominal ultrasound may reveal the condition and other associated fetal abnormalities, if any present

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Persistent Right Umbilical Vein?

• When Persistent Right Umbilical Vein (PRUV) is associated with an absence of ductus venosus, it may cause volume overload and severe hemodynamic effects leading to fetal hydrops
• In terminal cases, certain complications, such as polyhydramnios (increase amniotic fluid), cardiomegaly (heart enlargement), and fluid accumulation, may occur

It is more common for the extrahepatic type of PRUV to have associated anomalies than the intrahepatic type of PRUV.

• The extrahepatic type of PRUV is sometimes associated with single umbilical artery
• There is an association with other anomalies, such as trisomy 18 syndrome (chromosomal anomaly), Noonan syndrome, dextrocardia, and other cardiac, renal, and vertebral anomalies. In such cases, severe complications may be noted

How is Persistent Right Umbilical Vein Treated?

• Intrahepatic Persistent Right Umbilical Vein when associated with anomalies is managed according to the symptoms and complications noted
• A careful and periodic monitoring of the pregnancy is necessary, since the presence of extrahepatic type of PRUV is considered to be a high-risk pregnancy
• Treatment of extrahepatic type of PRUV may involve shunting (redirecting) of the blood supply, in order to prevent cardiac overload

How can Persistent Right Umbilical Vein be Prevented?

• Currently, there are no definitive methods available to prevent Persistent Right Umbilical Vein
• A careful and periodic monitoring of the pregnancy is advised and recommended

What is the Prognosis of Persistent Right Umbilical Vein? (Outcomes/Resolutions)

• When Persistent Right Umbilical Vein (PRUV) is an isolated event, the prognosis is more favorable than when it is associated with other congenital abnormalities. In such cases, the overall outcomes depend on the nature and severity of the condition
• Extrahepatic PRUV can be a life-threatening condition. After delivery, the baby should be carefully evaluated for heart defects and genetic abnormalities
• The outcome of Intrahepatic PRUV is generally good as there is minimal to no hemodynamic burden

Additional and Relevant Useful Information for Persistent Right Umbilical Vein:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/pregnancy-related-disorders/