What is the management and treatment for a pregnant woman with fetal umbilical vein varix?

Management of Fetal Umbilical Vein Varix

Immediate Diagnostic Workup

When fetal umbilical vein varix is identified, perform a comprehensive fetal anatomic survey and fetal echocardiography, as this condition is associated with structural anomalies in 35-48% of cases. 1

• Detailed fetal anatomic survey is mandatory to identify associated structural malformations, which occur in approximately one-third of cases 1
• Fetal echocardiography should be performed to evaluate for cardiac anomalies, as cardiovascular defects are among the most common associated findings 1
• Rule out isoimmunization (particularly Kell) through maternal antibody screening, as this has been reported in association with umbilical vein varix 1
• Consider amniocentesis for karyotyping if other structural anomalies are present, as chromosomal abnormalities (including triploidy) have been documented 1
• Assess for fetal anemia using middle cerebral artery peak systolic velocity Doppler, as hemolytic anemia from turbulent flow through the varix can occur 2

Surveillance Protocol for Isolated Umbilical Vein Varix

For isolated fetal intra-abdominal umbilical vein varix without associated anomalies, institute intensive fetal surveillance with serial ultrasounds every 2-3 weeks starting from diagnosis, as the clinical course is unpredictable with reported fetal mortality rates of 14-50%. 3, 2, 4

Serial Ultrasound Monitoring

• Perform ultrasound examinations every 2-3 weeks to assess varix size, detect thrombosis formation, and monitor for development of fetal hydrops 3, 4
• Evaluate for intra-umbilical cord thrombosis at each visit, as this complication occurs in 86% of extra-abdominal varix cases 2
• Monitor for signs of fetal circulatory compromise including cardiomegaly, hydrops, and decreased fetal movements 2
• Serial growth assessments should be performed, as fetal growth restriction has been reported 2

Doppler Assessment

• Weekly umbilical artery Doppler should be performed if fetal growth restriction develops 5
• Middle cerebral artery peak systolic velocity should be monitored to detect fetal anemia, particularly if turbulent flow is observed within the varix 2
• Assess for abnormal fetal heart rate patterns at each visit, as these occur in 50% of cases 2

Antithrombotic Prophylaxis Consideration

Low-dose aspirin prophylaxis may be considered from diagnosis until 35 weeks' gestation to reduce thrombosis risk within the varix, though this approach is based on limited case series data. 6

• One small case series of four patients managed with low-dose aspirin reported no thrombosis development and good neonatal outcomes 6
• This intervention remains investigational and should be discussed with patients as an option rather than standard of care 6

Timing and Mode of Delivery

Plan for delivery at 34-35 weeks' gestation after documentation of fetal lung maturity, or earlier if any signs of fetal distress, non-reassuring fetal status, or thrombosis develop. 3, 4

Delivery Timing Algorithm

• At 34 weeks' gestation: Proceed with delivery if fetal lung maturity is documented, as fetal demise can occur despite close monitoring 3, 4
• Before 34 weeks: Deliver immediately if any of the following develop:
  • Non-reassuring fetal heart rate patterns 2
  • Evidence of thrombosis within the varix 2, 4
  • Fetal hydrops 2
  • Severe fetal anemia (MCA-PSV >1.5 MoM) 2
  • Decreased fetal movements 2

Mode of Delivery

• Cesarean delivery should be strongly considered, particularly if fetal distress, anemia, or circulatory compromise is present 2
• The mode of delivery should prioritize rapid access to neonatal resuscitation given the risk of acute decompensation 2

Special Consideration for Extra-Abdominal Varix

Extra-abdominal umbilical vein varix carries higher risk than intra-abdominal varix, with 50% experiencing fetal heartbeat abnormalities and 14% resulting in fetal death. 2

• Extra-abdominal location is associated with 86% rate of intra-umbilical cord thrombosis 2
• These cases may require even more intensive surveillance with consideration for earlier delivery 2
• Hemolytic anemia from turbulent flow is a unique complication that requires monitoring with MCA-PSV Doppler 2

Critical Pitfalls to Avoid

• Do not defer delivery beyond 35 weeks in isolated cases, as unpredictable fetal demise can occur despite normal surveillance 4
• Do not assume normal outcome even with isolated findings and normal surveillance, as the natural history remains unpredictable with significant mortality risk 4
• Do not miss associated anomalies by performing incomplete anatomic survey, as nearly half of cases have additional structural defects 1
• Do not overlook fetal anemia as a potential complication requiring intrauterine transfusion 2

Neonatal Management

• Alert the neonatal team prior to delivery about the prenatal diagnosis 1
• Postnatal examination should be thorough, as structural anomalies may be revealed that were not detected prenatally 1
• Neonatal follow-up for thrombotic complications and assessment of liver function is warranted 6