Why is it important to diagnose chorionicity and how do we do it?

Area of Science:

• Perinatology
• Maternal-Fetal Medicine
• Twin Gestation

Background:

• Monochorionic (MC) placentation, designed for single fetuses, poses significant risks for twin pregnancies compared to dichorionic (DC) twins.
• Asymmetric placental sharing and interfetal vascular connections in MC placentas can lead to fetal growth discordance and severe complications.

Purpose of the Study:

• To review the obstetric complications associated with monochorionic twinning.
• To highlight the impact of placental vascular connections and cord anomalies on twin pregnancy outcomes.
• To emphasize the importance of early diagnosis and the current limitations in management strategies.

Main Methods:

• Review of existing literature on monochorionic twin complications.
• Analysis of the pathophysiology of twin-twin transfusion syndrome and twin reversed arterial perfusion.
• Discussion of diagnostic challenges and management considerations.

Main Results:

• MC twins experience higher rates of obstetric problems, including growth discordance, twin-twin transfusion syndrome, and twin reversed arterial perfusion due to interfetal vascular connections.
• Complications can arise from cord insertions, spontaneous demise of a co-twin, or selective termination procedures.
• Monoamniotic twins and discordant congenital anomalies further increase risks; diagnosis is optimal in the first trimester.

Conclusions:

• Monochorionic twinning presents unique and significant risks to both fetuses, often stemming from placental vascular anomalies.
• Effective management strategies are not yet fully established, and long-term follow-up data are insufficient.
• Consistent first-trimester chorionicity determination is critical for timely risk assessment and potential intervention.