Twin-Twin Transfusion Syndrome: Clinical Features

Twin to twin transfusion syndrome (TTTS) is a condition where there is an over-perfusion in one twin and under-perfusion in the other. Although more common in monochorionic twins, it has been reported to occur in diamniotic twins.

Clinical Features and Diagnosis:

Most important is the discrepancy in amniotic fluid volume.
1 twin would be oligohydramnios ( < 2cm deep vertical pool )
1 twin would be polyhydramnios ( > 8cm deep vertical pool)

WEIGHT DISCREPANCY IS NOT THE MAIN CRITERIA FOR DIAGNOSIS!
In some cases, there are no significant weight discrepancies.
If there are, the discordance should be > 15-20%

"Stuck twin appearance"



Anhydromnios fetus appear as if there are no separating membrane.

Discrepancies in size of umbilical cords.

Presence of hydrops or cardiac dysfunction in recipient twin.

Abnormal umbilical artery doppler in donor fetus.

Other features of monochorionic twins:

• Single placenta
• Gender concordance

Fetal Blood Sampling:
- Lower hematocrit level in donors
- Difference in hemoglobin levels.

Staging:

Quintero staging uses simple concept of staging involving presence/absence of oligo or polyhydromnios, bladder, abnormal dopple, hydrops fetalis, or fetal death.

A table can be seen in this Emedicine website.

References:

Creasy, Robert K., et al., Maternal-Fetal Medicine, Principles and Practice, 5th Ed.

Other Topics To Discuss:

- Management of TTTS
- Monochorionic twins
- Conjoint twins.