What is TAPS?
Twin anemia-polycythemia sequence (TAPS) is a symptom complex involving a significant hemoglobin difference between the two twins in a monochorial twin pregnancy characterized by both fetuses sharing only one placenta.
TAPS may occur in up to 13% after laser therapy in case of oversight of arterio-arterial anastomoses in feto-fetal transfusion syndrome (TTTS) and thus represents its complication. In case of re-TTTS after laser therapy (up to 14% in some studies), neonatal survival is only 43%. At the end of laser surgery for TTTS, it must be absolutely certain that all placental anastomoses between both the fetuses are thoroughly closed. Overlooking the anastomoses may actually worsen the situation.
How is the diagnosis made?
The diagnosis of TAPS is made by Doppler ultrasound. This involves measuring the maximum velocity in the middle cerebral artery (the main artery in the brain) with Doppler ultrasound. In fetal anemia, blood flow velocity increases significantly.
How is TAPS treated?
In case of combination with feto-fetal transfusion syndrome, laser coagulation of placental anastomoses is performed.
In this procedure, the arterio-venous anastomoses of the anemic child are closed first to allow blood transfusion from the sibling to the anemic child during surgery. This could contribute to the survival of both children.
How is the laser surgery performed?
Laser surgery is usually performed under local anesthesia of the abdominal wall and analogous to that performed in the presence of feto-fetal transfusion syndrome (TTTS). Ultra-thin 1 mm optics are used to reduce the risk of premature rupture of the membranes after fetoscopy by minimizing injury to the amniotic membrane.
The anastomoses are localized and coagulated by laser.
At the end of the operation, it is necessary to carefully check if all anastomoses are closed. Following this, amniotic fluid reduction can be performed using the surgical equipment.