Interpretation
It is apparent that placental communication vessels crossing between the
twins may affect hemodynamics of both cardiovascular systems in wide
variations. However, to date the pathophysiology of TTTS is still not
fully understood and a commonly accepted therapy to treat severe cases
of TTTS does not exist. Moreover, there are important unanswered
questions related to the AR protocol. How much of the amniotic fluid
volume should be removed? What should be the rate of fluid drainage?
What are the criteria for amniotic fluid drainage termination? Is the
procedure restricted to specific timing during gestation? The research
efforts to answer these open questions are still going on.
It has been reported that management of TTTS either with FLA or AR
prolongs the pregnancy without guarantee for normal growth of both
infants 8, 11. The present results demonstrated that
the controlled AR is safe and can be repeated if needed independent of
the gestation week. Therefore, we believe that controlled AR with slow
flow rate under gravity is less invasive then FLA. In contrast to
suggestions that the fluid should be drained as quickly as possible28, we have shown that gravity driven fluid drainage
at slow rates is more favorable for the fetuses, due to both a gradual
pressure drop and increase in the umbilical flow rate from mother to
fetus. Furthermore, it seems that gradual reduction of the amniotic
volume, as well as decreasing the amniotic pressure on the placental
chorionic vessels result in more moderate impact on the cardiovascular
system for both fetuses. Nevertheless, the controlled AR procedure
resulted in a higher survival rate and positive long-term outcomes
compared to other studies10, 11, 13, 26-28.