Controlled amnioreduction outcome
Amniotic pressures were measured prior, during and at the end of the AR
procedure. The pattern of the decreasing amniotic pressure during
removal of the excess volume of fluid is depicted in Figure 1. The
pressures reached a plateau at the end of the completed procedures
except the 5 patients in which AR was interrupted due to the patient
discomfort. There was no correlation between the amount of drained
amniotic volume, duration of AR procedure and the reached pressure
plateau. The obtained amniotic
pressures were compared with the normal pressures as reported by Fisket al 16. The pressure drop at each AR
procedure is shown in Figure 2 along with the reference range for
singleton pregnancies. The initial
pressures for all patients were
higher than the normal range. As expected, the post-procedure pressures
were lowered to be in the reference range in 61.1% of cases while
slightly higher than the norm in 38.9%.
The umbilical artery S/D values that were measured for each fetus pre-
and post-procedure are compared with the reference range for singleton
pregnancies 25. The initial S/D ratio of recipient was
higher (mean percent difference is 29.3%) in 3 cases, while in the rest
cases the donor twin had the higher S/D ratio.
Absence of end diastolic flow (AEDF)
occurred in 3 donors, and thus, an arbitrary value of 9 was given as the
initial one for graphic representation. All these donors showed some
hemodynamic improvement after the AR. In general, most (23 of 36, i.e.,
63.8%) of the post-procedure S/D ratio became within the normal range
according to the given weeks of gestation. Comparison of inter-twin
differences of S/D ratio values in pre- and post-procedure did not show
some tendency: inter-pair differences were significantly decreased after
the procedure in 7 twins, increased in 5 twins and were unchanged in 6
cases.