Severe Oligohydramnios Clinical Trial
Official title:
Alterations of the Uteroplacental and Fetal Pulmonary Circulation in Patients With Severe Idiopathic Oligohydramnios Following Amnioinfusion Therapy in a Longitudinal Study
The aim of this study is to compare the uteroplacental and pulmonary circulation of the fetuses with severe (AFI<5cm) idiopathic oligohydramnios (with unknown origin) to those in normal controls. Further purpose of the study is to measure the changes of the uteroplacental and fetal pulmonary circulation in patients presenting with severe idiopathic oligohydramnios, managed either with single amnioinfusion or with serial amnioinfusions.
Severe oligohydramnios (AFI<5) is an uncommon complication of pregnancy and it is often
associated with Preterm Premature Rupture of the Membranes (pPROM) or with the lethal
congenital abnormality. However, in very few cases it is idiopathic (with no obvious
etiopathology) and in the prevention of fetal complication (e.g. pulmonary hypoplasia) the
amnioinfusion is a treatment option for the persisting oligohydramnios.
Severe oligohydramnios for >14 days had a predicted mortality rate >90%. Although severe
oligohydramnios and pPROM may lead to pulmonary hypoplasia, all of these three factors are
independent predictors of pulmonary hypertension. It is obvious that there are some
alterations in the fetal pulmonary circulation in cases of severe oligohydramnios.
The preliminary study shows that single/serial amnioinfusion has some beneficial effects on
the outcome of the pregnancies complicated with severe idiopathic oligohydramnios: to
prolong the gestation, to reduce the number of premature labor and to prevent the adverse
neonatal outcome.
The investigators propose an open trial comparing baseline Doppler waveforms in the
uteroplacental and fetal pulmonary circulation in patients presenting with severe,
idiopathic olighydramnios (AFI<5, no apparent ethiopathology), managed either with single or
with serial amnioinfusions and in matched controls (matched in gestational age, parity and
gravidity, AFI>8). The patients will be followed up weekly in the fetomaternal unit, Dept.
of ObGyn for measuring AFI repeatedly to assess the need for further infusions. These will
be carried out when the AFI falls below 5cm again.
Inclusion criteria: Single pregnancy, severe (AFI<4 cm), idiopathic oligohydramnios between
the 18 and 34 weeks of gestation. The study is open and will be run by a single
ultrasonographer to avoid interobserver bias, and with a set of minimal number of outcome
measures recorded. Primary outcome: Doppler waveforms of the uteroplacental and fetal
pulmonary circulation.
Alterations in Doppler indices of the Ductus venosus, arteria umbilicalis, arteria uterina,
left and right arterial pulmonary branches: (1) systolic/diastolic ratio (S/D), (2) peak
systolic velocity; (3) time-averaged velocity; (4) maximum forward velocity during atrial
contraction; (5) pulsatility index (PI); (6) Pourcelot's resistance index (RI).
The pulsed Doppler measurements of the arterial pulmonary branches will be carried out from
a transverse cross-section of the fetal chest at the level of the cardiac 4-chamber view
after visualization with color Doppler. Depending on fetal position, the right or left lung
will be examined. Doppler waveforms (sample volume: 0.1-0.3 cm) will be first obtained from
the most proximal branch of the pulmonary artery, then in the middle lung region at equal
distance from the outer border of the heart and the inner thoracic wall and subsequently in
the distal lung region as close as possible to the fetal inner thoracic wall.
Secondary outcomes: Alterations of the Doppler waveforms during the progress of the
pregnancy.
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Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Diagnostic