• maternal pain (Analogic visual scale)
  

• Volume of amniotic fluid drained, duration of the drainage, uterine activity,frequency of significative alterations of FHR and histologic evidence of placental abruption.
  

Polyhydramnios is defined as more than 2 liters of amniotic fluid. Ultrasound diagnosis is made either by measurement of a deepest vertical pocket exceeding 8 cm, or by use of an amniotic fluid index (AFI) exceeding 25 cm. Potential complications of polyhydramnios are preterm labor, premature rupture of membranes, altered utero-placental perfusion, and maternal discomfort.

Amniodrainage has become an established technique to improve maternal comfort and reduce the risks of severe polyhydramnios in both singleton and twin pregnancies, decreasing uterine contractility, as well as over-stretching of membranes and uterus. It also acts on the pathological processes of twin to twin transfusion syndrome.

Several techniques are used to reduce symptomatic polyhydramnios. Passive gravitational drainage is long, does not allow to evacuate larger amounts of amniotic fluid and continuous maternal and fetal monitoring is difficult. The standard syringe technique is often a source of discomfort for both the patient and the operator. Continuous aspiration is faster and limits patient's discomfort.

The aim of this study was to compare the efficiency and maternal and fetal tolerance of these two latter techniques of amnioreduction.

A preliminary study permitted to assess the depression value created at the tip of the needle during amniodrainage: the syringe aspiration technique showed large depression variations from 0 to – 300 millimeters of mercury (mmHg). The continuous wall suction was thus chosen to be set to – 250 mmHg: depression at the needle's tip didn't vary during the procedure.