Intra-operative Feed Back on Traction Force During Vacuum Extraction: a Randomized Control Study of Mid and Low Metal Cup Deliveries.

The most common indications for vacuum extraction are dystocia and/or fetal asphyxia. The safety of assisted vaginal delivery with vacuum extraction has been discussed since its introduction almost fifty years ago. Serious complications such as asphyxia, intracranial hemorrhage and seizures are overrepresented at vacuum extraction compared to spontaneous vaginal delivery.

Little has been done to improve the procedure since the introduction. Safety measures recommended include restricting total time and number of pulls, a full 34 week gestation, and station of the head at the spines or below. A general advice is also to avoid excessive traction force. There is no general agreement to what a safe traction force might be. With exceeding force there seems to be an increased risk for rupture of the sagittal sinus and tearing of the falx at its attachment to the tentorium. Furthermore, when the fetal head is becoming exceedingly elongated and flattened, and as the cup pops off it might cause damage to the brain and blood vessels.

During the procedure the obstetrician is under significant stress and the subjective element of the evaluation of traction force is a concern. The difficult decision of whether to continue a heavy extraction or abort the operation is made under stressful conditions and based mostly on subjective impressions.

To provide the obstetrician with more objective information, the investigators developed a new device consisting of an intelligent handle hooked to the chain of a regular metal cup.