[A new vacuum extraction system with a ball joint and detachment warning--in vitro studies and clinical use]

The vacuum extractor is used in about 5% of deliveries. It is associated with a lower maternal morbidity than is forceps extraction. On the other hand, cephalhematomas, hyperbilirubinemia and cerebral hemorrhages in the baby are observed more frequently. The sudden detachment of the vacuum extractor with appreciable fluctuations in intracranial pressure in the baby is especially dangerous. In order to improve the conventional Malmström system, we have developed a new vacuum extractor and investigated its handling in vitro and in clinical application.

The essential constructional principle of the new vacuum extractor consists in a pivot lowered by ball bearings and a volume reduction of one third. Moreover, in two-chamber vacuum it is possible to give a warning of sudden detachment. The possible tractional force in kiloponds was determined at various angles (0 degree, 15 degrees, 30 degrees und 45 degrees) comparing the Malmström extractor with the new one and two-chamber system in a standardized apparatus. In addition, the new vacuum extractor was also used clinically in 43 women; besides the obstetric parameters, the handling was also appraised.

In the in-vitro experiments, a distinct decrease of the possible tractional force with increasing angles was shown for the Malmström extractor (0 degree--15.7 kp, 15 degrees--12.7 kp, 30 degrees--8.6 kp, 45 degrees--7.3 kp). The values for the new one-chamber system were significantly greater from a tractional angle of 15 degrees (0 degree--15.6 kp, 15 degrees--14.4 kp, 30 degrees--14.0 kp, 45 degrees--13.8). The clinical application of the new vacuum system was unproblematic and confirmed the feasibility of good traction. A very much smaller caput succedaneum was found in the baby. Especially in the training situation, the warning system enables a good surveillance before sudden detachment, but reduces the possible tractional force.

The new vacuum system appears to enable the vaginal surgical delivery to be improved compared to the conventional Malmström extractor. After these promising approaches, a multicenter study was commenced in order to enable better evaluation of their clinical significance.