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The development and testing of new instruments for operative vaginal delivery
B D Elliott1, L E Ridgway, M D Berkus
1Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio 78284-7836.
Objective:
Little innovation has occurred in recent years in the instruments available for operative vaginal delivery. The purpose of this study is to develop a technique to test the utility of an investigational device, the obstetric bonnet, and measure the forces it places on the fetal head.
Study Design:
We constructed a model of the fetal head capable of measuring both compression and vacuum created by an applied device. A total of 18 devices were tested to a maximum traction of 60 pounds.
Results:
A significant linear relationship exists between the traction applied and the compression (R2 = 0.42, p = 0.0004) and vacuum (R2 = 0.85, p = 0.0001) created. Compression and vacuum recorded at maximum recommended traction were 1.1 lb/sq in and 31 cm Hg, respectively.
Conclusion:
These findings explain the mechanics of this interesting device, and demonstrate forces that compare favorably with those known to occur with forceps or vacuum extraction.