The development and testing of new instruments for operative vaginal delivery

Brom D. Elliott, Louis E. Ridgway, Michael D. Berkus, Edward R. Newton, William Peairs

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


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. (Am J Obstet Gynecol 1992;167:1121–4.)

Original languageEnglish (US)
Pages (from-to)1121-1124
Number of pages4
JournalAmerican Journal of Obstetrics and Gynecology
Issue number4
StatePublished - 1992


  • Instrument-assisted delivery
  • fetal head
  • traction

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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