New design rigid and soft vacuum extractor cups: a preliminary comparison of traction forces

Women due for vacuum extraction were randomly allocated to delivery using one of two soft cups (Silc or Silastic) or two new design rigid cups (New Bird or O'Neil). Traction forces were recorded continuously and higher values were reached with the rigid than the soft cups (median 15.8, range 7.5-19.7 vs 11.1, 7.2-15.1 kg, P less than 0.01). Selection of the most appropriate vacuum cup for each clinical situation should take into account that the flexible cups are associated with less cosmetic disfigurement but have a lower capacity for traction.