Table 6.

Double-Wall Puncture Rates for Individual Needles and Some Groupings Based on Tip Sharpness, Gauge, and Length

Needle CharacteristicDouble-Wall Puncture Rate, %Double-Wall Puncture, n/n95% CI, %
Tip Sharpness
A-bevel, 21 gauge8.713/1494.7-14.5
I-bevel, 20 gauge0.00/110.0-28.5
B-bevel, all gauges11.88/685.2-21.9
 21 gauge13.55/374.5-28.8
 18 gauge9.73/312.0-25.8
21 gauge, any bevel, NS±9.718/1865.8-14.9
20 gauge, I-bevel, NSs-o0.00/110.0-28.5
18 gauge, B-bevel, NS±9.73/312.0-25.8
Length optimization
NS-, all gauges25.011/4413.2-40.3
 21 gauge, A-bevel and B-bevel22.09/4110.6-37.6
  21 gauge, A-bevel18.26/337.0-35.5
  21 gauge, B-bevel37.53/88.5-75.6
 18 gauge B-bevel66.72/39.4-99.2
NS+, all gauges5.410/1842.6-9.8
 21 gauge, A-bevel6.07/1162.5-12.0
  21 gauge, A-bevel, NSs-o9.27/763.8-18.1
  21 gauge, A-bevel, NShub0.00/400.0-8.8
 21 gauge, B-bevel, NSs-o6.92/290.9-22.8
 20 gauge I-bevel, NSs-o0.00/110.0-28.5
 18 gauge B-bevel, NSs-o3.61/280.1-18.3
  • Note: A-bevel, extra-sharp; B-bevel, of lesser sharpness customary for vascular access; I-bevel, of sharpness intermediate between A-bevel and B-bevel.

  • NS±, with or without a needle stop; NS+, with a needle stop; NS-, without a needle stop; NShub, original manufacturer's hub served as the needle stop; NSs-o, nylon screw-on mechanical needle stop.