Measurement of Temperature in Laparoscopic Tubal Sterilisation

In order to determine temperature changes during the course of laparoscopic tubal sterilization continuous measurements were made with a thermistor on 28 tubes. A high frequency laparoscopic instrument with a maximum current consumption of 6 amps and a maximum coagulation output of 600 watts was used. After coagulation with 20 watt outputs the temperature on the surface of the tube 1-2 mm from the coagulation forceps rose to 98 degrees C in 25 seconds and returned to the initial temperature of 37 degrees C 60-90 seconds after coagulation. With a 30-watt output 105 degrees C was registered after 8 seconds and normal temperature was regained in 60-90 seconds. Actual coagulation time was 35 seconds with 20 watts and 50 seconds with 30 watts. Sparks and flames were observed when outputs of 50-100 watts were used and at lower outputs when the tube was not firmly gripped. In these cases temperatu res of 260-600 degrees C were observed. As this can lead to charring and narcosis of tissues outputs should be limited and the tube gripped as firmly as possible along its entire length. An output of 30 watts with 60 seconds coagulation time is optimal. Temperature measurements a lso indicated that the coagulation forceps should be left in place for 3 0-40 seconds after normal coagualtion and 3-4 minutes when sparks have been observed.