Drainage after cholecystectomy In their paper on this subject (Annals, May 1982, vol. 64,p. 183) Messrs Ian Fraser, N W Everson, and J R Nash report a comparison of two cholecystectomy drainage methods in a randomised trial. We wish to take this opportunity to point out that the results of the trial should not be regarded as an appraisal of suction per se. The reason is simple. The trial compared suction drainage with passive (that is, static) drainage. The trial also made a comparison between drainage via two types of tube, one described as 'larger and more rigid' than the other. Thus two variables were involved in the comparison and there is no way of telling whether the differences which emerged should be ascribed to the difference in rigidity and size of the tubes or to the fact that suction was or was not applied. This is acknowledged by the authors and is apparent already from the title: 'A. .. trial of two drainage methods. .. ' With this in mind it is easier to understand why the results of the trial differ so much from those we obtained in a trial in which we tried to evaluate suction versus static drainage through the main wound versus a stab incision in a 2 by 2 design (1). In our comparison of suction versus static drainage the same medical grade polyvinyl chloride ester catheter was used with and without suction. In contrast to Fraser et al. we found that the amount of fluid drained was twice as large in patients with static drainage as in those with suction. Also in contrast to Fraser et al. we failed to detect a difference in the incidence of infection. The question submitted to a trial by Fraser et al. was practical in nature: what is the difference between drainage with Redivac bottle suction via a fine flexible tube on the one hand and static drainage using a more rigid 32-French Portex tube on the other? The question we submitted to a trial was: given a certain tube, what is the effect of suction? When questions are so different we cannot expect identical answers.