This is the first ever study to look at the sex biases in surgical equipment. Laparoscopy is widely used across urogynaecological procedures. The operating height in laparoscopy is raised due to the added laparoscopic instrument length and induced pneumoperitoneum of the patient. The height range of laparoscopic operating tables may pose a height barrier to female surgeons of shorter stature(1). We hypothesised commonly available operating tables across National Health Service (NHS) England are higher than optimal for female surgeons performing laparoscopy.

This was a prospective laparoscopic simulation study in the gynaecology department of a university hospital.  Urogynaecology consultants, trainees and students were recruited; 20 participants were needed for adequate power. Researchers measured the participant’s height, elbow height (floor to elbow when standing) and handspan (cm). Participants were instructed to complete a standard laparoscopic simulation exercise of ring transfer between pegs using a laparoscopic box-trainer (pyxus® HD, Inovus, Ltd, St Helens, UK). The simulator was placed on a height-adjustable patient bed. The same exercise was carried out at four operating heights in a randomised order where the operating height equated to 50%, 70%, 90% and 110% of the participants’ elbow height. The operating height was defined as the level of the simulation ports, which represent the level of the patient’s umbilicus following induced pneumoperitoneum in laparoscopy. These four heights were guided by previous studies indicating operating at 70% of elbow height may be optimal and the clinical practice of two male laparoscopic gynaecologic consultants (elbow heights 114cm and 115cm) whose preferred operating height equated to 90% of their elbow height. Operating at 50% and 110% of elbow height therefore analysed the lower and higher extremes of operating height. 

The randomised operating height order was generated via Microsoft Excel formula and aimed to reduce the bias of completing subsequent exercise repeats faster due to learning effects. To further analyse this potential bias, a subset of student participants were invited to repeat the simulation on a later occasion.
The outcomes measured were surgeon performance via simulation task completion time and number of errors, and surgeon comfort via self-reported Visual Analog Scale questionnaire.  A literature search of NHS table manufacturers and models was performed to identify the minimum heights of commonly available operating tables.

Shapiro-Wilk test was used to assess for distribution of data. One-Way Analysis Of Variance (ANOVA) and/or Altman-Bland were used for parametric parameters with data shown as means ± standard error of the mean (SEM). Wilcoxon signed rank test was used for paired, non-parametric parameters and Mann-Whitney U-Test was used for unpaired, non-parametric parameters with data shown as median, quartiles and overall ranges. Intra-class correlation (ICC) was calculated to analyse inter- and intra-rater reliability of task errors. Significance was defined as p<0.05.

There were 30 participants. Simulation when operating at 70% of surgeon elbow height yielded faster task completion time, mean 176.4s, than the highest height, 110%, mean 249.9s (p=0.026, 95% CI 6.212s to 140.9s). Surgeons made fewer errors when operating at 70% of elbow height, mean 19.7 errors, than at 110%, mean 31.4 errors (p=0.023, 95% CI 1.185 to 22.21 errors).
Reported comfort was highest when operating at 70% and 90% of elbow height. Simulation at 110% of elbow height was associated with increased shoulder discomfort (p<0.05).
Simulation times, errors and comfort scores did not differ between males (n=14) and females (n=16). Mean elbow height differed between males (116.6cm ±3.73) and females (104.6cm ±4.86)(p<0.001).
Following NHS Supply Chain models(2), the median minimum table height with standard or minimum mattress depth included is 69.75cm (IQR 66-75cm), although data was not available for the number of operating tables by manufacturer present across the UK. The NHS buyer’s guide to purchasing operating tables advised tables should lower to a minimum height of 72.5cm including mattress(3).

Under simulation, operating at 70% of elbow height optimises surgeon performance, with comfort optimised at 70% to 90% of elbow height. Surgeon sex did not impact upon performance nor comfort, suggesting no innate differences in ability. Data pertaining to minimum heights of commonly available operating tables across NHS England was limited; although buying standards were identified. Operating on the average size patient at 90% of elbow height, we estimate operating tables standards are too high for more than half of the male population and all of the female population. The minimum table height to accommodate surgeons of shorter stature should lower to approximately 28cm high, potentially lower with the addition of Trendelenburg tilt.

New laparoscopic operating with a lower minimum height of approximately 28cm high are necessary to optimise surgeon performance and comfort without bias against the female sex and surgeons of shorter stature. This is vital for patient safety and not biasing against different surgeons.

The ergonomics of women in surgery. Surg Endosc. 2014;28(4):1051-5
NHS Supply Chain. Architectural Surgical Medical Systems, Operating and Diagnostic Imaging Tables, Patient Stretchers and Trolleys, Medical Lasers and Related Accessories and Services. Supply Chain Coordination Limited; 2019
Buyer’s Guide: Operating Tables. NHS. Purchasing and Supplying Agency; 2009