Reply to LTE 5020976

Dear Professors Marco Gandini and Gessica Giusto

We are glad you have read, with interest, both ex vivo papers, and we are happy to address your questions regarding the methodology and, more specifically, the use of Vernier calipers as a measurement tool for jejunal luminal diameter.

The concern regarding a lack of standardization of the force used to open the calipers is justified. However, as there are no known standardized force‐adjustable calipers, we do not think this is a viable alternative. Further, if there were to be force‐adjustable calipers that could be used, what force would the authors apply? We do not know either the physiological normal forces found intra‐luminally in a single orientation, nor the pathologic forces of distended small intestine in a single orientation. In Sherlock et al., ¹ a standard distracting force was applied to jejunal sections, but they state the lumen size may not have been maximized because the tension placed on the stay sutures was subjectively less than that placed on stay sutures in clinical cases. Therefore, although force‐standardized calipers would remove subjectivity, the arbitrary force applied would also be a limitation of the methodology.

The author's concerns regarding the subjectivity of the measurement and overestimation due to stretching of cadaveric tissue are addressed in both manuscripts with the use of multiple measurements taken in succession and a mean generated. In the author's single case, a 20% increase in diameter was achieved. However, in the Baldwin and Gillen ² dataset, the mean of the SDs across all three measurements for the control lumen was only ±0.81 (range: 0.00–6.43), and the mean of the SDs for the three anastomosis lumen diameter measurements was only ±0.71 (range: 0.06–4.36). The mean of the SDs represents only a ±1.6% and ±1.3% deviation in measurements of control and anastomotic lumen diameter, respectively. Therefore, whilst it is possible to deliberately stretch the cadaveric material, this was not done in the study by Baldwin and Gillen. ²

The difference the authors highlight between Baldwin and Gillen ² (Figure 3), and the Seitz‐Cherner et al. ³ (Figure 4) is not a difference in the force applied to the Vernier calipers or the Vernier caliper use; it is due to a 30° transection angle in Baldwin and Gillen ² (Figure 3) being compared to a 60° transection angle in Seitz‐Cherner et al. ³ (Figure 4). This highlights an important finding in the study by Baldwin and Gillen ² and demonstrates why the 30° transection angle creates the greatest anastomotic index. The jejunum develops a mesenteric outpouching, which accounts for the increase in anastomotic index. A more appropriate comparison would be between Seitz‐Cherner et al. ³ (Figure 4) and Baldwin and Gillen ² (Figure 3a); both of these sections of jejunum are transected at 60° and stretched to the described physiological limit. These two sections appear similarly stretched with the use of the Vernier calipers. Without knowing the transection angle of the anastomosis performed by the authors in their single case, it is difficult to state definitively but our interpretation is that the jejunum appears similarly stretched in Baldwin and Gillen ² (Figure 3a), Seitz‐Cherner et al. ³ (Figure 4) and the authors' own (Figure 2). This further adds weight to the reliability and lack of variation in the technique if applied appropriately.

Regarding the difference in Vernier caliper use between Baldwin and Gillen ² and Seitz‐Cherner et al., ³ Baldwin and Gillen ² chose to use the larger forks of the Vernier calipers as the smaller forks failed to stay in the jejunal lumen during measurements. Whilst this is a difference in methodology between the two studies, it does not undermine either study's results or a comparison between the two studies. The larger forks were used consistently in the study by Baldwin and Gillen, ² and from these measurements, the anastomotic index ratio was generated. As the anastomotic index is a ratio of two measurements, as long as those two measures were performed in the same way (which they were in Baldwin and Gillen ² ) then the ratios are valid and comparable between the two studies. This difference in methodology was noted in the peer review process and addressed at the time.

We would like to take the time to thank the authors for their questions. We hope this answers these questions and helps interpretation of both studies. We would remind the authors that these studies are ex vivo and should be interpreted with care, as there is no accounting for healing, and the other variables encountered in clinical cases. We acknowledge there are other methods of determining luminal diameter, but these too have their limitations, and these should also be recognized. Vernier calipers have been used in numerous studies ¹ , ² , ³ , ⁴ and are a recognized method of measuring the intestinal lumen. The study by Baldwin and Gillen ² concludes that larger ex vivo studies and prospective case–control trials are required. We consider this a reasonable conclusion from this ex vivo study.

CONFLICT OF INTEREST STATEMENT

None.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.