Levrat’s rat model is often the first choice for basic studies of oesophageal adenocarcinoma. The position of the tracheal bifurcation represents the preferred location for the high-intrathoracic anastomosis following oesophagectomy for cancer and is thus of importance in basic research of oesophageal adenocarcinoma. In addition, it is also the typical location for trachea-oesophageal fistulae in congenital oesophageal atresia and its rat model. We thus analysed whether the position of the tracheal bifurcation would be affected by a rat’s growth throughout life. We analysed absolute and relative carinal position of the tracheal bifurcation and its relationship to oesophageal length in two cohorts of Sprague Dawley rats (RjHan:SD) of both sexes: one consisted of 30 eight-week old rats and the other of 20 rats aged between 15 and 444 days. We analysed their relationship by Pearson’s r and univariate linear regression. Bootstrap confidence intervals were calculated for all calculated coefficients. Absolute carinal position correlated with oesophageal length in the eight-week old cohort (r=0.4, 95% CI: 0.08-0.71, p=0.015) and those of different ages (r=0.92, 95% CI: 0.77-0.96, p=0.0066). Absolute carinal position increased with oesophageal length in both cohorts (F(1,28)=5.56; p=0.0256 and F(1,18)=94.93; p<0.0001 respectively). Consequently, relative tracheal bifurcation position was not influenced by oesophageal length in both cohorts (F(1,28)=2.49; p=0.1257 and F(1,18)=1.92; p=0.183). Absolute carinal position increased with oesophageal length, but relative position remained constant at around 30% of proximal oesophageal length throughout life
