Abstract: Objective　To explore the influence of the sellar floor fenestration on the microscopic endonasal transsphenoidal surgery for pituitary adenoma.　Methods　51 patients (including 22 cases of male and 29 cases of female，aged from 19 to 75) of pituitary adenoma patients who undergone microscopic endonasal transsphenoidal surgery at the 900th Hospital of the Joint Logistics Team from March 2014 to March 2015 were included in this retrospective analysis. Paranasal sinus CT and pituitary MRI scan were done for each patient before and after operation. Image fusion and reconstruction were done by Mimics15.0 software. The area of sellar floor fenestration and the vertical distance from the highest point of fenestration to planum sphenoidale were observed and measured. The relationships between them and the extent of tumor resection, intraoperative cerebrospinal fluid leakage, postoperative diabetes insipidus were analyzed retrospectively.　Results　The area of sellar floor fenestration in the total removal group was smaller than that of the incomplete resection group, while the ratio of sellar floor fenestration area to the largest tumor area in the total removal group was larger than that of the incomplete resection group. The vertical distance from the highest point of fenestration to planum sphenoidale in the intraoperative cerebrospinal fluid leakage group was shorter than that of the without intraoperative cerebrospinal fluid leakage group. The difference among of them was statistically significant (P<0.05). Logistic regression analysis showed that the ratio of sellar floor fenestration area to the largest tumor area and tumor invasion were independent predictive factors that influenced the extent of pituitary adenoma resection (P<0.05).  in There were no statistical difference on the area of sellar floor fenestration between the diabetes insipidus group and without diabetes insipidus group (P>0.05).　Conclusions　The relative insufficient of the sellar floor fenestration is one of the most important reasons for residual tumor. The higher position of the sellar floor fenestration, the more possible leakage of cerebrospinal fluid. The occurrence of postoperative diabetes insipidus were not associated with the size area of sellar floor fenestration.

Key words:  , Transsphenoidal surgery, 　Pituitary adenoma, 　Complication