Pituitary adenoma is a common benign tumor in the saddle area, accounting for about 15%-20% of intracranial tumors. With the development of microsurgical techniques and the update of corresponding equipment, transsphenoidal approach to remove pituitary adenoma has become the first choice and become more mature. The most serious complication of transsphenoidal surgery is severe intraoperative bleeding, which is not common in clinical practice, but once it occurs, it can have serious consequences and even endanger the life of the patient if not handled properly. From February 2002 to August 2008, we performed 327 cases of pituitary adenoma resection by transsphenoidal approach, among which 7 cases had severe bleeding, which are reported below. 1. Data and methods 1.1. General data: From February 2002 to August 2008, a total of 327 cases of pituitary adenoma were resected by transsphenoidal approach, of which 7 cases (2.14%) had severe intraoperative bleeding and 2 cases (0.61%) died, of which 4 cases were male and 3 cases were female. Age 38-52 years, average 43.5 years, 4 cases had visual impairment, 2 cases had amenorrhea lactation. 1.2, examination results: preoperative cranial magnetic resonance imaging (MRI) and CT coronal scan of paranasal sinuses were performed in all cases. According to the imaging results, the tumors were graded and staged according to the modified Hardy method. Tumor grading: 0 cases of grade 0, 1 case of grade A, 3 cases of grade B, 3 cases of grade C, 1 case of grade D, and 0 cases of grade F. Tumor staging: 1 case of stage I, 2 cases of stage II, 4 cases of stage III, and 0 cases of stage IV. Tumor size classification: microadenoma according to tumor diameter <1cm, large adenoma according to 1~4cm, and giant adenoma according to >4cm. In this group, there were 2 cases of macroadenoma and 5 cases of giant adenoma. There were 3 cases of pterygoid sinus dysplasia (anterior saddle type), 1 case of excessive pneumatization of pterygoid sinus, and 0.4cm~2.5cm distance of siphon of internal carotid artery bilaterally. 4 cases of non-functional adenoma and 3 cases of prolactin adenoma. 1.3, Surgical treatment: 7 patients were treated by single nostril approach through the pterygoid sinus. 5 cases had pituitary adenoma resection under the microscope and 2 cases had pituitary adenoma resection under the neuroendoscope. 1.4. Intraoperative hemorrhage management: 2 cases were suprasellar septal hemorrhage, 1 case was craniotomy for hematoma removal. 5 cases were subsellar septal hemorrhage, 2 cases were enlarged intercavernous sinus hemorrhage, 1 case was hematoma removal via pterygoid sinus. In one male patient, the pituitary adenoma was aggressive and broke through the saddle septum into the third ventricle and wrapped around the bilateral internal carotid arteries. He died 4d after surgery. In one female patient, the tumor was about 4.0cm×4.5cm×4.5cm, invaded bilateral cavernous sinuses, the tumor was tough, and after partial resection, the saddle septum was sunken, and there was cerebrospinal fluid leakage, and there was bleeding when the tumor was scraped at the cavernous sinus, and the bleeding point was compressed. Postoperative cranial CT showed hemorrhage in the saddle area and the third ventricle, and he died 3 d after surgery. Five cases of subsaddle septal type hemorrhage all improved. 1 female patient with anterior saddle type pterygoid sinus, preoperative MRI showed bilateral internal carotid artery siphon was only 0.4 cm, internal carotid artery hemorrhage during expansion of saddle base, compression was given, intraoperative blood transfusion 3000 ml, postoperative visual acuity of right eye was 5 cm visible finger movement, recovered to 0.5 after 6 months, and then underwent a second operation via pterygoid, intraoperative tumor total excision, no change in visual acuity after the second operation In 2 cases, the intercavernous sinus was obviously enlarged, and the bleeding was obvious when the saddle base dura was incised, and after rapid removal of the tumor, the bleeding was stopped by compression with quick gauze and gelatin sponge. In one case, the visual acuity worsened after surgery, and the repeat cranial CT showed hemorrhage in the tumor cavity, and hematoma removal from the tumor cavity was performed again. The tumor was seen to invade the rupture hole intraoperatively, and hemorrhage occurred in the internal carotid artery during resection. In one case of pituitary adenoma invading the slope, during the removal of the paranasal sinus and the slope tumor, the bone suture and the trauma surface kept bleeding more obviously, and the operation was terminated by compression with gelatin sponge and quick instant gauze to stop the bleeding, and the postoperative radiation therapy had better results. 3.Discussion Pituitary adenoma is one of the common intracranial tumors. With the development of endocrinology, neuroradiology, neurosurgery and neuropathology, especially the early diagnosis of pituitary microadenoma, the deepening of people’s understanding of this disease and the application of clinical MRI, the detection rate of pituitary adenoma has a tendency to gradually increase. The literature reports that 72%-98% of pituitary adenomas can be treated by transsphenoidal approach, especially those invading the pterygoid sinus, septal sinus and nasal cavity are more preferred. Severe intraoperative bleeding of transsphenoidal pituitary adenoma is its most serious complication, although it is not rare clinically, once it occurs if not handled properly it can cause serious consequences and even endanger the patient’s life. In our group of 327 patients, severe intraoperative bleeding occurred in 7 cases (2.14%) and 2 cases (0.61%) died.