Pre-operative examinations and assessments in bariatric and metabolic surgery are important. Don’t ignore or omit some important assessments and examinations for the sake of being cheap. These tests cost money, so bariatric surgery is not a package deal that can be discounted like a car repair. We only do the best, not the discount of shrinkage. 1, obesity status and related comorbidities detection: including the cause of obesity, the course of the disease, the current weight, the medical history of weight gain and loss, dietary habits (including energy, protein, fat, carbohydrates, the three major nutrients energy supply ratio, vitamins, minerals intake, etc.), living habits, etc.. A comprehensive understanding of the basic situation of obesity helps to analyze the main causes of obesity in patients and provide reference for surgery and postoperative care. 2.Determination of obesity morphological parameters: height, weight, BMI, waist circumference, hip circumference, body fat content, to understand the distribution of fat in patients, which helps to predict and prevent complications. 3.Routine laboratory tests: routine blood, routine urine, routine stool + occult blood, liver and kidney function, coagulation time/INR, D-dimer, blood group determination, C-reactive protein, infection immunological examination, fasting pepsinogen, fasting gastrin-17, postprandial gastrin-17, blood sedimentation, arterial blood gas analysis. Routine tests can respond to liver and kidney function, hematological disease screening and inflammatory status to avoid unnecessary risks caused by surgery. 4. Examination of glucose and lipid metabolism: fasting blood glucose, lipid profile, glycated hemoglobin, glycated albumin, OGTT, C-peptide level + insulin release test, anti-insulin antibody. Preoperative fasting blood glucose level is controlled below 7.8mmol/l and postprandial blood glucose is controlled below 10mmol/l, which is conducive to postoperative recovery and care. type 2 diabetic patients with almost loss of insulin cell function are contraindicated for surgery. 5. Detection of nutritional status: including serum albumin, prealbumin, serum iron, vitamin B12, folic acid, 25-hydroxyvitamin D and basal metabolic rate. Endocrine system tests: thyroid function (including autoantibodies related to thyroid etiology), parathyroid function, sex hormones, growth hormone, aldosterone, angiotensin 1. For suspected polycystic ovary syndrome, determination of fixed androgens, total/biologically active testosterone, dehydroepiandrosterone, and 4-androstendione is required. For clinical suspicion of Cushing’s syndrome, monitoring of adrenocorticotropic hormone, cortisol rhythm, 1 mg overnight dexamethasone suppression test and measurement of 24-hour urinary free cortisol are required. 7. Examination of cardiopulmonary function: Postoperative pulmonary complications and related mortality rank second only to the cardiovascular system. Those with a history of pulmonary disease should be examined preoperatively for pulmonary function as well as to determine the presence of sleep apnea. Ineffective cough and diminished airway reflexes can cause postoperative storage of secretions and increase susceptibility to bacterial invasion and pneumonia. Chest radiography can identify parenchymal lung lesions or pleural cavity abnormalities. Erythrocytosis may suggest hypoxemia. Cardiac ultrasonography is recommended in patients with suspected cardiac disease or pulmonary hypertension after routine ECG. If clinically suggestive of possible deep vein thrombosis, perform venous ultrasound of both lower extremities for evaluation. 8. Examination of the upper gastrointestinal tract: screening for Helicobacter pylori and gastroscopy. Preoperative upper gastrointestinal tract imaging can help determine whether the physiological anatomy of the gastrointestinal tract is normal. 9.Liver fat content determination: It is recommended that liver ultrasound can be used to understand the liver condition. Liver biopsy at the time of surgery to clarify the presence of occult steatohepatitis or cirrhosis. 10.Vascular examination: Patients with abnormally elevated lipids or atherosclerosis need to undergo carotid color ultrasound and intravascular intima-media thickness determination; patients with suspected and confirmed pre-diabetes or diabetes should also undergo retinal examination and fundus photography. For patients with a history of gout, it is recommended to consider prophylactic treatment of gout. In addition to medication, diet should be low in calories, fat and protein, salt and purine, and strict control of purine intake to avoid attacks. All patients should undergo an appropriate nutritional assessment, including micronutrient measurements, prior to surgery. Preoperative assessment of nutritional status should be more extensive for malnutrition absorption surgery than for restrictive surgery alone. In patients with malnutrition, it should be corrected preoperatively if possible. Pituitary MRI and adrenal CT are routinely performed in all patients to rule out neuroendocrine obesity. A psychosocial-behavioral assessment, including environmental, family and behavioral factors, should be performed in all patients prior to bariatric surgery. Patients with known or suspected psychiatric disorders or substance abuse or drug dependence should have a formal psychiatric evaluation prior to proposed bariatric and metabolic surgery. Patients undergoing gastric bypass surgery will have an impaired ability to metabolize alcohol in the body after surgery, with higher peak blood alcohol concentrations after surgery compared to before surgery and a prolonged return to normal levels given the same amount of alcohol consumed. All patients should be assessed for their ability to undergo preoperative and postoperative nutritional and behavioral changes. Patients are fully informed about the surgical approach to treating diabetes or morbid obesity, understand and are willing to accept the risk of potential complications of the procedure, and understand the importance of and are willing to accept postoperative changes in diet and lifestyle habits. The patient’s ability to actively cooperate with post-operative follow-up is also a consideration for surgical selection