In 2005, the International Study Group on Pancreatic Fistula (ISGPF) published the diagnostic criteria for pancreatic fistula, and only since then have the criteria begun to be standardized in the reporting of pancreatic fistula incidence. 2010, the Pancreatic Surgery Group of the Chinese Medical Association’s Surgery Branch published the Expert Consensus on the Prevention and Treatment of Common Postoperative Surgical Complications of the Pancreas (2010) (hereafter referred to as the Consensus). In the consensus, the diagnostic criteria for pancreatic fistula are defined as: fluid drainage from the anastomosis or pancreatic stump >10 mL/d on or after the 3rd postoperative day, with the concentration of amylase in the drainage fluid higher than 3 times the upper limit of normal plasma amylase for more than 3 consecutive days; or the presence of clinical symptoms (such as fever, etc.), the accumulation of fluid around the anastomosis detected by ultrasound or CT and the amylase concentration in the fluid confirmed by puncture higher than the upper limit of normal plasma The upper limit of amylase was confirmed by puncture to be 3 times higher than the normal plasma amylase. Also, grading criteria for pancreatic fistulas have been developed according to the different clinical manifestations (table below). In recent years, it is customary in the field of pancreatic surgery to refer to grade A pancreatic fistulas that are self-healing as biochemical fistulas and grade B and C pancreatic fistulas as clinically significant fistulas. It has been 10 years since the release of the international diagnostic criteria for pancreatic fistula, and there have been some modifications to this diagnostic and grading criteria for pancreatic fistula in both domestic and international studies. For example, the vast majority of grade A pancreatic fistulas diagnosed according to the current criteria do not have serious adverse consequences; however, the current diagnostic criteria cannot predict the occurrence of grade B and C pancreatic fistulas that may have serious adverse consequences. In this article, we will briefly introduce the evaluation and modification of the diagnostic and grading criteria for pancreatic fistula in recent years. Postoperative pancreatic fistula grading criteria 1. Evaluation of pancreatic fistula diagnosis and grading criteria 1.1 Reasonableness of pancreatic fistula grading criteria A review of the research on pancreatic fistula diagnosis and grading criteria in the past 10 years shows that the current grading criteria have a high degree of reasonableness and better reflect the severity of the patient’s condition, as evidenced by the significant correlation between the level of pancreatic fistula and the patient’s length of hospitalization, treatment time in the intensive care unit (ICU), and medical costs. The correlation between the level of pancreatic fistula and the length of hospitalization, ICU treatment time, and medical costs was significant. Shi Chenye et al. reported more than 300 cases of pancreaticoduodenectomy, in which the difference in hospital costs between patients with grade A pancreatic fistula and those without pancreatic fistula was not statistically significant, the average increase in hospital costs for patients with grade B pancreatic fistula was 20%, while the hospital costs for patients with grade C pancreatic fistula were three times higher than those for patients without pancreatic fistula; Pratt et al. The total length of stay, ICU stay and total medical costs of patients with pancreatic fistula were higher than those of patients without pancreatic fistula and patients with grade A pancreatic fistula, and the difference was statistically significant. 1.2 Limitations of pancreatic fistula grading criteria Retrospective criteria The grading of pancreatic fistula actually changes dynamically during the clinical consultation, and many patients’ pancreatic fistula may be grade A in the early stage with only elevated amylase in the drainage fluid and increased drainage, but may progress to grade B or C pancreatic fistula due to improper management or evolution of the disease itself. Therefore, the grading of a patient’s pancreatic fistula is not actually determined until the end of treatment. The existing diagnostic and grading system lacks parameters for clinical changes in patients after the onset of pancreatic fistula, and its value is important only for post-treatment statistics and analysis, but not for predicting regression when the fistula first occurs. The same criteria are used for distal and proximal pancreatic fistulas In terms of the mechanism of hazard, postoperative pancreatic fistulas after pancreaticoduodenectomy are not the same as those after pancreatic caudal resection, as the former has a simultaneous leakage of pancreatic, small bowel and bile most of the time, so pancreatic enzyme activation is more pronounced and prone to infection and bleeding, while the latter has a simple leakage of pancreatic fluid in most cases, with a lower likelihood of pancreatic enzyme activation, due to the absence of GI continuity changes, there is almost no leakage of intestinal fluid and the risk of infection is also lower. The final outcome of early grade A pancreatic fistulas at different sites is also likely to be different. Therefore, it has been suggested that different grading criteria are required for postoperative pancreatic fistulas after pancreaticoduodenectomy and caudal pancreatic resection. In a retrospective analysis of 1966 pancreatic surgery cases, 16 patients with grade A and B pancreatic fistulas who had a diagnosis of pancreatic fistula and whose final clinical outcome was death were graded as C. This may lead to some patients being graded inappropriately. final grading was defined as grade C. Such inappropriate grading in a retrospective clinical analysis can lead to an overestimation of the incidence of grade C pancreatic fistula and affect the accuracy of the evaluation of pancreatic fistula treatment methods. 2. Improvement of pancreatic fistula diagnostic criteria and grading The purpose of modifying the current pancreatic fistula diagnostic and grading criteria is to help make targeted clinical decisions by classifying pancreatic fistula patients as high-risk or low-risk at an early stage of fistula development. Accurate prediction will help in the hierarchical management of patients, such that patients with low-risk pancreatic fistula can be discharged with tubes and treated on an outpatient basis, while patients with high-risk pancreatic fistula should be intensively observed and treated accordingly. Such an individualized treatment approach is in line with the currently popular principles of precision medicine. 2.1 Timing and threshold of amylase testing The current diagnostic criteria only measure the amylase value of the drainage fluid on the 3rd postoperative day. Sutcliffe et al. suggested that the concentration of amylase in the drainage fluid on the first postoperative day has diagnostic value for pancreatic fistula and recommended intensive treatment for those with high values. The current criteria of diagnosing pancreatic fistula with a drainage amylase concentration of more than three times the serum amylase concentration, without considering the clinical significance of a further increase in drainage amylase, may lead to missing valuable clinical information. Ceroni et al. prospectively studied 135 cases of pancreaticoduodenectomy and found that the concentration of amylase in the drainage fluid was significantly higher in patients with grade B and C pancreatic fistulas than in grade A fistulas, and the risk of severe pancreatic fistula was significantly higher when the drainage fluid amylase concentration was >2820 U/L. 2.2 Other objective indicators Factors associated with the occurrence of pancreatic fistula include patient factors [such as body mass index (BMI), comorbidities, age, etc.], disease-related factors (such as pancreatic texture, pancreatic duct diameter, etc.), and surgery-related factors (such as intraoperative bleeding, surgical technique, and application of relevant drugs). It is recommended to introduce objective indicators from these factors to avoid bias caused by subjective judgment and to make the diagnostic and grading criteria more convincing. Preoperative predictive indicators As mentioned earlier, the current diagnostic criteria for pancreatic fistula cannot predict regression or the occurrence of severe pancreatic fistula, which is not conducive to the selection of individualized treatment plans for patients. If objective parameters predicting severe pancreatic fistula were added to this, it would help to better select treatment options and prepare both patients and physicians for the course of the disease.Roberts et al. prospectively studied 630 cases of pancreaticoduodenectomy in 8 centers in the United Kingdom, 141 (22.4%) pancreatic fistulas were diagnosed according to international standards, and a univariate analysis found that the patients’ preoperative BMI, prerenal fat thickness, pancreatic duct diameter on CT images, intraoperative total bilirubin concentration, pancreatic-intestinal anastomosis, pancreatic texture and TNM stage of postoperative pathology were found to be associated with the occurrence of pancreatic fistula, and a scoring system was established based on these parameters, and the higher the score, the higher the likelihood that the patient will have a severe pancreatic fistula. Postoperative predictive indicators Currently, many studies have found that abnormal changes in some of the indicators in patients with postoperative pancreatic fistula can indicate the possibility of worsening pancreatic fistula.Frymerman et al. found that the concentration of lipase in the drainage fluid on the first postoperative day was suggestive of the development of grade C pancreatic fistula; Gebauer et al. found that serum total bilirubin and C-reactive protein concentrations on the day of pancreatic fistula development were closely associated with an increased rate of reoperation. Eshuis et al [9], on the other hand, concluded that postoperative hyperglycemia was closely associated with the occurrence of pancreatic fistula. In summary, the current diagnostic and grading criteria for pancreatic fistula have important value for documentation and retrospective analysis, but have limited value in prospectively predicting the occurrence, progression, and regression of clinically severe pancreatic fistula. The addition of some objective preoperative and intraoperative indicators would help to improve the accuracy of predicting the occurrence of severe pancreatic fistula and thus guide targeted treatment. It is a future endeavor for pancreatic surgeons to integrate validated and effective indicators into the current system to make the criteria for pancreatic fistula diagnosis and grading precise and simple.