**2. Endoscopic diagnosis of CP**

CP is diagnosed when there is overt endocrine or exocrine dysfunction, atrophy, or calcification observed on imaging. However, these findings are observed in the later stages of the disease. EUS is highly beneficial for diagnosing early CP. Early diagnosis is essential for explaining symptoms, avoiding unnecessary explorations and therapies, investigating etiologies, adequate follow-up, explaining prognostic consequences, genetic evaluation, and appropriate therapy. Moreover, if there is a genetic mutation, total pancreatectomy and islet cell transplantation may be considered for malignancy risk.

EUS provides an opportunity to investigate the pancreatic parenchyma and ductal structures in detail. The parenchymal features of CP on EUS are hyperechoic foci, hyperechoic strands, lobularity, and cysts, and the ductal features are main ductal dilatation, duct irregularity, hyperechoic duct margins, visible side branches, and stones. In traditional EUS systems, the presence of five or more features reliably establishes the diagnosis of CP [3]. An international consensus panel, including 32 internationally recognized endosonographers, developed consensus criteria for EUS features of CP. In this Rosemont classification, the major criteria are hyperechoic foci with shadowing and main pancreatic duct (MPD) calculi and lobularity with honeycombing. Minor criteria are cysts, dilated ducts of ≥3.5 mm, irregular pancreatic duct contour, dilated side branches of ≥1 mm, hyperechoic duct wall, strands, non-shadowing hyperechoic foci, and lobularity with noncontiguous lobules (**Table 1**) [4].


*Consistent with CP: 1 major A and* ≥*3 minor features, 1 major A and 1 major B features, 2 major A features. Suggestive of CP: 1 major A and* ≤*3 minor features, 1 major B and* ≥*3 minor features. Indeterminate for CP: 3–4 minor, 1 major B alone or with <3 minor features. Normal:* ≤*2 minor without major features.*

**Table 1.** *Rosemont classification.*

### *Endoscopic Management of Chronic Pancreatitis DOI: http://dx.doi.org/10.5772/intechopen.107321*

Recent or active acute pancreatitis can cause overdiagnosis because of parenchymal hyperechoic strands and foci, lobularity, and hyperechoic duct walls. Acute inflammation of the pancreas can also obscure the underlying pancreatic mass. Therefore, EUS should be performed 4 weeks after an acute pancreatitis episode. Moreover, some of these EUS findings can be found normally in individuals as the age and among males, obese individuals, smokers, and alcohol consumers [5–8]. When the diagnosis of CP is debatable, EUS elastography, endoscopic pancreatic function test (ePFT), and distensibility of MPD can be combined with EUS to improve diagnostic success.

EUS elastography has been proposed as a novel and valuable modality for the evaluation of real-time tissue stiffness. It is mainly used in pancreatic tumors but is also highly beneficial in CP. Itoh et al. reported the correlation between parameters in EUS elastography (mean, standard deviation, skewness, and kurtosis) and histological fibrosis in the pancreas [9]. Iglesias-Garcia et al. showed the correlation between the strain ratio and Rosemont classification and exocrine dysfunction, evaluated by the carbon 13 mixed triglyceride breath test [10]. Homogenous stiffness on EUS elastography may also predict autoimmune pancreatitis. Both strain elastography and share wave elastography contributed to the diagnosis of CP using EUS.

The ePFT helped evaluate the exocrine function of the pancreas. In this procedure, gastroscopy was performed, and during the luminal examination, a test dose of secretin was intravenously administered. The gastric fluid was then aspirated as much as possible and discarded, and 3–5 cc post bulbar duodenal secretion was aspirated to rinse the gastric fluid from the suction channel. Furthermore, 3–5 cc duodenal fluid was aspirated as baseline collection; intravenous secretin (0.2 μg/kg) was administered slowly. Every 15 min, the duodenal aspirate was collected for 60 min. If the peak bicarbonate level was <80 mEq/L, then exocrine pancreatic insufficiency was considered. Its sensitivity was 92% and specificity 79% for early CP with normal imaging [11].

Inadequate distension of the MPD after secretin administration is another criterion used for the diagnosis of CP. Pancreatic duct dilatation after secretin stimulation lower than 50% of basal may be considered abnormal. In a study of 41 patients with clinically suspected CP, 77.3% had abnormal ductal compliance [12]. In current reports, additional criteria are suggested for EUS-based multimodal evaluation.
