Key Points
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Endoscopic ultrasound (EUS) imaging is subjective and often nonspecific in inflammatory diseases of the pancreas; therefore, the clinical history and presentation are important when making a final diagnosis.
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EUS-guided fine-needle aspiration (FNA) in inflammatory diseases of the pancreas is predominately used to exclude/diagnose superimposed malignant processes; the role of fine-needle biopsy (FNB) remains to be defined.
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Complementary imaging modalities such as elastography and contrast-enhanced imaging are in the experimental phase and are not recommended for routine use in the evaluation of patients with inflammatory diseases of the pancreas.
Introduction
Some of the most common pancreatic disorders that a gastroenterologist encounters are inflammatory processes, particularly acute and chronic pancreatitis. Imaging plays a key role in the diagnosis and management of these disorders. Due to the proximity to the pancreas and high-resolution imaging, endoscopic ultrasound (EUS) provides an ideal technique for evaluating the entire pancreas. The capability to obtain aspirates for cytologic evaluation and core biopsies for histologic examination allows for definitive diagnosis of benign and malignant pancreatic processes. Its role in the management of these common inflammatory disorders is evolving and becoming further defined.
Although much less common, autoimmune pancreatitis (AIP) and benign masses of the pancreas often provide diagnostic challenges for the gastroenterologist. Therefore, novel and complementary imaging modalities that can be performed at the time of EUS, namely elastography and contrast-enhanced EUS, are increasingly being used, although with still uncertain utility. This chapter focuses on the role of EUS imaging and tissue sampling for evaluating patients with suspected inflammatory diseases of the pancreas.
Endoscopic Ultrasound in the Nondiseased Pancreas
Endosonographically, the nondiseased pancreatic parenchyma typically has a homogenous salt and pepper appearance with a thin anechoic tubular structure that runs in the middle of the gland corresponding to the main pancreatic duct (MPD) ( Fig. 13.1 , Video 13.1 ). The outer contour of the pancreas is normally smooth without significant lobularity. The width of the pancreas in the head, body, and tail measures approximately 19 mm, 13 mm, and 12 mm respectively. The MPD diameter measures on average 2.2 mm in the head, 1.5 mm in the body, and 1 mm in the tail of the pancreas.
Normal Pancreas
EUS demonstrates the typical salt and pepper appearance of the pancreas in patients without disease pathology. (See Fig. 13.25 .)
The ventral anlage appears as a focal hypoechoic area in the head of the pancreas and can be seen in up to 75% of patients on EUS. Since the initial reports, the introduction of improved EUS processors and transducers now allows detection in nearly all patients. It is important to not mistake the ventral anlage for a pancreatic mass. Conversely, it is also important to remember that the normally appearing hypoechoic ventral anlage can mask the presence of a small neoplasia or other pathology. When occult pathology is suspected in this region, one may consider careful examination of the ventral anlage from both the bulb and second portion of the duodenum. In addition, use of the cine function and magnification can further aid careful examination.
Unfortunately, the pancreas often demonstrates an altered appearance, possessing some chronic pancreatitis-like features even in the absence of any apparent disease. In patients undergoing EUS for indications unrelated to pancreaticobiliary disease, at least one parenchymal and/or ductal abnormality can be seen in up to 28% of patients. The likelihood of EUS imaging abnormalities increases with patient age, particularly in patients >60 years old, and male gender. The most common abnormality is hyperechoic stranding. Other studies have shown that alcohol consumption at low levels increases the likelihood of detecting hyperechoic foci, MPD dilation, and ductal wall hyperechogenicity, whereas smoking increases the finding of hyperechoic foci. Small visible side branches <1 mm can also be seen in patients without pancreaticobiliary symptoms.
Chronic Pancreatitis
Brief Overview
Chronic pancreatitis (CP) results from progressive inflammation and scarring of the pancreas. Patients may initially present with recurrent acute pancreatitis and occasionally patients presenting with their first known episode of acute pancreatitis may already have structural and functional changes secondary to chronic pancreatitis. Pain, classically located in the epigastrium with radiation to the back and worsened by eating, is the most common symptom. When more than 85% to 90% of the pancreas is affected, patients may also manifest exocrine insufficiency (with steatorrhea, weight loss, and fat-soluble vitamin deficiency) and/or endocrine insufficiency (with glucose intolerance or diabetes mellitus).
Although the diagnosis of CP is straightforward in patients with severe disease manifested by the presence of calcifications and a dilated MPD, the diagnosis is far more challenging in early disease stages. Furthermore, whereas pancreatic calcifications most often result from CP, calcifications may be seen in other forms of pancreatic pathology including neuroendocrine tumors, intraductal papillary mucinous neoplasms, mucinous cystic neoplasia, serous cystadenoma, and some pancreatic adenocarcinomas. The pattern and extent of calcification often provides a diagnostic clue as patients with CP often manifest MPD and parenchymal calcification, the latter of which is often actually contained with peripheral side branches. In addition, a dilated MPD may result from other important pathologies including an obstructing neoplasia or main duct intraductal papillary mucinous neoplasm (IPMN) rather than CP.
The diagnosis of CP relies on a combination of symptoms, noninvasive radiographic imaging (computed tomography [CT], magnetic resonance imaging [MRI]/magnetic resonance cholangiopancreatography [MRCP]), and/or EUS. In patients with documented CP, the most common CT findings (in decreasing order of frequency) include a dilated MPD with secondary radicals (68%), pancreatic parenchymal atrophy (54%), pancreatic calcifications (50%), fluid collections (30%), focal pancreatic enlargement (30%), biliary ductal dilation (29%), alterations in peripancreatic fat (16%), and a normal pancreas (7%). Unfortunately, these CT findings are not specific for CP. CT is also used to help detect complications of CP and exclude other diseases associated with abdominal pain. MRI/MRCP, particularly with secretin stimulation, has improved sensitivity over CT for the detection of early CP. Findings on MRI/MRCP include MPD dilation, side-branch abnormalities, strictures, intraductal stones, intraparenchymal cyst formation, parenchymal atrophy, and abnormal decreased signal intensity on T1-weighted images of the pancreas with delayed and limited enhancement after contrast administration. MPD compliance with distention (normal is approximately 1 mm) and side-branch abnormalities after secretin stimulation has enhanced the ability of MRI to detect early CP.
Role of Endoscopic Ultrasound
The American Pancreatic Association (APA) recommends a step-wise approach to diagnose CP ( Fig. 13.2 ). In patients with compatible clinical signs and symptoms, the APA initially recommends a CT that, if nondiagnostic, should be followed by MRI/MRCP with secretin stimulation. The society recommends EUS only when the results of noninvasive imaging are nondiagnostic or inconclusive. If the EUS is inconclusive, the APA recommends pancreatic function testing with secretin administration. However, it should be noted that pancreatic function testing has a narrow role due to the limited availability, poor patient tolerance, and suboptimal diagnostic accuracy. Finally, the use of diagnostic endoscopic retrograde cholangiopancreatography (ERCP) may be considered only after the aforementioned evaluation when the diagnosis remains indeterminate. As the various clinical and imaging features of CP are often nonspecific and commonly seen in patients without pancreatic disease, it is important to interpret the findings with caution and in the appropriate clinical setting. This need is even greater when contemplating therapeutic interventions, for which EUS may have a role ( Figs. 13.3 to 13.8 , Videos 13.2 and 13.3 ).
A 48-Year-Old Male Presented With Clinical and CT Evidence of Chronic Pancreatitis With a Large Pancreatic Head Duct Stone and Upstream Ductal Dilatation
Three prior efforts at ERCP failed and the patient was referred for further evaluation and stone clearance. P Div_Major, Minor: EUS demonstrated a thickened bile duct wall indicative of downstream obstruction. EUS also revealed a remote location of the minor papilla, relative to the major papilla, initially establishing the diagnosis of pancreas divisum that had been missed on prior cross sectional imaging. The large stone was seen in the accessory duct. (See Fig. 13.27 .)
Video 13.3A 48-Year-Old Male Presented With Clinical and CT Evidence of Chronic Pancreatitis With a Large Pancreatic Head Duct Stone and Upstream Ductal Dilatation
Three prior efforts at ERCP failed and the patient was referred for further evaluation and stone clearance. P Div_MPD, SB, Atrophy: EUS demonstrated typical features of chronic pancreatitis including a dilated MPD, dilated side branches, and parenchymal atrophy. It is likely that some of the features were secondarily induced by the large stone and resulting obstructive changes. (See Fig. 13.28 .)
Endoscopic Ultrasound Imaging Characteristics
Endoscopic Ultrasound Criteria for Chronic Pancreatitis
Conventional EUS criteria for the diagnosis of CP rely on the evaluation of nine features. The four parenchymal features include hyperechoic foci (distinct 1 to 2 mm hyperechoic points), hyperechoic strands (hyperechoic irregular lines >3 mm), lobularity (2 to 5 mm lobules), and cysts (thin-walled hypoechoic structures >2 mm within the confines of the parenchyma), whereas the five ductal features include MPD dilation (>3 mm in the head, >2 mm in the body, and >1 mm in the tail of the pancreas), ductal irregularity, hyperechoic duct margins, visible side branches, and intraductal stones ( Figs. 13.9 to 13.12 , Videos 13.4 and 13.5 ). The ideal cutoff for the number of EUS criteria needed to diagnose CP varies among endosonographers, institutions, and study protocols. Many consider the finding of 1 to 2 criteria as indicative of a normal pancreas, 3 to 4 criteria indicate early CP, and ≥5 criteria consistent with CP. Understandably, the higher the threshold required for diagnosis, the lower the sensitivity and higher the specificity of the criteria.
Acute/Chronic CP
EUS in a patient with an acute exacerbation of chronic pancreatitis. In addition to the calcification, pancreatic and peripancreatic inflammatory changes are present. (See Fig. 13.33 .)
Video 13.5CP (Mild)
EUS demonstrates features that were considered indicative of mild or early chronic pancreatitis. These findings were confirmed by core biopsy. (See Fig. 13.35 .)
More recently, some have adopted the use of an alternate EUS-based classification system to diagnose CP (the Rosemont classification), which was developed from a consensus of internationally recognized endosonographers. The criteria are divided into major and minor criteria based on their perceived accuracy for diagnosing CP. In addition, the three major criteria are subdivided into major A and major B features depending on their predictive diagnostic accuracy. The major criteria include: hyperechoic foci with shadowing (major A), MPD calculi (major A), and lobularity with honeycombing (major B). The eight minor criteria include: lobularity without honeycombing, hyperechoic foci without shadowing, cysts, stranding, irregular MPD contour, dilated side branches, MPD dilation, and a hyperechoic MPD margin. Table 13.1 defines each criterion. Using these major and minor criteria, the Rosemont classification establishes a diagnosis that is “consistent with CP” if any of the following is present: 1 major A feature + ≥3 minor features, 1 major A feature + major B feature, or 2 major A features. EUS examinations “suggestive of CP” include the following: 1 major A + <3 minor features, major B and ≥3 minor features, or ≥5 minor features. Those classified as “indeterminate for CP” include: >2 minor features, <5 minor features without major features, or major B feature + <3 minor features. A “normal” result is one that has ≤2 minor features, excluding cysts, dilated MPD and side branches, hyperechoic foci without shadowing, and major features.
| Parenchymal Features | |
| Hyperechoic foci with shadowing | ≥3 echogenic structures ≥2 mm in length and width that shadow |
| Lobularity | Well-circumscribed, ≥5 mm structures with enhancing rim and relatively echo-poor center; ≥3 lobules in the body or tail need to be present With honeycombing: contiguous ≥3 lobules Without honeycombing: noncontiguous lobules |
| Hyperechoic foci without shadowing | ≥3 echogenic structures ≥2 mm in length and width with no shadowing |
| Cysts | Anechoic, round/elliptical structures with/without septations |
| Stranding | ≥3 hyperechoic lines ≥3 mm in length in at least 2 different directions with respect to the imaged plane |
| Ductal Features | |
| MPD calculi | Echogenic structure(s) within the MPD with acoustic shadowing |
| Irregular MPD contour | Uneven or irregular outline and ectatic course of the MPD; only assessed in the pancreatic body and tail |
| Dilated side branches | ≥3 tubular anechoic structures each measuring ≥1 mm in width, budding from the MPD; only assess from the pancreatic body and tail |
| MPD dilation | ≥3.5 mm in the body or ≥1.5 mm in the tail |
| Hyperechoic MPD margin | Echogenic, distinct structure greater than 50% of the entire MPD (on both the proximal and distal border) in the body and tail |
Comparison of Conventional and Rosemont Classification
As expected based on the definitions for each feature and multiple means in which the grouped criteria can be analyzed, the Rosemont classification is more stringent than the conventional classification and is more difficult to remember and employ in clinical practice. Comparative studies demonstrate that when using a cutoff of 3 criteria for the conventional classification more patients are diagnosed with CP; however, when using a cutoff of 5 features there is no significant difference in the number of patients diagnosed with CP using conventional classification as compared to the Rosemont classification when combining both “consistent with” and “suggestive of” CP. The Rosemont classification of “consistent with CP” is the most stringent threshold for diagnosing CP, even more than a cutoff of 5 features in the conventional means of classification.
Correlation of Endoscopic Ultrasound Findings and Surgical Histopathology
In a study assessing conventional EUS criteria in patients who later underwent pancreatic surgery, the presence of ≥4 criteria was the best predictor of histologic CP with a sensitivity, specificity, and accuracy of 90.5%, 85.7%, and 88.1%, respectively. There was also excellent correlation between the number of EUS features and the histologic fibrosis score ( r = 0.85, P < .0001). In particular, hyperechoic foci ( P < .0001), hyperechoic strands ( P > .001), lobularity ( P = .04), stones ( P < .001), dilated MPD ( P < .0001), irregular MPD ( P < .0001), irregular side branches ( P < .001), and hyperechoic MPD margins ( P = .03) were all significantly associated with fibrosis on histology. A dilated or irregular MPD had the highest sensitivity, specificity, and accuracy in determining the presence of fibrosis.
Another study also demonstrated that the presence of ≥4 EUS criteria predicted the presence of CP in patients who underwent total pancreatectomy with islet autotransplantation for noncalcific CP. However, the sensitivity, specificity, and accuracy in determining a fibrosis score ≥6 in the resected specimen was lower than the previous study at 61%, 75%, and 63%. They found a poor, but significant, correlation between EUS features and degree of fibrosis ( r = 0.24, P < .05). None of the individual conventional features was significantly predictive of the presence of fibrosis on univariate analysis. When linear regression was performed after adjusting for age, sex, BMI, smoking, and alcohol exposure, only MPD irregularity ( P = .02) was found to be predictive of CP. As expected, in another study that used a lower cutoff for the fibrosis score on surgically resected specimens (fibrosis score ≥2), the presence of ≥4 EUS criteria was shown to have a higher sensitivity and specificity of 84% and 100%, respectively.
The aforementioned study methodologies and results highlight a notable difficulty using the fibrosis score—namely, the lack of consensus regarding the appropriate threshold of this histologic criterion for diagnosing CP. Also, the use of a fibrosis score alone as a diagnostic gold standard for CP is problematic in that it may simply reflect the presence of “bland” fibrosis, which is fibrosis seen in the absence of parenchymal destruction or inflammation that is often present in asymptomatic patients without endocrine or exocrine dysfunction. Such “bland” fibrosis has been reported in the setting of alcoholism, advanced age, male gender, obesity, and cigarette smoking. This finding may be detected in patients without any evidence of CP with normal pancreatic imaging, function, and histology. However, there is some debate whether bland fibrosis indicates the presence of very early disease that is prone to progress in severity over time. This theory is unlikely to account entirely for this situation, given the unmatched finding of bland fibrosis in up to 60% versus the lifetime risk of 2% to 5% of CP in alcoholics. Whether bland fibrosis represents an early stage of CP and/or separate entity is unclear. Caution is needed when performing EUS because this clinically occult bland fibrosis may be indistinguishable from CP and can result in overdiagnosis ( Figs. 13.13 and 13.14 , Video 13.6 ).
CP (Normal)
EUS imaging demonstrates findings that were considered indicative of moderately severe chronic pancreatitis. However, core biopsy demonstrated a large quantity of completely normal pancreas. This patient highlights the limitations that can occur with EUS imaging. (See Fig. 13.36 .)
Certain individual and grouped criteria have been found to correlate with surgical pancreatic histology. In a study evaluating 100 patients with suspected CP who underwent EUS followed within 1 year by pancreatic resection, lobularity with honeycombing, hyperechoic foci with shadowing, dilated MPD, irregular MPD, and dilated side branches were each associated with histologically diagnosed severe CP. The highest odds ratio between EUS features and the histopathologic findings included hyperechoic foci with shadowing in the head of the pancreas and large duct diameter (odds ratio [OR] 10.9; 95% confidence interval [CI] 2.9 to 40.5), hyperechoic foci with shadowing in the head of the pancreas and calcifications (OR 8.8; 95% CI 2.6 to 28), pancreatic head cysts and pseudocysts (OR 12.9; 95% CI 3.2 to 52.3), MPD dilation in the head of the pancreas and large duct distortion (OR 12.8; 95% CI 2.6 to 62.9), dilated side branches in the head of the pancreas and large duct distortion (OR 6.4; 95% CI 1.9 to 22), lobularity with honeycombing in the body or tail of the pancreas and large duct distortion (OR 6.2; 95% CI 1.3 to 30.2), and cysts in the body or tail of the pancreas and pseudocysts (OR 32; 95% CI 4.6 to 222.6). Therefore, although the standard and Rosemont classification systems rely on evaluation of the body and tail of the pancreas, this study shows that findings in the head of the pancreas may also be important in the diagnosis of CP. However, until confirmatory data are generated, we encourage caution if adopting this practice given the common presence of altered EUS morphology within the pancreatic head even among patients without any clinical evidence of pancreatic pathology.
Interobserver Variability
One of the major limitations when using EUS to diagnose CP is the suboptimal interobserver variability (IOA). Using conventional criteria, IOA was determined between 11 expert endosonographers who reviewed EUS videotapes from 33 patients with suspected CP and 12 controls. The kappa was moderately good for the overall agreement on the presence of CP ( K = 0.45). In regard to individual features, only MPD dilation ( K = 0.6) and lobularity ( K = 0.51) had good agreement; the remaining seven features had poor IOA. Another study assessed same-day back-to-back EUS examinations by two different endosonographers on 24 patients without any evidence of pancreaticobiliary disease. Despite the lack of any clinical or imaging evidence of CP, 32% of patients had hyperechoic strands, 30% had hyperechoic ductal walls, 16% had hyperechoic foci, 14% had a dilated MPD, 9% had lobularity, and 5% had parenchymal cysts. The IOA between these two endosonographers was good for hyperechoic strands and parenchymal cysts, moderate for lobularity, dilated MPD, and hyperechoic foci, and fair for hyperechoic foci.
A multicenter study that compared IOA between expert endosonographers using both the conventional criteria and Rosemont classification found that there was moderate agreement ( K = 0.54; 95% CI 0.44 to 0.66) and substantial agreement ( K = 0.65; 95% CI 0.52 to 0.77), respectively. However, there was no statistically significant difference between classification systems. Other studies have similarly shown that the Rosemont classification does not improve IOA compared to the conventional classification.
Endoscopic Ultrasound Sampling
The main role of EUS FNA in CP is distinguishing focal (pseudotumoral) CP from pancreatic adenocarcinoma (PaC) and other neoplasias. PaC is found more commonly in patients with underlying CP than the general population with a cumulative risk of 1.8% (95% CI 1% to 2.6%) at 10 years and 4% (95% CI 2% to 5.9%) at 20 years. Some have found that EUS imaging alone may be insufficient in differentiating between the two. EUS FNA of pancreatic masses has a lower sensitivity in the presence of CP and more passes may be required to establish a diagnosis. The lower diagnostic sensitivity may result from incorrectly targeted biopsies due to the inability to discern the tumor from peritumoral CP changes with EUS imaging. In addition, cytologic interpretation is more challenging when specimens contain limited malignant material along with nontumoral CP material. For more details, see the section on Benign Pancreatic Masses.
Image-Enhancing Techniques in Endoscopic Ultrasound
Endoscopic Ultrasound Elastography
EUS elastography has been shown in several studies to enhance the EUS diagnostic accuracy of CP, with its objectivity helping to overcome the limitations of EUS interobserver variability. Elastography assesses tissue stiffness by applying slight compression and comparing images before and after compression to determine the degree of tissue displacement. In patients with known or suspected CP, there was a negative correlation with mean value and number of Rosemont features on EUS ( r = −0.59, P < .001). A mean elastography value of 90.1 ± 19.3, 73.2 ± 10.6, 63.7 ± 14.2, and 56.1 ± 13.6 was found in patients meeting the Rosemont criteria for normal, indeterminate for CP, suggestive of CP, and consistent with CP categories ( P < 0.001 for differences between each stage), respectively. A mean strain ratio (SR; quotient B/A ratio with area A corresponding to the largest possible area of the pancreatic parenchyma and area B as the reference area corresponding to the normal surrounding gut wall) taken from an average of the head, body, and tail was found to have a direct linear correlation to the number of EUS Rosemont criteria ( r = 0.813, P < 0.0001) with an area under the ROC curve of 0.949 (95% CI 0.916 to 0.982).
EUS elastography has also been used to predict exocrine insufficiency in patients with CP. The 13(C)-mixed triglyceride breath test was used to diagnose exocrine insufficiency in 35 patients (30.4%) diagnosed with CP by MRI/MRCP and EUS. A higher SR (quotient B/A ratio corresponding to the pancreatic parenchyma for area A and a soft peripancreatic reference as area B) of 4.89 (95% CI 4.36 to 5.41) was found in patients with pancreatic insufficiency than those with normal breath tests (2.99; 95% CI 2.82 to 3.16, P < .001). In addition, patients with a SR >5.5 were 92.8% likely to have pancreatic insufficiency.
Advanced Endoscopic Ultrasound Techniques
Endoscopic Ultrasound-Guided Celiac Plexus Block
Although many patients with CP suffer from abdominal pain that is occasionally severe and intractable, there are limited treatment options. Celiac plexus block (CPB) is an option in select patients and involves the injection of a local anesthetic and steroid into the celiac plexus and/or directly into celiac ganglia. CPB has historically been performed by surgeons or radiologists, but EUS-guided CPB has become the preferred approach due to the close proximity of the echoendoscope to the celiac takeoff, use of Doppler to confirm the lack of intervening structures, and continuous imaging to guide needle placement. More information regarding the indications, contraindications, risks, role, and technique may be found in Chapter 25 .
Acute Pancreatitis
Brief Overview
Acute pancreatitis (AP) most commonly presents as acute epigastric or left upper quadrant abdominal pain that may radiate to the back, chest, or flank. The diagnosis of AP is made when at least 2 of the following criteria are met: (1) abdominal pain consistent with the disease, (2) serum amylase and/or lipase >3 times the upper limit of normal, and (3) characteristic findings from abdominal imaging. As acute biliary pancreatitis is a main cause of AP (40% to 70%), transabdominal ultrasound has a primary role in the evaluation. Routine cross-sectional imaging with CT or MRI is not recommended, but may be considered in patients who do not improve after 48 to 72 hours.
Role of Endoscopic Ultrasound
Acute Biliary Pancreatitis
The ASGE guidelines concerning the role of endoscopy for suspected choledocholithiasis propose predictors of biliary disease as seen in Table 13.2 . The likelihood of choledocholithiasis was considered to be high (>50%) if any “very strong” predictor or both “strong” predictors were present. If no predictors were present, then the likelihood was low (<10%). An indeterminate likelihood (10% to 50%) of choledocholithiasis was considered in all other patients. Based on their recommendations, patients with high likelihood should undergo ERCP prior to cholecystectomy, whereas patients with low likelihood can be taken directly to cholecystectomy. Those in the indeterminate category should have a cholangiogram performed either intraoperatively or by preoperative EUS or MRCP. Some favor EUS in this situation due to the ability to perform ERCP and stone clearance in the same setting ( Fig. 13.15 , Video 13.7 ). By adopting these criteria and performing EUS in patients with an indeterminate likelihood, unnecessary ERCP may be avoided in nearly half (44%) of patients.
| Very strong predictors | CBD stone on transabdominal ultrasound Clinical ascending cholangitis Bilirubin >4 mg/dL |
| Strong predictors | Dilated CBD on ultrasound (>6 mm in patients with gallbladder in situ) Bilirubin 1.8–4 mg/dL |
| Moderate predictors | Abnormal liver biochemical test other than bilirubin Age >55 years old Clinical gallstone pancreatitis |
Sludge, Stone
In a patient with recurrent acute pancreatitis, EUS imaging of the distal bile duct identified a calcified stone that produced postacoustic shadowing (first arrow) and adjacent sludge that was nonshadowing (second arrow). (See Fig. 13.1 .)
A systematic review of randomized control or clinical trials that compared ERCP and EUS for suspected acute biliary pancreatitis found that EUS had a higher success rate of completion than ERCP, largely due to the presence of duodenal/ampullary edema that impaired performance of ERCP. It was estimated that a mean of 71.2% of unnecessary ERCPs could be avoided with the use of EUS. There were no adverse events in the EUS group, whereas 10 patients who underwent ERCP developed postsphincterotomy bleeding.
A study evaluating early EUS (within 24 hours of admission) in 41 patients with suspected acute biliary pancreatitis with a negative CT reported the detection of choledocholithiasis or bile duct sludge in 49% of patients. EUS has also proven useful in this setting through detection of ampullary adenocarcinoma that was otherwise undetected by cross-sectional imaging ( Figs. 13.16 to 13.18 , Video 13.8 ).
AIP and PaC
A 49-year-old female presented with painless jaundice. At the referring hospital she underwent nondiagnostic CT, MRI/MRCP, ERCP (×2), and EUS (×2) and she was referred for second opinion. EUS revealed a well-circumscribed 1.5 cm isoechoic ampullary mass that on cytology was diagnostic for an ampullary adenocarcinoma. (See Fig. 13.29 .) Additional EUS imaging revealed changes in the pancreatic tail that were concerning for AIP, which was confirmed on EUS guided core biopsy and surgical resection specimen. (See Figs. 13.21 and 13.22 .)
Acute Idiopathic Pancreatitis
Idiopathic pancreatitis is defined as pancreatitis without an established etiology after obtaining a thorough history (e.g., alcohol intake), laboratory testing (calcium, triglyceride), and imaging (transabdominal ultrasound, CT, and/or MRI/MRCP). EUS has been shown to be helpful in the evaluation of idiopathic AP, but unlike suspected acute biliary pancreatitis where EUS is performed during the index hospitalization to guide management, in this setting EUS is typically performed at least 4 to 6 weeks following the episode of acute idiopathic pancreatitis to allow the acute inflammatory changes to resolve. In patients with prior negative transabdominal ultrasound, CT and/or MRI/MRCP, EUS has been shown to determine a cause in 55% to 79% of patients. Biliary disease, including cholelithiasis, gallbladder sludge, choledocholithiasis, or common bile duct (CBD) sludge, is the most common etiology identified in patients with a positive EUS. Other findings such as CP, pancreas divisum, pancreatic cysts, tumors, and other pathology ( Figs. 13.19 and 13.20 ) may also be detected by EUS. A suggested algorithm for the approach to acute idiopathic pancreatitis can be seen in Fig. 13.21 .
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