EUS and Acute Pancreatitis

Robert KavittMarch 16, 2011

Definition of IAP (Idiopathic acute pancreatitis)

Imaging modalities in IAPReview of literature regarding use of

EUS in IAPEUS and gallstone pancreatitisEUS imagesEUS and autoimmune pancreatitis

EUS of a Normal Pancreas

BP: Body of pancreas

PD: Pancreatic duct

SV: Splenic vein

DefiningIdiopathic AcutePancreatitis (IAP)

Idiopathic Acute PancreatitisCause of acute pancreatitis unidentified in >10%, after

abd u/s, CT, and labsPatients often undergo ERCP, especially when they

have recurrent bouts of pancreatitisERCP establishes etiology in 30-60% of these patientsPredominant findings include biliary calculi, chronic

pancreatitis, pancreatic tumors, and SOD dysfunctionEUS should also be useful as it can diagnose missed

biliary tract disease, chronic pancreatitis, and small pancreatic tumors

EUS carries less risk than ERCP

Idiopathic Acute PancreatitisIn many cases the possibility of finding a cause of the

pancreatitis depends directly on how deep the etiological search is made

Can find gallbladder microlithiasis, SOD dysfunction, pancreas divisum, chronic pancreatitis, pancreatic tumors or cysts, long pancreatiobiliary junction, annular pancreas, choledococele, duodenal duplication cyst, or periampullary diverticulum as cause of acute pancreatitis

In patients under 40 without mechanical or anatomic causes, check gene mutations (mutations of cationic trypsinogen gene, serine protease inhibitor Kazal type 1, or mutation in CFTR)

If not corrected, up to 70% of acute pancreatitis episodes may recur, depending on the cause

Mortality rate 4-9% for acute pancreatitis

Imaging Modalities in

Idiopathic Acute Pancreatitis

ERCPHas been the 1st choice of diagnostic procedures

in patients with IAP for the past 3 decades10-15% rate of potentially severe complicationsAble to perform therapeutic maneuvers necessary

in up to 75% of these patientsSome authors advise ERCP only after 2nd episode

of IAP or after the 1st episode if severeOthers support systematic use of ERCP after 1st

IAP episode

MBE (Microscopic Bile Examination)

Microlithiasis present in up to 80% of IAP patients with gallbladders

MBE sensitivity 65-90%, specificity 88-100% in diagnosis of microlithiasis

MBE is falsely negative in 29-50% of patients with known gallbladder lithiasis

Not feasible in up to 20% of patients (due to inability to place nasoduodenal probe in 2nd portion of dudodenum, aspiration of inadequate material, or patient intolerance)

MRCPMay diagnose chronic pancreatitis, SOD

dysfunction, anatomic anomalies, and choledocholithiasis

May be useful, especially when combined with secretin test, showing a PPV for diagnosis of SOD dysfunction of 100% (NPV 64%)

EUS vs. MRCP49 patients with dx of idiopathic acute pancreatitis, evaluated

prospectively with EUS and MRCP, then diagnoses compared between the 2 modalities

In 28 patients (57%), EUS and/or ERCP diagnosed at least 1 possible cause

Diagnostic yield of EUS higher than MRCP (51% vs. 20%, p=0.001)Cholelithiasis and biliary sludge (24%) most frequent EUS dxPancreas divisum (8%) most frequent MRCP dxOnly in 3 cases (6%) did MRCP identify additional features in

patients etiologically undiagnosed using EUSEUS yield lower in patients with prior cholecystectomy (11% vs.

60%, p=0.008)

EUS

Diagnostic accuracy of 60-80% in patients with IAPOffers ability to FNA and analyze cyst fluid for tumor

antigens, fluid viscosity, mucin staining, amylase concentration, analysis of genetic mutations associated with tumors, and cytology

GIE 2009 (Artifon et al): Report of performing sphincterotomy on EUS

If microlithiasis is diagnosed, a cholecystectomy reduces the recurrence of pancreatitis from 66-75% in untreated patients to 10% in patients who undergo cholecystectomy

EUS in Idiopathic Acute Pancreatitis

Aim to determine utility of EUS in patients with idiopathic acute pancreatitis and whether subsequent ERCP is needed

Review of prospectively collected database, with follow-up telephone interviews

EUS diagnosis compared with final diagnosis and outcome

EUS in Idiopathic Acute Pancreatitis

• EUS revealed etiology of pancreatitis in 21/31

• Microlithiasis in 5• Chronic pancreatitis in 14• Pancreas divisum in 2• Pancreatic cancer in 1• Not diagnostic in 10 (32%)

EUS in Idiopathic Acute Pancreatitis

Mean follow-up period of 16 months; Dx changed in 4; 9 had ERCP because of persistent symptoms or recurrent pancreatitis

Conclusion: EUS determined etiology in two-thirds, and most did not require ERCP during follow-up period. EUS can be alternative to ERCP in patients with unexplained acute pancreatitis.

Disadvantages of EUS as Initial Endoscopic Test

This approach delayed diagnosis in 4 patients, whose diagnoses of pancreatic duct stone, SOD dysfunction, pancreas divisum, and IPMN were not made sonographically

In each of these cases, ERCP was performed because of recurrent symptoms, and demonstrated the correct diagnosis

J Pancreas, March 2009Retrospective analysis of all biliary EUS studies from

2000-200442 patients with negative prior radiological

investigations

EUS normal in 17, noted signs of recent acute pancreatitis but not other etiology in 8, noted cholelithiasis or microlithiasis in 9, combined gallstones/microlithiasis and choledocholithiasis in 6

1 patient had calculi in CBD but not the gallbladder1 patient had signs of chronic pancreatitis

J Pancreas, March 2009All patients with CBD stones underwent ERCP and

sphincterotomy, and stones were confirmed in allEUS provided additional diagnostic info in 17/42

(40.5%)Most cases of cholelithiasis can be diagnosed with

standard imaging modalities but when these fail to identify a cause, EUS has an important role to play.

J Pancreas, March 2009Stone pathology identified in 16/42 patients in

whom other imaging modalities failed to identify lithiasis

EUS has a reported sensitivity of up to 100% and specificity as high as 95.4%, with a negative predictive value as high as 100% for detection of CBD stones wich are the cause of acute biliary pancreatitis

EUS especially beneficial for detecting stones smaller than 5 mm

Then why not EUS everyone?

“Given the superiority of EUS over other imaging modalities, it may be argued that EUS be used in the investigation of all cases of acute pancreatitis in which no calculi are observed in either the gallbladder or CBD on trans-abdominal US…

However, given the limited availability of EUS and pressures on skilled operators to perform non-biliary investigations, we would suggest that all patients with acute pancreatitis undergo a trans-abdominal US and also have routine biochemical investigations to look for hypercalcaemia and hyperlipidaemia…

A careful drug history is important in particular in relation to statins as these drugs are now widely prescribed as lipid lowering agents, and are associated with acute pancreatitis. We then perform an MRCP as our next investigation of choice, with EUS limited to those in which no cause for acute pancreatitis has been identified. In the future, as EUS proliferates, it may then become the investigation of choice.”

EUS and Gallstone

Pancreatitis

Gallstone PancreatitisLiu et al GIE 2001: “Detection of choledocholithiasis by

EUS in acute pancreatitis: a prospective evaluation in 100 consecutive patients”

Study of 100 consecutive patients with acute pancreatitis who underwent transabdominal u/s, EUS, and ERCP

EUS was more sensitive than transabdominal u/s for detecting gallbladder stones (100% vs. 84%)

Sensitivities of ERCP and EUS for choledocholithiasis were both 97%

EUS correctly identified the absence of choledocholithiasis in 65 of 66 patients (specificity 98%)

Gallstone Pancreatitis

EUS may have a role in reducing uncertainty about whether there is a retained CBD stone in patients with gallstone pancreatitis.

EUS may help clarify the diagnosis in those with apparent idiopathic pancreatitis or abdominal pain in whom a biliary source cannot be firmly excluded.

EUS Images

Choledocholithiasis

Gallstone in Gallbladder

CBD Stones

Elongated stone in CBD

ERCP showing stone in CBD

Stone being removed from CBD with basket after sphincterotomy

EUS and AutoimmunePancreatitis

Autoimmune PancreatitisEnlargement of pancreatic gland, diffuse narrowing of

Wirsung duct with an irregular wallElevated IgG4Marked lymphoplasmacytic infiltration and dense

fibrosisIgG4 (cutoff 135 mg/dl)

Sensitivity 95%, Specificity 97%, for distinguishing autoimmune pancreatitis from pancreatic cancer

Type I: W. Europe and U.S. (IgG4 negative)Type II: Asia

Autoimmune PancreatitisFarrell et al, GIE 2004: “EUS findings in patients with

autoimmune pancreatitis”Features of autoimmune pancreatitis on EUS are easily

mistaken for malignancyDiffusely hypoechoic, enlarged pancreas, together with

chronic inflammatory cells in aspirated cytologic specimens, is supportive of the diagnosis of autoimmune pancreatitis

When combined with clinical data, EUS and EUS-guided FNA may support this diagnosis, may warrant a trial of steroids, and may prevent unnecessary surgery

Timing: When to EUS?Reports range from when patients resume food

intake, to when acute pancreatitis bout has resolved during admission, to 2-3 weeks after acute phase, to at least 4 weeks after acute episode (in order to ensure that parenchymal changes have resolved)

Likely should wait at least 4 weeks, to avoid misdiagnosis and to differentiate gallbladder microlithiasis related to acute pancreatitis fasting from previously present microlithiasis

But: Delay in EUS has potential risk of losing patient for f/u once asymptomatic, and a small pancreatic tumor could be missed