| Keywords
Endosonography, pancreatitis
Introduction
Endoscopic ultrasound (EUS) has proved to
be very sensitive for assessing pancreatic and biliary pathology
(1, 2). EUS's accuracy in pancreaticobiliary disease is complimented
by its low morbidity. As long as the echoendoscope is not
being forced through a stricture, EUS is reported to have
only the rare major complications generally associated with
upper endoscopic, i.e. perforation and cardiopulmonary problems
(3). Because of the combination of low morbidity and high
pancreaticobiliary accuracy, EUS is often used in preference
to diagnostic ERCP specifically to avoid the potential for
ERCP-induced pancreatitis. We report the second case of acute
pancreatitis associated with diagnostic EUS and believe this
very rare complication may need to be added to the rare risks
associated with diagnostic EUS.
Methods for EUS Capture
Images were scanned from original thermal
prints.
Case Summary
The patient is a 33 year old white male
with at least twelve bouts of relatively mild recurrent pancreatitis
over the past five or six years. His last attack resulted
in being briefly hospitalized two weeks earlier at which time
his maximum amylase was only 240 and an abdominal CT showed
minimal generalized pancreatic enlargement. The patient drank
only 3 to 4 beers per month and his lipids and calcium have
been normal. Previous abdominal ultrasounds had not shown
any gallbladder pathology and he had never had an ERCP. Interestingly,
the patient's father, a heavy alcohol user, also had recurrent
pancreatitis starting in his early thirties and died from
pancreatic cancer in his fifties.
As part of his initial evaluation at our
institution, the patient underwent a diagnostic EUS. He was
totally asymptomatic at the time. EUS was performed as previous
described (4) with a pre-EUS endoscopy (5) with the Pentax
EG 2901 videoendoscope (Pentax Precision Instrument Corp.,
Orangeburg, NY). This showed only some mild changes of reflux
esophagitis. Diagnostic EUS was then performed using the Olympus
GF-UM20 echoendoscope (Olympus America, Inc., Lake Success,
NY) at both 7.5 and 12 MHz. The echoendoscope was initially
handled by a senior gastroenterology fellow (AC) and subsequently
by a staff gastroenterologist (RAE). The total duration of
the procedure was 60 minutes with 45 minutes being spent in
the duodenum assessing the pancreatic and biliary ductal anatomy
to rule out pancreas divisum and examining the gallbladder.
The patient required 15 mg of midazolam and 150 mg of meperidine
to maintain sedation throughout the procedure. Approximately
200 ml of sterile water was insufflated into the duodenum
throughout the duodenal exam to optimize endosonographic visualization
using the Olympus endoscopic water insufflator Model UWS-1.
EUS showed the pancreatic duct was only
2 mm in maximal diameter but there were some changes, primarily
in the pancreatic head, consistent with chronic pancreatitis
(2). These changes included echogenic foci and stranding,
nodularity and echogenicity of the pancreatic duct wall (fig.
1). The patient had a prominent duct of Santorini with a "crossed-duct
sign" suggestive of a pancreas divisum (6). However,
after further evaluation, he appeared to have a normal "stack
sign" with the common bile duct and main pancreatic duct
simultaneously seen arising out of the main ampulla which
would make a classic pancreas divisum unlikely (7). His common
bile duct measured only 3 mm but the gallbladder neck contained
a 5-6 mm sessile somewhat echogenic polypoid lesion which
shadowed slightly (fig. 2). This lesion was most consistent
with a cholesterol polyp (8). The patient had a prolonged,
four hour stay in our endoscopy recovery room after the procedure
complaining of nausea which was eventually relieved by 25
mg of intramuscular promethazine. However, approximately ten
hours after the procedure the patient came back to our Emergency
Room complaining of progressively increasing, severe abdominal
pain and nausea.
His vital signs were normal but his bowel
sounds were hypoactive and he had diffuse abdominal tenderness
without rebound. On admission his laboratories showed WBCs
of 18,500, hemoglobin 15.8 g/dL, amylase 1,060 IU/L (28-100),
lipase 6,110 IU/L (166-292), calcium 8.7 mg/dL, triglycerides
137 mg/dL, normal electrolytes and normal liver tests. An
acute abdominal series showed only a non-specific bowel gas
pattern with no free air. An abdominal CT the next day revealed
mild heterogeneity of the pancreas with peripancreatic stranding
(fig. 3), a few fluid-filled loops of bowel consistent with
a local ileus, some free fluid around the tail of the pancreas
and spleen, bibasilar atelectasis and small bilateral pleural
effusions. The patient was treated with bowel rest, fluid
resuscitation, analgesics and made a slow recovery over the
next eight days and was discharged.
Discussion
Discussion: We believe this patient represents
the second case of acute pancreatitis reported after diagnostic
endoscopic ultrasound. Kulling et al. reported a remarkably
similar case of acute pancreatitis after a diagnostic EUS
(9). Like our case, their patient was young (a 22 year old
woman) and had idiopathic recurrent pancreatitis for a number
of years prior to the EUS. In addition, their patient had
an anomaly of the pancreas on subsequent ERCP, ansa pancreatica
(10). The etiology of recurrent pancreatitis in our patient
is still uncertain. The cholesterol polyp may suggest microlithiasis;
however, the history of pancreatitis in his father raises
the possibility of familial pancreatitis. The prominent duct
of Santorini may suggest our patient, like the previously
reported case, may have some anomaly of the pancreatic ductal
system. However, this has yet to be confirmed in our patient
as he is understandably reluctant to consider having an ERCP
at this time.
Although acute pancreatitis has been reported
after diagnostic endoscopy (11), it is an extraordinarily
rare complication. The mechanism by which endoscopy or diagnostic
EUS could cause pancreatitis is unknown. Since mechanical
trauma to the ampulla by either biopsy (12) or unsuccessful
attempts at cannulation during failed ERCP (13) can cause
acute pancreatitis, EUS- induced pancreatitis may likewise
be secondary to excessive mechanical trauma to the ampulla
in a patient predisposed to developing pancreatitis. This
may lead to ampullary spasm or edema resulting in excessive
pancreatic duct pressure and ensuing pancreatitis.
EUS may be more prone to inducing pancreatitis
than standard endoscopy for at least three reasons. High risk
patients with recurrent pancreatitis are often undergoing
diagnostic EUS as part of their evaluation. This type of patient
is clearly at higher risk for pancreatitis after ERCP or sphincter
of Oddi manometry (13). Additionally, much more time is typically
spent in the duodenum during EUS than with standard endoscopy
since it is there that the pancreatic head, ampullary region
and extrahepatic biliary tree is examined (14). Finally, the
water-filled balloon used for acoustic coupling may also result
in additional mechanical trauma to the ampullary region through
compression or rubbing. It is doubtful that water insufflation
into the duodenum could cause any clinically significant increase
in luminal pressure as the water can flow freely proximally
and distally through the duodenum. The acoustic energy produced
by the transducer of an echoendoscope is quite small (15)
and it would seem unlikely that it could induce pancreatitis
itself.
Since this case and the one previously reported
are nearly identical in their clinical circumstances, we believe
that acute pancreatitis should be added to the list of rare
complications associated with diagnostic EUS in patients with
a history of recurrent pancreatitis. Since tens of thousands
of EUS exams have been performed over the last decade with
now only two reported cases of pancreatitis, the incidence
of this complication must be very low. As demonstrated by
these two cases, this risk may be limited to those younger
patients with a significant previous history of recurrent
acute pancreatitis. It is unknown whether any change in EUS
technique could reduce the risk of pancreatitis in such high
risk patients. However, in patients with a history of recurrent
pancreatitis, it would make pathophysiologic sense to try
and minimize mechanical trauma to the ampulla during diagnostic
EUS by spending as short a time as possible in the duodenum,
avoiding excessive balloon insufflation and minimizing physical
contact between the echoendoscope and the ampulla.
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