Keywords
Double Duct Sign - Sphincter of Oddi Dysfunction - Endoscopic Ultrasound - Morphine
- Opium
Introduction
Dilatation of the common bile duct (CBD) along with pancreatic duct (PD) is an important
radiological sign suggesting an obstruction at the distal portion of both the CBD
and PD.[1] The presence of a double duct sign should ensure a careful search for underlying
etiology. Though periampullary malignancy is the most common cause, benign diseases
such as chronic pancreatitis and sphincter of Oddi dysfunction (SOD) can also lead
to double duct sign. SOD is due to a functional obstruction at papilla and high index
of suspicion is required for diagnosing this condition after ruling out other structural
causes. We hereby report a rare cause of SOD giving rise to a double duct sign.[2]
Case Presentation
A 57-year-old male businessman presented with complaints of episodes of noncolicky
epigastric pain, without any history of fever, jaundice, or weight loss. Each episode
used to last 5 to 6 hours with either spontaneous improvement or with parenteral analgesics.
Clinical examination was unremarkable without any icterus or abdominal lump. Blood
investigations revealed elevated liver enzymes that were suggestive of cholestatic/obstructive
pattern. Serum bilirubin value was normal (1.2 mg/dL), and serum alkaline phosphatase,
gamma glutamyl transpeptidase, serum glutamic pyruvic transaminase, and serum glutamic-oxaloacetic
transaminase values were 579 IU/L, 2,309 IU/L, 249 IU/L, and 186 IU/L, respectively.
Ca 19-9 was elevated to two times the upper limit of normal. Viral markers hepatitis
B surface antigen, anti-hepatitis C virus, immunoglobulin M (IgM) anti-hepatitis A
virus, IgM anti-hepatitis E virus were negative. Ultrasound (US) abdomen revealed
dilated CBD measuring 12 mm till the lower end without any stone or mass lesions,
and distended gallbladder with sludge. Triple-phase computed tomography revealed dilated
CBD and PD measuring 12 and 8 mm, respectively, till lower end without any mass lesion
([Fig. 1]). Magnetic resonance cholangiopancreatography showed dilatation of bilobar intrahepatic
biliary radicles, bile duct, and PD without any mass lesion ([Fig. 2]). Endoscopic US (EUS) ([Video 1]) was performed that showed dilated CBD and PD till ampulla without any mass lesion
or stone, smooth symmetrical narrowing of bile duct and PD at papilla, symmetrically
thickened ampullary without any mass lesion ([Fig. 3]), and normal pancreatic parenchyma without any evidence of chronic pancreatitis.
Based on clinical, biochemical and imaging findings, differential diagnoses of ampullary
neoplasm and SOD were considered. Human immunodeficiency virus serology was negative.
Clinical history was revisited, which revealed significant opium intake for the last
20 years for recreational purpose. Based on clinical findings, imaging, and EUS, patient
was suspected to have SOD, and decision to perform endoscopic retrograde cholangiopancreatography
(ERCP) and sphincterotomy was taken after explaining the procedure details and possible
complications to the patient. Side-view endoscopy revelated stenotic opening ([Fig. 4]) at the papilla, which could be cannulated with maneuvering. Endoscopic papillotomy
was performed that also revealed thick ampullary muscle. ([Video 1]) Ampullary biopsy was taken which did not reveal dysplasia or malignancy ([Fig. 5]).
Fig. 1 Computed tomography findings showing double duct sign.
Fig. 2 Magnetic resonance cholangiopancreatography findings showing double duct sign.
Fig. 3 Endoscopic ultrasound showing double duct in the absence of mass lesion and smooth
tapering of ducts.
Fig. 4 Side-view endoscopy showing stenotic and thickened papilla.
Fig. 5 Ampullary biopsy—negative for malignancy or granuloma.
Patient was discharged after 24 hours of the procedure and was symptom free after
3 months of procedure. Repeat investigations revealed normalization of liver function
test and Ca 19-9. Patient was advised to stop the opium intake and was advised for
enrollment in a de-addiction clinic. He is under continuous follow-up to rule out
the possibility of occult biliary malignancy.
Discussion
Dilated pancreatic and common bile duct (double duct sign) commonly occur due to periampullary
malignancy. Chronic pancreatitis and SOD are possible benign differentials that should
be considered in patients without mass lesion on imaging.
SOD refers to an abnormality of Sphincter of Oddi contractility causing obstruction
to the flow of bile or pancreatic juices.[3] Sphincter of Oddi manometry had been identified as a gold standard for diagnosis
of SOD; however, it is invasive and associated with morbidity and hence has been largely
abandoned. Patients with type 1 SOD should be treated with endoscopic sphincterotomy
without manometry.[4]
In our case, SOD was considered as likely possibility due to significant history of
opium intake and absence of mass lesion or chronic pancreatitis on imaging. EUS is
an important investigation to diagnose this condition by ruling out other etiologies
such as neoplastic lesions or chronic pancreatitis.[5] Other EUS findings supporting the diagnosis were smooth symmetrical narrowing of
ducts at ampulla and symmetrically thickened ampullary muscles. ERCP findings of circumferential
thickening of ampullary muscle also supported the diagnosis of SOD.
Morphine and its derivatives can increase sphincter tone and result in SOD.[6]
[7] Morphine use can cause a rise in basal pressure of sphincter of Oddi along with
a rise in amplitude and frequency of phasic contractions. CBD pressures have also
been shown to increase after morphine intake. Hence, opium deaddiction forms a cornerstone
in the management of opium-induced SOD as it helps to reverse the pharmacological
effects of morphine. However, prolonged opium use can also lead to bulky tumorous
changes in ampulla with ulceration.[8] In such cases, long-term improvement has been seen after endoscopic sphincterotomy.[7]
[9] Therefore, a history of opium abuse must be sought in every patient presenting with
double duct sign without evidence of a mass lesion causing ampullary obstruction.
Conclusion
Opium intake can lead to SOD and dilated PD and bile duct. EUS is an important diagnostic
modality in such cases to rule out small ampullary tumors. Endoscopic sphincterotomy
can lead to long-term relief of symptoms in patients with SOD.
Video 1
0:00-0:34: Endoscopic ultrasound examination revealed dilated bile duct and pancreatic duct
with smooth narrowing at ampulla, symmetrical thickening of ampullary muscle without
any mass lesion. 0:34-1:23: Cannulation of stenotic ampulla. 1:23- 2:18: Endoscopic sphincterotomy with balloon sweep of bile duct.
