A 30-year-old Indian woman was referred with recurrent episodes of acute pancreatitis;
she had experienced four episodes in the previous 7 months. There was no history of
alcohol or drug intake. She was diagnosed with idiopathic recurrent acute pancreatitis
(IRAP), as results of blood investigations, ultrasonography, computed tomography (abdomen),
and magnetic resonance cholangiopancreatography were normal. Linear endoscopic ultrasound
(EUS) was performed to diagnose the etiology of IRAP.
Linear EUS from the duodenal bulb showed a round echogenic shadow in the head of the
pancreas ([Fig. 1 a]). It also revealed a linear echogenic mobile structure without acoustic shadow in
the common bile duct (CBD) ([Fig. 1 b]). The linear echogenic mobile shadow was coiling within the CBD, confirming the
diagnosis of a biliary ascariasis ([Fig. 1 c]). This linear structure had two hyperechoic linear strips on either side of the
longitudinal anechoic lumen, representing the fluid-filled alimentary canal of the
worm (“double tube sign” or “inner tube sign”) ([Fig. 1 d, e]; [Video 1]). On side-viewing endoscopy, one creamy-white worm was seen, partially lying outside
the papilla. The worm was extracted using biopsy forceps and identified as Ascaris lumbricoides ([Fig. 2]; [Video 1]). The worm was 10 cm long. Subsequently, the patient received de-worming treatment
with albendazole. At the follow-up visit, the patient was asymptomatic, and EUS revealed
a normal CBD.
Fig. 1 Linear endoscopic ultrasound (EUS) images. a EUS from the duodenal bulb showed a round echogenic shadow in the common bile duct
(CBD). b A linear echogenic structure without acoustic shadow was seen in the CBD. On color
Doppler, blood flow could be seen in the inferior vena cava (IVC). c The linear echogenic shadow was seen coiling in the CBD. d, e The linear structure had two hyperechoic linear strips on either side of the longitudinal
anechoic lumen, representing the fluid-filled digestive tract of the worm (“double
tube sign” or “inner tube sign”). RRA, right renal artery.
Video 1: Linear endoscopic ultrasound from the duodenal bulb showed a linear echogenic
mobile structure without acoustic shadow coiling in the common bile duct, with two
hyperechoic linear strips on either side of the longitudinal anechoic lumen. On side-viewing
endoscopy, one creamy-white worm was visualized outside the papilla; it was removed
using biopsy forceps and identified as Ascaris lumbricoides.
Fig. 2 (Still Image) On side-viewing endoscopy, one creamy-white worm was seen partially
lying outside the papilla.
Ascaris lumbricoides infestation is endemic in tropical countries. Although most infections by roundworms
are asymptomatic, they can produce diverse manifestations, including hepatobiliary
and pancreatic complications [1]. Ascaris is a common etiology of acute pancreatitis in developing countries. The mechanism
of ascariasis-induced acute pancreatitis includes obstruction of the ampulla of Vater,
and invasion of the CBD or pancreatic duct [2]. Endoscopic intervention is the treatment of choice. Worms visible at the papilla
are removed endoscopically using a basket or forceps [3]. To conclude, biliary ascariasis should be considered in the differential diagnosis
of IRAP, particularly in endemic regions.
Endoscopy_UCTN_Code_CCL_1AF_2AZ
