Figure 1a

Figure 1b





Since its introduction in the early 1980s Endoscopic ultrasound (EUS) has gained popularity with the improvement of imaging, flexible endoscopes and larger channels to allow biopsies and interventions. EUS using 7.5 MegaHz frequency and 9 cm diameters (4.5 cm scan radius) is shown above (Figure 1a&b). EUS scan showed a dilated common bile duct (CBD) a hypoechoic tubular structure nearer to the transducer with hyperechoic structures within the CBD casting acoustic shadows. The portal vein is the tubular structure behind the CBD. A diagrammatic representation is shown below (Figure 2a). Figure 2b show the normal anatomy of the distal common bile duct area.


Figure 2a: Diagrammatic representation of the EUS image showing distal common bile duct viewed from within the duodenum with stones casting acoustic shadows.

Figure 2b: Distal common bile duct, pancreatic duct and the portal vein all in one view forming the ‘Stack sign’ (view from within the duodenum).  


EUS is particular good for examinations of structures close to the GI lumen and the role of EUS are well defined and evaluation of certain upper GI pathologies (Table 1). The indications for EUS continue to increase as the endoscope technology, accessories and our knowledge improve.


Use of EUS in the management of choledocholithiasis is particularly good for the low or moderate probability for CBD stones (i.e. normal US scan but abnormal cholestatic liver profile). Those with high probability (abnormal US scan and abnormal liver profiles should just proceed directly to ERCP). EUS can obviate the need for any ERCP intervention if the CBD is normal and hence avoid the associated risk of ERCP (pancreatitis 4-20% and bleeding <5%).



Table 1: Defined indication of EUS evaluations




Staging of oesophageal tumour


Staging of lung tumour


Assessment of mediastinal lymph nodes or structures


Local staging of gastric tumour


EUS guided transgastric drainage of abscess, pancreatic necrosis, biopsy of liver, pancreas, adrenal or lymph nodes


Evaluation of submucosal tumours/lesions (lipoma, leiomyoma, GIST, pancreatic rest cells, linnitus plastica etc...)


Evaluation of pancreatic tumour, cysts or infective lesions (including FNA)


Staging of pancreatic tumour


Transgastric drainage of abscess or collections/necrosis

Hepatobiliary Assessment of hepatic lesions especially in the left lobe
  Assessment of the biliary tree especially the distal common bile (commonly difficulty to examine with transcutaneous US)
  EUS guided CBD cannulation and drainage
Rectum Local staging of rectal tumour
  Assessment of rectal lesions: mucosal or submucosal
  EUS guided drainage of peri-rectal abscesses
Prostate Assessment/Staging of prostate carcinoma

EUS guided prostate FNA




Images prepared by Dr Chong Vui Heng, Consultant Gastroenterologist & Hepatologist, Department of Gastroenterology & Hepatology, RIPAS Hospital, Brunei Darussalam & Edited by Mr William Chong.

All images are copyrighted and property of RIPAS Hospital.