Endoscopic Ultrasound (EUS)

The fusion of two technologies involving endoscopy and ultrasound has led to development of a new technique called endoscopic ultrasound, or EUS. After the patient is sedated, the EUS scope is inserted like a gastroscope into the esophagus, stomach and duodenum. The ultrasound mode is then switched on to examine the internal lining (mucosa) of the esophagus, stomach, duodenum, the adjacent pancreas, bile duct and mediastinum structures in the chest. Cancers can be assessed for the depth of penetration (T-stage), the presence of abnormal lymph nodes (N-stage) and help to make decisions on treatment. EUS is performed as a day surgery procedure.

Some reasons to perform EUS

1. Diagnose the cause of a submucosal leisonn e.g. GIST, leiomyoma, lipoma, carcinoid
2. Diagnose the cause of bile duct blockage e.g. stone, tumour
3. Staging of cancer: to determine depth of cancer and lymph node involvement
4. Using a fine needle to obtain cells for diagnosis (FNAC)

A suspicious lump in the rectum - can it be safely removed?

A 50 -year old woman was diagnosed with a 1 cm lump lying under the mucosa (called submucosal lesion) during screening colonoscopy [A]. This was suspicious of a carcinoid tumor and an EUS was performed to assess the depth of penetration and determine if it could be safely removed without using surgery [B]. EUS confirmed the lump could be safely removed using endoscopic mucosal resection. This was performed and the tumor was a localized carcinoid tumor [C].

An enlarged lymph node in the chest - is it cancer?

A 38-year old woman felt a vague discomfort in her chest for a few weeks. Two years earlier, she had small cell cancer of the cervix that was treated with surgery and chemotherapy. A PET scan showed a “hot” area in the middle of her chest, situated behind the heart [D]. This was suspicious of cancer spread to a lymph node. Her oncologist wanted confirmation with a biopsy before starting chemotherapy. EUS was used to locate the abnormal lymph node and obtain cells for examination. The abnormal node was identified with EUS [E]. Using EUS guidance to avoid the heart and major vessels, a fine needle was inserted into the node to obtain samples of cells for analysis [F]. The procedure was performed under sedation and she went home after 4 hours of observation. The diagnosis was confirmed to be a small cell cancer [G].

Suspected pancreas tumor with normal CT scan

A 45-year old man had jaundice and suspicion of pancreas tumor but a CT scan did not identify any definite abnormality in the pancreas [H]. EUS was performed and identified a small tumor 1 cm in size [I]. He underwent surgery to remove the tumor which proved to be a bile duct cancer. EUS is a more accurate test than CT scan to identify small tumors in the pancreas or stones in the bile duct.

About the author. Dr Yap Chin Kong, is a leading Specialist and Senior Consultant in Gastroenterology, Liver Diseases and Endoscopy. He was awarded a Merit Scholarship to study Medicine at the National University of Singapore and graduated with a Bachelor of Medicine & Bachelor of Surgery degree in 1983. In 1988 he obtained his Masters degree in Medicine (Singapore) and became a Member of the Royal College of Physicians (United Kingdom). He became a Fellow of the Academy of Medicine (Singapore) in 1994 and a Fellow of the Royal College of Physicians (Edinburgh) in 2000. In 1992, he was awarded the Health Manpower Development Program Award by the Ministry of Health to pursue advanced training in therapeutic ERCP (Endoscopic Retrograde Cholangio-Pancreatography) at the Academic Medical Centre in Amsterdam, The Netherlands. After a year of extensive experience he returned in 1993 to develop endoscopy further at the Singapore General Hospital until he left for private practice in 2004. He pioneered the use of endoscopic ltrasonography at SGH for a decade. During this time, he taught many generations of medical students and post-graduate doctors. In 2002, he continued to pursue his interest in early cancers of the stomach and colon and visited the Showa University Hospital in Yokohama, and the National Cancer Centre in Tsukiji, Tokyo. He lectured and taught at workshops locally and internationally, combining the best of Western and Eastern techniques. A Master endoscopist, he developed an innovative cap-fitted gastroscopy technique that is used to help countless patients worldwide. He was President of the Gastroenterological Society of Singapore (1999 to 2003) and was President of the Asia-Pacific Digestive Week in 2003. He is currently in private practice at Mount Elizabeth Medical Centre. His broad specialist experience include advanced endoscopy techniques such as ERCP treatment of bile duct stones and pancreas diseases, endoscopic ultrasound, treatment of esophagus, stomach, colon and liver cancers, viral hepatitis and inflammatory bowel disease. He is Visiting Consultant to the National University Hospital and Kandang Kerbau Womens’ & Childrens’ Hospital where he supervises gastroenterologists-in-training and performs endoscopy for sick children.