Like other endoscopy procedures, EUS is safe and well tolerated. No procedure is without risk, but complications with EUS are quite rare. Complication rate for EUS without the fine needle aspiration is about 1:2000 (similar to the complication rate of other endoscopy procedures). The main complication of serious note is perforation (making a hole in the intestinal wall) that can potentially be repaired endoscopically or may even require surgical repair. This is quite rare and all precautions are taken to avoid it.
When FNA (biopsy) is performed there is a slightly higher risk of complications but are still uncommon (0.5-1.0%). Passing a needle through the gut wall may cause minor bleeding. If unusual bleeding occurs, the patient may be hospitalised briefly for observation, but blood transfusions are rarely needed. Infection is another rare complication of FNA. Infection can occur during aspiration of fluid from cysts and antibiotics may be given before the procedure. If the FNA is performed on the pancreas, pancreatitis (inflammation of the pancreas) can rarely occur. Pancreatitis calls for hospitalization, observation, rest, IV fluid, and medication for abdominal pain which usually resolves spontaneously in a few days