Parasites are common in developing nations. Worms usually affect small or large bowel, but extra-intestinal sites can occur. The commonest are round worms (e.g. Ascaris lumbricoides), these are seen as linear filling defects on MRI, and on ultrasound they appear as cylindrical double walled mobile or non-mobile structures. Unless there are numerous worms they usually don't cause biliary obstruction. These findings are present in our patient.