Q. A 28-year-old woman in her second trimester of pregnancy presents to the gastroenterology clinic with episodic right upper quadrant abdominal pain, particularly after meals. The pain is described as sharp and sometimes radiates to her back. She also reports episodes of nausea but no vomiting. There is no history of fever or jaundice. Her pregnancy has been otherwise uncomplicated. Physical examination reveals tenderness in the right upper quadrant but no signs of peritonitis. Given her pregnancy, the physician is cautious about the choice of imaging to evaluate for gallbladder disease. Considering the need for safe and effective imaging during pregnancy, which imaging modality is preferred for the evaluation of gallbladder disease in this patient?