Final answer:
Gallstones are hard stones formed from a buildup of bile in the gallbladder that cause acute pain. They can be removed using a catheter and ultrasound.
Step-by-step explanation:
Gallstones are hard stones created from a buildup of bile in the gallbladder. They cause acute pain and are often removed with a catheter and ultrasound. When a large amount of cholesterol accumulates in the gallbladder, it turns into solid particles, forming gallstones. Small gallstones can pass through the bile duct and be excreted, but larger ones may get stuck and cause pain. Treatment to remove gallstones usually involves a procedure called cholecystectomy.