Based on the patient's ultrasound results, the following differential diagnosis can be considered:

Single most likely diagnosis
- Gallstones: This is a common finding on ultrasound and can cause symptoms such as abdominal pain, especially after eating fatty foods.
Other Likely diagnoses
- Cholecystitis: Inflammation of the gallbladder, which can be caused by gallstones or other factors, and can present with abdominal pain, fever, and leukocytosis.
- Biliary sludge: A mixture of small particles and bile that can cause symptoms similar to gallstones.
- Hepatic cysts: Benign fluid-filled structures in the liver that can be incidentally found on ultrasound.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Liver abscess: A rare but potentially life-threatening condition that requires prompt antibiotic treatment and drainage.
- Hepatocellular carcinoma: A type of liver cancer that can present with non-specific symptoms and requires early detection for effective treatment.
- Portal vein thrombosis: A blood clot in the portal vein that can cause liver dysfunction and requires anticoagulation therapy.
Rare diagnoses
- Caroli's disease: A rare congenital disorder characterized by dilatation of the intrahepatic bile ducts.
- Choledochal cysts: Rare congenital anomalies of the bile ducts that can cause symptoms such as abdominal pain and jaundice.
- Mirizzi syndrome: A rare condition where a gallstone becomes impacted in the cystic duct and causes obstruction of the common bile duct.