A 68-year-old male, with a history of well-controlled hypertension, underwent an elective laparoscopic cholecystectomy on an outpatient basis and was subsequently transferred to a short-stay surgical ward for observation. He presented with chronic dyspepsia and confirmed cholelithiasis. Approximately 18 hours after the procedure, he develops a low-grade fever of 38.2C (100.8 F), reports mild dyspnea, and his oxygen saturation drops to 92% on room air. He describes a generalized chest discomfort rather than sharp pain. On physical examination, his blood pressure is 125/78 mmHg, pulse is 98/min, and respiratory rate is 20/min. Lung auscultation reveals diminished breath sounds and fine crackles at both lung bases. The surgical wound is clean and dry with no signs of erythema or swelling. His abdomen is soft with mild tenderness at the incision sites. Considering the most probable diagnosis, what is the immediate management strategy, and what specific imaging finding would definitively confirm this condition?

A 55-year-old man presents to an outpatient gastroenterology clinic complaining of recurrent, sharp right upper quadrant and epigastric pain that began approximately 4 weeks following an uneventful laparoscopic cholecystectomy. He describes the pain as similar in character to his pre-operative biliary colic, often radiating to his back, and states it is frequently accompanied by nausea, though he denies fever or vomiting. His wife also noted a subtle yellowish discoloration of his eyes over the past few days. On physical examination, he appears comfortable at rest with mild scleral icterus. Abdominal examination reveals tenderness in the right upper quadrant upon deep palpation, but no guarding or rebound tenderness. Bowel sounds are normoactive. Considering his clinical presentation, what is the most likely diagnosis, and what is the definitive next step in management to confirm and address this condition?

A 55-year-old woman is readmitted to the hospital complaining of persistent, diffuse lower abdominal pain, malaise, and fever, which initiated approximately two weeks ago, shortly after her emergent cholecystectomy for acute cholecystitis. Her vital signs upon admission are a blood pressure of 85/55 mmHg, pulse of 118/min, temperature of 39.1°C (102.4°F), and a respiratory rate of 22/min. Physical examination reveals generalized lower abdominal tenderness with guarding, but no rebound or rigidity. A urinalysis and chest x-ray are unremarkable, and a urine pregnancy test is negative. Initial laboratory findings show a significantly elevated white blood cell count and C-reactive protein. Considering her clinical presentation and laboratory findings, what is the most likely diagnosis, and what is the definitive next step in her management?

A 55-year-old male presents to the emergency department complaining of sudden onset severe right upper quadrant pain, radiating to his right shoulder, which started approximately 18 hours ago. He reports associated nausea, a single episode of vomiting, and subjective fever and chills. He denies any prior history of similar severe episodes but mentions occasional post-prandial discomfort after fatty meals. His past medical history is unremarkable, and he takes no regular medications. On physical examination, his temperature is 38.8 0C (101.8 0F), heart rate 98 bpm, blood pressure 130/80 mmHg, and respiratory rate 16 breaths/min. Abdominal examination reveals marked tenderness and guarding in the right upper quadrant, with a positive inspiratory arrest during deep palpation (Murphy's sign). Bowel sounds are diminished. There is no jaundice or scleral icterus. Initial laboratory studies are obtained. An abdominal ultrasound performed in the emergency department demonstrates diffuse thickening of the gallbladder wall, pericholecystic fluid, and an unequivocally positive sonographic Murphy sign. The common bile duct diameter is normal at 4 mm, and there is no evidence of choledocholithiasis. Given these findings, what is the most likely diagnosis and the optimal definitive management strategy, considering potential early complications?