This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
A 45 year old female presents with 48 hour history of right upper quadrant pain, dyspnea, non-productive cough, fever with chills and rigor. The pain radiates to right shoulder tip. She has history of perforated duodenal ulcer repair 3 weeks ago. Temperature 39.3degC. O/E there is acute tenderness over right hypochondrium. CXR shows right sided pleural effusion. Diagnosis 
Select and explain. 
A. Acute pancreatitis, B. Subphrenic abscess, C. Acute cholangitis, D. Pyonephrosis
B: Subphrenic abscess
Answer: B: Subphrenic abscess 
Explanation: Ans. (b) Subphrenic abscessRef: Bailey 26th edition Page 977* Bailey says- "Pus Nowhere, Pus Some where- search Pus Under the Diaphragm"* In a post op case (patient lying)- most dependent site of abscess formation is Subphrenic Space