This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Surgery
Shoulder pain post laparoscopy is due to 
Select and explain. 
A. Subphrenic abscess, B. CO2 retention, C. Positioning of the patient, D. Compression of the lung
B: CO2 retention
Answer: B: CO2 retention 
Explanation: Laparoscopy Needle used for pneumoperitoneum : Veress needle Most commonly used gas: CO2 Flow of gas : 1L/min Intra abdominal pressure : 12-15mmHg Trocar is inseed at or just below the umbilicus penetrating skin, superficial & deep fascia, fascia transversalis & parietal peritoneum Post-laparoscopy shoulder pain is due a to CO2 retention causing irritation of diaphragm & referred pain to the shoulder through phrenic nerve Ref: Sabiston 20th edition Pgno : 394-396