Shoulder pain post laparoscopy is due to:
CO2 retention [Ref: J Shoulder pain is although a minor complication is exceedingly common and is due to the presence of a significant amount of residual carbon dioxide in the peritoneal cavity, trapped under the diaphragm and causing irritation of the diaphragm and thus referred pain to the shoulder through the phrenic nerve.
Subphrenic abscess
CO2 retention
Positioning of the patient
Compression of the lung