I recently had Laparoscopic surgery, and the nurse told me I would experience pain in my shoulder and burping as the gas escapes my system. I looked up a bit of information on the "pain in my shoulder" claim, and its due to the CO2 gas irritating my phrenic nerve. So my first question is:

Why was the pain only in my right shoulder when there is a right and left phrenic nerve? Is it common for patients to experience pain in one or both shoulders? If CO2 causes pain/irritation, why not switch to another gas?

My second question revolves around the burping and the gas escaping my system. Basically, how? How is it that gas in my abdominal area escapes through my mouth? Is it through some absorption mechanism?

Thank you!


Does CO2 cause pain?

CO2 can cause pain by applying pressure on the diaphragm; also stretching of the diaphragm due to the body position can irritate the phrenic nerve (Indian Journal of Surgery).


It was once believed the resultant shoulder pain was simply due to reaction of the gas combining with water; or that it was merely trapped CO2. The actual cause of this irritation is the result of cellular death caused by the combination of a temperature change from the gas at 70oF and the drying effect of the gas at .0002%. Much of this irritation is centered on the diaphragmatic region. Experiments with gases other than CO2 i.e. helium, nitrous oxide and argon have all produced the same or similar effect (Center for Endometriosis Care).

Why they use CO2?

To begin, during Laparoscopy, CO2 (carbon dioxide) gas is injected through a special needle inserted just below your navel. This is done to create and maintain a distended abdomen; a condition called "pneumoperitoneum." For safety, cost and convenience, CO2 is used almost exclusively for this purpose (Center for Endometriosis Care).

Why is pain in the right shoulder?

The mechanism of laparoscopy-induced shoulder pain is mainly derived from carbon dioxide retention within the abdomen, subsequently irritating the phrenic nerve and causing referred pain in the C4 dermatome. Moreover, carbon dioxide trapped between the liver and the right diaphragm, irritating the diaphragm, also causes upper abdominal pain (JAMA Surgery).


In such hiatal surgeries including LAGB and in few gynecological surgeries, pain occurs preferentially on the left shoulder. This difference suggests that the region of surgery and position of the patient have an important influence on the site of pain. The cause is that in laparoscopic cholecystectomy the liver is separated from the undersurface of the diaphragm because of the reverse Trendelenburg with a right side up position of the patient. This leads to stretching of the right hemidiaphragm and the gas to be potentially trapped below the right diaphragm. Reverse is true for hiatal surgeries (Indian Journal of Surgery).

Where does CO2 go after surgery?

Most of the gas passively leaves the abdominal cavity through the surgical wounds immediately after the procedure. What happens with the rest:

Carbon dioxide readily dissolves in water and forms carbonic acid. Carbonic acid is then absorbed into the intravascular space...(JAMA Surgery)

CO2 is not released through the mouth and is not a direct cause of burping. Burping may result from the pressure of gas applied on the stomach and intestine.

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