© Center for Endometriosis Care/Ken Sinervo MD, MSc, FRCSC. All rights reserved. No reproduction permitted without written permission. Revised since original publication and current as of 2023. No external funding was utilized in the creation of this material. The Center for Endometriosis Care neither endorses nor has affiliation with any resources cited herein. The following material is for informational purposes only and does not constitute medical advice.

Anyone who has undergone Laparoscopic surgery knows about that shoulder pain. But if surgical work was done in the pelvis, why is there pain at the shoulder tip???

You're not alone if you've experienced this phenomenon.  The incidence of such pain varies from 35%-83% across patient populations, ranging from mild to severe, and in some cases, the pain has been reported to last even longer than 72 hours post-operatively (though this is less common).1  Moreover, in nearly 70% of cases studied, patients experienced the worst pain not immediately post-operatively - but up to 24 hours after their surgery.2  Read on to find out why this occurs - and what we have been doing for years at our Center to help effectively reduce and diminish this pain in our own patients.

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. Pneumoperitoneum is necessary to provide your surgeon with a better view of your organs (you can see an artist's rendering below).

However, this gas can also irritate the nerves and affect the physiology of the surrounding peritoneal tissue.

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.’ However, the actual cause of the irritation is the result of ‘cellular death’ (not as formidable as it sounds - this is simply a direct response to tissue injury, considered part of the wound-healing process itself) caused by the combination of a temperature change from the gas at 70°F and the drying effect of the gas at .0002%.3 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. Simply stated: when the CO2 gas irritates the diaphragmatic nerves, that pain is referred upwards through nerve connections, eventually landing in - and aggravating - the shoulder.

To be more specific: the diaphragm and shoulder share some of the same nerves; predominantly, the Phrenic nerve. The Phrenic nerve arises on each side of the neck, from the 3rd, 4th and 5th cervical spine roots. It passes downward between the lungs and the heart to reach the diaphragm (you can read more and see a medical sketch of this region here). Impulses through this nerve from the brain bring about the regular contractions of the diaphragm during breathing. In particular, carbon dioxide-induced Phrenic nerve irritation causes referred pain to cervical nerve 4 (C4). Carbon dioxide trapped between the liver and the diaphragm can also cause the familiar upper abdominal/shoulder pain.4

Removing or ‘washing out’ the residual gas does help reduce the incidence and severity of this pain in both the shoulder and upper abdomen. Some clinical trial studies determined that Pulmonary Recruitment Maneuvers and Intraperitoneal Normal Saline Infusions (INSI) reduced shoulder pain; with INSI proving a superior method.5 Preemptive analgesia is also helpful. Studies continue to further improve techniques towards ‘gasless laparoscopy’ as well, which is currently limited due to increased difficulty, impaired visualization, longer operative times and increased costs.6

In our Center, our surgeons are acutely aware of and take extreme concern with the comfort levels of our patients. We have demonstrated that this pain can be reduced through the effective techniques we practice, including not only removal of the C02 before the end of the procedure but, importantly, heating and humidifying the gas, which prevents cellular death and quite simply, results in less shoulder pain.7

We always utilize the latest technology and surgical practices to minimize pain and recovery time for all of our patients, including (but not limited to) use of Insuflow® technology. Insuflow® confers improved pain control and reduces the need for opioids and antiemetics in the postoperative period by humidifying and warming the CO2 to 95°F and 95% relative humidity. This practice has been proven in numerous studies to provide patients with the following benefits:

• Less patient pain means less need for long-term narcotic medication;

• Less narcotic pain medication leads to less nausea or bowel symptoms;

• Less shivering and hypothermia;

• Less tissue damage leading to decreased inflammatory response; and

• Shorter recovery time lowering overall hospital stay, therefore saving the patient money.

Still; even in the best of hands with use of the most meticulous techniques, some shoulder pain may persist - though it should begin declining markedly around the 48 hour mark.8

Anecdotal tips for coping include applying a heating pad to the affected shoulder, alternating between lying flat or on your side and ambulating (walking around), judicious use of post-operative analgesia, use of over the counter medications like GasX and consumption of hot liquids such as tea.  Of course - discuss options with your physician and always contact your surgeon if the pain becomes intolerable or persistent beyond a few days. 

Glossary:

• Cellular Death – a normal, regular process by the body to deliberately get rid of unwanted cells

• C02 – a colorless, odorless gas comprised of one carbon and two oxygen atoms abdominal cavity

• Laparoscopy - a minimally invasive surgical procedure used to diagnose and treat endometriosis (among many other disorders)

• Peritoneal tissue – the membrane that forms the lining of the abdominal cavity

• Phrenic Nerve – innervates the diaphragm and is responsible for, among other functions, breathing

• Pneumoperitoneum - surgical creation of a distended abdomen to lift and separate organs (non-surgical pneumoperitoneum = free air in the peritoneal cavity; this is a secondary health concern not addressed or in any way referred to within this article)

References

1., 4., 5. Tsai H, Chen Y, Ho C, et al. Maneuvers to Decrease Laparoscopy-Induced Shoulder and Upper Abdominal Pain: A Randomized Controlled Study. Arch Surg. 2011;146(12):1360-1366

2., 8. Hohlrieder M, Brimacombe J, Eschertzhuber S, Ulmer H, Keller C. A study of airway management using the ProSeal LMA laryngeal mask airway compared with the tracheal tube on postoperative analgesia requirements following gynaecological Laparoscopic surgery. Anaesthesia. 2007 Sep; 62(9):913-8

3., 7. Demco, L. Painless Laparoscopy?  Journal of the International Society for Gynecologic Endoscopy. February 2001 Volume 7 Issue 1

6. Goldberg J, Falcone T. “Gasless Gynecologic Laparoscopy.” Retrieved from http://hcp.obgyn.net/laparoscopy/content/article/1760982/1894615