What are some unexpected sources of abdominal pain?

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In studies, chronic abdominal pain and discomfort affect about 22% of the population, more commonly in women than in men. While severe chronic abdominal pain is less prevalent, it can be debilitating and cause significant distress. When it afflicts young men and women, it can put a pause on the patients’ schooling and work, not to mention daily life. The best treatment approach is an interdisciplinary one, including physicians, psychologists, and physical therapists.

In this post, I want to focus on the medical perspective on managing chronic severe abdominal pain. I want to in particular highlight some unexpected sources of abdominal pain. The good news is that sometimes these unexpected sources of abdominal pain are unexpectedly responsive to certain kinds of interventions.

In approaching abdominal pain, the first question that we have to answer is where’s the pain coming from. It turns out this is not a very easy question to answer. Just because a patient points at his or her stomach, does not mean that the pain is necessarily coming from this organ.

There are two additional possibilities to consider. It turns out many patients experience chronic abdominal pain from what we call “abdominal wall“–the skin, muscle, fat that surrounds the abdominal organs.

The reason why this distinction is important is because treatment for pain coming from the organs–so-called “visceral pain“–is quite different from that for pain coming from the abdominal wall–so-called “somatic pain“. The abdominal and pelvic organs are served by visceral nerves. On the other hand, the abdominal wall is served by somatic nerves.

To treat the visceral pain coming from, for example, the intestine or the stomach, we target the visceral nerves. To treat somatic pain coming from the abdominal wall, we target the intercostal nerves or their branches.

Finally, an important source of abdominal pain is “referred pain“. This is the phenomenon where the brain perceives pain as coming from a place where it is not. The classic example is where people who have heart attacks may experience left arm pain. For the abdomen, some patients have referred pain coming from the back–the paraspinal muscles–or from the side, the serratus anterior.