Abdominal pain is one of the most common complaints encountered in the acute care setting. Undifferentiated abdominal pain can be one of the most challenging conditions that a physician encounters on a daily basis. The decision regarding which labs or radiological tests to order can be frustrating and often unrevealing. Particularly in elderly patients, a difficult history and often inaccurate and changing physical examination can complicate the decision-making process.
There are many conditions that cause abdominal pain, but not all of them are best evaluated with ultrasound. However, there are certain situations in which bedside ultrasound is ideal. In any patient who presents with undifferentiated abdominal pain and is hemodynamically unstable, a quick bedside ultrasound can help to rule out free fluid or possible surgical causes of the pain, such as an abdominal aortic aneurysm. Other etiologies that bedside ultrasound can be useful for are biliary colic or acute cholecystitis, renal colic, bowel obstruction, and appendicitis.
The first distinction that should be made is whether or not the pain is diffuse or focal. This guides the physician in which abdominal areas should be evaluated first. The bedside ultrasound should begin with the evaluation of the most likely organ system to be causing the pain.
If the pain is diffuse, it is not always easy to pinpoint which organ system first became affected. Abdominal pain that is generalized is usually of higher concern for the physician as it indicates the progression of the disease. The concerning causes for diffuse abdominal pain include a perforated viscous, a bowel obstruction, the presence of new free fluid from a ruptured structure, or peritonitis in a patient with known ascites.
There are multiple causes of a perforated viscous, including a ruptured appendix, a diverticulitis, a perforated ulcer, a prolonged bowel obstruction, or a ruptured esophagus from excessive vomiting. The presence of fluid in the abdomen in a patient without liver disease or known ascites should raise the suspicion of an abdominal catastrophe, including perforated viscous. Free air is a specific finding for a perforated viscous, and ultrasound may be able to detect free air. When present, free air is best seen at the edge of the liver and will be seen as hyperechoic areas with dirty comet tails that are not within the bowel. Plain radiographs may also detect free air, but a CT scan is much more sensitive than either ultrasound or x-ray.
If a moderate to large amount of fluid is seen with a cirrhotic-looking liver (shrunken, irregular-shaped), then spontaneous bacterial peritonitis should be considered. Free fluid in a female with abdominal pain should lead to a search for gynecologic origin, such as a ruptured ovarian cyst, ectopic pregnancy with bleeding, or the extension of a pelvic infection. An elderly patient with diffuse abdominal pain and ...