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The intensivist caring for the critically ill patient may often consider abdominal pathology when assessing for the causes of the patient’s ill health. Patient symptoms, vital signs, and laboratory tests together with physical examination may leave the clinician with a broad differential diagnosis. Imaging is a frequent tool used to refine the differential diagnosis. Plain film of the abdomen can show obstructive bowel gas pattern or free air, mass effect from organomegaly or ascites, but gives limited information about solid organs. Computerized tomography (CT) is a better test for retroperitoneum, bowel, or for solid organ injury, but is neither portable nor obtained as quickly as bedside ultrasound. Magnetic resonance imaging generally is a relatively lengthy examination, is contraindicated in patients with pacemakers or some other implantable devices, and is often not readily available. Focused ultrasound, however, is quickly available and can often help to identify the problem or exclude diagnoses and assist with therapy.

The American Institute of Ultrasound in Medicine (AIUM) lists 13 indications for abdominal ultrasound (Table 20-1). Many of these indications may be the leading cause of a patient’s illness; all can complicate other medical conditions. Causes of pain, for instance, may be assessed by ultrasound. Pain due to acute cholecystitis or ureteral obstruction, peritonitis due to abscess, or vascular occlusions may be detected. The cause of biliary obstruction or explanation for a rapid drop in hematocrit may be identified. Palpable abnormalities can be confirmed. Obstructive uropathy can be evident as a cause of renal insufficiency. Ascitic fluid can be followed by serial examinations. Liver metastases may be the etiology of elevated liver function tests or explain the increased risk for pulmonary embolism. Bladder distension can be assessed in the neurogenic bladder of a patient with spina bifida. A focused examination for free fluid in the trauma patient may affect operative decisions. The transplant organ can be evaluated for early complications. Ultrasound guidance can also decrease the risk associated with vascular and body interventions. For the critically ill, a point-of-care ultrasound examination that combines an evaluation of abdominal organs, vascular structures, and the peritoneal spaces for fluid may focus the physicians’ attention to the most likely causes of a patient’s ill health.

TABLE 20-1AIUM Indications for Abdominal and/or Retroperitoneal Ultrasonography

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