Point-of-care intestinal ultrasound for acute abdominal pain in emergency departments
1Emergency Medicine, Red Cross Society Azumino Hospital, Japan
Background: Transabdominal ultrasound (US) can aid in the diagnosis of common and uncommon intestinal diseases. Recent clinical studies have shown that emergency physician (EP)-performed point-of-care ultrasound (POCUS) is useful for the diagnosis of common intestinal diseases, such as small bowel obstruction (SBO) and acute appendicitis.
SBO: The utility of surgeon-performed US for the diagnosis of SBO and early recognition of strangulation was evaluated in the 1990s. In recent years, two studies demonstrated the high accuracy of POCUS performed by well-trained EPs for the diagnosis of SBO. In addition, the diagnostic accuracy of EP-performed POCUS and radiology-performed US were not found to be significantly different. These studies also showed that the test performance of EP-performed US was superior to that of X-ray in the diagnosis of SBO. However, large-scale prospective studies are needed to support drastic changes in the management of SBO.
Acute appendicitis: Computed tomography (CT) was found to have a superior test performance to US in the diagnosis of acute appendicitis; however, US is recommended as the first-line imaging modality, especially in young, female, and slender patients, in light of the low radiation exposure. Recent studies from the field of emergency medicine have addressed the diagnostic performance of EP-performed POCUS in evaluating suspected acute appendicitis. They demonstrated the feasibility of reducing the length of stay in emergency departments and avoiding CT given the high positive predictive value in some patients. A meta-analysis including 17 studies revealed that EP-performed POCUS had an excellent performance for diagnosing acute appendicitis, similar to that of radiologist-performed US, and an even better diagnostic performance for pediatric acute appendicitis. The high operator dependence may be a problem; therefore, more effective educational techniques must be developed.
Colitis: The evaluation of colitis with EP-performed POCUS is not common at present; however, the modality is promising when POCUS is performed in addition to a physical examination. The ascending and descending colon are usually fixed to the retroperitoneum at the right and left sides, respectively. Such typicality in location usually allows for detection without substantial difficulty. Generally, the diagnosis of infectious colitis is based on clinical symptoms with a stool analysis. However, some patients with infectious colitis have a presentation similar to that of acute appendicitis. Furthermore, POCUS can show portions of the abnormal colon with wall thickening, which may suggest specific causes, such as infection due to Yersinia, Salmonella, or Campylobacter jejuni. The clinical symptoms associated with transient ischemic colitis include crampy left or lower abdominal pain, diarrhea and mild rectal bleeding. The descending colon is involved most of the time. Symmetric wall thickening in the colon can be detected with POCUS. In addition, the areas of maximal tenderness tend to be found directly over the colon when applying pressure with an ultrasound probe.
Conclusion: Point-of-care intestinal US for acute abdominal pain in emergency departments is thus considered to be a promising modality for the rapid and accurate assessment of common intestinal diseases.