In the past few months there have been multiple studies published on imaging for acute abdominal pain. In a longitudinal study of imaging in patients with acute abdominal pain in emergency departments (Pines et al 2009), CT use increased from 10.1% in 2001 to 22.5% in 2005. Ultrasound use increased from 11.1% to 13.6% over the same time period. However, detection rates for appendicitis, diverticulitis, and gall bladder disease did not increase and admission rates did not decrease.
Another paper (Pines 2009b) found that risk-taking behavior correlated with ordering imaging studies in emergency department patients with abdominal pain but that fear of malpractice did not.
Two studies looked at sequential imaging strategies in patients with acute abdominal pain. In a study of acute appendicitis (Poortman et al) found that using ultrasound, followed by CT scan in cases where the ultrasound is negative, had high diagnostic accuracy without adverse events related to delay in diagnosis. Although ultrasound had less diagnostic accuracy than CT, it can be used as the primary imaging modality and avoid the disadvantages of CT such as radiation exposure and use of contrast agents.
A similar study in the UK (Lameris et al for the OPTIMA study group 2009) was reported on patients with urgent acute abdominal pain. CT detected more urgent diagnoses than did ultrasonography: sensitivity was 89% for CT and 70% for ultrasonography but a conditional strategy with CT only after negative or inconclusive ultrasonography yielded the highest sensitivity, missing only 6% of urgent cases. With this strategy, only 49% of patients would have CT.
The conditional strategy (ultrasound followed by CT only if the ultrasound is negative) thus appears to be quite accurate, safe, efficient and economical and avoids some of the potential adverse effects of CT scanning.
Pines JM. Trends in the Rates of Radiography Use and Important Diagnoses in Emergency Department Patients With Abdominal Pain. Medical Care 2009; 47: 782-786
Pines JM, Hollander JE, IssermanJA et al. The association between physician risk tolerance and imaging use in abdominal pain. J Emerg Med 2009; 27: 552-557
Poortman P, Oostvogel HJM, Bosma E et al. Improving Diagnosis of Acute Appendicitis: Results of a Diagnostic Pathway with Standard Use of Ultrasonography Followed by Selective Use of CT. J Am Coll Surg 2009; 208: 434-441
Laméris W, Adrienne van Randen A, H Wouter van Es HW, et al., on behalf of the OPTIMA study group. Imaging strategies for detection of urgent conditions in patients with acute abdominal pain: diagnostic accuracy study. BMJ 2009; 338: b2431 Published 26 June 2009