The ultrasound shows a noncompressible, blind-ended, finger-shaped structure in the RLQ just anterior to the iliac artery, which is consistent with acute appendicitis. The iliac artery (dark round circle toward the bottom of the image), and the appendix (finger-shaped structure entering from the right side of the image at a depth of 1 to 2 cm) can be clearly seen. The next step in treatment is to initiate intravenous antibiotics and to consult with a surgeon to determine whether further diagnostic testing is required.

Typically in cases of appendicitis, imaging usually consists of computed tomographic (CT) imaging with intravenous (not oral) contrast. CT scan has 95% sensitivity and 95% specificity for the diagnosis of appendicitis, although it may perform slightly worse in patients who are very thin. The downsides of CT scanning are that it exposes the patient to a substantial amount of ionizing radiation and may delay treatment.

Alternatives to CT scanning include no imaging, magnetic resonance imaging (MRI), and ultrasound. These options should be considered in patients in whom the risk of radiation exposure is extremely high (eg, younger or pregnant patients) and/or when the suspicion of another serious condition is high, such as with the elderly.


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The no-imaging option may be appropriate if the pretest probability of appendicitis is very high and the surgeon wants to operate without imaging, or if the pretest probability is very low and home observation is chosen as the best course of treatment. It is important to consult with the patient on the risks and benefits of either of these strategies.

MRI is an accurate method for the diagnosis of appendicitis, but due to multiple factors it is rarely used except in cases involving pregnant women. The downsides of MRI include availability, which is usually more limited than CT or ultrasound, and the extra screening and scanning time required, which may delay further treatment. 

Ultrasound is useful in the diagnosis of appendicitis in thin patients, with some studies showing performance almost as good as CT. Test performance for ultrasound, however, varies with the experience of the sonographer and is affected by the patient’s body habitus. CT should be used to follow a nondiagnostic ultrasound when there is a high degree of suspicion for appendicitis.

In this case, the surgeon required a CT scan to confirm the diagnosis before proceeding with the operation. The scan confirmed acute appendicitis.

Brady Pregerson, MD, is an emergency physician at Cedars-Sinai Medical Center in Los Angeles and at Tri-City Medical Center in Oceanside, California.

Reference

Pregerson DB. Orthopedics: basics and open injuries. In: Emergency Medicine 1-Minute Consult Pocketbook. http://www.erpocketbooks.com/emergency_medicine_reference_books/quick-essentials-emergency-medicine/. 2017;5.