Acute appendicitis can be catastrophic if timely intervention is not provided. Many studies worldwide have regarded ultrasound as a reliable imaging modality to not only diagnose appendicitis and its ensuing complications, but also provide an alternative differential diagnosis, if need be. Some studies have shown comparable accuracy when comparing ultrasound to unenhanced helical CT scan, and therefore ultrasound is often employed due to its cost effective nature and easy portability.
Graded compression ultrasonography is the technique used to visualize the appendix. The proposed radiologic criteria to diagnose non-perforated acute appendicitis include visualization of a non-compressible, aperistaltic appendix with an outer diameter of 6 mm or more. A target appearance of the appendix may be seen in the transverse view. Peri-appendiceal fluid and appendicoliths may also be noted. The appendicoliths commonly obstruct the lumen of the appendix as is seen in our case, and trigger the inflammation. Enhanced vascularity demonstrated by color Doppler in the wall of the appendix may support the diagnosis. A complex cystic mass in the right iliac fossa may be seen if an appendicular abscess forms. In cases with a high index of clinical suspicion for a perforated appendix, presence of loculated pericecal fluid even in the absence of visualization of the appendix should raise concern for the diagnosis, however other etiologies which could result in a similar appearance, such as perforated right sided diverticulitis, would have to be excluded and CT scan may be necessary then.
Han, et al reported the utility of a saline enema to aid visualization in the pediatric patient. Sometimes however, technical factors, such as obese or muscular patients, a deeply located appendix and lack of operator expertise, may hinder the visualization of the inflamed appendix. In such circumstances and in patients with atypical presentations, an alternative modality, usually CT, is performed.