Teaching Case

3 days history of being generally unwell, pyrexial, and with increasing abdomen distension.

The boy presented with a 3 days history of being generally unwell, pyrexial, and with increasing abdomen distension. In the first instance a chest and abdominal radiographs were performed (figure 1 and 2 ). Following transfer to our centre an abdominal ultrasound was performed.
Chest radiograph and abdominal radiograph demonstrated dilated loops of small bowel with a soft mass containing calculus within the right upper quadrant( figure 1 and 2 ). Ultrasound with a 7.5 Mhz curvilinear probe revealed a distended subhepatic appendix containing fluid and an acoustic shadow producing faecolith over which the child was tender. In addition there was some mild free fluid adjacent to the tip of the appendix. These finding were confirmed at operation following intravenous hydration and antibiotics. The gallbladder was normal with no evidence of gall stones.

Over all age ranges acute appendicitis has an incidence of 6%; within the age group of our patient, acute appendicitis can be a paediatric emergency as the child is not able to give a history with presentation in a myriad number of ways typically mimicking pneumonia or urinary tract infection. Subsequently when diagnosis is made there is more likely to be peritonitis or even perforation. Hence early imaging with chest, abdominal radiography and abdominal ultrasound can assist in the management in children with indeterminate clinical findings.
Ultrasound features in appendicitis in addition to sonographic point tenderness include a distended appendix (>6mm), noncompressible, presence of faecolith, periappendiceal fluid, and increased vascularity on Doppler imaging. Occasionally it can be difficult to demonstrate the appendix particularly when retrocaecal. In these instances, following an indeterminate US, CT in child who remains unwell may well demonstrate the appendicitis and associated complications. However we should be guarded about an approach where every child has a CT without a preceding US.
During development the appendix is formed in the normal rotated gut as a bud from the caecal swelling which initially lies in the subhepatic space. In the ensuing weeks the caecum swelling descends into the right iliac fossa forming the ascending colon and hepatic flexure subsequently the appendix can lie from the subhepatic space to right side of the pelvis with approximately 50% being retrocaecal in position. Hence in the older child with a typical vague initial pain which localises to an atypical site for appendicitis, abdominal ultrasound would be appropriate.