An unusual cause of abdominal pain in an infant

Clinical History

A five-month-old female with no medical history presented to her local hospital unsettled, with fever, abdominal distention and discomfort. WCC (10.6) and CRP (42) were raised. The presence of a petechial rash meant she received empirical treatment for bacterial meningitis before being transferred to our institution after little improvement.

Imaging Findings

Two departmental ultrasounds were performed. The first, on the day of admission, demonstrated normal peristalsing small bowel loops and fluid-filled large bowel loops on the left side of the abdomen, but limited views of the right owing to air-filled loops. No evidence of intussusception was seen. The second ultrasound, a day later, demonstrated a non-compressible, fluid-filled, inflamed appendix measuring approximately 8.5mm in diameter with surrounding fat induration. There was a small amount of free fluid within the pelvis.

Discussion

The differential diagnosis of infants with abdominal pain is difficult as presentation is non-specific, they are unable to vocalise their symptoms, raised inflammatory markers are non-specific and the range of pathology is wide [1]. This frequently results in a delayed diagnosis and treatment with increased morbidity and mortality[2]. Ultrasonography is an important tool which can help guide clinicians to a diagnosis. It has the advantage of being minimally invasive and involves no radiation.

The incidence of appendicitis between birth and age 4 is 1-2 cases per 10,000 children, per year, which increases to 25 cases per 10,000 children, per year, between 10 and 17 years of age [3]. However, perforation rates are higher as the age of the patient decreases. One study showed 100% perforation rate for children under the age of one year old resulting in higher rates of post-operative complication [2]. Delay in time to treat is thought to be a major contributing factor. As a result of its rarity amongst infants there is much less written within the literature about its diagnosis, especially the use of ultrasound. Literature does show USS to be a valuable tool in children under the age of three with high sensitivity (95%) and specificity (90%) for diagnosis of appendicitis [4], however, there has been no proposed ultrasound criteria for appendicitis in young children, where the appendix is still growing, unlike in children over 3, where the normal appendix has reached its adult proportions [5]. Ultrasonographic measurement of infantile appendicitis is limited to case reports with one report describing the preoperative sonographic diagnosis of acute appendicitis in a nine month old infant, with an appendix diameter of 7mm [6]. As far as we are aware our case is the youngest reported case of pre-operative sonography.

In conclusion, although rare, appendicitis as a cause of abdominal pain and sepsis should be considered in an infant. Symptoms in these patients are non-specific and USS can be a very useful diagnostic tool. While there is no published data with specific measurements for appendicitis, it is still an accurate diagnostic tool. Where uncertainty remains, a repeat ultrasound can be helpful.

Our patient underwent an open appendicetomy which revealed a perforated appendix and pus within the abdomen. She was also treated with a course of intravenous antibiotics. Postoperatively, she developed ileus which required six days of parenteral nutrition but she was discharged with no concerns ten days after admission.

Differential Diagnosis List

Final Diagnosis

Acute appendicitis

URL:	https://www.eurorad.org/case/12972
DOI:	10.1594/EURORAD/CASE.12972
ISSN:	1563-4086