Pediatrics: Boys may not need CT or US to diagnose appendicitis

CT and ultrasound imaging do not have a meaningful impact on the negative appendectomy rate (NAR) for boys older than five years, according to a study published in the May issue of Pediatrics. The findings led the authors to recommend use of a decision algorithm that incorporates age and gender.

“Advanced imaging with CT and ultrasound has become routine in many children undergoing diagnostic evaluation for pediatric appendicitis because of the relatively limited performance of clinical intuition and clinical decision rules,” wrote Richard G. Bachur, MD, of the division of emergency medicine at Children’s Hospital and Harvard Medical School in Boston, and colleagues.

Although initial applications of advanced imaging were limited to equivocal cases, use of CT and ultrasound has expanded to include children with more typical presentations of appendicitis and those with low likelihood of appendicitis. Meanwhile, although CT provides improved diagnostic performance, concerns about ionizing radiation have led some researchers to suggest an ultrasound-only model or a staggered approach that employs ultrasound as the first-line imaging modality and reserves CT for use only if needed.

Bachur and colleagues sought to examine the use of CT and ultrasound for age and gender subgroups of children undergoing appendectomy and to study the association between imaging and NARs among these subgroups.

The researchers examined data from 8,959,155 visits to 40 pediatric emergency departments from 2005 to 2009 and identified 55,227 children diagnosed with appendicitis. Children were categorized by gender and age—younger than five years of age, five to 10 years and older than 10 years.

Among the final study population of 52,290 children who underwent appendectomy, the overall NAR was 3.6 percent.

When Bachur and colleagues analyzed the imaging data, they found CT rates exceeded ultrasound rates for each age and gender subgroup. Children younger than five years were most likely to undergo exams in both modalities. These children and girls older than 10 years had the highest NARs. Boys older than five years had the lowest rate of negative appendectomy regardless of imaging, wrote the authors.

The patient-level analysis revealed:

• Boys older than five years had lower NARs compared with younger boys;

• Pre-appendectomy CT was significantly associated with lower NARs only among boys younger than five years;
• Ultrasound was associated with a higher NAR among boys younger than age five years;
• Use of CT was associated with significantly lower NARs among girls younger than five years; and
• Girls older than 10 years had significantly higher NARs than boys.

Bachur and colleagues noted that one of the factors fueling increased CT use was its ability to identify early appendicitis and subsequently reduce perforation rates. “The current data continue to support the inverse association and NARs that likely led to the surge of diagnostic imaging among children with abdominal pain.”

However, age and gender should be accounted for in evaluation algorithms, they continued. The need for stratification by age and gender is particularly clear among boys older than five years. “The value of diagnostic imaging for this subgroup appears to be limited with regard to this particular outcome,” Bachur et al wrote.

The researchers acknowledged several limitations to the study: use of administrative data to infer clinical management and outcomes, inability to analyze patients evaluated for appendicitis who did not undergo an appendectomy and lack of access to imaging data prior to transfer to the referral centers.

Bachur and colleagues concluded that the routine use of CT and ultrasound can reduce NARs for children younger than five years and girls older than 10 years. However, routine use of CT and ultrasound in boys older than age five years with suspected appendicitis (and no other clinical concerns) should be limited, according to the researchers.