When combined, data from two standard diagnostic tests commonly obtained in children evaluated for abdominal pain can help ED physicians and pediatric surgeons identify patients who should be sent to the OR for prompt removal of an inflamed appendix; those who may be admitted for observation; and those who safely may be discharged home, according to a new study.
Results were published online Feb. 19 as an “article in press” in the Journal of the American College of Surgeons.
For the study, researchers from Boston Children’s Hospital retrospectively examined major categories of ultrasound findings in 845 children who had suspected appendicitis with blood tests that signal bacterial infection and were seen in the ED between 2010 and 2012.
According to the study’s authors, it is believed to be one of the first studies to show adding the white blood count and polymorphonuclear leukocyte differential data can significantly improve the clinical value of ultrasound in diagnosing appendicitis in children.
“Ninety percent of all hospitals perform laboratory studies and ultrasound when there is a reasonable suspicion of appendicitis in children,” lead author Shawn J. Rangel, MD, MSCE, FACS, pediatric surgeon at Boston Children’s, said in a news release. “Hospitals tend to look at the results of these studies independently, however, and the improved diagnostic value of using these in a complementary fashion has not yet been reported. The diagnostic evaluation approach in this study can be used by other institutions as a diagnostic tool to help ED physicians and surgeons provide better care by avoiding treatment delay in very high-risk patients and unnecessary admissions for very low-risk patients.”
ED physicians and surgeons typically order ultrasound scans to obtain images of the appendix and the surrounding tissues in children with acute abdominal pain to look for evidence of appendicitis. However, the scans often do not lead to a definitive conclusion about the presence or absence of appendicitis. In this study, a radiologist could not identify a normal appendix or any evidence of appendicitis on sonogram in more than half of all patients with suspected appendicitis. This relatively high rate of equivocal studies is not uncommon in children, however, and has been reported at other hospitals that also routinely evaluate children with abdominal pain.
An elevated WBC and a shift in the PMN% differential tend to be sensitive indicators of appendicitis, according to the release. However, these changes are not always present in children with appendicitis, and such changes might be abnormal even in children who do not have the disease.
Of the 845 children in this study, 393 (46.5%) had appendicitis. The investigators found an elevated WBC count in 560 of the patients; 348 of them had appendicitis (62.1%) and 212 (37.9%) were negative for appendicitis. Lab results showed a PMN% shift in 581 of the study participants, with 340 (58.5%) positive for appendicitis and 241 (41.5%) negative for appendicitis.
When sonographic and laboratory findings were paired, the ability to identify children with and without appendicitis was improved significantly, the study found. The risk of appendicitis rose from 79.1% to 91.3% when laboratory studies indicated a bacterial infection and sonography showed primary signs of appendicitis, such as increased blood flow or a thickening in the wall of the appendix. The risk of appendicitis rose from 89.1% to 96.8% when laboratory results were abnormal and the sonogram showed secondary signs of appendicitis, e.g., fat near the appendix.
The ability to single out children who did not have appendicitis also was improved substantially, the researchers found. In children where the ultrasound showed neither a normal appendix nor evidence of appendicitis (the largest single category of ultrasound findings), the percentage of children who did not have appendicitis rose from 46% to 98.2% when laboratory studies were within normal ranges.
The approach outlined in this study differs from other methods of assessing the risk that a child may have appendicitis. The Pediatric Appendicitis and Alvarado Scores typically combine a child’s clinical presentation and laboratory data to determine whether a child has a high-, medium- or low-risk of appendicitis. The scores have not been proven to be reliable in a clinical setting in a number of prospective studies, however, and do not take into account the important diagnostic information provided by ultrasound.
The approach followed in the Boston Children’s Hospital study can be adapted to individual settings.
“Any institution can read our study and readily reproduce what we did,” Rangel said in the release. “We are not advocating that other hospitals adopt our sonographic categories or laboratory value cut-offs for WBC and PMN values, but rather to work collaboratively with their radiologists and emergency room physicians to develop their own approach for categorizing sonographic findings in their patients with suspected appendicitis, and then develop risk profiles that are tailor-made for their patients after incorporation of their institution’s laboratory data.
“Institutions can use the risk profiles as educational vehicles and clinical guidelines decision tools to help emergency department physicians and surgeons avoid unnecessary computed tomography scans and admissions for observation for very low-risk patients, and avoid treatment delays in very high-risk patients,” he said in the release.
Study abstract: http://dx.doi.org/10.1016/j.jamcollsurg.2015.01.039