Inflammation Markers Aid in Predicting the Need for CT after Ultrasound in Acute Abdominal Pain

By Elizabeth Gardner

Patients who go to the emergency department (ED) with acute abdominal pain need a diagnosis as soon as possible, but ultrasound (US) — the quickest and least invasive imaging option — often doesn't yield enough information. The patient then is generally given a CT examination in addition to US.

Rippel

Seeking a possible solution, researchers from Klinikum Augsburg Hospitals in Germany sought to determine whether the ER could triage patients more quickly and efficiently using lab results to identify which patients with abdominal pain would need a CT scan.

On Wednesday, presenter Katharina Rippel, MD, shared findings suggesting that lab tests for systemic inflammation, combined with a medical history, can identify which patients will need a CT scan, allowing the ED to save time by skipping the US exam and proceeding directly to a CT scan.

Test results for inflammation markers are generally available within half an hour of giving the sample to the lab, Dr. Rippel said. So if the ED drew blood before doing a history and physical exam, there would be little to no delay in making a decision about which imaging exam is most appropriate.

Researchers analyzed electronic health records for 484 consecutive patients who presented to the ED over a two-month period with acute abdominal pain and were first referred for an abdominal US examination.

The study analyzed results for lab tests to determine systemic inflammation, including white blood cell count (WBCC) and C-reactive protein (CRP), as well as prior medical history and CT scans of the abdomen that were performed within 36 hours of the US exam. Subgroup analyses were performed for patients without documented hospital admission during a 12-month period preceding presentation to the ED. Out of the initial group, 38 patients were excluded because they had no lab test results. Of the remainder, 15 percent underwent additional abdominal CT within 36 hours.

Predicting Need for CT Could Save Time in ED

Results showed that patients who underwent additional CT were significantly more likely to have had lab results indicating inflammation. The lab values were especially likely to be correlated with a CT scan if the patient had not been hospitalized in the previous 12 months and had no history of malignancy.

In one sample case, a patient had a normal US but CRP and WBCC results indicated inflammation. A CT scan revealed acute appendicitis with perforation.

"Usually a CT scan alone is enough to detect the relevant illnesses, but due to the potential side effects, we try to diagnose primarily with ultrasound," Dr. Rippel said."We tried to find the parameters that would predict the need for CT in order to save time in the emergency department."

Dr. Rippel said the findings have led the emergency and internal medicine departments to discuss a possible change in protocol, if these results are confirmed by additional studies. She hopes to do further research that will identify other subgroups where inflammation markers have high predictive value, using other lab results such as bilirubin, or physical exam findings such as right upper quadrant pain that are easy to identify in medical records.