Imaging strategies for detection of urgent conditions in acute abdominal pain

A study in this week's issue of the British Medical Journal investigates imaging strategies for detection of urgent conditions in patients with acute abdominal pain.

Professor Stoker and colleagues from the Netherlands identified an optimal imaging strategy for the accurate detection of urgent conditions in patients with acute abdominal pain.

The research team conducted a fully paired multicenter diagnostic accuracy study with prospective data collection in emergency departments of 2 university hospitals and 4 large teaching hospitals.

Participants 1021 patients with non-traumatic abdominal pain of over 2 hours’ and under 5 days’ duration.

Exclusion criteria were discharge from the emergency department with no imaging considered warranted by the treating physician, pregnancy, and hemorrhagic shock.

All patients had plain radiographs, ultrasonography, and computed tomography after clinical and laboratory examination.

A panel of experienced physicians assigned a final diagnosis after 6 months and classified the condition as urgent or non-urgent.

The team's main outcome measures included sensitivity and specificity for urgent conditions, percentage of missed cases and false positives.

65% of patients had a final diagnosis classified as urgent

British Medical Journal

Exposure to radiation for single imaging strategies, conditional imaging strategies, and strategies driven by body mass index and age or by location of pain.

The researchers found that 65% of patients had a final diagnosis classified as urgent.

The initial clinical diagnosis resulted in many false positive urgent diagnoses, which were significantly reduced after ultrasonography or CT.

CT detected more urgent diagnoses than did ultrasonography, and sensitivity was 89% for CT and 70% for ultrasonography.

A conditional strategy with CT only after negative or inconclusive ultrasonography yielded the highest sensitivity, missing only 6% of urgent cases.

With this strategy, the team found that only 49% of patients would have CT.

Alternative strategies guided by body mass index, age, or location of the pain would all result in a loss of sensitivity.

Professor Stoker's team concludes, "Although CT is the most sensitive imaging investigation for detecting urgent conditions in patients with abdominal pain, using ultrasonography first and CT only in those with negative or inconclusive ultrasonography results in the best sensitivity and lowers exposure to radiation."