Imaging strategies for detection of urgent conditions in patients with acute abdominal pain: diagnostic accuracy study

Wytze Laméris, Adrienne van Randen, H Wouter van Es, Johannes P M van Heesewijk, Bert van Ramshorst, Wim H Bouma, Wim ten Hove, Maarten S van Leeuwen, Esteban M van Keulen, Marcel G W Dijkgraaf, Patrick M M Bossuyt, Marja A Boermeester, Jaap Stoker, OPTIMA study group, Wytze Laméris, Adrienne van Randen, H Wouter van Es, Johannes P M van Heesewijk, Bert van Ramshorst, Wim H Bouma, Wim ten Hove, Maarten S van Leeuwen, Esteban M van Keulen, Marcel G W Dijkgraaf, Patrick M M Bossuyt, Marja A Boermeester, Jaap Stoker, OPTIMA study group

Abstract

Objective: To identify an optimal imaging strategy for the accurate detection of urgent conditions in patients with acute abdominal pain.

Design: Fully paired multicentre diagnostic accuracy study with prospective data collection.

Setting: Emergency departments of two university hospitals and four large teaching hospitals in the Netherlands.

Participants: 1021 patients with non-traumatic abdominal pain of >2 hours' and <5 days' duration. Exclusion criteria were discharge from the emergency department with no imaging considered warranted by the treating physician, pregnancy, and haemorrhagic shock.

Intervention: All patients had plain radiographs (upright chest and supine abdominal), ultrasonography, and computed tomography (CT) after clinical and laboratory examination. A panel of experienced physicians assigned a final diagnosis after six months and classified the condition as urgent or non-urgent.

Main outcome measures: Sensitivity and specificity for urgent conditions, percentage of missed cases and false positives, and exposure to radiation for single imaging strategies, conditional imaging strategies (CT after initial ultrasonography), and strategies driven by body mass index and age or by location of pain.

Results: 661 (65%) 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: sensitivity was 89% (95% confidence interval 87% to 92%) for CT and 70% (67% to 74%) for ultrasonography (P<0.001). A conditional strategy with CT only after negative or inconclusive ultrasonography yielded the highest sensitivity, missing only 6% of urgent cases. With this strategy, only 49% (46% to 52%) 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.

Conclusion: 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.

Conflict of interest statement

Competing interests: None declared.

Figures

https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4787309/bin/lamw628354.f1_default.jpg
Fig 1 Flow chart of study protocol. *Completed for all 1021 patients
https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4787309/bin/lamw628354.f2_default.jpg
Fig 2 Management of patients after completion of the diagnostic protocol. *Laparoscopy converted to laparotomy in 26 patients
https://www.ncbi.nlm.nih.gov/pmc/articles/instance/4787309/bin/lamw628354.f3_default.jpg
Fig 3 Diagnostic performance of all imaging strategies presented in receiver operating characteristics space. Numbers correspond to strategies in the box; strategy 5 is ultrasonography in all patients with computed tomography if ultrasonography is negative or inconclusive. See web appendix for more information

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Source: PubMed

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