The results of this retrospective observational study confirm the hypothesis that, within the prehospital setting, it is challenging to safely assess patients with abdominal pain and triage them to self-care. The revisit rate was 16.3%. Furthermore, 6 patients (3.1%) were assessed to be incorrectly triaged to self-care by the EMS team, thereby endangering patient safety. This statement is made despite the fact that the EMS team’s compliance with guidelines can be considered relatively high.
The prehospital compliance to guidelines has been shown  to vary between 7.8–95%. Compliance with examination and treatment recommendations is generally lower compared to compliance with monitoring recommendations. This could also be observed in the present study. There are several reasons for the low guideline compliance in the prehospital setting, including the low evidence level in the guidelines that are being used, prevailing attitudes and workplace culture, and the physical format of the guidelines . Accordingly, this can be an explanation for the poor use of the triage handbook in the present study. One study  has shown that paper-based guidelines can be cumbersome to use effectively in connection to patient assessment in the prehospital context.
The EMS team in this study had low compliance when it came to conducting focused examinations, such as abdominal auscultation, inspection and palpation. These are important examinations in the management of patients with abdominal pain. However, even properly performed examinations cannot rule out serious conditions. For example, one study showed that half of patients with peritonitis had normal bowel sounds and that palpation had low sensitivity and specificity for peritonitis . In more than two-thirds of the cases examined, a physician was not contacted for advice; thus, there might be room for improvement to decide the right level of care. A previous study has reported decreased ambulance transport to the ED for patients with low priority conditions when ambulance nurses and physicians collaborate concerning the right level of care . It is important to highlight that the consequences of inferior training in patient assessment already at the internship level of ambulance training. Incomplete assessments and anamnesis in the hospital field might be less dangerous when the patient is under observation for a longer time, the same shortcomings in patient assessment is more dangerous when “treat and release” in the prehospital setting.
The population in the current study is relatively young compared to patients with abdominal pain who are typically admitted to EDs . This is a positive finding, as it probably means that most elderly patients are transported to hospitals. Elderly patients are more likely than younger patients to have severe aetiologies behind their abdominal pain. It has been shown that both mortality and misdiagnosis increase exponentially with each decade of age past 50 [20, 23].
Furthermore, EMS teams have limited opportunities to safely assess and examine patients with abdominal pain. For example, point-of-care blood tests are unusual, and it is impossible to have a patient undergo an X-ray examination on the spot. The common examination methods available are inspection, palpation and auscultation. It is also possible to measure ECG and vital parameters. Anamnesis is also a very important aspect of the examination done in the prehospital setting. At the same time, patients with abdominal pain are also difficult to assess at the ED, despite opportunities for more advanced examinations. Patient history and physical examinations have a sensitivity of 0.25 and a specificity of 0.92 compared to patient history, physical examination, laboratory analysis, acute abdominal series radiographs and non-enhanced helical computed tomography, with a sensitivity of 0.92 and a specificity of 0.90 . Thus, overall, it is difficult to achieve a good assessment of patients with abdominal pain in a prehospital setting.
Meanwhile, we found that oxygen saturation is a critical clinical predictor associated with the risk of a return visit within 96 hours after the initial assessment, with a lower oxygen saturation indicating an increased risk of a return visit. The risk increased even above 90%. Previous studies have indicated that low oxygen saturation in the early phase is associated with an increased risk of adverse events amongst patients with acute myocardial infarction  and an increased risk of death amongst patients suffering from stroke . The mechanisms behind these findings can only be speculated upon. A reasonable hypothesis is that when diseases in other organs are so severe that they influence respiration, it can be considered a serious sign.
Furthermore, our findings indicate the need for an accurate decision support tool so that not all patients have to be transported to an ED for evaluation. In developing such a tool, the definition of time-sensitive conditions must be carefully considered. Diseases, such as appendicitis and cholecystitis, should most likely be included in such a definition, regardless of any complication.
The main limitation of the present study is the low number of included patients. A study with a larger population could provide a better picture of the prehospital assessment and triage of patients with abdominal pain. Nevertheless, even though generalisability is limited by the small number of patients, the total number from 1 year of ambulance assignments is relatively large enough to highlight potential medical risks amongst patients triaged to self-care. Transferability to other ambulance organisations with similar guidelines should be approached with some caution.
Another limitation is the retrospective study design, which does not allow subsequent analyses of patients’ conditions or diagnoses when they are asked to remain at home. It has been suggested that there is a lack of a clear definition of what constitutes time-sensitive conditions . The current study found that certain diseases could be included in further discussions to improve the precision of prehospital assessment and avoid delayed treatments for patients who require acute hospital care.