There is very little research on the prehospital care of patients with abdominal pain, even though one retrospective EMS review of 5298 transports revealed that abdominal pain was one of the most frequent patient complaints transported by EMS.30 Key questions that need to be studied include:

• Which patients with abdominal pain need to be transported by a paramedic based unit
  
• Which patients with abdominal pain need to be transported to a center with 24 / 7 CT capabilities
  
• Which patients with abdominal pain have anunderlying vascular emergency and need to be transported to a center with access to a vascular surgeon
  
• Which patients with abdominal pain can be treated with an analgesic in the field
  

There are no good outcome studies that provide guidance on these and other questions. It is clear that, if a patient is mis-triaged in the field, access to life saving interventions may be impacted. For example, if a patient with hypotension and severe sudden onset abdominal pain radiating to the back is transported to a hospital without rapid access to a vascular surgeon, the chance of a good outcome (repair of the abdominal aneurysm without ischemic insult) is threatened.

Kennedy et al³¹ created a gender and age specific medical priority dispatch system (MPDS) in an attempt to determine which patients with abdominal pain required or would benefit from ACLS transport. Upon reviewing 343 rescue runs utilizing the gender and age specific MPDS, they determined that dispatch protocols must incorporate information beyond age and gender classification alone to avoid “over triage” of patients to an ACLS transport. Lammers et ³² created a six tiered dispatch system for patients with the chief complaint of abdominal pain. The tiers ranged from no ambulance dispatched, to an ambulance dispatched for every call of abdominal pain, to protocols with dispatch of an ambulance based on gender, age, and symptom gradation. Utilizing this system, the rate of over triage for ACLS transport was 10 - 51%. The rate of under triage was 4 - 7%. He concluded that no specific protocol had significant advantage over the other. The interesting question that arises from both of these studies is whether these studies identified the correct range of age and / or the correct definition of an emergency condition. Many emergency providers might disagree with the choice of the age range chosen (35 - 45 years old) and the definition of an abdominal complaint emergency (defined as risk of rapid deterioration, significant morbidity, or death if not treated within one hour), which necessitated ACLS transfer.

The issue of how to best treat patients with non-traumatic abdominal pain during transport poses more questions than answers. Table 1 provides general guidelines for prehospital care based on the best available evidence. Several authors have suggested that giving analgesia to patients with the chief complaint of nontraumatic acute abdominal pain is beneficial and the risk involved (masking peritoneal signs) is minimal.^33-35 However, these studies are hospital based and the use of analgesics is made after an evaluation by a physician. Pointer and Harlan³⁶ extrapolated hospital based findings to the prehospital arena and determined that EMS personnel could give morphine sulfate to patients with abdominal pain with no apparent safety or misuse issues, though this awaits validation by a well designed prospective study.