the use of ultrasound in the prehospital setting. New ultrasound technology is lightweight, provides high‐quality resolution, and can withstand a wider range of environmental conditions. Some paramedics have been trained in the focused assessment with sonography in trauma (FAST) exam as well as abdominal aortic ultrasound to evaluate for aneurysm. Multiple studies have shown that under close physician supervision, the point‐of‐care FAST exam and abdominal aorta ultrasound are feasible and useful in the prehospital setting [6–8]. They can provide earlier information regarding the patient’s condition, leading to more informed triage decisions, reduced time to diagnosis, and improved delivery to definitive care (see Chapter 69).
Several studies have evaluated prehospital lactic acid measurement in nontrauma patients. There may be potential benefit for undifferentiated patients with abdominal pain. Elevation in prehospital lactate has been linked to mortality and may provide information superior to that of the patient’s vital signs in detecting occult shock, as well as facilitating resuscitation at an earlier stage in patient care [9–11].
Historically, there have been eloquent expressions of concern regarding analgesic administration to not‐yet‐diagnosed patients with abdominal pain [12–15]. The general foundation for reluctance to pursue pain relief is belief that pain provides an important diagnostic clue, and any attenuation could lead to delayed or missed diagnosis of important pathology. Proponents of treating abdominal pain with analgesics stress that a more comfortable patient is better able to participate in a reliable physical examination, and diagnostic tools and accuracy have improved greatly since concerns were articulated. They further point out that adverse outcomes related to diagnostic efficiency are not directly associated with analgesic administration [15–20]. Thus, the goal for EMS has generally evolved. Pain should be treated to the extent that it facilitates a detailed history and physical exam from a patient who is alert and able to cooperate. Opioids have been the mainstay of pain management. However, other agents may also provide value in specific circumstances and, barring general contraindications, include nonsteroidal anti‐inflammatory drugs (e.g., ketorolac), acetaminophen, and nondissociative doses of ketamine [21].
With regard to resuscitating patients with abdominal pain and suspected or known intra‐abdominal hemorrhage, such as ruptured aortic aneurysm or ruptured ectopic pregnancy, attempts to restore normotensive states may not be possible in the prehospital environment. In fact, it may be harmful. These conclusions are drawn from animal and clinical studies of hemorrhagic shock that demonstrate that some level of “permissive hypotension” may improve outcomes [22–24]. Animal research showed no differences in organ perfusion, cardiac output, and lactic acid levels between permissive hypotension and normotensive resuscitation groups. It defined permissive hypotension as 60% of baseline mean arterial pressure [25].
Urinary catheters serve as both a management tool and source of some abdominal pain. Their presence and functionality should be noted during patient examination. Patients with both indwelling urethral and suprapubic catheters are at risk for urinary tract infections, mechanical obstruction, or catheter displacement. EMS clinicians may be trained to place urinary catheters, observing sterile technique, to relieve bladder distention. They should be educated that patients with recent urethral procedures or bleeding from the urethral meatus should not be catheterized due to risk of urethral injury.
Disposition
It is difficult for EMS personnel to identify patients who do not require transport and to make a decision regarding the need for medical evaluation in an ED. It is possible that a patient may not require EMS transport but may still require medical evaluation. Researchers have previously evaluated the accuracy of such decisions. When EMS clinicians were compared with physicians regarding need for patients to be transported, EMS clinician judgment was 22.1% sensitive and 80.5% specific [26]. The presence of abdominal pain was found to be highly associated with the need for transport as judged by the physicians. On the other hand, one study found 84% over‐triage with regard to provision of ALS care to patients with abdominal pain [27]. Significant under‐triage may also occur; 11% in one investigation [28]. Multiple evaluations have confirmed significant under‐triage by EMS personnel for a variety of medical conditions [29–31]. These studies reaffirm the need to exercise caution in approaching transport decisions in patients with abdominal complaints.
Special populations
There are certain populations who are at particular risk for poor outcomes and require an attentive approach.
Elderly
In 2016, there were 49.2 million people age 65 and over in the United States, accounting for 15% of the population [32]. By 2030, the number is projected to represent nearly 21% of the total U.S. population [33]. This population represents high‐volume users of the EMS system [34]. Compared to younger patients, geriatric patients have higher mortality when admitted to a hospital with abdominal pain and a higher rate of surgical intervention [34–36]. One third of elderly patients who present with abdominal pain require surgery, as compared with 10% for other adult patients [37].
The higher mortality rate in geriatric patients is due to several factors. Elderly patients delay seeking medical care for abdominal complaints and will often present later in their disease processes than younger patients. They tend to have more vague symptoms, which can make the evaluation difficult. The elderly have a decreased perception of abdominal pain [38]. Because of this, many elderly patients with significant underlying pathology are misdiagnosed with benign conditions.
Use of medications such as beta‐blockers, nonsteroidal anti‐inflammatory drugs, pain medications, anticoagulants, and steroids are more common in this population. In addition, other physiologic responses including fever, immune responsiveness, rebound tenderness, and laboratory abnormalities may not be as prominent in the older patient. Complex medical problems predispose this population to certain conditions, such as abdominal aortic aneurysm and mesenteric ischemia.
Common diagnoses found in the geriatric population with abdominal pain include diverticulitis, diverticulosis, small bowel obstruction, volvulus, malignancy, perforated viscous, urinary tract infection, appendicitis, and biliary tract disease. This list is not all‐inclusive. As mentioned previously, cardiac or pulmonary pathology can also present as abdominal pain, and must be entertained based on the patient’s history and physical exam. Additional historical information about abdominal pain as related to food intake, vomiting and/or diarrhea, melena or bright red blood per rectum, previous abdominal surgeries, fever, sick contacts, and other areas of pain should be elicited. Focus is necessary on the cardiac, pulmonary, and abdominal components of the physical exam. Cardiac and pulse oximetry monitoring is recommended.
Females of Childbearing Age
Females of childbearing age represent a particular challenge because the number of problems that cause abdominal pain in this population must be expanded to include conditions involving the pelvic organs. Specifically, ectopic pregnancy, ovarian torsion, ruptured ovarian cyst, and tubo‐ovarian abscess (TOA) as a consequence of pelvic inflammatory disease are significant causes of pain in this population. The difficulty in evaluating these possibilities lies in the fact that neither pelvic examination nor pregnancy testing are routinely available in the prehospital setting. Many patients do not know they are pregnant, and the physical exam is not reliable in establishing the diagnosis of pregnancy.
Ectopic pregnancy is one of the leading causes of pregnancy‐related deaths in women. Hemorrhagic shock from a ruptured ectopic pregnancy should be considered in any female of appropriate age with hypotension and abdominal pain. A past history of PID, known tubal pregnancy, prior tubal surgery, or intrauterine device use increases the likelihood of ectopic pregnancy.
Pelvic pain caused by ovarian torsion tends to be sudden in onset in reproductive‐age females. It is typically described as sharp and knife‐like. Right‐sided torsion is more common. The signs and symptoms of a ruptured ovarian cyst are difficult to distinguish from torsion. TOA occurs in approximately 1%‐4% of patients with