postbariatric surgery patients, and immunocompromised patients. Additionally, many significant extra‐abdominal conditions can present with mostly abdominal complaints.
Abdominal pain is the most frequent chief complaint in the emergency department, accounting for almost 9% of the total visits [1]. It is also one of the most common reasons to call EMS. At least 1 in 20 EMS calls is for abdominal complaints [2]. It is especially concerning in those over 60 years old, as one study found that 58% were admitted to the hospital and 18% needed surgical intervention [3]. Thus, EMS clinicians encounter patients with abdominal pain on a regular basis, but options for patient assessment and management are limited.
Approach to the patient with abdominal pain
Assessment and management of abdominal pain patients in the prehospital setting are difficult for a variety of reasons. The following objectives apply:
The initial priority must be to recognize patients with abnormal vital signs and provide hemodynamic support;
Consider life‐threatening conditions that can present with abdominal complaints (Box 19.1);
Recognize high‐risk patient populations, including the elderly, children, females of childbearing age, and patients who are immunocompromised (e.g., human immunodeficiency virus [HIV] patients, cancer patients, transplant patients, others receiving immunosuppressive agents); andBox 19.1 Life‐threatening conditions causing abdominal painAbdominal aortic aneurysm (ruptured)Acute myocardial infarctionAortic dissectionBowel obstruction/perforationDiabetic ketoacidosisEctopic pregnancy (ruptured)Envenomation (e.g., black widow spider bite)Mesenteric ischemiaPancreatitisPeritonitisPoisoning/overdose (e.g., iron tablets)Tubo‐ovarian abscess
Be aware of extra‐abdominal and systemic illnesses that can present with abdominal pain, including acute myocardial infarction, pneumonia, and diabetic ketoacidosis (Box 19.2).
Anatomy and physiology considerations
The peritoneum provides a potential space for air, blood, or other fluids in pathologic conditions. Some structures, such as the kidneys, ureters, pancreas, aorta, and portions of the duodenum, lie in the retroperitoneum. This area contains less sensory innervation, accounting for decreased pain perception and often poor localization of pathologic conditions involving these structures. The lungs, pleural cavity, and base of the heart are all in close proximity to the abdominal cavity and can be involved in conditions that may be perceived as abdominal pain.
The abdomen is traditionally divided into four quadrants by a vertical and horizontal line through the umbilicus. Use of the quadrant description provides not only common terminology, but it is also an important determinant in the development of a differential diagnosis of abdominal complaints (Box 19.3).
Box 19.2 Systemic causes of abdominal pain
Acute myocardial infarction
Acute intermittent porphyria
Black widow envenomation
Diabetic ketoacidosis
Familial Mediterranean fever
Glaucoma
Heavy metal poisoning
Hereditary angioedema
Hyperthyroidism
Poisoning/overdose (iron, others)
Pneumonia
Streptococcal pharyngitis
Sickle cell vaso‐occlusive crisis
Shingles (Zoster herpticus)
Uremia
Vasculitis
Pathologic states may cause different types of pain: visceral, somatic, or referred pain. Luminal or capsular distention will typically produce visceral pain by stimulation of nerves surrounding a hollow or solid organ. Because the innervation of organs is sparse and multisegmented, this pain is usually dull and poorly localized. When caused by an obstructive process, the pain is typically intermittent or colicky. Distention of a solid organ tends to produce more constant pain (e.g., hydronephrosis, hepatitis). Visceral pain is typically associated with other autonomic phenomena such as anorexia, nausea, and vomiting.
Somatic abdominal pain typically results from irritation of the parietal peritoneum from infection or inflammation. The pathologic process stimulates peripheral nerves, and the pain tends to be more intense and distinct than visceral pain. The evolution of acute appendicitis involves both visceral and somatic pain. Early obstruction and distention of the appendix generates dull, poorly localized pain around the umbilicus. As inflammation progresses, the parietal peritoneum becomes involved and the pain becomes localized to the right lower quadrant.
Referred pain is at a site not directly involved with the disease process. Visceral and somatic nerves from different areas converge at the spinal cord allowing for misinterpretation of location by the brain. An example is irritation of the diaphragm by blood in the peritoneal cavity as might be seen following a ruptured ectopic pregnancy. This is perceived as shoulder pain because both the diaphragm and the skin near the shoulder share the C4 sensory level. Other common sites of referred pain are indicated in Table 19.1.
History and physical examination
An organized assessment must be applied to any patient with a presenting complaint of abdominal pain. A careful history will yield an appropriate list of potential etiologies in most patients.
Box 19.3 Etiologies of abdominal pain by anatomical location
Right upper quadrant
Cholelithiasis/cholecystitis
Acute hepatitis
Acute pancreatitis
Renal colic
Duodenal ulcer
Right lower lobe pneumonia
Myocardial infarction
Right lower quadrant
Acute appendicitis
Cecal diverticulitis
Colitis (Inflammatory bowel disease)
Renal colic
Abdominal aortic aneurysm
Inguinal hernia
Testicular/ovarian torsion
Ectopic pregnancy
Pelvic inflammatory disease
Ovarian cyst
Endometriosis
Left upper quadrant
Pancreatitis
Renal colic
Gastric ulcer
Gastritis