Approaching the Acute Abdomen
Abdominal pain is one of the most challenging chief complaints in EMS because the abdomen contains organs from multiple body systems, and pain can be referred from distant structures. The differential diagnosis for abdominal pain includes hundreds of conditions, from benign gastritis to life-threatening aortic aneurysm rupture. Your goal in the prehospital setting is not to diagnose the cause but to identify patients with potentially surgical or life-threatening conditions and transport them appropriately.
The abdomen is divided into four quadrants by imaginary lines through the umbilicus. Right upper quadrant (RUQ) organs include the liver, gallbladder, and right kidney. Left upper quadrant (LUQ) organs include the spleen, stomach, and left kidney. Right lower quadrant (RLQ) organs include the appendix and right ovary. Left lower quadrant (LLQ) organs include the sigmoid colon and left ovary. Midline structures include the aorta, bladder, and uterus.
Types of Abdominal Pain
Understanding the three types of abdominal pain helps narrow the differential:
- Visceral pain: Caused by stretching or distension of a hollow organ. It is typically dull, crampy, poorly localized, and often felt in the midline. Examples include early appendicitis (periumbilical pain) and bowel obstruction.
- Parietal (somatic) pain: Caused by irritation of the peritoneum. It is sharp, well-localized, and worsened by movement or coughing. The transition from visceral to parietal pain (such as periumbilical pain migrating to the RLQ in appendicitis) suggests disease progression.
- Referred pain: Felt at a location distant from the source. Classic examples include shoulder pain from diaphragmatic irritation (ruptured spleen or ectopic pregnancy), back pain from aortic aneurysm or pancreatitis, and jaw pain from cardiac ischemia.
Physical Assessment Techniques
When examining the abdomen, always start palpation in the quadrant farthest from the patient's pain to avoid causing guarding before you have a chance to assess the rest of the abdomen. Assess for tenderness, rigidity, distension, guarding (voluntary tightening of abdominal muscles), and rebound tenderness (pain when you release pressure). A rigid, board-like abdomen suggests peritonitis and is a surgical emergency. Pulsatile masses in the midline suggest an abdominal aortic aneurysm; do not palpate deeply if you suspect this condition.
Red Flags and Transport Decisions
Certain findings indicate life-threatening abdominal emergencies requiring rapid transport: signs of shock (tachycardia, hypotension, pale and diaphoretic skin), rigid abdomen, pulsatile abdominal mass, abdominal pain in a pregnant patient (especially with vaginal bleeding), and abdominal pain with syncope. Position the patient for comfort, usually with knees flexed. Provide antiemetics if available per protocol. Avoid giving food or water, as surgical intervention may be needed. Establish IV access if within your scope and the patient shows signs of shock.