What is an important sign to look for when assessing for peritonitis in abdominal injuries?

Guarding and rebound tenderness are critical signs to observe when assessing for peritonitis in cases of abdominal injuries. Guarding refers to the involuntary tensing of the abdominal muscles in response to pain, which often indicates irritation of the peritoneum. Rebound tenderness occurs when pressure applied to the abdomen is suddenly released, causing pain; this is also a sign of peritoneal irritation. The presence of these symptoms typically suggests inflammation in the abdominal cavity and can indicate serious conditions such as appendicitis or other abdominal injuries requiring immediate intervention.

In this context, increased heart rate and increased body temperature can also be linked to peritonitis, but they are not as specific as guarding and rebound tenderness in pinpointing the condition. Swelling in the extremities is generally associated with different clinical conditions and is not a classic sign of peritonitis. Hence, the combination of guarding and rebound tenderness provides a more direct and reliable indication of peritoneal irritation, making it the most important sign to look for in this assessment.