Why are tenderness, rebound tenderness, and muscle rigidity referred to as the triad?

Under normal circumstances, the combination of tenderness, rebound tenderness, and muscle rigidity is known as peritoneal irritation signs, which are commonly considered typical clinical manifestations of acute peritonitis. Causes of peritoneal irritation may include infection, trauma, acute appendicitis, perforated peptic ulcer, acute pancreatitis, etc. It is recommended to seek medical attention promptly, identify the underlying cause, and receive symptomatic treatment under the guidance of a qualified physician. Specific analyses are as follows:

1. Infection

Infections may arise from conditions such as appendicitis or cholecystitis. When organs or tissues within the abdominal cavity become infected and are not treated promptly, the infection may spread into the peritoneal cavity, leading to reactions such as tenderness, rebound tenderness, and muscle rigidity. It is advisable to maintain good personal hygiene, prevent intestinal infections, and treat related diseases in a timely manner.

2. Trauma

Trauma may result from incidents such as traffic accidents or falls. If trauma damages the peritoneum, bacteria may invade the peritoneal cavity and subsequently trigger peritoneal irritation signs. Therefore, it is important to enhance safety awareness in daily life to prevent accidental injuries.

3. Acute Appendicitis

The causes of acute appendicitis may include obstruction of the appendix lumen and bacterial invasion. During acute appendicitis, inflammation causes thickening of the appendix wall, potentially leading to luminal obstruction and bacterial infection. When inflammatory substances and toxins leak into the abdominal cavity, they irritate the peritoneum, causing localized pain and protective muscle tension. Tenderness occurs in the region where the appendix is located—typically the right lower quadrant; rebound tenderness results from pain caused by sudden release after pressure, which stretches the peritoneum; muscle rigidity is a protective reflex of the abdominal muscles to minimize discomfort. This condition is often accompanied by symptoms such as fever, nausea, and loss of appetite. Medications such as cefixime tablets, amoxicillin capsules, and racemic hyoscine butylbromide tablets may be used as directed by a physician to alleviate symptoms.

4. Perforated Peptic Ulcer

Peptic ulcers may be caused by Helicobacter pylori infection, excessive gastric acid secretion, or inappropriate use of nonsteroidal anti-inflammatory drugs (NSAIDs). When a gastric or duodenal ulcer perforates, gastric acid leaks into the abdominal cavity, irritating the peritoneum and triggering severe pain and inflammatory responses, possibly resulting in congestion and edema, thereby producing peritoneal irritation signs. Symptoms may include sudden severe abdominal pain, vomiting, and bloating. Treatment may involve medications such as metronidazole tablets, morphine hydrochloride tablets, and ranitidine hydrochloride tablets, administered under medical supervision.

5. Acute Pancreatitis

Possible causes of acute pancreatitis include gallstones, alcohol consumption, and hyperlipidemia. In acute pancreatitis, the pancreas undergoes autodigestion, releasing large amounts of pancreatic enzymes and inflammatory mediators that can stimulate an inflammatory response in the peritoneum, leading to the aforementioned symptoms. Additional symptoms may include loss of appetite, fever, and severe upper abdominal pain. Pain relief and infection control may be managed under medical guidance using medications such as cefotaxime sodium for injection, alfentanil hydrochloride injection, metronidazole tablets, and octreotide acetate injection.

It is recommended that once the triad of signs is detected, peritonitis should be highly suspected, and early diagnosis and treatment initiated. Additionally, patients should ensure adequate rest and nutritional support to promote recovery.