Nursing care
Peritonitis nursing care: what to assess and what to do first
Written and reviewed by Dana Whitfield, RN, MSN · 5 min read · Updated September 2026
Short answer
Peritonitis is inflammation of the peritoneum, usually from a ruptured or infected abdominal organ, that can rapidly progress to sepsis. A board-like rigid abdomen with rebound tenderness is the hallmark finding, and the patient's stillness, lying motionless because movement worsens the pain, is itself part of that sign. Early recognition and fluid resuscitation are the priority.
The pathophysiology in one pass
Peritonitis is inflammation of the peritoneum, the membrane lining the abdominal cavity and covering the abdominal organs. It is most often secondary, following perforation of an organ such as a ruptured appendix, perforated peptic ulcer, diverticular rupture, or bowel perforation, which spills bacteria or chemical irritants directly into the normally sterile peritoneal cavity.
The peritoneum reacts to this contamination with a widespread inflammatory response: vasodilation, fluid shift into the peritoneal space, and a paralytic ileus as bowel motility shuts down. Fluid loss into the abdomen can be substantial, and combined with the systemic inflammatory response, this is what pushes peritonitis toward hypovolaemic shock and sepsis if the source is not controlled quickly.
Assessment findings that matter
The defining finding is a board-like rigid abdomen with rebound tenderness (pain that is worse when pressure is released than when it is applied). The patient typically lies still, often with knees drawn up, because any movement, coughing, or even the vibration of a bumpy ambulance ride sharply worsens the pain. That stillness is not a separate observation from the rigidity; it is the same guarding mechanism showing itself in how the patient holds their body, and recognising it as part of the sign, not just an incidental behaviour, is what distinguishes a strong assessment.
Expect fever, tachycardia, and hypotension as the systemic response develops, along with nausea, vomiting, and absent or diminished bowel sounds from the developing ileus. Abdominal distension progresses as fluid and gas accumulate. Trend vital signs closely: a rising heart rate and falling blood pressure in this picture signal progression toward septic shock, not a plateau to wait out.
What the exam asks about this
NCLEX-style questions test recognition of the rigid, board-like abdomen with rebound tenderness as an emergency finding requiring immediate physician notification, not a routine documentation item. A question describing this presentation is testing whether the candidate escalates rather than schedules a repeat assessment for later in the shift.
A second common angle tests prioritisation: given a peritonitis patient with several needs at once, pain, fluid loss, infection risk, the correct first action is usually related to airway, circulation, or urgent surgical notification, since peritonitis is fundamentally a surgical emergency until proven otherwise. Questions may also test the reasoning behind withholding oral intake and laxatives, and behind avoiding heat application to the abdomen, both of which can worsen an underlying perforation or inflammatory process.
Nursing interventions in priority order
Notify the physician immediately once rigidity and rebound tenderness are identified; this finding does not wait for the next round. Establish IV access and begin fluid resuscitation, since significant third-space fluid loss into the peritoneal cavity is common and hypovolaemia is an early threat.
Keep the patient NPO in anticipation of surgery, and insert a nasogastric tube if ordered to decompress the stomach and relieve pressure on a paralytic bowel. Position the patient for comfort, typically semi-Fowler's with knees flexed, which reduces tension on the abdominal wall. Monitor vital signs frequently for signs of progressing sepsis, and administer analgesia and antiemetics as ordered, while withholding oral fluids, food, and any laxative or enema, since these can worsen the underlying process ahead of surgical evaluation.
Medications and monitoring
Broad-spectrum IV antibiotics are started promptly once peritonitis is suspected, typically covering both gram-negative and anaerobic organisms, since the exact source is often not yet identified. IV fluids, crystalloids initially, are titrated to urine output and haemodynamic response to correct the third-space losses.
Analgesia is given for comfort but should not delay or mask the assessment needed to determine surgical urgency; document pain response carefully rather than simply treating the number. Monitor white cell count, lactate, and urine output as markers of infection burden and perfusion, and track for signs of evolving sepsis, tachycardia, hypotension, altered mental status, and reduced urine output, since these indicate the systemic response is outpacing resuscitation.
When to escalate
Escalate immediately for a new rigid, board-like abdomen with rebound tenderness in any patient, particularly one who was previously stable, since this can represent an acute perforation. Escalate for hypotension, a rising heart rate, falling urine output, or altered mental status, all of which point toward septic shock developing on top of the underlying peritonitis.
A sudden, severe increase in abdominal pain in a patient already being monitored for a related condition, appendicitis, diverticulitis, a peptic ulcer, warrants urgent reassessment, since it can indicate the organ has just perforated. Peritonitis confirmed or strongly suspected is a surgical emergency; the nursing role is to recognise it fast, resuscitate, and get the surgical team involved without delay.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our gastrointestinal practice questions are the closest set to what this page covers.
Common questions
What is the classic abdominal finding in peritonitis?
A board-like rigid abdomen with rebound tenderness. The patient typically lies very still, often with knees drawn up, because movement sharply worsens the pain, and that stillness is itself part of the clinical picture, not a separate finding.
Why is a peritonitis patient kept NPO?
Because peritonitis is treated as a surgical emergency until the source is controlled, and oral intake is withheld in anticipation of surgery and because paralytic ileus makes normal digestion unreliable regardless.
What is the priority nursing action when rebound tenderness and rigidity are found?
Notify the physician immediately. This finding suggests peritonitis, which can progress rapidly to septic shock, so it is treated as an urgent escalation rather than a routine documentation item.
Why are vital signs monitored so closely in peritonitis?
Because significant fluid shifts into the peritoneal cavity combined with a systemic inflammatory response can rapidly progress to hypovolaemic and septic shock. Rising heart rate, falling blood pressure, and reduced urine output signal that progression is underway.
Should heat or laxatives be given to a patient with suspected peritonitis?
No. Both can worsen an underlying perforation or inflammatory process, so they are withheld until the abdomen has been fully evaluated and the surgical team has determined it is safe.