Severe, unrelenting abdominal pain is one of the most frightening symptoms a person can experience. While many stomach aches are benign, intense and constant pain can be a sign of a life-threatening medical emergency known as peritonitis. This condition is severe inflammation of the peritoneum, the thin membrane that lines the inner wall of the abdomen and covers most abdominal organs. Peritonitis is most often caused by a bacterial or fungal infection that results from a rupture or perforation of an abdominal organ. It can rapidly lead to systemic infection (sepsis), shock, and organ failure. Understanding the signs of peritonitis and recognizing it as a true medical emergency is critical, as immediate hospital treatment is essential for survival.

Peritonitis is a serious and potentially life-threatening inflammation of the peritoneum, the thin tissue lining the inside of the abdominal wall and covering abdominal organs. It typically occurs when the peritoneal cavity is infected by bacteria, fungi, or irritants, leading to pain, fever, and abdominal tenderness.

Peritonitis is a medical emergency requiring immediate attention. If left untreated, it can lead to sepsis, organ failure, and death. The condition can arise suddenly (acute) or be part of a chronic illness, especially in people undergoing peritoneal dialysis.

Healthcare providers classify peritonitis into different types based on its cause:

• Secondary Peritonitis: This is the most common type. It is caused by a hole or rupture (perforation) in an abdominal organ, which spills bacteria, digestive juices, and other contents into the peritoneal cavity.
• Spontaneous Bacterial Peritonitis (SBP): This is an infection that develops directly in the peritoneal fluid without a hole in an organ. It occurs almost exclusively in people who have ascites (a large buildup of fluid in the abdomen), which is most often a complication of severe liver disease (cirrhosis).
• Peritonitis related to Peritoneal Dialysis (PD): This type occurs in people receiving peritoneal dialysis for kidney failure, where the dialysis catheter can be a site for bacteria to enter the peritoneal cavity.

Peritonitis can occur when the peritoneum becomes contaminated, either by infection or chemical irritation. This contamination can happen from perforation of a hollow organ, inflammation, or an external medical procedure.

Causes of Secondary Peritonitis: This form is caused by any condition that leads to a perforation of an organ within the abdomen, allowing bacteria from the digestive tract to spill out. The most common causes include:

• Ruptured Appendix: A classic cause. When appendicitis is not treated, the inflamed appendix can burst, spilling infectious material.
• Perforated Peptic Ulcer: A hole that erodes through the wall of the stomach or duodenum, leaking stomach acid and bacteria.
• Perforated Diverticulum: Diverticulitis is the inflammation of small pouches (diverticula) in the colon wall. A severe case can lead to a rupture.
• Bowel Perforation: A hole in the small or large intestine can be caused by a number of conditions, including a bowel obstruction, inflammatory bowel disease (Crohn’s disease), or intestinal infections like typhoid fever.
• Trauma: A penetrating injury, such as a stab wound, or blunt abdominal trauma can rupture an organ.
• Pancreatitis: Severe inflammation of the pancreas can cause inflammatory enzymes to leak into the abdominal cavity, leading to chemical irritation followed by infection.
• Other Abdominal Issues: A ruptured ectopic pregnancy, a perforated gallbladder, or complications from abdominal surgery can also lead to peritonitis.

Causes of Spontaneous Bacterial Peritonitis (SBP): In SBP, there is no hole or rupture. Infection develops in pre-existing ascitic fluid. This occurs in patients with advanced liver cirrhosis because their compromised immune system and other factors allow bacteria from the gut to migrate through the intestinal wall and into the abdominal fluid.

Causes of PD-Related Peritonitis: This is typically caused by contamination of the peritoneal dialysis catheter during the connection or disconnection process. Common skin bacteria, like Staphylococcus, are often the culprits.

You get peritonitis when bacteria, fungi, or irritants (like bile or stomach acid) enter the sterile peritoneal cavity. This entry can occur from inside the body (organ perforation) or from the outside (e.g., dialysis catheter).

Risk factors for Secondary Peritonitis include having any of the following conditions:

• Appendicitis
• Diverticulitis
• Peptic ulcer disease
• Crohn’s disease or ulcerative colitis
• Gallbladder disease
• Pancreatitis

Risk factors for Spontaneous Bacterial Peritonitis (SBP) include:

• Liver Cirrhosis with Ascites: This is the number one risk factor. The leading causes of cirrhosis globally include chronic Hepatitis B, chronic Hepatitis C, and alcoholic liver disease.
• Kidney failure requiring dialysis.

The primary risk factor for PD-Related Peritonitis is being a patient on peritoneal dialysis. I always educate patients on clean technique; they’re at ongoing risk for peritonitis with every catheter exchange.

Peritonitis typically causes sudden, severe abdominal symptoms, often accompanied by systemic signs of infection.

The hallmark signs and symptoms include:

• Severe and Constant Abdominal Pain: The pain is often described as sharp and is relentless. It is made significantly worse by any movement, coughing, or even light touch.
• Extreme Abdominal Tenderness: The abdomen is exquisitely tender when touched.
• Abdominal Rigidity: The muscles of the abdominal wall become involuntarily stiff and hard, a state often described by doctors as a “board-like” abdomen. This is a protective reflex to protect the inflamed organs.
• Rebound Tenderness: A classic sign where the pain is worse when the doctor presses on the abdomen and then quickly releases the pressure.

In addition to these abdominal signs, a person with peritonitis will quickly develop systemic signs of a severe infection as their body begins to go into shock. These include:

• Fever and chills
• Nausea and vomiting
• Loss of appetite
• A rapid heart rate (tachycardia)
• Low blood pressure (hypotension)
• Reduced urine output
• Confusion, disorientation, or lethargy

It is important to note that the signs of SBP in a patient with liver disease can be much more subtle, sometimes presenting only with a low-grade fever, worsening ascites, or a change in mental status.

Diagnosis is primarily clinical, supported by laboratory tests and imaging studies.

• Physical Examination: The diagnosis is often strongly suspected based on the physical exam alone. The presence of a rigid, tender abdomen with rebound tenderness is a classic indicator of peritonitis.
• Blood Tests: A complete blood count (CBC) will be done immediately, which will typically show a very high white blood cell count, indicating a severe infection. Other blood tests will be done to check electrolyte imbalances and assess kidney and liver function.
• Imaging Studies:
  • An abdominal X-ray may be performed to look for “free air” under the diaphragm. The presence of free air is a definitive sign of a perforated organ.
  • A Computed Tomography (CT) scan of the abdomen is the most valuable imaging test. It can often pinpoint the source of the infection, such as a ruptured appendix with an associated abscess (a walled-off pocket of pus), or signs of a perforated ulcer.
• Paracentesis: For a patient with ascites and suspected SBP, a diagnostic paracentesis is performed. A doctor uses a needle to draw a sample of the ascitic fluid from the abdomen. This fluid is sent to the lab to be analyzed for a high white blood cell count and to be cultured to identify the specific bacteria causing the infection.

Clinically, paracentesis is invaluable in spontaneous peritonitis. It helps us tailor antibiotic therapy and confirm the diagnosis early.

Peritonitis is a medical emergency that requires immediate antibiotic treatment and, in many cases, surgical intervention.

Initial Resuscitation and Medical Management

The first steps are focused on stabilizing the patient and fighting the infection.

• Intravenous (IV) Fluids: Large volumes of IV fluids are given immediately to treat dehydration and combat the low blood pressure and shock caused by the widespread inflammation.
• Broad-Spectrum IV Antibiotics: Powerful antibiotics are started right away, even before the specific bacteria are identified.
• Pain Control: Pain medication is given to manage the severe pain.
• Supportive Care: This may include placing a nasogastric tube to decompress the stomach and closely monitoring vital signs, urine output, and oxygen levels.

Source Control: The Definitive Treatment

For secondary peritonitis, medical management alone is not enough. The underlying source of the contamination must be fixed.

• Emergency Surgery (Laparotomy): In most cases of secondary peritonitis, emergency surgery is required. A surgeon will make an incision to open the abdomen, identify the source of the infection (e.g., the ruptured appendix or perforated ulcer), and repair it.
• Abdominal Washout: During the surgery, the entire peritoneal cavity will be thoroughly washed out with large amounts of sterile salt water to remove as much of the contaminating bacteria, pus, and debris as possible. Drains may be left in place temporarily.

Complications

If not treated rapidly, peritonitis can lead to severe and often fatal complications.

• Sepsis and Septic Shock: The infection can spread into the bloodstream, triggering a body-wide inflammatory response that leads to a catastrophic drop in blood pressure and multi-organ failure.
• Intra-abdominal Abscess: Pockets of pus can become walled off within the abdomen, requiring drainage.
• Adhesions: Scar tissue can form within the abdomen as it heals, which can lead to a future bowel obstruction.

Peritonitis is a grave medical emergency that represents a catastrophic failure of the body’s natural barriers. Whether caused by a ruptured appendix, a perforated ulcer, or an infection in a patient with liver disease, the resulting inflammation of the abdominal lining can rapidly lead to sepsis and death. The hallmark symptoms of severe, constant abdominal pain with a hard, tender abdomen are red flags that demand immediate action. The prognosis for peritonitis depends almost entirely on the speed of diagnosis and the initiation of aggressive treatment, including IV antibiotics and, in most cases, emergency surgery.

• Cleveland Clinic. (2023). Peritonitis. Retrieved from https://my.clevelandclinic.org/health/diseases/17792-peritonitis
• Mayo Clinic. (2023). Peritonitis. Retrieved from https://www.mayoclinic.org/diseases-conditions/peritonitis/symptoms-causes/syc-20376247
• National Institutes of Health, MedlinePlus. (2023). Peritonitis. Retrieved from https://medlineplus.gov/ency/article/001335.htm