**Core Concept**
Primary bacterial peritonitis is a condition characterized by the presence of bacteria in the ascitic fluid of patients with cirrhosis, without any apparent source of infection. It is a serious complication that can occur in patients with cirrhosis, often leading to significant morbidity and mortality.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of primary bacterial peritonitis. This condition is thought to occur due to the translocation of bacteria from the gut into the ascitic fluid, facilitated by the impaired immune function and increased gut permeability in patients with cirrhosis. The presence of ascites and the severity of liver disease are key risk factors for the development of primary bacterial peritonitis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because primary bacterial peritonitis can indeed occur in patients with cirrhosis and ascites, making it a condition to be considered in this context.
* **Option B:** This option is incorrect because primary bacterial peritonitis is a well-documented complication in patients with cirrhosis and ascites, and this option does not provide a valid exception.
* **Option C:** This option is incorrect because primary bacterial peritonitis is a recognized complication in patients with cirrhosis and ascites, and this option does not provide a valid exception.

**Clinical Pearl / High-Yield Fact**
Primary bacterial peritonitis is a medical emergency that requires prompt recognition and treatment. Patients with cirrhosis and ascites should be screened for this condition with diagnostic paracentesis, and empiric antibiotic therapy should be initiated if the ascitic fluid culture is positive.

**Correct Answer:** D