**Core Concept:** Diagnostic peritoneal lavage (DPL) is a diagnostic procedure performed to determine the cause of peritonitis, which is an acute inflammation of the peritoneum (the lining of the abdominal cavity). DPL involves flushing the peritoneal cavity with a sterile fluid, withdrawing it, and analyzing the fluid for cellular and biochemical markers.

**Why the Correct Answer is Right:** The correct answer, **DPL is confirmed positive by an increased white blood cell (WBC) count**, is based on the principle that the peritoneum becomes inflamed during peritonitis, causing a significant increase in the number of leukocytes (white blood cells) present in the peritoneal fluid. The presence of a high WBC count indicates a bacterial infection or inflammation, which confirms the diagnosis of peritonitis.

**Why Each Wrong Option is Incorrect:**

A. **Leucopenia (decreased WBC count)** is incorrect because a decrease in WBC count in the peritoneal fluid is a sign of a non-inflammatory process or sterile peritonitis, which is not the case in peritonitis.

B. **Normal peritoneal fluid pH** is incorrect because a normal pH of the peritoneal fluid does not rule out peritonitis. In fact, in some cases, the pH may be normal even in the presence of peritonitis due to the buffering capacity of the peritoneal fluid.

C. **Normal glucose concentration** is incorrect because a normal glucose concentration in peritoneal fluid does not exclude peritonitis. Inflammatory processes can lead to increased glucose absorption from the blood into the peritoneal fluid, resulting in an elevated glucose concentration.

D. **Absence of polymorphonuclear cells (PMNs)** is incorrect because polymorphonuclear cells (PMNs) are an essential part of the acute inflammatory response. The absence of PMNs in the peritoneal fluid is more likely in sterile peritonitis or non-inflammatory conditions, making it an inappropriate parameter for confirming peritonitis.

**Clinical Pearl:** In cases where the white blood cell count is not elevated due to the presence of infection and is < 10 cells/mm³, other diagnostic methods should be considered, such as peritoneal biopsies or cultures, to confirm the diagnosis of peritonitis. **Why the Correct Answer is Right:** The correct answer, **an increased WBC count**, is based on the fact that an elevated white blood cell count in the peritoneal fluid indicates the presence of infection or inflammation in the peritoneum, which is a hallmark of peritonitis. The inflammatory response leads to an increase in the number of leukocytes in the peritoneal fluid, primarily polymorphonuclear cells (PMNs), which serve as a marker for inflammation and infection. **Core Concept:** Peritonitis is an acute inflammation of the peritoneum, often caused by bacterial infections or other factors like trauma or malignancy, which can lead to the release of inflammatory mediators and leukocytes into the peritoneal cavity. This results in increased leukocytes, primarily polymorphonuclear cells (PMNs), in the peritoneal fluid. **Why Each Wrong Option is Incorrect:** A. **Absence of polymorphonuclear cells (