Acute suppurative peritonitis refers to inflammation of the peritoneum and peritoneal cavity caused by bacterial infection, chemical irritation, or physical damage. It is one of the most common acute abdominal conditions encountered in surgery. Based on etiology, it can be classified as bacterial or non-bacterial; based on pathogenesis, as primary or secondary; based on the extent of involvement, as localized or diffuse; and based on clinical progression, as acute, subacute, or chronic.
Anatomical and Physiological Overview
The peritoneum is divided into two anatomically continuous layers: the parietal peritoneum and the visceral peritoneum. The parietal peritoneum lines the inner surfaces of the abdominal wall, the visceral side of the diaphragm, and the pelvic walls, while the visceral peritoneum covers the surfaces of internal organs as their serosal layer. The visceral peritoneum suspends or anchors the internal organs to the diaphragm, posterior abdominal wall, or pelvic wall, forming structures such as the omentum, mesentery, and ligaments.
The peritoneal cavity, also referred to as the abdominal cavity, is the potential space between the parietal and visceral peritoneum. This cavity is closed in males but communicates with the external environment in females through the fallopian tubes, uterus, and vagina. Under normal conditions, the peritoneal cavity contains 75–100 mL of clear yellow fluid, which serves as a lubricant. In cases of pathological processes, the cavity can accommodate several liters of fluid or gas. Anatomically, the cavity is divided into the greater peritoneal cavity and the lesser sac, which communicate via the epiploic foramen (also known as Winslow's foramen).
The greater omentum, which extends from the greater curvature of the stomach to the transverse colon, drapes over the small intestine like an apron. It is rich in blood supply and fat tissues, has significant mobility, and can migrate to the site of a lesion, encapsulating it to localize inflammation and promote repair of the affected area.
The parietal peritoneum is primarily innervated by somatic nerves, making it sensitive to various stimuli and capable of precise pain localization. When inflamed, the parietal peritoneum in the anterior abdominal wall may exhibit clinical signs such as localized tenderness, rebound tenderness, and muscle rigidity. These are key diagnostic indicators of peritonitis. Stimulation of the central portion of the diaphragm's peritoneum can cause referred pain to the shoulders or hiccups through phrenic nerve reflexes. In contrast, the visceral peritoneum is innervated by autonomic nerves and responds primarily to stretching, increased intraluminal pressure, inflammation, or compression with poorly localized, dull pain. This type of pain often manifests in the central abdomen or periumbilical region and, under intense stimulation, can trigger bradycardia, hypotension, and intestinal paralysis.
The surface of the peritoneum consists of a layer of flat mesothelial cells. Beneath it lie the basement membrane and subserosal layer, which contain connective tissue, adipocytes, macrophages, collagen, and elastic fibers. The surface area of the peritoneum is nearly equivalent to the surface area of the entire body skin, approximately 1.5 square meters. It functions as a bidirectional semipermeable membrane, allowing the passage of water, electrolytes, urea, and other small molecules. Small amounts of peritoneal fluid are secreted into the cavity, containing lymphocytes, macrophages, and shed epithelial cells.
During acute inflammation, the peritoneum secretes large amounts of exudate to dilute toxins and mitigate stimulation. Macrophages in the exudate phagocytose bacteria, foreign bodies, and damaged tissues. Fibrin deposition occurs around lesions, leading to adhesions that prevent the spread of infection and promote tissue repair. However, these adhesions can also result in extensive fibrous bands within the abdominal cavity. If the intestines become angulated, twisted, or form masses due to these adhesions, intestinal obstruction may develop.
The peritoneum has a highly efficient absorptive capacity, allowing the absorption of fluids, blood, air, and toxins from the abdominal cavity. In severe peritonitis, large amounts of toxic substances may be absorbed, potentially leading to septic shock.
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