## Sites of Peritoneal Metastasis in Ovarian Cancer **Key Point:** The omentum is the most common site of peritoneal metastasis in advanced ovarian cancer, involved in up to 80% of stage III–IV cases. ### Frequency of Peritoneal Involvement Sites | Site | Frequency | Pathophysiological Basis | |---|---|---| | **Omentum** | 80% (most common) | Rich vascularization; large surface area; gravity-dependent spread; "tumor sink" | | **Peritoneal surface (liver dome)** | 60–70% | Dependent peritoneal surface; gravity-assisted accumulation | | **Rectosigmoid peritoneum** | 50–60% | Dependent pouch; peritoneal fluid pooling | | **Paracolic gutters** | 40–50% | Lymphatic drainage pathways; peritoneal fluid flow | | **Diaphragmatic peritoneum** | 30–40% | Lymphatic drainage from peritoneal cavity | **High-Yield:** The omentum is often the site of **"omental caking"** — a dense, nodular infiltration that is pathognomonic for advanced ovarian cancer and is a key finding during staging laparotomy. ### Pathophysiology of Omental Involvement 1. **Anatomical factors:** The omentum is a large, highly vascularized structure with extensive peritoneal surface 2. **Gravity-dependent spread:** Malignant cells shed from the ovary settle in dependent areas; the omentum is a major dependent site 3. **Lymphatic drainage:** The omentum drains lymph from the peritoneal cavity, facilitating metastatic seeding 4. **Growth advantage:** The omentum provides a rich microenvironment supporting tumor growth ("tumor sink") **Clinical Pearl:** Omental resection (omentectomy) is a standard component of **cytoreductive surgery** in ovarian cancer and is performed regardless of whether omental disease is grossly evident, as microscopic involvement is common. **Mnemonic:** **OPRD** — Omentum (most common), Peritoneal surface (liver dome), Rectosigmoid, Diaphragm — in order of decreasing frequency. [cite:Park 26e Ch 23]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.