Why does primary peritoneal cancer cause abdominal swelling?

The peritoneum is a thin lining around many abdominal organs. Primary peritoneal cancer can irritate this lining and interfere with the normal movement and drainage of fluid. Fluid may then build up as ascites, making the abdomen feel tight, heavy, or increasingly full. The lining may also become thicker or develop areas of tumour, adding to pressure and discomfort. Swelling can be accompanied by early fullness when eating, bloating, abdominal or back discomfort, nausea, or changes in bowel movements.

Abdominal swelling has other causes, including constipation, digestive conditions, liver disease, and fluid retention from other illnesses. Swelling alone does not establish primary peritoneal cancer. A clinician may use an examination, blood tests, ultrasound or other imaging, and sometimes a sample of abdominal fluid to find the cause.

Arrange a medical assessment if swelling persists, increases, or comes with reduced appetite, unexplained weight change, pelvic discomfort, or breathlessness. Note how quickly it changes, whether meals make the fullness worse, and any bowel or urinary changes. Wear comfortable clothing and take prescribed medicines as directed, but avoid self-starting water tablets or strict fluid restriction before a clinician identifies the cause.

Seek urgent care for severe or rapidly worsening abdominal pain, repeated vomiting, inability to pass stool or gas, fever, fainting, confusion, or new difficulty breathing. A very tense abdomen with breathlessness may need prompt treatment to relieve pressure and check for complications.

Ask what may be causing the fluid, which scan or procedure is needed, and how symptoms can be relieved. Ask how to monitor swelling at home and which changes should trigger urgent review.