# Malignant pleural effusion and ascites

Source: https://onco.cc/terms/pleural-effusion/  
OnCo record `pleural-effusion` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Fluid that builds up around the lung (pleural effusion) or in the abdomen (ascites) because cancer cells irritate the lining and block lymph drainage; it causes breathlessness or a swollen, tight belly.

## Summary

Both are signs of advanced disease (stage IV in lung cancer; a criterion in Child-Pugh and BCLC for liver cancer) and both are diagnosed and relieved by draining the fluid, which can also be sent for cytology and ctDNA. Repeated drainage, indwelling catheters, pleurodesis and, for ascites, diuretics or intraperitoneal therapy are the management options; effective systemic treatment of the cancer is what stops the fluid re-forming. Ovarian cancer classically presents with ascites.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: pleural effusion; effusion; effusions; ascites; malignant ascites; paracentesis

## Notes

- Lung cancer: Cancer Research UK says fluid can build up between the two sheets of tissue covering the lungs when cancer inflames them or blocks the drainage, that the extra fluid stops the lungs expanding fully so you take shallower breaths and work harder to breathe, that breathlessness may be the first and only symptom although cough and chest pain also occur, and that if you suddenly become breathless or your breathing gets worse you should call 999 or go to A&E straight away.
- NICE NG122 (1.15.1) says to perform pleural aspiration or drainage in an attempt to relieve the symptoms of a pleural effusion, and (1.15.2) to offer talc pleurodesis to people who would experience long-term symptomatic benefit from aspiration or drainage.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Malignant_pleural_effusion
- Wikipedia: https://en.wikipedia.org/wiki/Malignant_pleural_effusion
- Cancer Research UK: fluid on the lungs (pleural effusion): https://www.cancerresearchuk.org/about-cancer/coping/physically/breathing-problems/fluid-on-lungs-pleural-effusion
- NICE NG122: lung cancer, palliative interventions and supportive and palliative care: https://www.nice.org.uk/guidance/ng122/chapter/Palliative-interventions-and-supportive-and-palliative-care
- Macmillan: breathlessness: https://www.macmillan.org.uk/cancer-information-and-support/impacts-of-cancer/breathlessness

## Connected records

- terms: [Child-Pugh score](https://onco.cc/terms/child-pugh/), [Malignant pleural effusion](https://onco.cc/terms/malignant-pleural-effusion/), [Palliation in lung cancer: breathlessness, pleural effusion, blocked airway, bone and brain](https://onco.cc/terms/lung-palliation-breathlessness-effusion-obstruction/), [Peritoneum and peritoneal metastases](https://onco.cc/terms/peritoneum/), [Pleura](https://onco.cc/terms/pleura/), [Pleurodesis and indwelling pleural catheter](https://onco.cc/terms/pleurodesis/)
- cancers: [Hepatocellular carcinoma](https://onco.cc/cancers/hcc/), [Lung cancer (all types)](https://onco.cc/cancers/lung-cancer/), [Mesothelioma](https://onco.cc/cancers/mesothelioma/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/), [Ovarian cancer](https://onco.cc/cancers/ovarian/), [Small-cell lung cancer](https://onco.cc/cancers/sclc/)
- fronts: [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- trials: [AMPLE](https://onco.cc/trials/ample/), [TIME2](https://onco.cc/trials/time2/)

---
JSON: https://onco.cc/api/v1/entities/pleural-effusion.json