# Seroma after breast surgery

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

## TL;DR

A collection of clear fluid under the wound or in the armpit after breast or lymph node surgery. It is common, it is not an infection, and it can be drained with a needle if it is uncomfortable, though it often comes back and settles on its own.

## Summary

Cancer Research UK lists seroma among the possible problems after mastectomy: fluid collecting around the operation site can cause swelling and pain, a nurse or doctor can drain it with a needle and syringe if it is painful, the fluid can build up again after being drained, and you should tell your doctor or nurse if you think one is developing. It distinguishes this from a haematoma, where blood collects in the tissues and the area feels hard, and from wound infection, whose signs it gives as a temperature above 37.5 C or below 36 C, redness or a change in the normal colour of the breast, warmth, pain or swelling, discharge from the wound, feeling cold and shivery, or feeling generally unwell. Those infection signs are the ones that mean the 24-hour advice line rather than waiting. This is orientation from public patient pages, guidelines and the trials themselves, not advice for your case: your own team's instructions and 24-hour number come first, and no figure on this page is a prediction about you.

## Fields

- Kind: Term
- Last checked: 2026-09-25
- Also known as: fluid collection after breast surgery; seroma

## Sources

- Cancer Research UK: possible problems after mastectomy: https://www.cancerresearchuk.org/about-cancer/breast-cancer/treatment/surgery/after-surgery/problems-after-mastectomy
- NICE NG101: early and locally advanced breast cancer, recommendations (updated 2025): https://www.nice.org.uk/guidance/ng101/chapter/Recommendations

## Connected records

- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/)
- terms: [Lumpectomy (breast-conserving surgery)](https://onco.cc/terms/lumpectomy/), [Mastectomy](https://onco.cc/terms/mastectomy/)

---
JSON: https://onco.cc/api/v1/entities/seroma-after-breast-surgery.json