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Peritoneal washings and what they show | CION Cancer Clinics
Peritoneal washing cytology checks for loose cancer cells inside the abdomen. During an operation the surgeon rinses the area with salt water, collects it, and a pathologist looks at it under a microscope. Negative means no cancer cells were seen; positive means they were. What a positive result changes depends on the type of cancer, and this page explains how. CION Cancer Clinics’ surgical oncologists in Hyderabad can talk this through with you.
MI
Medically reviewed by Dr. Mohammed ImaduddinConsultant Surgical Oncologist · MBBS, MS (General Surgery), MCh (Surgical Oncology) · last reviewed September 2026, next review due September 2027
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On this page
- What does "peritoneal washing cytology" mean on my report?
- How are peritoneal washings taken and read?
- What does each result on the report mean?
- Does a positive washing mean the same for every cancer?
- What do families misunderstand about washings?
- What can a washing result not tell you?
- Common questions about peritoneal washings
The short answer
What does "peritoneal washing cytology" mean on my report?
Peritoneal washing cytology is a test for loose cancer cells inside the abdomen. During an operation, the surgeon rinses the abdomen with salt water, collects it, and a pathologist checks it under a microscope. Negative means no cancer cells were seen. Positive means they were.
Why anyone looks for loose cells
The peritoneum is the thin lining of the abdomen. Some cancers shed cells into the space it covers before any lump forms there. These cells are far too small for a CT, MRI or PET-CT to show. Washings are the only practical way to find them, and finding them can change the stage and the plan.
The word "cytology"
Cytology means looking at single cells or small clusters, rather than a solid piece of tissue. It is quicker than a tissue biopsy, but it gives less information, which is why some results come back as "atypical" or "suspicious" rather than a clear yes or no.
A washing result is one piece of the stage. It is always read together with what the surgeon saw and what the tissue samples show.From theatre to report
How are peritoneal washings taken and read?
Taken at the start
Washings are collected early in the operation, before the organs are handled much. You are under a general anaesthetic and feel nothing. It adds very little time.
Rinse and collect
Sterile salt water is poured over the lining, often in the pelvis and upper abdomen, and then drawn back up. If fluid is already present, it may be sampled directly.
Prepared in the laboratory
The fluid is spun so the cells collect at the bottom. They are spread on slides and stained, and sometimes set in a small block for extra tests.
Read and reported
A pathologist looks for cancer cells and compares them with the main tumour. The report usually takes several days, and it goes to your surgeon before it comes to you.
Not sure whether this applies to you?
Ask an oncologistReading the result
What does each result on the report mean?
What the report says
What it means in plain words
Negative for malignant cells
No cancer cells were seen in the fluid
Positive for malignant cells
Cancer cells were seen, even if nothing was visible to the surgeon
Reactive mesothelial cells
Normal lining cells that look irritated, often after surgery or inflammation. Not cancer
Atypical cells
Cells that look unusual but not clearly cancer. Your team decides how much weight to give it
Suspicious for malignancy
Probably cancer cells, but not certain. Often treated with caution, sometimes checked again
It depends on the cancer
Does a positive washing mean the same for every cancer?
No. The same result can change the plan a great deal in one cancer and very little in another.
Stomach cancer
A positive washing counts as spread, even when the surgeon sees nothing. It usually means a major operation is not done straight away, and chemotherapy becomes the first treatment.
Pancreas cancer
Positive washings are also treated as spread in the staging system. Many teams then move away from a large operation, though practice varies and your team will explain their view.
Ovarian cancer
If the cancer seems confined to the ovaries, positive washings move it to a slightly higher early stage. That can affect whether chemotherapy is advised after surgery.
Cancer of the womb
Washings are still often taken and recorded, but in the current staging system they no longer change the stage on their own. Your team reads them alongside everything else.
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Commonly believed
What do families misunderstand about washings?
"The surgeon saw nothing, so the positive washing must be a mistake."
Loose cells can be present with no visible deposit at all. That is exactly why washings are taken. If you are unsure, it is fair to ask whether the slides have been reviewed by a second pathologist.
"Washing the abdomen spreads the cancer around."
The salt water is collected, not left behind, and the test only finds cells that were already there. It does not move cancer anywhere it had not already reached.
"Atypical means it is cancer and they are softening the news."
Atypical genuinely means uncertain. Irritated normal cells can look odd. Ask how the team is treating the result, and whether any further test would help settle it.
Did you know
A washing result never decides a plan on its own at CION. It is discussed at a tumour board, where surgical, medical and radiation oncologists read it together with the scans, the operation notes and the tissue report.
Being straight with you
What can a washing result not tell you?
A washing result cannot tell you how the cancer will behave, how long anything will take, or how well treatment will work. It is one finding among several, and its meaning depends on the type of cancer and on what else was found.
A negative result is not a full all-clear
Negative washings are good to hear, but cells can be missed, and the final stage also rests on the tissue removed and the lymph nodes, the small filtering glands. Wait for the whole report before drawing conclusions.
Questions to ask your team
Does this result change my stage? Does it change what you recommend next? If it says atypical or suspicious, how are you treating it? Has a second pathologist looked at the slides? Write the questions down and bring the family member who helps with decisions.
If you have a washing report and cannot make sense of it, call the helpline. Someone will read it through with you.Questions we are asked
Common questions about peritoneal washings
Does a positive washing mean the cancer has spread?
It means cancer cells were found loose in the abdomen. For stomach and pancreas cancer, that is counted as spread in the staging system. For ovarian cancer it raises the early stage. For cancer of the womb it is recorded but does not change the stage on its own. Ask what it means for your type.
Is the washing done as a separate operation?
No. Washings are taken during an operation you are already having, most often a staging laparoscopy or the main cancer operation. It adds very little time and no extra cut. You will not feel anything, and there is usually no separate recovery.
How long does the result take?
Usually several days, because the fluid has to be prepared and stained before it can be read. Occasionally a quick look is done during the operation, but the final report comes later. Your surgeon will normally explain it at your follow-up appointment.
Can a positive result be wrong?
It is uncommon, but irritated normal lining cells can look unusual, especially after earlier surgery. That is why reports sometimes say atypical or suspicious instead of a firm yes. Asking for the slides to be reviewed by a second pathologist is a reasonable request.
If washings are positive, will I still have surgery?
It depends on the cancer and on everything else found. For some cancers the large operation is put aside and chemotherapy comes first. For others surgery goes ahead with extra treatment after. Your team weighs this, and should tell you plainly what they recommend and why.
Can washings be repeated after chemotherapy?
Sometimes. For some stomach cancers, a second laparoscopy with washings is done after chemotherapy to see whether the cells have gone. Whether that is useful in your case is a question for your surgeon and oncologist together.
What is the difference between washings and ascites fluid?
Ascites is fluid that has already collected in the abdomen on its own, often causing swelling. It can be drained with a needle and checked. Washings are salt water put in and taken out during an operation, used when there is little or no fluid to sample.
Who should explain the result to us?
Your surgeon or oncologist, not the report on its own. The wording is written for doctors and is easy to misread. Bring the report, the family member who helps with decisions and your written questions to the appointment. If you are waiting and worried, call the helpline.
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Dr. C. Raghavendra Reddy
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Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
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Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
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Surgical Oncologist
Dr. Vinay Mamidala
MBBS, MS(General Surgery), M.Ch(Surgical Oncology), FMAS, FARIS(Ongoing)
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Surgical Oncologist
Dr. Vajja Sandeep Kumar
MBBS, MS (General Surgery), DrNB (Surgical Oncology), FALS Oncology
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Sources
- National Cancer Institute — Stomach Cancer Treatment (PDQ) - Patient Version
- National Cancer Institute — Ovarian Epithelial, Fallopian Tube, and Primary Peritoneal Cancer Treatment (PDQ) - Patient Version
- Cancer Research UK — Laparoscopy
- American Cancer Society — Cancer Staging
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Staging Laparoscopy ExplainedThe operation during which washings are usually takenSurgical Staging in Gynaecological CancerHow washings fit into ovarian and womb cancer stagingWhat Happens If Staging Surgery Finds Spread?How the plan changes after a positive resultThe Pathology Report After SurgeryThe other report words you are likely to meet
Talk to us
Have a washing report you do not understand?
Send it to us or call the helpline. A surgical oncologist will go through what it says and what it means for the next step. One helpline serves every CION centre.