Medical Oncologist
CION Cancer Clinics
Spontaneous bacterial peritonitis: the infection in the fluid to know about | CION Cancer Clinics
Spontaneous bacterial peritonitis, or SBP, is an infection of the fluid that collects in the belly when the liver is scarred. It needs hospital care the same day it is suspected. This page explains the symptoms, including the quiet ones such as confusion or less urine, how a fluid test confirms it, how it is treated, and how families can lower the chance of it coming back. At CION Cancer Clinics, our team supports patients and families through symptoms, follow-up and life during and after treatment.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed October 2026, next review due October 2027
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The short answer
What is spontaneous bacterial peritonitis?
Spontaneous bacterial peritonitis, often shortened to SBP, is an infection of the ascites, the fluid that collects in the belly when the liver is scarred. It is serious, it can come on quietly, and it needs hospital treatment the same day it is suspected.
Why it happens
The word spontaneous means there is no obvious cause, such as a wound or a burst bowel. In cirrhosis, germs from the gut can slip into the blood and settle in the fluid. The fluid has little natural defence against them, so a small number of germs can grow into a real infection.
Who is most at risk
People with cirrhosis and ascites, especially when the liver is weaker, the fluid is low in protein, there has been a recent bleed from swollen veins, or there has been an episode of SBP before. Liver cancer on top of cirrhosis does not cause SBP directly, but it often comes with the kind of liver and fluid in which SBP happens. Our page on infections in cirrhosis explains why these infections escalate so fast.
Caught early, SBP is treated with antibiotics. The danger lies in waiting.What to watch for
What are the symptoms of SBP?
Some people have a clear fever and pain. Others only seem a little more unwell than usual. Both need the same urgent response.
The obvious signs
- Fever or shivering
- Belly pain or tenderness that is new or worse
- A belly that hurts to touch or press
- Vomiting, or loose motions
The quiet signs families miss
In older people and in weak livers, the only change may be in behaviour or energy.
- New confusion, drowsiness or odd behaviour
- Deeper yellow eyes or skin
- Passing much less urine
- Simply looking worse, without a clear reason
Sometimes, no symptoms at all
SBP can be found only because a sample of fluid was tested during a routine tap or a hospital admission. This is one reason doctors test the fluid whenever someone with ascites is admitted.
With a home drain
Cloudy fluid in the bottle, redness around the tube, or any of the signs above. Read more on living with a permanent drain at home.
Not sure whether this applies to you?
Ask an oncologist
!
Go to hospital today
If someone with cirrhosis and fluid in the belly has a fever, new belly pain, new confusion or drowsiness, or is passing very little urine, go to hospital today. Tell the staff the person has cirrhosis and ascites, and ask whether the fluid will be tested. Do not wait to see if it settles, and do not start leftover antibiotics at home.
In hospital
How is SBP diagnosed and treated?
A small sample of fluid
A doctor numbs the skin and draws a little fluid with a fine needle, guided by ultrasound if needed. This diagnostic tap is quick. It is the only reliable way to confirm SBP.
Testing the fluid
The laboratory counts a type of white cell in the fluid and tries to grow the germ. A high count is enough to start treatment, even before the germ is known.
Antibiotics, started quickly
Treatment usually begins in hospital, often through a drip. The choice of antibiotic depends on local patterns and on any antibiotics taken recently. A repeat sample may be taken to check it is working.
Protecting the kidneys
SBP can tip the kidneys into failure. Many people are given albumin through a vein, and blood tests watch the kidneys closely. See hepatorenal syndrome for why this matters.
On your report
The words you will meet, in plain language
- Ascites
- Fluid collecting inside the belly, around the gut. In liver disease it comes from raised pressure in the liver's veins and low protein in the blood.
- Peritonitis
- Inflammation or infection of the thin lining of the belly. The word spontaneous means no hole or wound caused it.
- Diagnostic paracentesis
- Drawing a small sample of belly fluid with a needle to test it. It is different from a large drain to relieve tightness.
- Neutrophil count
- The number of infection-fighting white cells in the fluid. Your doctor reads this against a set cut-off to decide whether SBP is present.
- Culture
- Growing the germ from the fluid in the laboratory. It is often negative even when SBP is present, so treatment does not wait for it.
- Preventive antibiotic
- A long-term antibiotic for people at high risk or after a first episode, to lower the chance of it coming back.
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Commonly believed
What families often think, and what is true
"No fever means no infection."
In cirrhosis, the body's response is often weak. New confusion, less urine or general worsening can be the only signs. Treat them as seriously as a fever.
"We can manage it with tablets from the local pharmacy."
SBP needs a fluid test to confirm it, the right antibiotic, and close watch on the kidneys. Guessing at home loses time that matters, and the wrong tablet can hide the problem.
"Once it is treated, it is gone for good."
SBP often comes back in the same person. That is why many people are kept on a preventive antibiotic afterwards. Do not stop it without asking the doctor who prescribed it.
"Draining the fluid caused the infection."
A tap done with clean technique rarely introduces infection. In SBP the germs usually come from the gut, through the blood. Testing the fluid at a tap is how many cases are found early.
Being straight with you
What this page cannot tell you
It cannot tell you whether your relative has SBP now. Only a fluid test can show that, and it needs to happen in hospital, the same day. If you are reading this because someone at home has a fever or new confusion, stop reading and take them in.
It cannot choose the antibiotic
Which antibiotic, for how long, and whether a preventive course is needed are decided by the treating team, often with a hepatologist. CION coordinates hospital care and fluid testing through accredited partner hospitals, and your CION oncologist will review any episode before the next cancer treatment.
Who this does not apply to
Peritonitis caused by a burst bowel, an ulcer or surgery is a different emergency, often needing an operation. Fluid caused by cancer on the lining of the belly, as in ovarian or bowel cancer, carries different risks. If that is your situation, see the two kinds of ascites.
Questions we are asked
Common questions about SBP
Is SBP an emergency?
Yes. It can quickly harm the kidneys and bring on confusion, and it is far easier to treat when found early. Anyone with cirrhosis and ascites who develops fever, belly pain, new confusion or much less urine should go to hospital today, not at the next clinic visit.
Is SBP contagious to the family?
No. The germs come from the person's own gut and cause trouble because the liver and fluid have weak defences. Family members cannot catch it from caring for them, sharing meals or helping with a drain. Normal handwashing is enough.
How long does treatment take?
Most people stay in hospital for several days while antibiotics are given and the kidneys are watched. The exact length depends on how quickly the person improves and on any other problems, such as confusion or kidney strain. The team will tell you what to expect.
Why does he need to take antibiotics for so long afterwards?
Because SBP tends to come back. A preventive antibiotic lowers that chance. It is usually taken for as long as the fluid and the risk remain. Never stop or switch it on your own, and tell every doctor that it is being taken.
Does SBP mean the cancer has spread?
Not by itself. SBP is an infection linked to cirrhosis and ascites, not a sign of cancer spread. It can mean the liver is under strain, which your oncologist will take into account when planning the next step of treatment.
Can cancer treatment continue after an episode?
Often, once the infection is controlled and the kidneys and liver have settled. Treatment may be paused or adjusted for a while. The CION team reviews blood results and recovery before deciding, and will explain the reasons in plain words.
Can we prevent SBP at home?
Keep the salt plan, take water tablets and any preventive antibiotic exactly as prescribed, and keep any drain clean. Do not use acid tablets for long periods unless a doctor says they are needed. Above all, act fast on early signs.
Who can we call if we are unsure?
If there is fever, pain, confusion or very little urine, go to hospital first and call afterwards. For questions about prevention or the treatment plan, call the CION helpline. One helpline serves every CION centre.
Your Specialists
Meet CION's liver cancer specialists. Bring your scan reports and liver blood tests.
Our medical and surgical oncologists plan liver cancer care together, weighing the tumour and how well your liver works before choosing surgery, a liver-directed procedure or medicines.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
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Sources
- MedlinePlus — Peritonitis - spontaneous bacterial
- Merck Manual Consumer Version — Ascites
- Cleveland Clinic — Ascites: What it is, Symptoms, Causes & Treatment
- NHS — Cirrhosis
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.
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Related pages
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Worried about infection with fluid in the belly?
If there is fever, pain or confusion, go to hospital today first. For questions about prevention or how an episode affects cancer treatment, we can help you plan the next step. One helpline serves every CION centre.