Abdominal Abscess: Symptoms, Causes, Diagnosis, and Treatment (2026 Guide)

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026

Last updated: August 2026

TL;DR

An abdominal abscess is a pocket of pus and infected fluid that forms in your belly, most often because of a bacterial infection. Typical signs include new, severe, constant pain (sometimes in the abdomen, lower back, shoulder, or chest), fever, loss of appetite, nausea, and unexplained weight loss. Healthcare providers treat it with antibiotics plus a drainage procedure, most commonly percutaneous abscess drainage (PAD), in which a catheter is guided into the abscess by CT or MRI. With treatment, the abscess is usually eliminated, but without treatment it can lead to life-threatening sepsis and organ failure.

Quick Answer

What is an abdominal abscess?

• A pocket of pus and infected fluid that forms in the abdomen; bacterial infections are the most common cause.

• Key warning signs are new, severe, constant pain, fever, loss of appetite, nausea, and unexplained weight loss.

• It is diagnosed with a physical exam, blood count, and imaging — a CT scan of the abdomen and pelvis is the most common test.

• Treatment combines antibiotics with drainage (usually a catheter placed through the skin, called percutaneous abscess drainage), and typically cures the condition.

What Is an Abdominal Abscess?

An abdominal abscess is a pocket of pus and infected fluid that forms in your abdomen (belly). The infected fluid can make you sick, and sepsis can develop if the abscess is not treated with antibiotics and a procedure to drain it.

Abdominal abscesses happen for many reasons, most of which are out of your control. What you can do is get treatment as soon as you suspect something is going on in your belly. Treatment typically cures the condition, but without treatment, an abdominal abscess can be life-threatening.

What Are the Types of Abdominal Abscesses?

Healthcare providers classify abdominal abscesses by the part of the belly that the abscess affects.

Type	Where it forms	Notes
Intraperitoneal abscess	Below the diaphragm, around the intestines, pelvis, or stomach	Includes subphrenic abscess, which forms in the space between the diaphragm and the liver
Retroperitoneal abscess	In the kidneys or pancreas	Forms behind the abdominal cavity lining
Visceral abscess	Within a solid organ	Most often the spleen or the liver

What Are the Symptoms?

The specific symptoms of an abdominal abscess differ depending on the abscess's location. If you are like most people, your symptoms may include new, severe, and constant pain that may be in your upper abdomen, lower back, shoulder, or chest. Fever is common, as are loss of appetite, nausea, and unexplained weight loss.

Because pain in the shoulder or chest can also signal an abdominal abscess, the location of your discomfort is not always a reliable guide to where the problem is. Fever or persistent pain should always prompt a call to your healthcare provider.

What Causes an Abdominal Abscess?

Like most abscesses, abdominal abscesses happen when you have a bacterial infection. When bacteria enter your body, your immune system sends white blood cells to get rid of the bacterial intruders. This process causes inflammation that kills nearby tissue. When tissue dies, a pocket forms and fills with pus, creating an abscess.

You may develop an abdominal abscess if you have a bacterial infection that starts in your belly, or if you develop an infection after abdominal surgery. An injury such as a gunshot wound or stab wound can also let bacteria into your belly.

Certain conditions that cause inflammation raise the risk as well. These include Crohn's disease, diverticulitis, and pelvic inflammatory disease (PID).

Cause	How it leads to an abscess
Bacterial infection starting in the belly	Bacteria trigger inflammation that destroys tissue and creates a pus-filled pocket
Inflammatory conditions (Crohn's disease, diverticulitis, PID)	Ongoing inflammation creates an environment where infection and abscess formation take hold
Infection after abdominal surgery	Bacteria introduced during or after surgery can seed a pocket of infection
Injury (gunshot or stab wound)	Trauma carries bacteria into the belly where an abscess can develop

Without treatment, an abdominal abscess can cause serious, life-threatening conditions like sepsis and organ failure.

How Is an Abdominal Abscess Diagnosed?

A healthcare provider will do a physical examination and ask about your symptoms. They will order a complete blood count (CBC) and imaging tests.

The imaging tests that may be used include an abdominal ultrasound, a chest X-ray, a CT scan of the abdomen and pelvis, and an MRI scan. A CT scan is the most common test used to find an abdominal abscess.

If needed, a provider may perform a fine needle aspiration to get a sample of pus from the abscess. A pathologist will test the sample to identify the bacteria causing the infection, which helps target antibiotic treatment.

How Is an Abdominal Abscess Treated?

Treatment combines antibiotics to fight the infection with a procedure to drain pus from the abscess. Your provider may recommend percutaneous abscess drainage (PAD).

PAD involves placing a drain or catheter into the abscess so that pus can flow into a connected bag. The provider uses a CT scan or MRI scan to guide the catheter into place. You may receive local anesthesia before the procedure, so you are awake but do not feel pain. You may need to keep the catheter and bag in place for a few days after the procedure so the abscess can drain completely.

PAD is a minimally invasive procedure, but like similar procedures it may cause complications such as bleeding, pain, or a surgical wound infection.

Treatment component	Purpose	What to expect
Antibiotics	Fight the bacterial infection	Taken as prescribed alongside the drainage procedure
Percutaneous abscess drainage (PAD)	Drain pus from the abscess	Catheter placed under CT or MRI guidance with local anesthesia; you stay awake without pain
Drain and collection bag	Allow complete drainage	Often kept in place for a few days after the procedure

What Is the Outlook?

If you are like most people, antibiotics to fight the infection plus treatment to drain pus from an abdominal abscess will eliminate the abscess.

There is one important caveat. Abdominal abscesses happen because you have a condition that causes inflammation and infection. While treatment may clear up the bacterial infection, it will not resolve the underlying condition. Managing the root cause, such as Crohn's disease or diverticulitis, remains essential to preventing another abscess.

When Should You See a Healthcare Provider?

Contact your provider if you have symptoms like fever or persistent pain. These symptoms may mean you have another abdominal abscess.

If you have a condition that raises your risk, such as Crohn's disease or diverticulitis, ask your healthcare provider about the symptoms that could mean an abscess is developing in your belly. Knowing those warning signs means you will know when you should contact a provider.

Conclusion

An abdominal abscess is essentially the body's way of walling off an infection it cannot clear on its own. When bacteria reach the belly through infection, inflammation, surgery, or injury, immune cells rush in, nearby tissue dies, and a pocket of pus forms. Left alone, that pocket can turn into sepsis or organ failure, which is why timing matters far more than toughness.

The good news is that this condition is highly treatable. A CT scan usually finds it, antibiotics attack the infection, and a small guided catheter does the rest. For most people, this combination eliminates the abscess entirely. The one thing drainage cannot fix is the underlying condition that allowed the abscess to form in the first place, so follow-up care for conditions like Crohn's disease or diverticulitis is a vital part of staying abscess-free.

Fever plus new, severe, constant belly pain? Do not wait it out. Contact your healthcare provider promptly, and mention any recent surgery, injury, or inflammatory condition, since these details help pinpoint the diagnosis quickly.

Frequently Asked Questions

What is an abdominal abscess?

A pocket of pus and infected fluid that forms in the abdomen, most commonly caused by a bacterial infection. Without treatment, it can lead to life-threatening sepsis and organ failure.

What are the symptoms of an abdominal abscess?

New, severe, and constant pain that may appear in the upper abdomen, lower back, shoulder, or chest, along with fever, loss of appetite, nausea, and unexplained weight loss.

How is an abdominal abscess diagnosed?

Through a physical exam, symptom history, a complete blood count, and imaging. A CT scan of the abdomen and pelvis is the most common test, alongside ultrasound, chest X-ray, and MRI. A fine needle aspiration may sample the pus to identify the bacteria.

How is it treated?

With a combination of antibiotics to fight the infection and drainage of the pus. The most common procedure is percutaneous abscess drainage (PAD), where a catheter is guided into the abscess by CT or MRI under local anesthesia and left in place for a few days.

Is percutaneous abscess drainage a surgery?

No, it is a minimally invasive procedure. You stay awake under local anesthesia, and a thin catheter drains the pus into a collection bag. Possible complications include bleeding, pain, or wound infection.

Can an abdominal abscess be cured?

For most people, antibiotics plus drainage eliminate the abscess. However, the treatment clears the infection, not the underlying condition (such as Crohn's disease or diverticulitis) that made the abscess possible, so that condition needs ongoing management.

Is an abdominal abscess dangerous?

Untreated, it can cause sepsis and organ failure, which are life-threatening. With prompt treatment, the outlook is good for most people.

References

This article is based on medically reviewed clinical information, including Abdominal Abscess, supplemented by the StatPearls entry on abdominal abscess (NIH National Library of Medicine) and the Merck Manual Professional Version entry on intra-abdominal abscesses.

This article is for educational purposes only and is not a substitute for professional medical advice. An untreated abdominal abscess can become life-threatening; severe, constant abdominal pain with fever should be evaluated by a healthcare professional promptly.