What is an Abscess?

A potential complication of inflammatory bowel disease (IBD) is an abscess. An abscess is a collection of pus. Abscesses form when inflammation extends deep into wall of the intestine and an infection develops. Fluid containing white blood cells, dead tissue, and bacteria builds up in the infected area.¹ Abscesses are more common in people with Crohn’s disease, occurring in about 10% to 30%, but they can also occur in people with ulcerative colitis about 20% of the time.^2,3

In people with Crohn's disease, abscesses are likely to form at the end of the small intestine (ileum), where it joins the large intestine, or at the place where the intestine is rejoined after surgery (called an anastomosis.² In ulcerative colitis, abscesses form in the large intestine as the disease only affects the large intestine.⁴

Abscesses can also form in the area behind an intestinal blockage, where food and waste build up.⁵ They can form in and around fistulas. Some people with Crohn’s disease develop an abscess near the anus or rectum.⁶

Symptoms of an abscess with Crohn’s or colitis

Pain and fever are symptoms of an abscess. You or your health care provider may be able to feel the mass in your belly.²

What other conditions can cause abscess?

Abscesses can develop in numerous places around the body that get injured or infected.^1,7 You can see abscesses that form in or under the skin and around the teeth. Abscesses can also form in areas such as the liver, brain, or spinal cord. Certain conditions increase the risk of an abscess. These conditions include weak immune system, diabetes, inflammatory disease, recent surgery, or an untreated infection.

How are abscesses evaluated?

If you have signs and symptoms of an abscess, your health care provider may recommend having a computed tomography (CT) scan.² A CT scanner uses x-rays to create detailed cross-sectional pictures of areas in your body.⁸ You may be asked to drink a liquid contrast material before the CT scan. The contrast material helps the radiologist to see your small intestine better.⁹ The radiologist will evaluate how thick the inflamed area is and whether a fistula has formed.²

Your doctor may also use ultrasound to look at the abscess.⁶

How are abscesses treated?

Most abscesses must be drained. Two techniques can be used to drain an abscess:

• Minimally invasive procedure called “percutaneous abscess drainage”
• Open surgery

The minimally invasive technique is used when possible.² It is performed in the hospital.¹⁰ The area will be numbed and you may be sedated. Using CT, ultrasound, or an x-ray, the doctor will find the abscess. He or she will make a small surgical opening (incision) near the abscess. The doctor will insert a thin tube (catheter) through the incision and into the abscess. The fluid will begin to drain from the abscess. It may take 7 to 10 days for all the fluid to drain. Most people start to feel better in the first 2 days.² You will be given antibiotics to clear up the infection. The drains are often left in place to ensure that the infection clears entirely.

After the abscess drains, some people need additional surgery to remove the affected section of intestine.²

What are complications of abdominal abscess and IBD?

Abscesses can come back after they have been drained. Some studies have shown that as many as 75% to 85% of people needed surgery in the 3 to 7 years after abscess drainage.² However, the rate of surgery is not this high in all studies.

In some people with Crohn's disease, abscesses can cause abnormal connections to form between the intestines and other organs.² These connections are called fistulas. People who have an abscess and fistula are much more likely to need surgery.

Having an abscess before surgery for Crohn’s disease nearly doubles the risk of developing a serious infection in the abdomen.¹¹ For this reason, your surgeon may postpone surgery for several weeks until the infection has completely cleared up.²