An abscess is a pocket of inflamed tissue filled with pus. Abscesses can form anywhere on the body (inside and outside). They’re most commonly found on the surface of the skin.
An abdominal abscess is a pocket of pus located in the abdomen. It may form:
- behind the abdominal cavity (which contains most of the digestive organs)
- below the diaphragm (the muscle used during inhalation)
- within the abdominal compartment
Abdominal abscesses can also form in or around organs in the abdomen, including the liver, pancreas, and kidneys. Abdominal abscesses may develop for no apparent reason, but they’re usually caused by a bacterial infection. They can also occur after intra-abdominal surgery, or after an injury to the abdomen.
Abdominal abscesses are normally caused by trauma or infection. Intra-abdominal abscesses (abscesses within the abdomen) can develop when an organ ruptures or an infection or inflammation caused by other conditions spreads. Such conditions include appendicitis, pancreatitis, and Crohn’s disease. Depending on where the abdominal abscess is located, additional causes may be to blame.
Mid-abdomen abscesses usually form due to a ruptured organ in the mid-abdominal region, such as the intestines or appendix. They can also stem from diseases that affect the abdominal organs, such as irritable bowel disease. An infected wound in the area may also cause an abscess to form.
Below the Diaphragm
Abdominal abscesses develop below the diaphragm when infected fluid gets into the area. This is normally the result of an internal injury or ruptured organ.
Behind the Abdominal Cavity
Retroperitoneal abscesses, abscesses behind the abdominal cavity, are located on or behind the peritoneum. The peritoneum is the membrane that lines the abdominal organs and cavity. Abscesses may form when the surrounding organs become inflamed or infected.
General symptoms of abdominal abscesses include:
- feeling unwell
- abdominal discomfort
- abdominal pain
If an infection is present, you may also develop:
- weight loss (due to loss of appetite)
Additional symptoms can occur depending on the location of the abdominal abscess. These symptoms include:
- sharp or dull pain in the area containing the abscess
- lower back pain, typically in the area behind the abdominal abscess, that becomes worse when you move your hips
- diarrhea (often a symptom of a pelvic abscess)
- pain on the right side of your abdomen (symptom of a liver abscess)
The symptoms of an abdominal abscess are similar to symptoms of other, less serious conditions. Your doctor may run an imaging test to make a proper diagnosis. An ultrasound is typically the first diagnostic tool used. Other imaging tests, such as a CT scan or MRI, also help your doctor see the abdominal organs and tissues.
An abdominal ultrasound uses high-frequency sound waves to create images of organs in the abdomen.
During the test, you’ll lay on a table with your abdomen exposed. An ultrasound technician will apply a clear, water-based gel to the skin over the abdomen. Then they’ll wave a handheld tool called a transducer over the abdomen. The transducer sends out high-frequency sound waves that bounce off body structures and organs. The waves are sent to a computer, which uses the waves to create images. The images allow your doctor to closely examine organs in the abdomen.
Computerized Tomography (CT) Scan
A CT scan is a special X-ray that can show cross-sectional images of a specific area of the body.
The CT scanner looks like a large circle with a hole in the middle, called a gantry. During the scan, you’ll lay flat on a table, which is positioned in the gantry. The gantry then begins to rotate around you, taking images of your abdomen from many angles. This gives your doctor a complete view of the area.
A CT scan can display ruptures, localized abscesses, organs, abdominal growths, and foreign objects in the body.
Magnetic Resonance Imaging (MRI)
An MRI uses large magnets and radio waves to create images of the body. The MRI machine is a long magnetic tube.
During this test, you’ll lie on a bed that slides into the tube’s opening. The machine produces a magnetic field that surrounds your body and aligns water molecules in your body. This allows the machine to capture clear, cross-sectional images of your abdomen.
An MRI makes it easier for your doctor to check for abnormalities in the tissues and organs in the abdomen.
Abscess Fluid Sample Analysis
Your doctor may take a sample of fluid from the abscess and examine it to make a better diagnosis. The method for obtaining a fluid sample depends on the location of the abscess.
Drainage is the first step in treating an abdominal abscess. Needle drainage is one of the methods used to drain pus from an abscess.
During this procedure, your doctor will use a CT scan or ultrasound to insert a needle through your skin and directly into the abscess. Your doctor will then pull up on the syringe to remove all the fluid. After draining the abscess, your doctor will send a sample to the lab for analysis. This will help determine which antibiotics to prescribe.
Some cases may require surgery. For example:
- to clean out the abscess
- if the abscess is difficult to reach with a needle
- if an organ has ruptured
Your doctor will give you general anesthesia to put you to sleep throughout the surgery. During the procedure, the surgeon will make a cut in the abdomen and locate the abscess. They’ll then clean the abscess and attach a drain to it so pus can drain out. The drain will stay in place until the abscess heals. This usually takes several days or weeks.
Antibiotics are usually prescribed to treat the infection causing the abscess and to prevent infection from the drainage procedure.