Peritoneal Abscess

A peritoneal abscess is a serious infection where pus accumulates in the abdomen, requiring prompt medical attention. Early detection and proper treatment with antibiotics and drainage can prevent life-threatening complications like sepsis and organ failure.

Table of contents

• What is a peritoneal abscess?
• Causes and risk factors
• Symptoms
• Diagnosis
• Treatment
• Outlook and complications

What is a peritoneal abscess?

A peritoneal abscess, also called an intra-abdominal abscess, is a pocket of infected fluid and pus located inside the belly. This type of abscess can form near or inside organs such as the liver, pancreas, or kidneys, or it can develop in the spaces between organs^[2][4]. When bacteria enter your body, your immune system sends white blood cells to fight the infection. This process causes inflammation that kills nearby tissue. When tissue dies, a pocket forms and fills with pus, creating an abscess^[4].

Healthcare providers classify peritoneal abscesses based on where they develop in the abdomen. Intraperitoneal abscesses can form below the diaphragm, around the intestines, pelvis, or stomach. Retroperitoneal abscesses occur in the kidneys or pancreas. Visceral abscesses develop within solid organs like the spleen or liver^[4][7].

Peritoneal abscesses represent a significant medical challenge and are considered intra-abdominal complications that require careful management^[2]. Without proper treatment, these abscesses can lead to serious, life-threatening conditions including sepsis (a dangerous blood infection) and organ failure^[4].

Causes and risk factors

Like most abscesses, peritoneal abscesses happen when you have a bacterial infection. The most common bacteria involved include Escherichia coli (E. coli), Klebsiella, Proteus, and Enterobacter, along with anaerobic bacteria (bacteria that grow without oxygen) such as Bacteroides and Fusobacterium^[14]. Sometimes Enterococcus bacteria and, less commonly, Staphylococcus aureus and Streptococci are also involved^[14].

Peritoneal abscesses can develop for several reasons. You may develop an abscess if you have a bacterial infection that starts in your belly, or if you have conditions that cause inflammation such as Crohn’s disease (a type of inflammatory bowel disease), diverticulitis (inflammation of small pouches in the intestine), or pelvic inflammatory disease^[4][5]. These infections often occur when organs rupture or leak, such as a burst appendix, a perforated intestine, a ruptured ovary, or a perforated diverticulum^[5][7].

Abdominal surgery or trauma can put you at risk for developing a peritoneal abscess. If you develop an infection after abdominal surgery or have an injury like a gunshot wound or stab wound that lets bacteria into your belly, an abscess may form^[4][21]. People with weakened immune systems, perforated ulcer disease, or infections in the liver, gallbladder, pancreas, or bile ducts are also at higher risk^[5].

Poorly managed mild intra-abdominal diseases can progress to abscess development. In some cases, bacteria may pass through your blood to reach an organ in your belly, and sometimes no specific reason can be found for an abscess^[5][2].

Symptoms

Most people with a peritoneal abscess experience constant abdominal pain and fever. The specific symptoms can differ depending on where the abscess is located in your abdomen^[4][7].

Common symptoms include new, severe and constant pain that may be in your upper abdomen, lower back, shoulder, or chest. You may also experience fever, loss of appetite, nausea, and unexplained weight loss^[4]. Some people develop a swollen belly, diarrhea, chills, lack of appetite, weakness, or cough^[5].

The pain from a peritoneal abscess may be found only in one area of your belly or spread over most of your abdomen. It may be sharp or dull and can become worse over time^[5]. Depending on the abscess location, you may have pain in your back, chest, or shoulder. Pain felt in one shoulder when the abscess is below the diaphragm is an example of referred pain, which occurs because the shoulder and diaphragm share the same nerves^[7].

Many symptoms of a peritoneal abscess can be similar to symptoms of having the flu, which makes it important to seek medical attention if symptoms persist or worsen^[5].

Diagnosis

Early detection of peritoneal abscesses plays a critical role in successful treatment. Your healthcare provider will perform a physical examination and ask about your symptoms. They will check for tenderness in your abdomen and may feel for a palpable mass^[4][7].

Several tests help diagnose a peritoneal abscess. Your provider will order a complete blood count (CBC) to check for signs of infection. A high white blood cell count is a possible sign of an abscess or other infection^[4][5]. They may also order a comprehensive metabolic panel to check for any liver, kidney, or blood problems^[5].

Imaging tests are essential for confirming the diagnosis. A computed tomography (CT) scan of your abdomen and pelvis is the most common and helpful test because it provides good imaging quality and is performed quickly^[4][2][12]. Other imaging tests that may be used include abdominal ultrasound, chest X-ray, or magnetic resonance imaging (MRI) scan^[4][5].

Your provider may perform a fine needle aspiration to obtain a sample of pus from the abscess. This procedure involves inserting a needle through the skin into the abscess, usually with the help of ultrasound or CT scan guidance. A medical pathologist will test this sample to identify the specific bacteria causing the infection, which helps your provider choose the most effective antibiotics^[4][5].

Treatment

The treatment for a peritoneal abscess combines antibiotics to fight the infection and a procedure to drain pus from the abscess. Drainage of pus is mandatory and represents the first line of defense against progressive sepsis^[11][2].

You will be given antibiotics to treat the abscess. Treatment typically starts with intravenous antibiotics in the hospital, and you may continue receiving IV antibiotics at home. Later, you may switch to antibiotic pills^[4][5]. Highly effective antibiotic combinations such as tazobactam/ceftolozane with metronidazole or metronidazole/ceftriaxone can effectively combat challenging bacterial infections including Gram-negative and anaerobic bacteria^[2].

Your particular situation will determine how long you need to take antibiotics. It’s important to take all of your antibiotics, even if you feel better, to ensure the infection is completely cleared^[5].

Percutaneous abscess drainage (PAD) has become the standard treatment for most intra-abdominal abscesses. This procedure involves placing a drain or catheter into the abscess so that pus can flow into a connected bag. Your provider uses a CT scan or MRI scan to guide the catheter into place^[4][11]. You may receive local anesthesia before the procedure so you’re awake but don’t feel pain. The drain typically stays in place for days or weeks until the abscess heals^[4][5].

CT-guided or ultrasound-guided percutaneous drainage is considered first-line therapy because it avoids anesthesia, prevents difficult laparotomy, reduces the possibility of wound complications from open surgery, and may reduce the length of hospitalization^[11]. The complication rate of percutaneous abscess drainage is low, at approximately 2.5%^[14].

Surgical drainage may be necessary if your abscess cannot be reached safely using a needle through the skin, if drainage is inadequate, or if your appendix, intestines, or another organ has burst^[5][11]. Surgery remains the most effective method to treat abscesses when other methods fail^[2]. The surgeon will make an incision into the belly area, clean and drain the abscess, and place a drain that stays in until the abscess heals^[5].

Outlook and complications

With proper treatment, peritoneal abscesses can typically be cured. How well you respond to treatment depends on the cause of the abscess, how severe the infection is, your overall health condition, and how quickly treatment begins^[5].

Without treatment, a peritoneal abscess can cause serious, life-threatening complications. The infection can grow and damage nearby blood vessels and organs. Sometimes bacteria from an abscess can enter the bloodstream, causing sepsis that spreads to distant organs and tissues. Such spread can be fatal^[4][7].

Untreated abscesses can lead to multiple serious conditions. If the abscess ruptures, the infection may spread to the chest and lead to pneumonia. The infection can also extend into the jaw and neck or cause organ failure^[4].

Early detection and prompt treatment are essential to prevent these complications. Following your healthcare provider’s instructions carefully, completing the full course of antibiotics, and attending all follow-up appointments are important steps in ensuring complete recovery and preventing recurrence^[5].