What is Abdominal Abscess?
Infections in the abdominal area usually occur after inflammation or damage to parts of the digestive system. In less common instances, they may start in the reproductive or urinary systems. These infections often involve multiple types of bacteria and can lead to severe conditions such as an abscess within the abdomen or an inflammation of the inner lining of the abdomen.
An abdominal abscess is a pocket filled with damaged cells, enzymes, and remnants from either an infection or non-infectious source. It usually indicates a serious health issue in the patient. In many cases, our body’s response may be to isolate this abscess with surrounding tissues like the layers in the abdomen. Abdominal abscesses are quite common and serious. It’s crucial to diagnose and treat them promptly to prevent severe outcomes.
Generally speaking, cases of severe body response to infection caused by breaks in the upper part of the digestive system are associated with less risk to life and wellbeing than when those breaks happen in the colon.
What Causes Abdominal Abscess?
Intra-abdominal infections typically occur when the body’s natural defenses in the gut are compromised, allowing the normal bacteria living in the bowel to infect the abdominal cavity. The type of bacteria involved in these infections can vary depending on whether they originate from the small or large intestine.
Common causes of such infections include appendicitis, conditions like diverticulitis and inflammatory bowel disease, colon cancer, or surgeries that have been performed on the colon. In these instances, the bacteria most commonly involved are types of coliforms (including Escherichia coli, Klebsiella spp, Proteus spp, and Enterobacter spp), streptococci, enterococci, and a range of bacteria that do not need oxygen to grow. Furthermore, two major types of bacteria commonly found in abdominal infections are Bacteroides fragilis and E. coli, with B. fragilis being highly invasive in such scenarios.
In the early stages of abdominal sepsis, a severe body-wide infection, coliform bacteria play a major role, while anaerobic bacteria (those that don’t need oxygen to survive) are more involved in the later stages, often leading to abscess formation. When the upper part of the intestines or a peptic ulcer perforates, it can result in infections with aerobic and anaerobic gram-positive bacteria or Candida spp.
Certain factors such as previous antibiotic use or exposure can alter the gut bacteria, making infections more likely to come from hospital-associated microbes like Pseudomonas aeruginosa and other drug-resistant organisms. In hospital settings, bacteria like Enterococci are more likely to be found than in infections originating in the community.
Candida infections can occur both in the small and large intestine, particularly in people with a history of antibiotic use, those with weakened immune systems, and those with a history of recurrent infections.
Most intra-abdominal abscesses, which are collections of pus in the abdomen, are caused by bacteria from the gastrointestinal tract. These abscesses often result from perforations in the stomach or intestines due to conditions like peptic ulcer disease, appendicitis, and diverticulitis, or chronic complications related to pancreatic disorders, ischemic bowel disease, and surgery-related complications. Other causes can include abdominal injuries like stab or gunshot wounds, complications with surgical repairs, certain types of bowel obstructions like volvulus and intussusception, gallstones, and fistula formation due to gallstone ileus. Rarely, these abscesses can form due to injections. As such, abscesses in the abdomen can involve organisms such as Escherichia coli, Bacteroides, Neisseria, Chlamydia, and Candida.
Risk Factors and Frequency for Abdominal Abscess
Intra-abdominal abscesses are often the result of an issue with an organ inside the abdomen and can frequently occur after surgery. For example, about 70% of these abscesses happen after an operation, with 6% of patients who’ve had colorectal surgery developing an abscess afterwards. Particularly, abscesses in the liver make up 13% of all intra-abdominal abscesses. The majority of these hepatic abscesses, or abscesses in the liver, are found in the right lobe, likely due to its larger size and better blood supply. Also, complicated intra-abdominal infections, termed cIAIs, are often traced back to the top three organ-related causes for patients being admitted to the hospital with septic shock. These are serious infections with a mortality rate that can reach 40%.
Signs and Symptoms of Abdominal Abscess
Patients with an abscess, or pocket of pus, inside their abdomen often experience abdominal pain, a high body temperature, lack of appetite, a rapid heartbeat, or a sluggish bowel movement that lasts for an extended period of time. They may or may not have a noticeable lump in their belly. If the abscess is located in the back part of the abdominal cavity or deep inside the pelvic region, they might not show apparent symptoms. In such circumstances, the condition might be suspected due to a lingering fever, mild liver problems, or a prolonged sluggish bowel movement.
After a surgery, identifying an abdominal abscess can be challenging because the pain medications and antibiotics the patients are usually taking can obscure infection signs. If the abscess is under the diaphragm (the muscle that helps us breathe), the patient might experience pain in the tip of the shoulder, have an uncontrollable desire to hiccup, or have a lung condition (atelectasis) where some parts of the lungs do not inflate fully.
Patients with an abscess in their abdomen frequently show signs of dehydration, low urine output, rapid heartbeat, fast breathing, and a condition called respiratory alkalosis, which involves too much alkaline (or not enough acid) in the blood.
There are certain signs that indicate the abscess is primarily caused by anaerobic infections (infections caused by bacteria that can survive without oxygen). These signs include:
- A bad smell coming from the abscess
- Formation of gases which one can feel under the skin during a physical examination, or visible in blood vessels including those around the liver (hepatic-portal venous gas)
- Gram stain tests of the abscess’ contents showing a variety of bacteria, including those that don’t need oxygen to survive
- Typical symptoms of infections caused by the Clostridium bacteria, such as severe inflammation of the intestines (necrotizing enteritis).
Testing for Abdominal Abscess
Blood tests may not provide a specific diagnosis for an intra-abdominal abscess, but they can show signs of infection such as an increased white blood cell count, abnormal liver function, anemia, or a reduced number of platelets. The presence of specific bacteria can sometimes be found in the blood, but this is not always the case. One of the most commonly found bacteria, when present, is Bacteroides fragilis.
Ordinary abdominal x-rays are not very effective in identifying an intra-abdominal abscess, so a CT scan is the best test to perform. This type of scan can show the exact location and size of the abscess, as well as other signs like thickened bowel walls and interrupted bowel movements known as ileus. Treatment of such abscess almost always involves antibiotics, which are usually delivered directly into a vein.
If the abscess is isolated, it can be drained using a CT-guided aspiration procedure. This method can help avoid general anesthesia and complications related to surgical wounds. It also prevents the spread of the abscess to other parts of the abdomen.
For some people, ultrasound may also help identify abdominal abscesses.
Nuclear scans, which were once used for abscess detection, are now rarely used. This is because the process is time-consuming and often results in false positives.
Treatment Options for Abdominal Abscess
Broad-spectrum antibiotics and proper hydration are crucial for patients with abdominal issues. Once results come back from testing, doctors can adjust antibiotic treatments based on the specific bacteria causing the problem. Intravenous hydration is often needed, and a tube can be inserted into the stomach to help relieve pressure and decrease vomiting.
A common method called percutaneous CT-guided drainage can be used to drain abdominal abscesses. It is a straightforward procedure that can be performed under local anesthesia and could lead to a quicker hospital discharge. In many cases, patients show improvement within 48 hours after the procedure. Usually, when the abscess is localized, the drainage success rate is over 90%.
Percutaneous abscess drainage (PAD), a form of this type of drainage, is a well-accepted treatment for post-surgery abdominal abscesses. The method was first introduced in the 1970s, and initial outcomes showed a success rate of approximately 86%. Even though factor affecting success rates have not been fully confirmed, adults with a single appendix abscess tend to have higher success rates than those with multiple abscesses. Non-surgical management of appendix abscesses in children tends to yield favorable results, especially with smaller abscesses.
In terms of when to use drainage procedures, it tends to vary based on what caused the abscess, but abscesses sized 3 to 6 cm are usually treated with drainage if they originate from a diverticular condition.
If a patient’s condition does not improve within 24 to 48 hours, a consultation with a surgeon becomes necessary. If surgery is needed, dead tissue will be taken out, and any internal scar tissue can be separated. This process often requires follow-ups in the intensive care unit and significant fluid replenishment. If the abscess is localized and treated promptly, the prognosis tends to be good.
Pelvic abscesses present their unique challenges but can be effectively drained either through the rectum or vagina. Endoscopic ultrasound-guided drainage offers a less invasive treatment option with a high likelihood of success if the patient selection and technique are correct, along with proper follow-up care.
Open surgery for an abdominal abscess can be difficult due to potential internal scar formation and lack of clear anatomical pathways for the separation.
The definitive treatment for a subdiaphragmatic abscess, another type of abscess, is drainage. Currently, the standard care is percutaneous drainage, which is less invasive but can be highly effective, and has significantly improved patient outcomes. CT-guided drainage is considered the gold standard treatment and has certain advantages, such as not requiring general anesthesia, avoid surgical wound complications, and decreasing hospital stays.
However, if drainage fails, then surgical drainage may be considered. A laparoscopic technique could be less invasive while providing a clear view of the abdominal cavity. If the laparoscopic technique does not yield improvements, open surgery might be necessary. Recently, open abdomen therapy (OAT) is being used more frequently, especially for managing abdominal pressure and trauma patients.
With a timely intervention, most patients recover well with the help of supportive care like intravenous hydration. Those who worsen and develop septic shock may need intensive care unit admission. Additional support, like mechanical ventilation, vasopressors, and dialysis, might be needed for those with significant organ failures.
What else can Abdominal Abscess be?
- Long-lasting digestive blockage
- Unexplained fever
- Crohn’s disease
- Inflammatory bowel disease causing ulcers in the colon (also known as Ulcerative colitis)
- Complex infection near the rectum
- Ruptured colon cancer
- Abdominal pocket filled with pus (also known as Diverticular abscess)
What to expect with Abdominal Abscess
Before modern technology like CT scans, the health outlook for people with abdominal abscesses was quite poor. Nowadays, thanks to CT scans, these conditions can be diagnosed much earlier, which has helped to lower the risk of serious complications. In fact, many cases are now managed using CT-guided drainage, which leads to better patient outcomes. However, if an abdominal abscess is not diagnosed and treated, the risk of death is extremely high.
Certain factors can increase the risk of death and complications, including:
- Being of an advanced age
- Failures across multiple organs
- Having multiple surgeries recently
- Having a complex abscess
- A delay in diagnosing the abscess
Possible Complications When Diagnosed with Abdominal Abscess
An abdominal abscess can cause several serious problems, including:
- Multiorgan failure, which is when several vital organs stop working at once
- Formation of a fistula, an abnormal connection between two parts of the body
- Septic shock, a life-threatening condition that happens when a major infection leads to dangerously low blood pressure
- Bowel perforation, which can happen after CT-guided drainage and surgery
- Deep vein thrombosis, a blood clot in a deep vein in your body
- Malnutrition, when your body doesn’t get enough nutrients
- Death
Recovery from Abdominal Abscess
People who have an abscess in their abdomen will generally need to stay in the hospital for treatment. It’s common for them to have follow-up imaging tests to make sure that the abscess has completely gone after they have received treatment.
Some patients might need total parenteral nutrition depending on how complicated their abscess is.
Since these patients are frequently in weakened condition, they are recommended to have physical therapy. This helps them regain their muscle strength and flexibility.
