What Is a Splenic Abscess?
A splenic abscess is similar to an abscess anywhere else in the body, and it is a localized collection of pus (necrotic inflammatory tissue) in the spleen due to an underlying infection. It is often seen as an associated complication of a pathological condition rather than a disease entity. A few conditions that cause splenic abscesses are infective endocarditis, acquired immunodeficiency syndrome (AIDS), acute pancreatitis, etc.
What Is a Spleen?
Spleen is an abdominal organ present just above the stomach, and it is a secondary lymphoid organ and hence part of the lymphatic system. The primary function of the spleen is immunity, and it acts as a filter for germs that get into the bloodstream.
The different functions of the spleen are -
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It acts as a storage organ for various immune cells. The spleen sends these immune cells through the blood to wherever they are needed.
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It also disposes of the old worn-out red blood cells.
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It also stores platelets which are responsible for clotting the blood in case of injury.
The spleen is a highly vascularized organ that is supplied by the splenic artery and splenic vein. It is often treated as a non-vital organ because the functions of the spleen are also performed by the bone marrow, liver, and lymphoid organs. Because of its location, the spleen is easily prone to injury and infection and, if not treated immediately, will lead to a rupture of the organ that can be life-threatening. The treatments include repair, partial splenectomy, and occasionally even total splenectomy may be performed.
What Causes Splenic Abscess?
A splenic abscess is rarely seen because of its efficient phagocytic activity; however, in immunosuppressed patients (patients with weakened immunity due to certain conditions like cancer, diabetes, AIDS, etc.), the spleen’s ability to fight the infection is reduced, resulting in infection and inflammation.
The main causes of splenic abscess are -
1) Immunodeficiency Conditions - A few conditions where the immunity of the patient is compromised are cancer, chemo and radiation therapy, AIDS, diabetes, transplant recipients, and autoimmune disorders. In transplant recipients and autoimmune disorders, immune deficiency is caused due to the prolonged use of immunosuppressive drugs, which predispose the spleen to infections which in turn cause a splenic abscess.
2) Infection - Infection of just the spleen does not occur, it can happen when the infection has transferred from a distant organ (metastatic infection) or from adjacent infected tissue (contiguous infection).
- Examples of metastatic infection are infective endocarditis, endovascular infections, sepsis, pulmonary abscess, diverticulitis, etc.
- Examples of contiguous infections are perinephric abscess and necrotic pancreatitis.
The infection can be bacterial (Streptococcus, Staphylococcus), fungal (Mycobacterium), viral (HIV), or parasitic (Echinococcus granulosus). Occasionally, a splenic abscess has been observed in patients who were receiving embolization treatment for splenic artery pseudoaneurysm, which occurs due to acute pancreatitis.
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Splenic Infarction - It is a condition when the blood flow to the spleen is compromised, causing ischemia and necrosis. This, when coupled with an infection, increases the chances of a splenic abscess.
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Trauma - Spleen is the most common site of injury, either in an accident, blunt force trauma, or a fight. In an attempt to repair the damage, the spleen triggers an inflammatory reaction which leads to abscess formation.
Splenic abscesses are also increasingly seen in intravenous drug users. Although a splenic abscess may not directly kill the patient, when associated with immunocompromised conditions, it has been shown to cause mortality in 80 % of the total affected patients.
What Are the Symptoms of a Splenic Abscess?
The following are the symptoms of a splenic abscess -
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Fever.
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Pain and tenderness in the upper left quadrant.
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Leukocytosis (increased white blood cell count).
A physical examination will reveal -
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Muscle guarding in the upper left quadrant.
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Edema in the adjacent soft tissues.
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Costovertebral tenderness.
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Left basilar rales.
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Dullness at the base of the left lung.
What Are the Tests Done for a Splenic Abscess?
Different kinds of imaging can be used to diagnose a splenic abscess; depending on the surgeon and availability, any of the following tests may be requested-
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Plain Radiograph - This is usually insensitive in evaluating a splenic abscess, but it can help in the initial diagnosis with the help of indirect signs like the presence of gas in the abscess or a reactive left-sided pleural effusion.
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Ultrasound - A splenic abscess is poorly demarcated with varying septal thickness and gas bubbles. Hyperechogenicity with distal dirty shadowing in the ultrasound suggests a splenic abscess.
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Computed Tomographic (CT) Scan - Minimum peripheral enhancement, ascites, and adjacent pleural effusion are seen in a CT scan in affected patients.
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Magnetic Resonance Imaging (MRI) - The imaging characteristics in an MRI depends on the size and the infectious agent causing the abscess. For example, a low signal is seen in an abscess that is filled with proteinaceous content, and a high signal is seen if the abscess is filled with necrotic inflammatory infiltrate (pus).
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Nuclear Medicine - It is a specialty in which radioactive materials that target diseased organs are sent into the body. Nuclear medicine can be used for diagnosis and treatment in case of a splenic abscess; indium 111 leukocyte scan and Ga-67 scans (both are radioactive forms of indium and gallium) will show photopenic abscess cavity.
How Is a Splenic Abscess Treated?
The first line of treatment is high-dose parenteral broad-spectrum antibiotics; if this fails, the surgeon will opt for a splenectomy which is the gold standard for treating a splenic abscess.
The surgery can be an open procedure or can be done with the help of a laparoscope.
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Open Splenectomy - After anesthesia, an incision is made in the midline of the abdomen extending through the skin, subcutaneous tissue, fascial layers, and into the peritoneal cavity.
The muscles are retracted, and the attached ligaments are divided from the spleen and ligated. The spleen is mobilized by dissecting the adhesions, and the associated splenic artery and vein are anastomosed with a stapler. The spleen is removed en bloc and carefully removed off the field, and sent for histopathological examination.
The surgeon inspects the field for any accessory spleen, and once hemostasis is achieved, the fascia is closed, and the overlying skin edges are approximated and sutured.
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Laparoscopic Splenectomy - In this approach, the surgeon places several multiple incisions instead of one large one. A laparoscope (an optic-fiber instrument with a camera attached to it) is inserted through one of the incisions, which helps to visualize the underlying anatomy.
The camera transmits real-time video to the monitor in the operating room. Once the abdomen is thoroughly inspected, the surgeon introduces special surgical instruments through the accessory incisions and proceeds with the resection of the spleen. The resected spleen is placed into an endoscopic retrieval bag and removed through a small incision. After hemostasis is achieved, the multiple incisions are sutured up, and the patient is transferred to the intensive care unit, where they are monitored till the vitals are stable.
Apart from the splenectomy, a minimally invasive approach called percutaneous aspiration is also an option for splenic abscess. It is chosen for patients who are at high risk for surgery and offers a temporary solution to avoid an otherwise life-threatening infection.
What Are the Complications of Splenectomy and Percutaneous Aspiration?
The risk of bleeding, infection, and hemorrhage that are also seen in every surgery is also applicable to surgeries on the spleen. The specific complications seen in splenectomy and percutaneous aspiration are-
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Pneumothorax.
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Atelectasis.
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Life-threatening hemorrhage.
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Left-sided pleural effusion
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Subphrenic abscess.
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Perforation of the stomach, small bowel, and colon.
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Pancreatic fistula.
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Postsplenectomy thrombocytosis.
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Pneumonia.
Splenectomy is always a risk because, after the surgery, patients are susceptible to infections easily, which is why they should constantly update their immunizations.
Conclusion:
A splenic abscess is often difficult to diagnose, which is why in the past, it was seen as a rare occurrence, but with the advent of new technology, clinicians are able to easily identify and treat it promptly. Effective treatment involves a combination of surgery and broad-spectrum antibiotics. Post-surgery, the patient should be educated about the importance of vaccination and possible sepsis due to them no longer being protected by the spleen- an efficient immunomodulator.
