What is Splenic Artery Aneurysm?
A splenic artery aneurysm, or SAA, happens when the splenic artery, a blood vessel in the body, enlarges more than 50% from its standard size. The regular size of the splenic artery can vary, but it’s typically between 0.43 cm to 0.49 cm.
True SAAs involve all the layers of the artery wall, which may become thin but don’t break. On the other hand, “pseudoaneurysms” occur when there’s a tear in the innermost layer of the artery, causing blood to flow into a new pathway and form a blood clot around the artery. These usually happen due to injury or artery inflammation often caused by conditions like pancreatitis.
Out of all the blood vessel swellings in the guts, or “visceral artery aneurysms” (VAAs), SSA is the most common, accounting for 60% to 70% of all diagnosed cases. The hepatic artery, another major blood vessel, is affected in 20% of VAA cases, while the celiac or mesenteric arteries, blood vessels in the digestive system, represent 10% of all reported VAA cases.
What Causes Splenic Artery Aneurysm?
There are certain risk factors that can be changed or controlled to help prevent the formation of splenic pseudoaneurysms, which are abnormal bulges that occur in a blood vessel in the spleen. These risk factors include hardening of the arteries (atherosclerosis), high blood pressure in the vein that carries blood to the liver (portal hypertension), having a liver transplant, pregnancy, and connective tissue disorders like Marfan or Ehler-Danlos syndrome.
Recent studies have found that up to 21% of people diagnosed with long-term pancreatitis, a condition where the pancreas gets inflamed over a long period, may develop splenic pseudoaneurysms.
There are also some risk factors that can’t be changed or controlled, such as being older or being female. Splenic artery pseudoaneurysms have been linked to both blunt and penetrating injuries as well as medical-related injuries due to medical instruments.
Risk Factors and Frequency for Splenic Artery Aneurysm
Splenic artery aneurysm (SAA) is not common in the general population, affecting less than 1% of people. This is largely because many SAA cases don’t have symptoms and therefore aren’t detected. A recent study found that SAAs are more prevalent in women, accounting for 78% of cases.
- For non-pregnant patients, the death rate from SAA rupture ranges from 25% to 40%.
- Mother’s risk of death due to SAA rupture goes up to 75% during pregnancy.
- The risk of the fetus dying can be as high as 95% if the mother has an SAA rupture.
Signs and Symptoms of Splenic Artery Aneurysm
The most common symptom of Splenic Artery Aneurysm (SAA) is a vague pain in the upper central or left side of the abdomen, which might spread to the left shoulder. Other symptoms can be bleeding in the digestive tract, evidenced by vomiting blood or passing stools with blood, or bleeding into the pancreatic duct that causes blood in the bile. While true aneurysms might not show any symptoms, pseudoaneurysms always do. An uncommon but serious complication of SAA is rupture, characterized by sudden widespread abdominal pain and a shock condition due to severe blood loss. This is often coupled with signs of a critical surgical condition.
Rupture of SAA is more common in women with multiple children and patients with portal hypertension, a condition of increased blood pressure within the portal vein. This happens because of raised portal blood flow. Reports suggest that the risk of SAA rupture ranges between 2% to 10%, but this risk is much larger – 76% to 83% – in patients showing symptoms.
Testing for Splenic Artery Aneurysm
An abdominal CT scan, which uses X-rays and a computer to create detailed images, is the best method to diagnose splenic artery aneurysms (SAA) and similar conditions. This type of scan, especially when combined with an injected dye (IV contrast), is great at finding small SAAs and gives doctors a good idea of the internal structures for planning surgery.
Magnetic resonance imaging (MRI), which uses strong magnetic fields and radio waves to produce images, is another option. This can be particularly useful for patients with ongoing kidney problems where the use of a dye with CT scans can be harmful.
Another medical imaging technique, Contrast angiography (CA), is proven to be the most accurate test to identify SAAs. It involves injecting a dye into the bloodstream and then taking X-ray pictures. This technique can also be therapeutic, which means it can help treat the condition as well.
Endoscopic ultrasound, a procedure that involves using a thin tube with an ultrasound device at the end, is a reliable method to separate SSA from other similar-seeming conditions like pancreatic pseudocysts.
Treatment Options for Splenic Artery Aneurysm
If you have an aneurysm (a bulging, weak section in the wall of an artery) that is larger than 2 cm, doctors typically recommend taking action rather than simply keeping an eye on it. This is because larger aneurysms have a higher risk of rupturing, which can be life-threatening. Other reasons for intervention include if you’re having symptoms, if you’re a woman of childbearing age or pregnant, or if you have cirrhosis and are planning liver transplant surgery or a procedure to improve blood flow to your liver.
The standard approach to treating these aneurysms is open surgery. Surgeons remove the aneurysm and reroute blood flow around it, which is particularly suitable for aneurysms close to the beginning or middle of the splenic artery, the artery that supplies blood to the spleen. If the aneurysm is towards the end of the artery or if there are problems with the abdomen that make surgery difficult, surgeons may also remove the spleen. If the aneurysm has ruptured, it’s a medical emergency that requires surgery to stop the bleeding. Doctors try to preserve the spleen whenever possible since it has important functions in the body, but they will remove it if it’s the only way to stop the bleeding.
An endovascular approach, which involves inserting a small tube called a catheter into the artery to treat the aneurysm, is becoming more popular. The specific technique used depends on the type and location of the aneurysm, whether the splenic artery will be preserved, and the condition of the surrounding arteries. Aneurysms that are elongated and bulge all the way around the artery can be treated with a stent graft (a tube made of fabric and metal that reinforces the artery wall). Bulging, bag-shaped aneurysms that are winding or bendy are often treated with coiling techniques that fill the aneurysm with tiny metal coils to help clot blood and prevent rupture. False aneurysms, which occur when an artery wall is injured and blood leaks out into the surrounding tissue forming a sac, can be treated by blocking the arteries feeding the aneurysm or filling the sac itself. However, doctors try to avoid blocking the part of the splenic artery closest to the spleen.
A minimally invasive laparoscopic approach, which involves making small incisions in the abdomen through which long, thin surgical instruments are inserted, is a safe alternative for elective splenic aneurysm repair. Various techniques can be used, such as tying off the splenic artery or removing the spleen. If the aneurysm’s wall is severely inflamed and stuck to the tail of the pancreas, surgeons may need to remove part of the pancreas as well. Benefits of this approach compared to open surgery include quicker recovery, shorter hospital stay, and less pain after surgery. It’s also a suitable and safe option for pregnant patients due to minimal manipulation of the contents of the abdomen, which reduces the risk of preterm labor.
What else can Splenic Artery Aneurysm be?
Here are some medical conditions that may relate to the main topic:
- Congenital Antitrypsin Deficiency
- Cystic Medial Necrosis
- Ehlers-Danlos Syndrome
- Marfan Syndrome
- Neurofibromatosis
- Polyarteritis Nodosa
- Systemic Lupus Erythematosus
- Takayasu Arteritis
