What is situs inversus?

Situs inversus is a rare genetic condition in which the organs in your chest and abdomen are positioned in a mirror image of normal human anatomy. Nearly all of the organs in your chest and abdomen develop in your body in a left-right formation. In situs inversus, your organs develop in a right-left formation.

For example, the left atrium of your heart and your left lung may be on the right side of your chest. In your abdomen, your liver and gallbladder may be on the left side of your body instead of your right side. Your stomach and spleen may be on the right side of your body instead of your left side.

Situs describes the position or orientation of your organs in your chest and abdomen. In normal human anatomy, the placement of your organs is called situs solitus. The terms situs inversus or situs inversus totalism describe a complete reversal of the disposition of your organs.

Situs inversus can occur alone (isolated) with no other abnormalities. But it can also occur with other birth defects or as part of a syndrome. Situs inversus is frequently seen in a condition called primary ciliary dyskinesia. In addition, 5% to 10% of people with situs inversus have a congenital heart defect.

What are the different types of situs inversus?

The main types of situs inversus are dextrocardia and levocardia:

  • Dextrocardia with situs inversus: This type occurs when the tip (apex) of your heart points toward the right side of your chest. Your other organs are flipped too.
  • Levocardia with situs inversus: This type occurs when the apex of your heart is pointing toward the left side of your chest like normal but your other organs are flipped. This type is rarer and is frequently associated with other cardiac defects.

For any other abnormality in the left-right development of your organs, the term situs ambiguous is used. This occurs when several of your organs are in abnormal positions but they’re not in an easily defined pattern.

How common is situs inversus?

Situs inversus affects about 1 in every 10,000 people. The condition is more common in people assigned male at birth.

SYMPTOMS AND CAUSES

How does situs inversus happen?

A genetic mutation in one or more of several different genes causes situs inversus. More than 100 genes have been linked to defects related to sidedness in your body. Some of these genes include ANKS3, NME7, NODAL, CCDC11, WDR16, MMP21, PKD1L1 and DNAH9.

Situs inversus is inherited in an autosomal recessive pattern. This means both parents need to pass a mutated gene onto their children for them to inherit the genetic trait or condition.

Why does situs inversus occur?

There are many reasons why situs inversus may occur. Risk factors for the condition include:

  • Biological family history of cardiac defects.
  • Biological family history of noncardiac anomalies.
  • Diabetes in the birthing parent.
  • Use of cough suppressants during pregnancy.
  • Use of tobacco products during pregnancy.
  • Low socioeconomic status.

What are the symptoms of situs inversus?

You may not develop any symptoms with situs inversus. Although your organs are reversed, they’re often still functional. So you wouldn’t notice any signs or complications.

If you have situs inversus along with another condition or defect, you may have symptoms from the other disease or disorder. For example, cardiac defects may cause heart problems. Primary ciliary dyskinesia may cause a mucus buildup in your lungs. This condition can lead to chronic bronchitis and sinusitis.

DIAGNOSIS AND TESTS

How is situs inversus diagnosed?

Your healthcare provider may discover situs inversus while you’re being treated for another reason.

They may notice the condition when they listen to your heartbeat. In a person with normal anatomy, the heartbeat is usually the loudest on the left side of the chest at the lowest point of their heart. If you have situs inversus, your heart points to the right and your heartbeat will be the loudest on that side.

Your healthcare provider may use various imaging tests to confirm the diagnosis. These tests can also help them determine which organs are affected. These tests may include:

  • X-ray.
  • Ultrasound.
  • Computed tomography (CT) scan.
  • Magnetic resonance imaging (MRI) scan.

MANAGEMENT AND TREATMENT

How is situs inversus treated?

Many people don’t know they have situs inversus. It doesn’t cause any signs or symptoms that would require treatment. If you do have complications related to another defect or condition, your healthcare provider will treat the symptoms of that disease. Your provider will not recommend surgery to reverse your organs.

Although you may not receive treatment, it’s important to alert all of your healthcare providers if you know you have situs inversus. This is because future ailments can become more difficult to diagnose when you have a mirrored anatomy. For example, your provider may rule out appendicitis if you have pain on your lower left side, which could delay urgent treatment. (Appendicitis in normal anatomy presents with pain on the lower right side.)

In addition, all of your providers should know about your condition before they perform any kind of surgery or procedure. Surgeons may need more time and flexibility when operating on a person with situs inversus.

PREVENTION

How can I prevent situs inversus?

Situs inversus is the result of a rare genetic mutation. For this reason, there’s no way to prevent the condition.

What is the life expectancy of someone with situs inversus?

Most people with situs inversus can expect a normal life span. You may not know you have the condition and may not experience any symptoms or complications. If your condition is associated with another health issue or defect, your outlook (prognosis) will vary depending on your diagnosis and treatment.

Can you get pregnant with situs inversus?

People with situs inversus can get pregnant and have an uneventful pregnancy with the condition.