Situs inversus is a rare congenital condition in which the main organs in the chest and abdomen are positioned as a mirror image of their usual location. This means that some organs may be on the opposite side of the body from where they are typically found.
This condition can cause no symptoms, especially when the organs are working normally. However, it may lead to symptoms such as abdominal pain, difficulty breathing, or bluish skin.
Situs inversus is caused by genetic mutations passed from parents to children. These mutations affect embryo development during pregnancy, causing the organs to develop on the opposite, mirrored side.
Main symptoms
The main symptoms of situs inversus are:
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Headache or a feeling of pressure in the face
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Difficulty breathing, shortness of breath, or respiratory discomfort
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Nausea and vomiting
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Bluish skin or lips, or paleness
Situs inversus typically causes no symptoms when the organs function normally despite their reversed positions.
However, if an organ doesn't work properly, symptoms depend on which organ is affected. Common issues include recurrent respiratory infections (such as sinusitis, bronchitis, or pneumonia), bowel obstruction, and heart problems.
According to the Genetic and Rare Diseases Information Center, situs inversus totalis can occur alone or as part of a syndrome, and congenital heart defects are present in about 5% to 10% of affected people.
Confirming a diagnosis
Situs inversus is diagnosed by a pediatrician or primary care provider based on symptoms, a physical exam, and imaging tests.
The doctor may order tests such as an X-ray, CT scan, MRI, or ultrasound to confirm the position of the organs and determine which are affected.
Possible causes
Situs inversus is caused by genetic mutations that affect embryonic development during pregnancy.
In some cases, it follows an autosomal recessive inheritance pattern, meaning both parents may carry the mutation. However, it can also occur sporadically without a clear inheritance pattern.
Situs inversus is often associated with genetic syndromes, such as Kartagener syndrome.
Main types
Situs inversus can be classified into several types:
1. Situs inversus totalis
Situs inversus totalis is characterized by a complete mirror-image reversal of the organs in the chest and abdomen, such as the intestines, liver, stomach, spleen, esophagus, pancreas, heart, and lungs.
2. Situs inversus partialis
Situs inversus partialis is characterized by the reversal of only some organs.
3. Situs inversus abdominalis
Situs inversus abdominalis occurs when all organs in the abdominal region are reversed.
4. Situs ambiguous
Situs ambiguous is characterized by the liver being located in the midline of the body, the spleen being absent or duplicated, or signs of intestinal malrotation.
5. Dextrocardia
Dextrocardia is a type of situs inversus in which only the heart is located on the right side of the body instead of the left side. This may affect heart function and cause complications such as heart failure.
Treatment options
In cases where situs inversus does not cause symptoms, treatment may not be necessary.
When other associated conditions are present, treatment depends on the symptoms that develop.
In general, surgery to reposition the organs is not recommended.