# Situs inversus

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Situs_inversus
> Markdown URL: https://mediated.wiki/source/Situs_inversus.md
> Source: https://en.wikipedia.org/wiki/Situs_inversus
> Source revision: 1348196497
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

***Situs inversus*** is a [congenital condition](/source/Congenital_disorder) in which the major [visceral organs](/source/Organ_(anatomy)) are reversed or [mirrored](/source/Mirror_image) from their normal positions. The normal arrangement of internal organs is known as *[situs solitus](/source/Situs_solitus)*. Many people with *situs inversus* have no medical symptoms resulting from the condition, although cardiac problems are the most common complication. Until the advent of modern medicine, it was usually undiagnosed.

It is found in about 0.01% of the population (1 in 10,000 people). Most commonly, it involves complete transposition (right to left reversal) of all of the [viscera](/source/Viscera), known as *situs inversus totalis*. The heart is not in its usual position in the left chest, but is on the right, a condition known as *[dextrocardia](/source/Dextrocardia)* (lit. 'right-hearted'). Because the relationship between the organs is not changed, most people with *situs inversus* have no associated medical symptoms or complications.[1]

An uncommon form of *situs inversus* is [isolated levocardia](/source/Isolated_levocardia), in which the position of the heart is not mirrored alongside the other organs. Isolated levocardia carries a risk of heart defects, and so patients with the condition may require surgery to correct them.

In rarer cases, such as *[situs ambiguus](/source/Situs_ambiguus)* or heterotaxy, *situs* cannot be determined. In these patients, the liver may be midline, the spleen absent or multiple, and the bowel malrotated. Often, structures are duplicated or absent altogether. This is more likely to cause medical problems than *situs inversus totalis*.[2]

## Signs and symptoms

In the absence of congenital heart defects, individuals with *situs inversus* are homeostatically normal, and can live standard healthy lives without any complications related to their medical condition. There is a 5–10% prevalence of [congenital heart disease](/source/Congenital_heart_disease) in individuals with *situs inversus totalis*, most commonly [transposition of the great vessels](/source/Transposition_of_the_great_vessels). The incidence of congenital heart disease is 95% in *situs inversus* with [levocardia](/source/Levocardia).[citation needed]

Many people with *situs inversus totalis* are unaware of their unusual anatomy until they seek medical attention for an unrelated condition, such as a [rib fracture](/source/Rib_fracture) or a bout of [appendicitis](/source/Appendicitis). The condition may also be discovered during the administration of certain medicines or during tests such as a [barium meal](/source/Barium_meal) or [enema](/source/Enema).[3] The reversal of the organs may then lead to some confusion, as many signs and symptoms will be on the atypical side. For example, if an individual with *situs inversus* develops [appendicitis](/source/Appendicitis), they will present to the physician with lower left abdominal pain, since that is where their appendix lies.[note 1] Thus, in the event of a medical problem, the knowledge that the individual has *situs inversus* can expedite diagnosis. People with this rare condition should inform their [doctors](/source/Physician) before an examination, so the doctor can redirect their search for [heart sounds](/source/Heart_sound) and other [signs](/source/Sign_(medicine)). Wearing a [medical identification tag](/source/Medical_identification_tag) can help inform health care providers in the event the person is unable to communicate.[citation needed]

*Situs inversus* also complicates [organ transplantation](/source/Organ_transplantation) operations as donor organs will more likely come from *situs solitus* (normal) donors. As hearts and livers are [chiral](/source/Chirality), geometric problems arise in placing an organ into a cavity shaped in the mirror image. For example, a person who requires a heart transplant needs all their [great vessels](/source/Great_vessels) reattached to the donor heart. However, the orientation of these vessels in a person with *situs inversus* is reversed, necessitating steps so that the blood vessels join properly.

## Cause

Further information: [Primary ciliary dyskinesia](/source/Primary_ciliary_dyskinesia) and [Left-right asymmetry (biology)](/source/Left-right_asymmetry_(biology))

*Situs inversus* is generally an [autosomal recessive](/source/Recessive_gene) [genetic](/source/Genetics) condition, although it can be [X-linked](/source/X-linked) or found in identical ["mirror image" twins](/source/Twin#Mirror_image_twins).[4]

About 25% of individuals with *situs inversus* have an underlying condition known as [primary ciliary dyskinesia](/source/Primary_ciliary_dyskinesia) (PCD). PCD is a dysfunction of the [cilia](/source/Cilium) that occurs during early [embryonic development](/source/Embryonic_development). Normally functioning cilia determine the position of the internal organs during early development, and so embryos with PCD have a 50% chance of developing *situs inversus*. If they do, they are said to have [Kartagener syndrome](/source/Kartagener_syndrome), characterized by the [triad](/source/Medical_triad) of *situs inversus*, chronic [sinusitis](/source/Sinusitis), and [bronchiectasis](/source/Bronchiectasis). Cilia are also responsible for [clearing mucus](/source/Mucociliary_clearance) from the lung, and the dysfunction causes increased susceptibility to lung infections. Kartagener syndrome can also manifest with male infertility as functional cilia are required for proper sperm flagella function.[citation needed]

A marked increase in cases was observed several months after the lifting of the [zero-COVID-19 policy in China](/source/Chinese_government_response_to_COVID-19), which coincided with a rise in [SARS-CoV-2](/source/SARS-CoV-2) infections. This rare clinical evidence suggests a possible link between [infection during pregnancy](/source/COVID-19_in_pregnancy) and the development of situs inversus in the fetus, specifically during gestational weeks 4–6, the critical period for organ positioning.[5]

## Effect on anatomy

The condition affects all major structures within the [thorax](/source/Thoracic_cavity) and [abdomen](/source/Abdomen). Generally, the organs are simply transposed through the [sagittal plane](/source/Sagittal_plane). The heart is located on the right side of the thorax, the [stomach](/source/Stomach) and [spleen](/source/Spleen) on the right side of the abdomen, and the [liver](/source/Liver) and [gall bladder](/source/Gall_bladder) on the left side. The heart's normal right atrium occurs on the left, and the left atrium is on the right. The lung anatomy is reversed, and the left lung has three lobes while the right lung has two lobes. The intestines and other internal structures are also reversed from the normal, and the [blood vessels](/source/Blood_vessel), [nerves](/source/Nerve), and [lymphatics](/source/Lymph_vessels) are also transposed.

If the heart is swapped to the right side of the thorax, it is known as "*situs inversus* with [dextrocardia](/source/Dextrocardia)" or "*situs inversus totalis*". If the heart remains on the normal left side of the thorax, a much rarer condition (1 in 2,000,000 of the general population), it is known as "*situs inversus* with [levocardia](/source/Levocardia) or "*situs inversus incompletus*".

*Situs inversus* of the optic disc may occur unilaterally or bilaterally, associated with reduced [binocularity](/source/Binocularity) and [stereoacuity](/source/Stereoacuity) resembling [monofixation syndrome](/source/Monofixation_syndrome). It is characterized by the emergence of the retinal vessels in an anomalous direction (from the nasal rather than the temporal aspect) with dysversion (tilt) of the optic disc.[6]

Research into [handedness](/source/Handedness) among individuals with *situs inversus* has yielded conflicting results. Research from 2004 indicated that the prevalence of left-handedness in those individuals with *situs inversus* and [primary ciliary dyskinesia](/source/Primary_ciliary_dyskinesia) was not significantly different from the general population with *situs solitus*.[7] However, more recent research published in 2023 reported a significant increase in left-handedness, finding that 26% of individuals with *situs inversus* were left-handed, a rate much higher than the 10.6% typically observed in the general population.[8]

## Diagnosis

Diagnosis of *situs inversus* can be made using [imaging techniques](/source/Medical_imaging) such as [X-ray](/source/X-ray), [ultrasound](/source/Ultrasound), [CT scan](/source/CT_scan), and [magnetic resonance imaging](/source/Magnetic_resonance_imaging) (MRI).[9]

Any potential treatment would involve a complete and highly invasive surgical rearrangement of the internal viscera of the patient. Such a procedure is unnecessary, given that *situs inversus* rarely causes any additional symptoms. No treatment, medical or surgical, is prescribed for *situs inversus* individuals, with medical professionals instead treating any other symptoms the patient may have with awareness of the unique anatomy of the patient.[citation needed]

## Occurrence

*Situs inversus* is rare, affecting 0.01% of the population.[10][11]

## History

[Dextrocardia](/source/Dextrocardia) (the [heart](/source/Heart) being located on the right side of the [thorax](/source/Thoracic_cavity)) was seen and drawn by [Leonardo da Vinci](/source/Leonardo_da_Vinci),[citation needed] and then recognised by [Marco Aurelio Severino](/source/Marco_Aurelio_Severino) in 1643. *Situs inversus* was first described more than a century later by [Matthew Baillie](/source/Matthew_Baillie).[2]

## Etymology

The term *situs inversus* is a short form of the [Latin](/source/Latin) phrase *situs inversus viscerum*, meaning "inverted position of the internal organs".

## Notable cases

See also: [List of fictional characters with situs inversus](/source/List_of_fictional_characters_with_situs_inversus)

Notable individuals with documented cases of situs inversus include:

- [Enrique Iglesias](/source/Enrique_Iglesias) (b. 1975), Spanish singer, songwriter, actor and record producer.[12]
- [Catherine O'Hara](/source/Catherine_O'Hara) (1954–2026), Canadian-American actress, writer, and comedian.[13]
- [Randy Foye](/source/Randy_Foye) (b. 1983), American former professional [basketball](/source/Basketball) player in the [NBA](/source/NBA). He has suffered no discernible complications, and the condition did not affect his career as a professional athlete, as all his organs are in reverse.[14]
- [Ginggaew Lorsoungnern](/source/Ginggaew_Lorsoungnern) (1950–1979), Thai convict executed by firing squad. Her condition was discovered after she was shot in the left side of her chest and survived. After waking up in the morgue she was taken back and executed.[15]
- [Tim Miller](/source/Tim_Miller_(yoga_teacher)) (b. 1951), director of the Ashtanga Yoga Center in Carlsbad, California.[16]
- Rose Marie Bentley (1918–2017 or 2018), [Molalla](/source/Molalla,_Oregon), Oregon woman who unknowingly had the rare variant *situs inversus* with [levocardia](/source/Levocardia), and lived to 99 years without any complications. She [donated her body](/source/Body_donation) to [Oregon Health & Science University](/source/Oregon_Health_%26_Science_University), where her condition was discovered during an anatomy class after students noticed the unusual arrangement of her heart's blood vessels, prompting further investigation of the cadaver.[17][18]

## See also

- [Asplenia](/source/Asplenia)
- [Chirality (mathematics)](/source/Chirality_(mathematics))
- *[Ectopia cordis](/source/Ectopia_cordis)*
- [Johann Friedrich Meckel, the Elder](/source/Johann_Friedrich_Meckel,_the_Elder)
- [Polysplenia](/source/Polysplenia)

## Notes

1. [Intestinal malrotation](/source/Intestinal_malrotation) can also cause the appendix to be on the left side.

## References

1. ["Definition of Situs inversus totalis"](http://www.medicinenet.com/script/main/art.asp?articlekey=5499). *[MedicineNet](/source/MedicineNet)*. [Archived](https://web.archive.org/web/20190202223121/https://www.medicinenet.com/script/main/art.asp?articlekey=5499) 2019-02-02 at the Wayback Machine. Retrieved 2015-05-12.

1. ["Situs Inversus Imaging: Overview, Radiography, Computed Tomography"](http://emedicine.medscape.com/article/413679-overview). *EMedicine*. 26 April 2016.

1. [medscapestatic.com](http://img.medscapestatic.com/pi/meds/ckb/78/22378tn.jpg); *Situs inversus* of the large intestine discovered after administering a barium enema, [eMedicine](/source/EMedicine)

1. Gedda L, Sciacca A, Brenci G, etal (1984). "Situs viscerum specularis in monozygotic twins". *Acta Genet Med Gemellol (Roma)*. **33** (1): 81–85. [doi:10.1017/S0001566000007546](https://doi.org/10.1017/S0001566000007546). [PMID 6540028](https://pubmed.ncbi.nlm.nih.gov/6540028)

1. Guo, Zhenming; Luo, Yingchun; Bi, Yan; Liu, Liangjie; Qi, Yuan (November 2024). ["Association between situs inversus and maternal SARS-CoV-2 infection at gestational age 4–6 weeks"](https://linkinghub.elsevier.com/retrieve/pii/S2666634024002915). *Med*. **5** (11): 1433–1441.e3. [doi:10.1016/j.medj.2024.07.009](https://doi.org/10.1016/j.medj.2024.07.009). [PMID 39094582](https://pubmed.ncbi.nlm.nih.gov/39094582)

1. Kothari, M. & Chatterjee, D. N. (2010). "Unilateral situs inversus of optic disc associated with reduced binocularity and stereoacuity resembling monofixation syndrome". *Indian Journal of Ophthalmology*. **58** (3): 241–242. [doi:10.4103/0301-4738.62654](https://doi.org/10.4103/0301-4738.62654). [PMC 2886260](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2886260). [PMID 20413932](https://pubmed.ncbi.nlm.nih.gov/20413932)

1. I.C. McManus; N. Martin; G.F. Stubbings; E.M.K. Chung; H.M. Mitchison (22 December 2004). "Handedness and situs inversus in primary ciliary dyskinesia". *Proceedings of the Royal Society B: Biological Sciences*. **271** (1557): 2579–2582. Royal Society. [doi:10.1098/rspb.2004.2881](https://doi.org/10.1098/rspb.2004.2881). [PMC 1691902](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1691902). [PMID 15615683](https://pubmed.ncbi.nlm.nih.gov/15615683)

1. Gerrits, Robin & Vingerhoets, Guy (2023). ["Brain functional segregation, handedness and cognition in situs inversus totalis: A replication study"](https://psyarxiv.com/erpx8/). *Neuropsychologia*. **191**. [doi:10.1016/j.neuropsychologia.2023.108731](https://doi.org/10.1016/j.neuropsychologia.2023.108731). [PMID 37949213](https://pubmed.ncbi.nlm.nih.gov/37949213)

1. Fulcher, Ann S.; Turner, Mary Ann. *Abdominal Manifestations of Situs Abnormalities in Adults*. RadioGraphics, 2002. 22(6). p. 1440. [http://pubs.rsna.org/doi/pdf/10.1148/rg.226025016](http://pubs.rsna.org/doi/pdf/10.1148/rg.226025016)

1. Soccorso, Giampiero & Ninan, George K. (February 2012). "Through the looking-glass what you found there". *World Journal of Pediatrics*. **8** (1): 86. [doi:10.1007/s12519-012-0336-6](https://doi.org/10.1007/s12519-012-0336-6). [PMID 22282384](https://pubmed.ncbi.nlm.nih.gov/22282384)

1. Eitler, Katalin; Bibok, András; Telkes, Gábor (3 March 2022). "Situs Inversus Totalis: A Clinical Review". *International Journal of General Medicine*. **15**: 2437–2449. [doi:10.2147/IJGM.S295444](https://doi.org/10.2147/IJGM.S295444). [ISSN 1178-7074](https://www.worldcat.org/issn/1178-7074). [PMC 8901252](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8901252). [PMID 35264880](https://pubmed.ncbi.nlm.nih.gov/35264880)

1. Silver, Katie (28 April 2015). ["Here's why some people are left-handed, according to science"](http://www.sciencealert.com/here-s-why-are-some-people-left-handed-according-to-science). *sciencealert.com*. Science Alert. [Archived](https://web.archive.org/web/20181225075744/https://www.sciencealert.com/here-s-why-are-some-people-left-handed-according-to-science) 25 December 2018 at the Wayback Machine. Retrieved 23 May 2016.

1. Commanducci, Massimo (October 15, 2009). ["Catherine O'Hara: particulars"](https://www.theglobeandmail.com/arts/catherine-ohara-particulars/article1203604/). *[The Globe and Mail](/source/The_Globe_and_Mail)*. Retrieved February 7, 2021.

1. ["Rookie T-Wolf's Organs Reversed"](http://wcco.com/sports/Minnesota.Timberwolves.Randy.2.371610.html). [Archived](https://web.archive.org/web/20090107130409/http://wcco.com/sports/Minnesota.Timberwolves.Randy.2.371610.html) 2009-01-07 at the Wayback Machine. Retrieved 2021-02-07.

1. Jaruboon, Chavoret (8 January 2015). [*The Last Executioner: Memoirs of Thailand's Last Executioner*](https://books.google.com/books?id=80oYBgAAQBAJ&pg=PT100). Maverick House. ISBN 978-1-908518-41-5.

1. ["Tuesday September 16th – Encinitas – "God's Hospital""](https://timmiller.typepad.com/blog/2014/09/tuesday-september-16thencinitas-gods-hospital.html). *Tuesdays with Timji*

1. Foden-Vencil, Kristian (April 8, 2019). ["Mollala Woman Lived 99 years with organs inversed"](https://www.opb.org/news/article/oregon-mollala-woman-situs-inversus-ohsu-discovery/). *OPB*. Retrieved February 7, 2021.

1. Sandee LaMotte (8 April 2019). ["She lived for 99 years with organs in all the wrong places and never knew it"](https://www.cnn.com/2019/04/08/health/99-year-old-backward-organs-medical-oddity/index.html). *CNN*

## Further reading

- McManus, Chris (2002). *Right Hand, Left Hand*. [Harvard University Press](/source/Harvard_University_Press). ISBN 0-674-00953-3. this book was the 2003 [Aventis winner](/source/The_Aventis_Prizes_for_Science_Books) and has a description of the history behind the discovery of this[vague] medical condition.
- Yokoyama T, Copeland NG, Jenkins NA, Montgomery CA, Elder FF, Overbeek PA (1993). "Reversal of left-right asymmetry: a situs inversus mutation". *Science*. **260** (5108): 679–682. [Bibcode:1993Sci...260..679Y](https://ui.adsabs.harvard.edu/abs/1993Sci...260..679Y). [doi:10.1126/science.8480178](https://doi.org/10.1126/science.8480178). [PMID 8480178](https://pubmed.ncbi.nlm.nih.gov/8480178)
- Lowe LA, Supp DM, Sampath K, etal (1996). ["Conserved left-right asymmetry of nodal expression and alterations in murine situs inversus"](https://zenodo.org/record/1233182). *Nature*. **381** (6578): 158–161. [Bibcode:1996Natur.381..158L](https://ui.adsabs.harvard.edu/abs/1996Natur.381..158L). [doi:10.1038/381158a0](https://doi.org/10.1038/381158a0). [PMID 8610013](https://pubmed.ncbi.nlm.nih.gov/8610013). [S2CID 4316534](https://api.semanticscholar.org/CorpusID:4316534)
- Levin M (1997). "Left-right asymmetry in vertebrate embryogenesis". *BioEssays*. **19** (4): 287–296. [doi:10.1002/bies.950190406](https://doi.org/10.1002/bies.950190406). [PMID 9136626](https://pubmed.ncbi.nlm.nih.gov/9136626). [S2CID 8035548](https://api.semanticscholar.org/CorpusID:8035548)
- Levin M, Pagan S, Roberts DJ, Cooke J, Kuehn MR, Tabin CJ (1997). "Left/right patterning signals and the independent regulation of different aspects of situs in the chick embryo". *Dev. Biol.*. **189** (1): 57–67. [doi:10.1006/dbio.1997.8662](https://doi.org/10.1006/dbio.1997.8662). [PMID 9281337](https://pubmed.ncbi.nlm.nih.gov/9281337)
- Logan M, Pagán-Westphal SM, Smith DM, Paganessi L, Tabin CJ (1998). "The transcription factor Pitx2 mediates situs-specific morphogenesis in response to left-right asymmetric signals". *Cell*. **94** (3): 307–317. [doi:10.1016/S0092-8674(00)81474-9](https://doi.org/10.1016/S0092-8674(00)81474-9). [PMID 9708733](https://pubmed.ncbi.nlm.nih.gov/9708733). [S2CID 14375165](https://api.semanticscholar.org/CorpusID:14375165)
- Stern CD, Wolpert L (2002). "Left-right asymmetry: all hands to the pump". *Curr. Biol.*. **12** (23): R802–803. [Bibcode:2002CBio...12.R802S](https://ui.adsabs.harvard.edu/abs/2002CBio...12.R802S). [doi:10.1016/S0960-9822(02)01312-X](https://doi.org/10.1016/S0960-9822(02)01312-X). [PMID 12477404](https://pubmed.ncbi.nlm.nih.gov/12477404)

## External links

- [Chest X-ray & CT scan](http://rad.usuhs.edu/medpix/medpix.html?mode=image_finder&action=search&srchstr=situs%20inversus&srch_type=all#top) [Archived](https://web.archive.org/web/20141021205626/http://rad.usuhs.edu/medpix/medpix.html?mode=image_finder#top) 2014-10-21 at the Wayback Machine Radiology Teaching File

---
Adapted from the Wikipedia article [Situs inversus](https://en.wikipedia.org/wiki/Situs_inversus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Situs_inversus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.