Situs inversus

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Classification according to ICD-10
Q89.3 Situs inversus
ICD-10 online (WHO version 2019)

Situs inversus ( lat. Inverted position ) is the medical term for the full picture of a heterotaxia , a rare, inherently non-pathological feature of anatomy in which the individual organs are mirror-inverted on the other side of the body. The antonym is the situs solitus , i.e. the standardized position of the organs in the body. Synonyms of situs inversus are: inversio viscerum, situs inversus viscerum, situs inversus totalis , situs perversus, situs transversus, situs rarior, situs transversus viscerum, situs oppositus, situs inversus completus.

In the situs inversus partialis , only either the thoracic organs (i.e. the halves of the heart and the lungs) or the abdominal organs are transversely reversed. In the situs inversus incompletus there is no dextrocardia. In the rare situs inversus viscerum specularis , only one of the two identical twins is affected.

The situs ambiguus forms a third type of organ situs , i.e. neither situs inversus nor situs solitus.

All of these location names are not included in the official lists of medical nomenclature .

In analogy to chemistry, the situs inversus is also referred to as a chirality of the internal organs. Rotational mirroring does not lead to self-image in any higher living being, but axis mirroring does . These living beings are built up asymmetrically . The affected twins, one of which has a situs inversus viscerum specularis , on the other hand, could be made to coincide with the other sibling (such as the symmetrical hands, feet or ears of a person) by means of a rotational mirroring, but not by an axis mirroring .

Situs inversus in humans

Situs inversus in a CT image of the chest: the heart is on the right (R = right, L = left, A = anterior = front, P = posterior = back)
Abdominal view of the same patient: the liver can be seen on the left

The situs inversus (viscerum) occurs in about 1 in 8,000 to 25,000 people and in half of people with primary ciliary dyskinesia ( Kartagener's syndrome ). For example, in people with this heterotaxia, the liver is on the left and, in contrast, the spleen is on the right.

Medical specialties

In order not to overlook appendicitis (appendicitis), the possibility of a situs inversus should also be considered if there is pain in the left lower abdomen.

According to the mirror-inverted position of the heart ( dextrocardia , Greek dexios = "right", kardia = "heart"), the leads of the ECG must be adapted; it must u. a. in the chest wall leads, the electrodes are attached to the thorax in a mirror image of situs solitus patients. In terms of differential diagnosis , polarity reversal must be considered. Some people with Patau syndrome (trisomy 13) have dextrocardia, while the other organs are laid out as usual. This mirror-image shift to the right of only the heart is also called situs inversus cordis . In cardiology, a distinction is made between five different forms of a malposition of the heart : dextrocardia in the situs solitus, levocardia in the situs inversus, a mesocardia with a middle heart, a dextroposition or a levoposition in the case of extracardiac cause and an ectopia cordis . When looking at a chest x-ray image, one should also think of dextrocardia or a right-left confusion .

In some cases of infantile nephronophthisis , the situs inversus occurs as a result of a genetic mutation of the gene for the right-left orientation. A situs inversus can also occur with chondrodystrophia fetalis .

Situs inversus in animals

Snails normally have right-handed snail shells. The incidence of left-handed Roman snails is estimated at around 1: 10,000 to 1: 1,000,000. In such animals, which are referred to as snail kings , all organs (e.g. heart, respiratory and sexual opening) are reversed.

The reason for this is a maternal factor in the migrating snail (Lymnaea peregra) , the dextral protein. This protein determines the direction of movement of the cilia in morphogenesis - growth factors are distributed by the cilia and thus determine how the housing is shaped. Since it is a maternal factor, the dextral protein can be stored in the oocyte and thus ensure normal development even in homozygous - recessive offspring.

Individual evidence

  1. ↑ Maxim Zetkin , Herbert Schaldach (Ed.): Lexicon of Medicine. 16th edition. Ullstein Medical, Wiesbaden 1999, ISBN 3-86126-126-X , p. 1859.
  2. ↑ Duden : The dictionary of medical terms. 4th edition. Bibliographisches Institut , Mannheim / Vienna / Zurich 1985, ISBN 3-411-02426-7 , p. 634.
  3. ^ Günter Thiele (ed.): Handlexikon der Medizin. Volume 4: S − Z. Urban & Schwarzenberg , Munich / Vienna / Baltimore without year, p. 2259.
  4. ↑ Otto Dornblüth : Dictionary of clinical art expressions. 1st edition. Verlag von Veit & Comp., Leipzig 1896, p. 122.
  5. ↑ L. Gedda et al .: Situs viscerum specularis in monozygotic twins. In: Acta Genet Med Gemellol (Roma). Volume 33 (1), 1984, pp. 81-85.
  6. ↑ Walter Siegenthaler et al. (Ed.): Textbook of internal medicine. 3. Edition. Georg Thieme Verlag , Stuttgart / New York 1992, ISBN 3-13-624303-X , p. 251.
  7. ^ Rainer Klinge: The electrocardiogram. 5th edition. Georg Thieme Verlag , Stuttgart / New York 1987, ISBN 3-13-554005-7 , pp. 268-270.
  8. ^ Hans Hermann Börger: EKG information. 5th edition. Steinkopff Verlag , Darmstadt 1987, ISBN 3-7985-0710-4 , p. 67.
  9. ^ Cook-Sup So: EKG atlas. Echo-Verlag, Cologne 1987, ISBN 3-926518-05-7 , p. 204 f.
  10. ↑ Egbert Nusser et al.: Differential diagnosis of the EKG. 1st edition. Schattauer Verlag , Stuttgart / New York 1977, ISBN 3-7945-0497-6 , p. 78.
  11. ↑ Hexal Pocket Dictionary Medicine. 2nd Edition. Urban & Fischer , Munich / Jena 2000, ISBN 3-437-15010-3 , p. 724.
  12. ↑ George Csapo: Conventional and intracardiac electrocardiography. 4th edition. Documenta Geigy, Wehr (Baden) 1980, p. 75.
  13. ↑ Harrison's Internal Medicine. 18th edition. Volume 3, McGraw-Hill , Berlin 2012, ISBN 978-3-940615-20-6 , p. 2553.
  14. ^ Georg-Winfried Schmidt: Guide to infant and paediatrics. (= Medicine of today. Volume 12). 5th edition. Tropon-Werke, Cologne 1981, p. 171.
  15. ^ Body structure of Roman snails
  16. ↑ Information about the Snail King

Web links

  • Christoph Drösser: In the right place. In: time online. June 8, 2006. (zeit.de)