Situs ambiguus

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Situs ambiguous or situs ambiguus (the latter spelling is more correct etymologically, but the former spelling is very common), also known as heterotaxy, is a rare congenital defect in which the major visceral organs are distributed abnormally within the chest and abdomen.

The normal position of the organs is known as situs solitus; situs inversus is a condition in which the usual positions of the organs are reversed from left to right as a mirror image of the normal condition. If these are the two extreme positions on a continuum of asymmetric thoracic and abdominal organ formation, situs ambiguous covers everything in between.

Classically, it comprises:

More rarely, vascular abnormalities are found, including interrupted inferior vena cava, bilateral superior or inferior venae cavae, intrahepatic interruption of the inferior vena cava with connection to the azygos or hemiazygos veins, and aberrant portal veins.

Causes

Although its etiology is poorly understood, it has been found to be linked to maternal diabetes mellitus[1], [2], family history of malformations, and parental cocaine use[3], suggesting both genetic and environmental[4] factors play a role.

See also

Footnotes

  1. Martinez-Frias ML. Heterotaxia as an outcome of maternal diabetes: an epidemiological study. Am J Med Genet. 2001 Mar 1;99(2):142-6.
  2. Maeyama K, Kosaki R, Yoshihashi H, Casey B, Kosaki K. Mutation analysis of left-right axis determining genes in NOD and ICR, strains susceptible to maternal diabetes. Teratology. 2001 Mar;63(3):119-26.
  3. Kuehl KS, Loffredo CA. Risk factors for heart disease associated with abnormal sidedness. Teratology 2002. 66:242-248.
  4. Kuehl KS, Loffredo CA. Population-based study of l-transposition of the great arteries: possible associations with environmental factors. Birth Defects Res Part A Clin Mol Teratol 2003. 67:162-167.

External links

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