Anomalies of lateralization in man: a case of total situs inversus.

Total or complete visceral situs inversus is the complete inversion of position of the thoracic and abdominal viscera. The aim of this study is to report a case of complete situs inversus and to review our knowledge of the anomalies of lateralization. A case of complete sinus inversus was discovered incidentally during anatomic dissection in a female subject aged 87 years. The thoracic and abdominal organs had a position symmetric with the normal. This was associated with a common mesentery and incomplete rotation of the colon, placing the cecum under the left lobe of the liver. These alimentary anomalies were discovered in adult life during a surgical operation for small intestinal occlusion, as evidenced by the abdominal scar and peritoneal adhesions. No cardiac, pulmonary, splenic or facial sinus anomalies were encountered. The incidence of complete situs inversus is estimated as 1/8000 in the general population. It may be isolated or associated with malformations, especially cardiac or alimentary. It may be discovered in infancy because of associated anomalies but often remains asymptomatic and discovered by chance in adult life. Complete situs inversus may form part of the multiple malformational syndromes such as that of Kartagener, with recessive autosomal transmission (complete situs inversus, bronchiectasis, chronic sinusitis, male infertility), which represents 20-25% of cases of complete situs inversus. In view of the frequency of this type of anomaly, a knowledge of anomalies of lateralization is essential in clinical practice.