SIRENOMELIA AND CAUDAL REGRESSION SYNDROME – THE RARE CONGENITAL ANOMALIES

Abstract

Sirenomelija i sindrom kaudalne regresije su rijetke kongenitalne malformacije. Iako se sirenomelija prijašnjih godina smatrala teškim oblikom sindroma kaudalne regresije, danas se zna da su to dva različita stanja kojima je zajedničko da različitim patogenetskim mehanizmima nastaju u ranom embrionalnom razvoju ploda. Za sirenomeliju se smatra da nastaje zbog tzv. »fenomena krađe krvi«, a sindrom kaudalne regresije zbog poremećaja u diferencijaciji mezoderma. Jedan i drugi poremećaj nastaju u ranom embrionalnom razvoju ploda tijekom četvrtog postkoncepcijskog tjedna, za vrijeme razdoblja gastrulacije. U prikazu dva slučaja antenatalno dijagnosticiranih malformacija prikazane su razlike u patogenezi, pridružene anomalije, antenatalna dijagnostika te prognoza, s posebnim naglaskom na antenatalni probir malformacija koji omogućuje rano postavljanje dijagnoze te indikaciju za rano, manje traumatično dovršenje trudnoće.Sirenomelia and caudal regression syndrome present a rare congenital malformation. Although sirenomelia was thought to be severe type of the caudal regression syndrome in the previous years, it is known today that the sirenomelia and the caudal regression syndrome are, in fact, two mutually diverse states. Both states appear during the early embryogenic development of the fetus due to the different pathogenic mechanisms. The sirenomelia is considered to appear due to the vascular steal theory, whereas the caudal regression syndrome appears due to the disorder of the mesoderm differentiation. The sirenomelia and caudal regression syndrome come into existence in the early embryologic development of the fetus during the fourth postconceptional week at the period of gastrulation. The two reported case studies show the distinction between the pathogenesis, as well as the associated anomalies based upon the antenatally diagnosed malformations. The antenatal diagnostics and prognosis are discussed, especially emphasizing the antenatal screening of the malformations which enables the early diagnosis, as well as the indications for the early and less traumatic pregnancy termination