Causes Of Sirenomelia: Its Symptoms, Diagnosis And Treatment

Sirenomelia is a rare congenital birth defect in which the legs and feet of the infant are fused together in a way so as to appear like tail of a mermaid. Therefore it is also called mermaid syndrome. It is a fatal condition. Along with the lower body developmental anomaly, there may be other associated defects such as absence of kidney, bladder and genital organs, imperforate anus, spina bifida, etc.

Sirenomelia is rare and it may occur in 1 out of 100000 births. The exact cause is not known, but pregnant women with diabetes increases the risk of mermaid syndrome in the developing fetus.

Genetic mutation and malfunction of blood vessels in the fetus is also suspected to give rise to sirenomelia.

More than half cases result in stillbirth and the rest half may not survive more than 2 hours to 1 day after birth. Even if the infant is born without complication of kidney and bladder, there is little hope for surviving after surgical intervention.

What Are The Causes Of Sirenomelia?

The exact cause of sirenomelia is not known. Researchers suspect genetic and environmental role for development of this birth defect in an individual. Pregnant woman suffering from diabetes or severe illness during pregnancy is believed to be one of the possible causes of sirenomelia.

It is also believed to occur due to defect in development of vascular system during the embryo stage. As some individuals with sirenomelia have single artery leaving the aorta in the abdominal region instead of branching of two arteries that carry the blood to embryo tail. Lack of blood supply and nutrients in this caudal portion of the embryo gives rise to malformed legs.

Pregnancy below the age of 20, coming in contact with teratogens in environment are also suspected to cause mermaid syndrome. This rare developmental defect is seen more often in males as compared to females. The condition is also seen more in one out of two identical twins than dizygotic twins.

Signs And Symptoms Of Sirenomelia

The physical malformation may greatly vary from one individual to another, but fused legs and feet are always present and they are the primary indicators of sirenomelia.

  • Fusion of legs and feet with the skin. It appears as if the baby has single leg right in the middle.
  • Presence of one foot or both feet with rotation of foot so that the back of foot faces on front.
  • Tiny and fused pelvic bones.
  • Short colon.
  • Absence of kidney and bladder.
  • Imperforate anus. A thin skin covering which blocks the anal passage.
  • Absence of genital organs, both internal as well as external.
  • Bulge protruding out from spinal column.
  • Underdeveloped lungs.

Diagnosis And Treatment For Sirenomelia

Diagnosis of the mermaid syndrome is possible before birth of the child. During second trimester sonography helps to reveal any birth defect such as sirenomelia. After birth, physical examination actually helps to determine sirenomelia.

Sirenomelia in majority of cases is fatal condition. At least half of the cases are stillbirth babies and the rest half do not live more than 2 to 24 hours after birth.

However, if the newborn survives for 24 hours and has good functioning kidney, then doctors may try to separate the joined legs and rebuild whatever defects are present with surgical intervention. It may take several surgeries to rebuilt malformed organs and tissues. Even after successful surgeries the prognosis is not favorable.

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