Sirenomelia (also known as the mermaid syndrome) is a rare congenital malformation characterised by the fusion of lower limb structures.

The estimated incidence is at ~1 in 60,000-70,000 of pregnancies 9. There may be greater male predilection (somewhat paradoxical given the usage of mermaid).

While it was previously thought as beloning the same spectrum as the caudal regression syndrome, this proposition is now heavily debated and it is now thought to result from a seperate pethogenesis. A vascular steal phenomenon causing severe ischemia to the caudal portion of the fetus is often accepted.

The lower extrametities typically appear fused into a single limb and there can be sacral agenesis to varying degrees.

Ancillary sonographic features:

The condition of often fatal and incompatible with life (contrary to popular fairy tales). Exceptional cases without renal agenesis may survive. Depending on the country you live in, a termination of pregnancy could be considered in appropriate situations.

Derives from the Latin words: siren meaning "a partly female creature in Greek legend whose beautiful singing lured sailors to their deaths" and melia meaning limb

For mild forms consider:

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Article information

rID: 13421
Tag: cases
Synonyms or Alternate Spellings:
  • Mermaid syndrome
  • Sirenomalia sequence
  • Mermaid fetus

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