Sirenomelia is a serious medical problem that leads to fusion of the legs and feet due to skeletal and spinal malformation. Read and find out all about the various types, causes, symptoms, diagnosis and treatment of this disorder.

Sirenomelia Definition

It is an uncommon congenital malformation which is characterized by the fusion of legs and feet of patients, which appear like a mermaid’s tail. This lethal inborn disorder of the lower portion of the body is related with a number of other birth defects including anomaly of the kidney, genitalia and intestine. The deformity occurs among the infants and is associated with caudal repression. Affected newborns do not survive more than 24 hours after birth.

This disorder is also referred to by a number of other names, such as:

  • Sirenomelus
  • Mermaid malformation
  • Sirenomelia sequence
  • Fused legs and feet
  • Mermaid syndrome
Image Source via Wikimedia Commons

Sirenomelia ICD9 Code

The ICD9 code for this syndrome is 759.89.

Sirenomelia Incidence

This is an uncommon congenial deformity and occurs in 1 out of every 100,000 live births in the US. Infants suffering from this disorder die within a day or two due to the abnormal development of kidney and urinary bladder. Sirenomelia has been reported among different ethnic groups of the world and is common among infants born to pregnant women suffering from Diabetes mellitus.

This congenial syndrome affects identical twins rather than fraternal twins and is less likely to occur among single births.

Sirenomelia Features

Infants affected with this syndrome are similar to mythical siren. Such newborns have amphibian eyes and floppy ears. Patients suffering from this condition have poorly structured gastrointestinal and urogenital systems along with imperforate anus. Such individuals suffer from renal agenesis and lack of urethra and bladder.

Sirenomelia Causes

The exact cause of this disorder is still unknown. However, according to a few medical studies, it occurs due to the malfunctioning of the normal vascular supply from the lower aorta in utero. This autosomal dominant condition is life-threatening in nature and is caused due to various environmental factors and genes which mutate and give rise to malformations in the legs and feet. According to a few medical theories, abnormalities in the blood circulating system of the body inside the embryo at an early period can also serve as the cause of the congenital fusion of the legs and feet. Mothers suffering from diabetes mellitus are more prone to the disorder.

Sirenomelia Symptoms

Sirenomelia sequence is characterized by the developing symptoms and signs that signify its occurrence. The primary indicators are fused feet and legs along with a number of warning signs including:

  • Miniature, fused, small and poorly structured pelvic bones
  • Malfunctioning kidneys
  • Imperforated anus
  • Blind ending colon
  • Inborn anomaly in the upper portions of the body including lungs, heart, arms, brain and spine
  • Poorly structured and small external and internal genitalia
  • Immature and underdeveloped lungs arising due to oligohydramnios, often leading to death.

Sirenomelia Diagnosis

Physicians recommend that physical examination of newborn baby is mandatory to determine the diagnosis. A few tests which help to detect the existence of Mermaid syndrome among the infants include:


This procedure helps to conduct the prenatal diagnosis which is obvious at the second trimester of pregnancy.


This procedure helps to perform an antenatal diagnosis of Sirenomelia sequence and helps doctors to determine the right treatment option for it.

Sirenomelia Treatment

Treatment is applicable for newborns who survive even 24 hours after delivery. Affected newborns having functioning kidneys are recommended for surgical procedures and management. Surgical operations to rebuild the gastrointestinal and urinary outlet tracts are essential for such patients. The extent of procedures and therapies for Mermaid syndrome patients depends on the severity of the birth defect.

Sirenomelia Prognosis

Due to the birth defects which involve the gastrointestinal tract and the kidneys, Mermaid syndrome is always considered to be fatal. More than 50% of all affected newborns die before delivery and the rest who survive, last for few minutes to 2 days.

Sirenomelia Complications

This is a severe congenial disorder. If left untreated, the disorder can give rise to number of complications in the body including:

  • Absence of kidneys
  • Deficiency of urinary tract
  • Heart deformities

Sirenomelia Prevention

Since the actual reason for Mermaid syndrome is still unknown, doctors cannot recommend procedures and safety guidelines to prevent its occurrence. Hence, the prevention of this severe form of caudal regression is almost impossible.

Sirenomelia Pictures

Check out images of infants affected by this disorder.

Picture 1 – Sirenomelia


Picture 2 – Sirenomelia Image

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