Journal of Postgraduate Medicine
 Open access journal indexed with Index Medicus & ISI's SCI  
Users online: 518  
Home | Subscribe | Feedback | Login 
About Latest Articles Back-Issues Articlesmenu-bullet Search Instructions Online Submission Subscribe Etcetera Contact
 :: Next article
 :: Previous article 
 :: Table of Contents
 ::  Similar in PUBMED
 ::  Search Pubmed for
 ::  Search in Google Scholar for
 ::  Article in PDF (138 KB)
 ::  Citation Manager
 ::  Access Statistics
 ::  Reader Comments
 ::  Email Alert *
 ::  Add to My List *
* Registration required (free) 

  IN THIS Article
 ::  Case Report
 ::  Discussion
 ::  References
 ::  Article Figures

 Article Access Statistics
    PDF Downloaded244    
    Comments [Add]    
    Cited by others 2    

Recommend this journal


Year : 2006  |  Volume : 52  |  Issue : 3  |  Page : 219-220

Sirenomelia: MRI appearance

1 Departments of Radiology, Obstetrics, Sultan Qaboos University Hospital, PO Box 38, Sultan Qaboos University, Muscat PC 123, Oman
2 Departments of Gynecology, Sultan Qaboos University Hospital, PO Box 38, Sultan Qaboos University, Muscat PC 123, Oman

Correspondence Address:
S Sawhney
Departments of Radiology, Obstetrics, Sultan Qaboos University Hospital, PO Box 38, Sultan Qaboos University, Muscat PC 123
Login to access the Email id

Source of Support: None, Conflict of Interest: None

PMID: 16855327

Rights and PermissionsRights and Permissions

How to cite this article:
Sawhney S, Jain R, Meka N. Sirenomelia: MRI appearance. J Postgrad Med 2006;52:219-20

How to cite this URL:
Sawhney S, Jain R, Meka N. Sirenomelia: MRI appearance. J Postgrad Med [serial online] 2006 [cited 2023 Oct 3];52:219-20. Available from:

Sirenomelia is an extremely rare congenital anomaly with a reported incidence of up to 1 in 100,000 live births. More than 300 cases have been reported in the world literature. In the vast majority of cases, the associated anomalies, especially renal agenesis are incompatible with life, though there have been very few survivors, even with hypoplastic kidneys.[1]

 :: Case Report Top

A 26-year-old woman (consanguineous marriage) delivered a stillborn baby at 31 weeks gestation. She had not undergone an antenatal ultrasound examination. All her laboratory investigations were normal. The baby had discolored skin, folded ears, low lying nipples, low back mass and fused lower limbs. No genitalia were identified. A single cloacal opening was seen on the lower back. Clinical photograph [Figure - 1] and MRI study [Figure - 2][Figure - 3][Figure - 4] were performed on the stillborn baby.

In this patient MRI demonstrated the characteristic features of this rare anomaly, viz., fused lower limbs, medially rotated acetabuli and femoral heads, single midline fibula, single cloacal opening, abrupt conical termination of aorta at D12 level and hypoplastic kidneys. The unusual feature of this case was the presence of a well-defined identifiable sacrum.

 :: Discussion Top

Sirenomelia is a condition characterized by fusion of the pelvic girdle and lower extremities into a single conical structure, and is considered a part of the spectrum of the caudal regression syndrome. The lower extremity is always inverted and externally rotated, so that the knee is situated posteriorly, and the toes points posteriorly.[2] In these children, the coccyx is absent and sacrum is partially or wholly absent.[3] The fused lower extremities may have a normal number of bones, partial fusion of bones, or no bones at all. The etiology of sirenomelia is uncertain. In addition to defective mesodermal embryogenesis, a vitelline artery steal syndrome has been proposed by some authors.[4] It is presumed that a large artery, likely to be a derivative of the vitelline artery arises from the aorta high in the abdominal cavity, beyond which the aorta and its branches are hypoplastic. This results in a 'vitelline artery steal', which diverts blood and nutrients away from the caudal portion of the embryo to the placenta. Maternal diabetes mellitus shows a possible weak association with sirenomelia.[5] There is an apparent overlap between in the phenotypic manifestations of sirenomelia and the VACTERL complex (vertebral, anal, cardiovascular, tracheal, esophageal, renal and limb), with at least three of the components of VACTERL shown in all cases of sirenomelia, in addition to the lower limb deformities, with more severe involvement of the gastrointestinal and genitourinary systems.[6] Antenatal sonographic screening maybe helpful in detecting fetal genitourinary anomalies associated with sirenomelia, however, oligohydramnios can often prevent optimal assessment.

 :: References Top

1.Smith DW, Jones KL. Recognisable patterns of human malformation. Genetic, embryologic and clinical aspects. 2nd ed. Saunders: Philadelphia; 1976. p. 486-7.  Back to cited text no. 1    
2.Naidich TP, Mc Lone DG, Harwood-Nash DC. Spinal dysraphism. In : Newton TH, Potts EG, editors. Mordern neuroradiology. Vol 1. Computed tomography of the spine and spinal cord. Clavadel Press: CA; 1993.  Back to cited text no. 2    
3.Hendry DW, Kohler HG. Sirenomelia ("Mermaid"). J Obstet Gynaecol 1956;63:865-70.  Back to cited text no. 3  [PUBMED]  
4.Stevenson RE, Jones KL, Phelan MC, Jones MC, Barr M, Clericuzio C, et al . Vascular steal: The pathogenetic mechanism producing sirenomelia and associated defects of the viscera and soft tissues. Pediatrics 1986;78:451-7.  Back to cited text no. 4    
5.Schuler I, Salzano FM. Patterns in multi-malformed babies and the question of the relationship between sirenomelia and VACERL. Am J Med Genet 1994;49:29-35.  Back to cited text no. 5    
6.Duncan PA, Shapiro LR. Interrelationships of the hemifacial microsomia-VATER, VATER, and sirenomelia phenotypes. Am J Med Gen 1993;47:75-84.  Back to cited text no. 6  [PUBMED]  


[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]

This article has been cited by
1 Diagnosis of fetal congenital limb deformities by MRI
Dong, S.-Z., Zhu, M., Mao, J.-P., Zhong, Y.-M., Zhang, H.
Chinese Journal of Radiology. 2008; 42(11): 1143-1146
2 Sirenomelia; A case report and review article
Mahjoub F, Aliehpour AA


Print this article  Email this article
Previous article Next article
Online since 12th February '04
2004 - Journal of Postgraduate Medicine
Official Publication of the Staff Society of the Seth GS Medical College and KEM Hospital, Mumbai, India
Published by Wolters Kluwer - Medknow