Determination of Foetal cases of Sirenomelia Sequence with Their Embryological Correlations

Abstract

A thorough investigation of a congenital anomaly “Sirenomelia” of the foetus is a rare malformation that makes life impossible. This is a very rare occurrence, and hearing such cases is heartbreaking. The sequence was named after the mythical Greek sirens and was first described by Rocheus in 1542 and Palfyn in 1953. Sirenomelia sequence is also known as Mermaid Syndrome because it has two fused lower limbs that resemble a mermaid's tail, according to Greek mythology. Sirenomelia was previously thought to be an extreme case of Caudal Regression Syndrome (CRS); however, CRS is now thought to be caused by a lower spinal trunk ending anomaly (Frog-like). It includes a wide range of anomalies, such as partial or complete agenesis of the thoraco-lumbosacral spine and pelvic deformities. Sirenomelia may be caused by blastogenesis abnormalities affecting multiple midline primordial structures during the final stages of Gastrulation at the caudal eminence. This causes insufficient migration and differentiation of mesoderm, which is responsible for a variety of defects in the caudal region, and it also affects blood distribution to the fetus's caudal region. In the literature, approximately 300 cases have been reported, with a male: female ratio of 3:1. Typically, these infants do not survive more than 24 hours. Even after surgery, only a small percentage of patients survive. Aim: The aim of this study is Comprehensive study of Foetal cases of Sirenomelia Sequence with emphasis on prenatal diagnosis and Pathological features of sirenomelia. An ultrasound scan may be useful in detecting this anomaly early in pregnancy. In the face of a poor prognosis, earlier intrauterine diagnosis allows for less traumatic therapeutic abortion, minimising pregnancy termination at advanced gestation. Observation & Results: We found two cases of the Sirenomelia sequence. The first patient was a 25-year-old primigravida who was admitted to the hospital at 24 weeks of pregnancy. Prenatal ultrasound revealed severe Oligohydramnios and fusion of the lower limbs, indicating Sirenomelia; the pregnancy was terminated. The second case involved a 25-year-old primigravida who gave birth to a stillborn full-term baby whose gender could not be determined. The specimen was obtained from a private nursing home and was identified as Sirenomelia.Both cases had no relevant history of consanguineous marriage, tobacco smoking, or drug use, among other things. Both foetuses were taken to the anatomy dissection hall for a thorough autopsy. This paper reported the findings, along with a brief assessment of the literature, discussion of etiopathogenesis, and embryological correlation.