OP02.05: First trimester diagnosis of Sirenomelia

Abstract

Sirenomelia or Mermaid Syndrome is a rare lethal congenital anomaly with an incidence of 1 in 60000.We report a case diagnosed in first trimester using 2D US and colour Doppler. Omphalocele is seen in this case. This case emphasises the importance of looking for anomalies in first trimester. Diagnosis of Sirenomelia should be easier in first trimester as liquor is in good amount. A 25 years old G2P1 with previous LSCS with unremarkable medical and family history underwent sonography at 12 weeks. The live singleton fetus had single lower limb, omphalocele with herniation of liver and stomach. Lower limb showed two femur, single bone in mid segment and a single bifurcated foot. There was fixed extension and mobility at hip and knee was restricted. CD showed single umbilical artery and reversal of A wave in DV. Upper limb and spine were normal. After counselling about poor prognosis, patient lost to follow-up. The US diagnosis of sirinomelia is based on fusion of lower limbs and associated skeletal, spinal, renal, cardiac and abdominal wall anomalies. Single UA is seen in majority cases. Vascular steal and defective blastogenesis are two proposed theories of etiopathogenesis. Strong correlation is seen with diabetes. Male fetus are more affected. Early diagnosis in first trimester is easy due to good amount of amniotic fluid. In later gestation due to renal agenesis/dysgenesis there is severe oligohydramnios and diagnosis is relatively difficult. Also early diagnosis minimises trauma related to termination in later gestation. Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.