A preterm neonate born at 34 weeks’ gestation to a 22-year-old primigravida mother from a non-consanguineous marriage was delivered by emergency lower segment caesarean section for fetal distress and presented with congenital physical anomalies. The mother did not attend regular antenatal check-ups and did not undergo a targeted anomaly scan. There was no history of gestational diabetes mellitus, hypertension, fever, rash, radiation exposure, drug intake (including antiepileptics or retinoids), tobacco, or alcohol use during pregnancy. There was no family history of congenital anomalies. At birth, the neonate weighed 1.8 kg and had poor respiratory effort with APGAR scores of 3 and 4 at 1 and 5 minutes, respectively. On examination, there was complete fusion of both lower limbs forming a single tapering extremity with the absence of feet and toes Image 1a. External genitalia were absent and anal opening was not visible. A single umbilical artery was noted. Facial features were consistent with Potter’s facies, including large, low-set dysplastic ears, receding chin, narrow thorax, epicanthal folds, and small slit-like mouth. A sacral outpouching was present. Upper limbs appeared normal. Radiographic evaluation revealed the absence of the sacrum, a single fused femur, and a single fused tibia Image 1b, consistent with Type VI sirenomelia as per the Stocker and Heifetz classification. Chest radiograph showed diffuse bilateral opacification suggestive of pulmonary hypoplasia.Image 1: Clinical photograph (a) of the neonate showing characteristics fused lower limbs with a single foot, consistent with Sirenomelia. Potter’s facies is also appreciable with low-set ears and micrognathia. Plain radiograph (b) of the same neonate demonstrating fusion of the femora and tibiae, absent fibulae, and sacral agenesisDespite aggressive resuscitative measures, the baby developed progressive hypoxemia and could not be stabilized. The neonate succumbed within 1 hour of birth, likely due to severe pulmonary hypoplasia and multisystem congenital anomalies, which were incompatible with life. Further evaluation, including abdominal ultrasonography and echocardiography, could not be completed due to early demise. Autopsy was declined by the family. Sirenomelia (mermaid syndrome) is an extremely rare and usually fatal congenital anomaly characterized by the fusion of the lower limbs and severe visceral malformations, most commonly renal agenesis, anorectal atresia, sacral agenesis, pulmonary hypoplasia, and a single umbilical artery. Although previously considered an extreme form of caudal regression syndrome, it is now recognized as a distinct entity.1 The pathogenesis remains unclear, with two principal mechanisms proposed: the vitelline artery steal phenomenon causing hypoperfusion of the caudal embryo and defective blastogenesis during early embryonic development.2 Maternal diabetes and teratogenic exposures have been described as risk factors, although sporadic cases are common. First-trimester ultrasonography can detect the characteristic features and allow the early counseling due to the uniformly poor prognosis.3 Our case demonstrated typical findings, including fused lower limbs, sacral agenesis, single umbilical artery, and pulmonary hypoplasia, consistent with Type VI sirenomelia, which was incompatible with life. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Grotra et al. (Wed,) studied this question.