Sirenomelia at twin pregnancy: Case Report

Objective

Sirenomelia is a rare congenital anomaly (1/600.000-1.000.000) evaluated in the major form of caudal regression syndrome. It is characterized by a variety of anomalies. Sirenomelia is mostly fatal. Here we aimed to present a case with sirenomelia which diagnosed in the 2nd trimester in twin pregnancy.

Case 

32-year-old woman,gravida 3, para 2, was referred to our outpatient clinic at the gestational age of 32 weeks and 5 days with fetal anomaly in twin pregnancy. She had no history of drug or alcohol abuse and no family history of fetal malformations. Ultrasound examination confirmed of 32 weeks and 5 days diamniotic, viable fetuses. The measurements of the first fetus were consistent with 33 weeks of pregnancy. The measurements of the second fetus were consistent with 32 weeks of pregnancy. In the second fetus severe oligo-hydramnios, fused lower extremities and a single umbilical artery were detected at ultrasonographic examination. Kidneys were not identified by ultrasonoraphic examination and ultrasonoraphic examination showed absent bladder. At 37 weaks of gestation the patient delivered first baby weighing 3000 gr, 48 cm and second baby weighing 2000 gr, 38 cm with elective cesarian section. At the first baby’s apgar scores were 9, 10 at one and five minutes and at the second baby’s apgar scores were 6, 8 at one and five minutes. On the physical examination, second baby’s lower extremities were fused. The external genitalia had not developed except for a small bud. The anus was not open, it had a single umbilical artery. At the sixth hour of delivery the baby was accepted as exitus.Postnatal ultrasound revealed multicystic dysplastic horseshoe kidneys and absence of the bladder. Cytogenetic analysis revealed a normal male fetus (46, XY).

Discussion

Sirenomelia is a rare congenital anomaly. Diagnosis of sirenomelia at second trimester can be difficult because of oligo-hydramnios due to renal agenesis. During the first trimester the amniotic fluid volume is usually normal, unrelated to the fetal urine production. Therefore, anatomic survey of the fetus during first trimester or early second trimester can provide early prenatal diagnosis. An early diagnosis of this lethal condition is important in order to allow prenatal counseling for possible pregnancy termination.

Keywords

Sirenomelia, congenital anomalies, oligohydramnios