Prenatal diagnosis of Siamese twins after in vitro fertilization with preimplantation genetic diagnosis

Background: Siamese or undivided twins are one of the most formidable complications of monozygotic twins. This pathology has an extremely poor prognosis and, as a rule. Pregnancy in this case results in premature termination.

Case report: The paper describes a case of the earliest prenatal diagnosis of Siamese twins in the Russian Federation. The case can be considered unique, as the pregnancy has occurred in a woman having a history of unsuccessful pregnancy with a fetus with multiple malformations. It has been considered that this pathology cannot practically occur after in vitro fertilization (IVF); however, the review of foreign and Russian literature says the opposite and the probable cause may be an injury of the pellucid zone of the blastocyst. The pregnancy described in the paper resulted from IVF with preimplantation genetic diagnosis. This method of genetic diagnosis allows one to select genetically healthy embryos with a normal number of chromosomes, but it is incapable of excluding this pathology. In the Perinatal Cardiology Center, the patient at 8 weeks and 2 days’ gestation was diagnosed with congenital anomalies in embryos. Short tandem repeat (STR) markers were analyzed using the quantitative fluorescence polymerase chain reaction (QF PCR) assay that did not reveal aneuploidies of chromosomes 7, 13, 15, 16, 18, 21, 22, Х, and Y.

Conclusion: The earliest diagnosis of this pathology is as relevant as possible, since it allows a reduction of both the risks of postoperative complications and the patient’s psychological trauma associated with unviable pregnancy termination, since it happens during the first trimester even before the onset of the fetal period.