Objective: To describe the occurrence and management of conjoined twins (CTs) in a trichorionic quadruplet pregnancy after the transfer of three embryos obtained by intracytoplasmic sperm injection (ICSI) that had undergone assisted zona hatching (AZH) using a noncontact laser.
Design: Case report.
Setting: Private and public IVF centers.
Patient(s): A 38-year-old nulliparous woman.
Intervention(s): IVF, diagnosis by two-dimensional, three-dimensional, and four-dimensional ultrasound, selective termination at 12 weeks gestation.
Main outcome measure(s): Clinical follow-up and delivery.
Result(s): After diagnosis, counselling, and selective termination, the subsequent prenatal course was uneventful, and two healthy boys were delivered by elective cesarean section at 38 weeks gestation.
Conclusion(s): Monozygotic twinning (MZT) and CTs could complicate multifetal pregnancies obtained by assisted reproduction techniques. The relationship between CTs, IVF, and AZH should be better studied to fully understand the mechanisms that lead to MZT (with the possible role of AZH) and CTs in MZT, in particular. Three-dimensional and four-dimensional ultrasound improve prenatal assessment of the condition. Selective embryo reduction is a safe procedure for the management of these pregnancies.