Monochorionic triplets following intracytoplasmic sperm injection: a report of two consecutive cases

Monochorionic triplet pregnancies are very rare. Here we report 2 cases of multiple pregnancies with monochorionic triplets following intracytoplasmic sperm injection (ICSI) and day 3 embryo transfer. The 2 women concomitantly underwent controlled ovarian hyperstimulation due to male factor infertility. Following oocyte retrieval, ICSI and assisted hatching (AH) were performed, and the 2 women conceived consecutively. One patient had a quadruplet pregnancy, which included monochorionic triplets, while the other had monochorionic triplets. Selective embryo reduction by intracardiac KCl injection targeted at 2 of the triplets was performed on the patient with the quadruplet pregnancy, but the third triplet also died. The gestation continued as a singleton pregnancy, and the patient gave birth to a healthy female baby at 38 weeks. The other patient gave birth to 3 healthy female babies at 34 weeks. Possible etiologic factors for the formation of monozygotic splitting among women undergoing assisted reproduction treatment are discussed.