Monozygotic twinning and IVF/ICSI treatment: a report of 11 cases and review of literature

Abstract

Monozygotic twinning is a relatively rare event in in-vivo conception, being estimated to occur in 0.42% of all births. The underlying mechanism for monozygotic twin formation is the division of the embryo early in its development. Separation of cells may theoretically occur before or after inner cell mass formation. In this analysis we report 11 cases of monozygotic twins resulting from IVF or intracytoplasmic sperm injection (ICSI) treatment cycles performed between 1991 and 1998 at St James's University Hospital, Leeds, and Bourn Hall Clinic, Cambridge, UK. Six cases (55%) followed treatment with ICSI and seven cases (64%) were in women aged > or = 35 years. This article also reviews the scientific literature discussing information pertaining to frequency, aetiology and potential complications of the monozygotic twinning phenomenon. We conclude that patients at risk of monozygotic twinning are those aged >35 years of age and those who had artificial opening in the zona pellucida by application of micromanipulation techniques. Women undergoing assisted conception treatment, particularly those with these two risk factors, must be informed of the low but definite risk of monozygotic twinning when counselled regarding the number of embryos to be transferred and chances of multiple births.

Conjoined Twin in Triplet Pregnancy Occurring after ICSI, Cryopreservation, and Assisted Hatching

“…W i th in th e g en er a l p op ul at io n, mo no ch or i on ic monozygotic twins occur at the rate of 1 in 250 pregnancies ( approximately 0.4%) [3]. Several reports state that the overall rate of monozygotic twins in pregnancies involving assisted reproductive technology was 0.84 to 8.9% of all pregnancy [8][9][10][11][12][13][14][15]. Not only assisted reproductive technology, but also ovulation induction induced monozygotic twins [14].…”

Monozygotic Twin Pregnancy Associated with In Vitro Fertilization: Report and Revision of Three Cases Presented in a Clinic at 10,925 Feet Above Sea Level

“…Alikani et al (2003) found MZT in 2.4% of ICSI cycles in contrast to 1.6% in conventional IVF cycles. Abusheika et al (2000) reported that there is a higher incidence of MZT in the group of patients who were treated with ICSI (8.9%) when compared with conventional IVF (0.9%). Knopman et al (2010) found no significant difference in the incidence of MZT (2.0%) in their study group when ICSI was performed in 1410 cycles or IVF in 3039 cycles.…”

Incidence, Sex Ratio and Perinatal Outcomes of IVF and ICSI Monozygotic Twin Pregnancies Following either Cleavage or Blastocyst Stage Embryo Transfer

“…It has been theorised that techniques which manipulate the zona such as ICSI and assisted hatching may cause MZ twins to form due to the construction of an aberrant opening that allows spontaneous herniation of the blastocyst [19]. The zona is considered to act as a barrier that limits the degree in which the inner cell mass can divide and disruption of this barrier may contribute to the twinning process [20]. Knopman et al state that the delayed implantation time seen for blastocyst transfer may contribute to the increased risk whereas Carrillo-Vadillo et al [21] and Franasiak et al [17] declare that the prolonged culture exposure may cause a decline in the integrity of the zona pellucida leading to an increased chance of the embryo dividing due to the herniation of the blastomeres.…”