- Email: [email protected]
Conjoined twins after intracytoplasmic sperm injection and transfer of day-3 embryos
CASE REPORT Conjoined twins after intracytoplasmic sperm injection and transfer of day-3 embryos Ramazan Mercan, M.D., Ozgur Oktem, M.D., Zeki Salar, M.D., Alp Nuhoglu, M.D., Basak Balaban, M.Sc., and Bulent Urman, M.D. Assisted Reproduction Unit, Women’s Health Center, VKV American Hospital, Istanbul, Turkey
Objective: To report a case of conjoined twins conceived through assisted reproduction after intracytoplasmic sperm injection (ICSI) and the transfer of three eight-cell embryos on day 3. Design: Case report. Setting: Assisted reproduction unit of a private hospital. Patient(s): A 32-year-old patient underwent ICSI and received three embryos. Intervention(s): Ovarian stimulation and ICSI. Main Outcome Measure(s): Images of the embryos and ultrasound images of the fetuses. Result(s): One embryo measuring 7 weeks, relatively big in size and bizarre in appearance with one heartbeat, was detected on transvaginal ultrasound at 6 weeks, 4 days of pregnancy. Two weeks later, another ultrasound was performed; two fetuses with a common heart were observed. In 10th week of pregnancy, two fetuses with two hearts and an attached thorax were observed. A diagnosis of thoracopagus was made, and the pregnancy was terminated. Conclusion(s): Conjoined twins conceived through assisted reproduction are extremely rare. This case, which occurred after transfer of cleavage-stage embryos, suggests that ovulation induction, ICSI, and assisted hatching may also play roles in addition to other factors commonly proposed to be responsible for conjoined twining, such as in vitro culture condition, culture time, and blastocyst-stage transfer. (Fertil Steril 2011;96:e111–4. 2011 by American Society for Reproductive Medicine.) Key Words: Conjoined twins, assisted reproduction, intracytoplasmic sperm injection, IVF
Assisted reproductive technologies (ART) are associated with an increase in the incidence of both heterozygotic and monozygotic multifetal pregnancies (MZT). Monozygotic twinning occurs in 0.40% to 0.45% of all births and in 2.2% after single-embryo transfer (1, 2). Conjoined twins constitute 1% of monozygotic twins, and they occur in 1 per 100,000 to 200,000 spontaneous pregnancies (3). It has been reported that the incidence of monochorionic pregnancies increases by eight times in ART cycles (4). Several factors have been proposed in the etiology of monozygotic pregnancies including ovulation induction (5), intracytoplasmic sperm injection (ICSI) (6), blastocyst-stage transfer (7), culture conditions (8), assisted hatching (9), and the experience of the embryologist (10). Conjoined twins (11) are considered a variant of monozygotic twinning. Two mechanisms have been proposed in the etiology of conjoined twins. Fission theory proposes the incomplete separation of embryonic discs at around 13 to 15 days after fertilization at the end of the twinning spectrum (12). Fusion theory postulates that
Received December 6, 2010; revised May 31, 2011; accepted June 1, 2011; published online July 1, 2011. R.M. has nothing to disclose. O.O. has nothing to disclose. Z.S. has nothing to disclose. A.N. has nothing to disclose. B.B. has nothing to disclose. B.U. has nothing to disclose. Reprint requests: Ramazan Mercan, M.D., Vehbi Koc Foundation American Hospital, Women’s Health Center, Assisted Reproduction Unit, Guzelbahce sokak no. 20, 34365 Nisantasi, Istanbul, Turkey (E-mail: [email protected]).
0015-0282/$36.00 doi:10.1016/j.fertnstert.2011.06.002
secondary fusion occurs between two embryos that were initially separated (13). The prognosis depends on the type of intertwin connection and the associated malformations. In this report, we present a case of conjoined twins in a twin pregnancy after ICSI and transfer of three eight-cell embryos on day 3.
CASE REPORT A 32-year-old nulliparous woman presented with 4 years of primary infertility. The couple’s infertility work-up was unremarkable except for oligomenorrhea. She had several cycles of ovulation induction with clomiphene citrate and intrauterine insemination followed by one fresh IVF cycle and one frozen embryo transfer cycle without success. In a second fresh IVF cycle using recombinant follicle-stimulating hormone and a long protocol, 12 oocytes were harvested; and nine of them were mature, and ICSI was performed 2 hours after oocyte pick up. Three good-quality, eight-cell embryos were transferred on the third day (Fig. 1). Vaginal progesterone gel was administered for luteal support beginning on the day of oocyte retrieval. The b-human chorionic gonadotropin (b-hCG) level was 309 mIU/mL and 773 mIU/mL at 12 and 14 days after embryo transfer, respectively. Transvaginal ultrasound was performed at week 6, day 4 of pregnancy, and one embryo measuring 7 weeks was observed, which was relatively big in size and bizarre in appearance with a single heartbeat. Repeat ultrasound 2 weeks later revealed two fetuses with a common heart. In the 10th week of pregnancy, two fetuses with two hearts, attached at the thorax, were observed,
Fertility and Sterility Vol. 96, No. 2, August 2011 Copyright ª2011 American Society for Reproductive Medicine, Published by Elsevier Inc.
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FIGURE 1 The images of eight-cell embryos transferred.
Mercan. Conjoined twins after IVF-ICSI. Fertil Steril 2011.
and a diagnosis of thoracopagus was made (Fig. 2). After a consultation with the pediatric surgeon, the family elected termination of the pregnancy.
DISCUSSION Monozygotic twinning after IVF was first reported in 1984 (14), and since that time several studies have demonstrated an increased occurrence of monozygotic twins associated with ART procedures (1). According to the first and most extended theory, monozygosity is caused by a breach in the integrity of the zona pellucida, herniation of the blastomeres, and splitting of the embryo (9). In this scenario, it is expected that ICSI and assisted hatching should increase the incidence of monozygotic twinning. Indeed, a higher MZT rate has been reported after ICSI cycles compared with IVF treatment (6). Assisted hatching also has been associated with MZT (9). However, recent studies failed to confirm an association between ICSI and/or assisted hatching and monozygosity (15, 16). Although ovulation induction itself has also been proposed in the etiology of MZT, the mechanism is unknown (5).
Previous studies have shown that the incidence of monozygotic twinning is increased after blastocyst transfer compared with cleavage-stage embryos (7, 10, 15). In 2006, the American Society for Reproductive Medicine Practice Committee noted that, based on the available literature, blastocyst transfer ‘‘results in an increased incidence of MZT varying between 2.7% and 13.2%,’’ and thus MZT remains a major drawback to routine blastocyst transfer for all ART patients (17). In a recently published retrospective study, the incidence of MZTwas found to be 1.57% in the blastocyst-stage transfer group compared with 0 in the cleavage-stage transfer group, and the difference was statistically significant (18). In a recent meta-analysis Chang et al. (19) reviewed the published literature and found that the incidence of MZT is indeed increased in blastocyst-stage transfer compared with cleavage-stage cycles. They also found that with studies published after 2002 there was no increase in the incidence of MZT compared with cleavage-stage cycles (odds ratio 1.00; 95% confidence interval, 0.43–2.32). This meta-analysis included only two studies, and one of them had only a small number of patients. They concluded that separate patient-specific underlying factors rather than the ART technique
FIGURE 2 Ultrasonography images of conjoined twins as (A) conventional and (B) four dimensional.
Mercan. Conjoined twins after IVF-ICSI. Fertil Steril 2011.
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Conjoined twins after IVF-ICSI
Vol. 96, No. 2, August 2011
Mercan. Conjoined twins after IVF-ICSI. Fertil Steril 2011.
2 1 0 2 þ NA NA þ 11 w, 3 d 8w 9w 11 w 4 3 2 4 3 2 1 NA 38 34 30 22 8 9 10 11
1 2 1 1
0 1 0 0
Day 3 Day 5 Day 2 NA
Fresh Fresh Fresh NA
ICSI ICSI ICSI OI
þ ND ND NA
3 2 1 NA
0 1 0 NA þ þ 10 w 11 w, 3 d 10 w 2 4 3 3 4 2 36 37 20 5 6 7
0 2 ND
0 1 ND
Day 3 and 5 Fresh ND FET ND Fresh
IVF ICSI IVF
ND
1 3 2
1 1 þ NA 8 w, 4 d 28 w 3 2 2 1 3 2 ICSI ICSI Fresh Fresh ND ND 0 0 1 2 28 30 3 4
Note: Cases 1, 2, 3, 6, 8, and 11 were quadruplet or triplet pregnancy. Cases 7 and 9 were in two gestational sacs. Cases 4, 5, and 10 were single gestational sac. CS ¼ cesarean section; FET ¼ frozen-thawed embryo transfer; ICSI ¼ intracytoplasmic sperm injection; NA ¼ not applicable; ND ¼ not documented; NVD ¼ vaginal delivery; OI ¼ ovulation induction.
Allegra et al. (30) Hirata et al. (31) Poret at al. (32) Mendilcioglu and Simsek (33)
Shimizu et al. (27) Maymon et al. (28) Charles et al. (29)
Goldberg et al. (25) Fujimori et al. (26)
Boulot et al. (23) Skupski et al. (24)
NVD Ongoing in third trimester NVD (37 w) CS (30 w neonatal death) Termination (11 w) Elective CS (38 w) Premature delivery (21 w) Elective CS (38 w) NVD (39 w) Termination (11 w) CS (36 w) 1 1 þ þ 10 w 12 w 3 3 2 2 2 4 þ IVF IVF Fresh Fresh ND Day 3 0 2 ND ND 27 35 1 2
Study Result No. of No. of Gestational IVF Assisted embryos gestational No. of age at Elective No. of cycle Treatment hatching transferred sacs fetuses diagnosis termination fetuses Day of ET Case Age Gravity Parity
TABLE 1
The reported cases of conjoined twins occurring after assisted reproduction.
Fertility and Sterility
used could predispose particular patients to MZT. In contrast, in the study by Papanikolaou et al. (20) there were no cases of MZT in 73 blastocyst-stage pregnancies compared with 3.4% in the cleavagestage group. Also, in another recently published retrospective study, the incidence of MZT was found to be 1.8% in the blastocyst group and 2.6% in the cleavage-stage group in patients undergoing singleembryo transfer (2). Thus, the role of blastocyst transfer in the increased MZT rate is still in question. Another factor proposed to be associated with monozygosity is prolonged embryo culture (9, 10). Prolonged in vitro culture might harden the zona pellucida, contributing to the formation of MZT (8). On the contrary, other researchers argue that it is not prolonged culture time but in vitro culture conditions, such as high levels of glucose in the medium (8), responsible for the increased incidence of MZT. Steinman et al. (21) proposed that the long exposure time of a blastocyst to lower calcium levels in culture predisposes the blastocyst to inner cell mass division as the intracellular bonds are destabilized. Moayeri et al. (22) have described a decrease in the incidence of MZT with blastocysts over an 8-year period, which they attributed to the improvement of blastocyst culture. The decrease in MZT incidence also could be related to an increase in embryologists’ experience over the time (22). To our knowledge, 11 cases of conjoined twins have been reported in the literature: six cases with ICSI, one with assisted hatching, three with both ICSI and assisted hatching, and one with IVF (23–33) (Table 1). Almost all cases were associated with zona manipulation either with ICSI or assisted hatching. Seven of cases were reported as a part of a triplet pregnancy, but three of them had only conjoined twins. A case of conjoined twins was been reported after ovulation induction with only clomiphene citrate (33). We report a case of conjoined twins after a cleavagestage transfer. We perform 1,000 to 1,200 ICSI cycles per year, and we have observed our first case of conjoined twins, which suggests that in vitro culture condition, culture time, or blastocyst-stage transfer was not responsible in our case. In our case, ovulation induction, ICSI, and assisted hatching could be considered in the etiology. Although genetic factors have been suggested in the etiology of MZT (34), the family history in our case was unremarkable. Conjoined twins are classified by taking into account the most prominent site of connection. The most common varieties are thoracoomphalopagus (28%), thoracopagus (18.5%), and omphalopagus (10%) (35). The prognosis depends on the type and severity of the connection and the associated malformations, but usually it requires extensive surgery. The role of ultrasonography is not restricted to the diagnosis of the conjunction; it can also help in defining the prognosis of the conjoined twins by determining the degree of the union. Previous studies reported ultrasonographic diagnosis as early as the 8th week of pregnancy. In our case, we suspected an anomaly as early as 6 weeks, 4 days of pregnancy, and we confirmed the diagnosis at 8 weeks of pregnancy, comparable with the case reports of others. All reported cases have demonstrated that ultrasound diagnosis is possible in the first trimester of pregnancy. Although we confirmed the diagnosis week 8, the severity of connection was confirmed at week 10 of the pregnancy. Both fetuses had separate organs, but a long segment of thorax was attached. In conclusion, MZT and conjoined twins should be kept in mind in all ART cycles, irrespective of the possible etiologic factors, including the day of transfer, assisted hatching, culture conditions, the embryologist’s experience, and family history.
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REFERENCES 1. Aston KI, Peterson CM, Carrell DT. Monozygotic twinning associated with assisted reproductive technologies: a review. Reproduction 2008;136:377–86. 2. Papanikolaou EG, Fatemi H, Venetis C, Donoso P, Kolibianakis E, Tournaye H, et al. Monozygotic twinning is not increased after single blastocyst transfer compared with single cleavage-stage embryo transfer. Fertil Steril 2010;93:592–7. 3. Rees AE, Vujanic GM. Epidemic of conjoined twins in Cardiff. Br J Obstet Gynaecol 1993;100:701. 4. Wenstrom KD, Syrop CH, Hammitt DG, Van Voorhis BJ. Increased risk of monochorionic twinning associated with assisted reproduction. Fertil Steril 1993;60:510–4. 5. Derom C, Vlietinck R, Derom R, Van den Berghe H, Thiery M. Increased monozygotic twinning rate after ovulation induction. Lancet 1987;1:1236–8. 6. Tarlatzis BC, Qublan HS, Sanopoulou T, Zepiridis L, Grimbizis G, Bontis J. Increase in the monozygotic twinning rate after intracytoplasmic sperm injection and blastocyst stage embryo transfer. Fertil Steril 2002;77:196–8. 7. Behr B, Fisch JD, Racowsky C, Miller K, Pool TB, Milki AA. Blastocyst-ET and monozygotic twinning. J Assist Reprod Genet 2000;17:349–51. 8. Cassuto G, Chavrier M, Menezo Y. Culture conditions and not prolonged culture time are responsible for monozygotic twinning in human in vitro fertilization. Fertil Steril 2003;80:462–3. 9. Alikani M, Noyes N, Cohen J, Rosenwaks Z. Monozygotic twinning in the human is associated with the zona pellucida architecture. Hum Reprod 1994;9: 1318–21. 10. Milki AA, Jun SH, Hinckley MD, Behr B, Giudice LC, Westphal LM. Incidence of monozygotic twinning with blastocyst transfer compared to cleavage-stage transfer. Fertil Steril 2003;79:503–6. 11. Piccart-Gebhart MJ, Procter M, Leyland-Jones B, Goldhirsch A, Untch M, Smith I, et al. Trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer. N Engl J Med 2005;353:1659–72. 12. Volpes A, Sammartano F, Coffaro F, Mistretta V, Scaglione P, Allegra A. Number of good quality embryos on day 3 is predictive for both pregnancy and implantation rates in in vitro fertilization/intracytoplasmic sperm injection cycles. Fertil Steril 2004; 82:1330–6.
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13. Spencer R. Theoretical and analytical embryology of conjoined twins: part II: adjustments to union. Clin Anat 2000;13:97–120. 14. Yovich JL, Stanger JD, Grauaug A, Barter RA, Lunay G, Dawkins RL, et al. Monozygotic twins from in vitro fertilization. Fertil Steril 1984;41: 833–7. 15. Wright V, Schieve LA, Vahratian A, Reynolds MA. Monozygotic twinning associated with day 5 embryo transfer in pregnancies conceived after IVF. Hum Reprod 2004;19:1831–6. 16. Schachter M, Raziel A, Friedler S, Strassburger D, Bern O, Ron-El R. Monozygotic twinning after assisted reproductive techniques: a phenomenon independent of micromanipulation. Hum Reprod 2001;16: 1264–9. 17. Practice Committee of American Society for Reproductive Medicine. Blastocyst culture and transfer in clinical-assisted reproduction. Fertil Steril 2006;86: S89–92. 18. Sharara FI, Abdo G. Incidence of monozygotic twins in blastocyst and cleavage stage assisted reproductive technology cycles. Fertil Steril 2010;93:642–5. 19. Chang HJ, Lee JR, Jee BC, Suh CS, Kim SH. Impact of blastocyst transfer on offspring sex ratio and the monozygotic twinning rate: a systematic review and meta-analysis. Fertil Steril 2009;91:2381–90. 20. Papanikolaou EG, Camus M, Kolibianakis EM, Van Landuyt L, Van Steirteghem A, Devroey P. In vitro fertilization with single blastocyst-stage versus single cleavage-stage embryos. N Engl J Med 2006;354: 1139–46. 21. Steinman G. Mechanisms of twinning. II. Laterality and intercellular bonding in monozygotic twinning. J Reprod Med 2001;46:473–9. 22. Moayeri SE, Behr B, Lathi RB, Westphal LM, Milki AA. Risk of monozygotic twinning with blastocyst transfer decreases over time: an 8-year experience. Fertil Steril 2007;87:1028–32. 23. Boulot P, Deschamps F, Hedon B, Laffargue F, Viala JL. Conjoined twins associated with a normal singleton: very early diagnosis and successful selective termination. J Perinat Med 1992;20: 135–7. 24. Skupski DW, Streltzoff J, Hutson JM, Rosenwaks Z, Cohen J, Chervenak FA. Early diagnosis of conjoined
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twins in triplet pregnancy after in vitro fertilization and assisted hatching. J Ultrasound Med 1995;14: 611–5. Goldberg Y, Ben-Shlomo I, Weiner E, Shalev E. First trimester diagnosis of conjoined twins in a triplet pregnancy after IVF and ICSI: case report. Hum Reprod 2000;15:1413–5. Fujimori K, Shiroto T, Kuretake S, Gunji H, Sato A. An omphalopagus parasitic twin after intracytoplasmic sperm injection. Fertil Steril 2004;82:1430–2. Shimizu Y, Fukuda J, Sato W, Kumagai J, Hirano H, Tanaka T. First-trimester diagnosis of conjoined twins after in-vitro fertilization-embryo transfer (IVF-ET) at blastocyst stage. Ultrasound Obstet Gynecol 2004;24:208–9. Maymon R, Mendelovic S, Schachter M, Ron-El R, Weinraub Z, Herman A. Diagnosis of conjoined twins before 16 weeks’ gestation: the 4-year experience of one medical center. Prenat Diagn 2005;25:839–43. Charles A, Dickinson JE, Watson S, Phillips N, Yovich J. Diamniotic conjoined fetuses in a triplet pregnancy: an insight into embryonic topology. Pediatr Dev Pathol 2005;8:666–72. Allegra A, Monni G, Zoppi MA, Curcio P, Marino A, Volpes A. Conjoined twins in a trichorionic quadruplet pregnancy after intracytoplasmic sperm injection and quarter laser-assisted zona thinning. Fertil Steril 2007;87:189.e9–12. Hirata T, Osuga Y, Fujimoto A, Oishi H, Hiroi H, Fujiwara T, et al. Conjoined twins in a triplet pregnancy after intracytoplasmic sperm injection and blastocyst transfer: case report and review of the literature. Fertil Steril 2009;91:933.e9–12. Poret H, Blanchard M, Lemseffer M, Royere D, Guerif F. Conjoined twins after intracytoplasmic sperm injection and transfer of a single day 2 embryo: case report. Fertil Steril 2010;93:268.e7–9. Mendilcioglu I, Simsek M. Conjoined twins in a trichorionic quadruplet pregnancy after ovulation induction with clomiphene citrate. Fetal Diagn Ther 2008;24:51–4. Abusheikha N, Salha O, Sharma V, Brinsden P. Monozygotic twinning and IVF/ICSI treatment: a report of 11 cases and review of literature. Hum Reprod Update 2000;6:396–403. Kaufman MH. The embryology of conjoined twins. Childs Nerv Syst 2004;20:508–25.
Vol. 96, No. 2, August 2011
Objective: To report a case of conjoined twins conceived through assisted reproduction after intracytoplasmic sperm injection (ICSI) and the transfer of three eight-cell embryos on day 3. Design: Case report. Setting: Assisted reproduction unit of a private hospital. Patient(s): A 32-year-old patient underwent ICSI and received three embryos. Intervention(s): Ovarian stimulation and ICSI. Main Outcome Measure(s): Images of the embryos and ultrasound images of the fetuses. Result(s): One embryo measuring 7 weeks, relatively big in size and bizarre in appearance with one heartbeat, was detected on transvaginal ultrasound at 6 weeks, 4 days of pregnancy. Two weeks later, another ultrasound was performed; two fetuses with a common heart were observed. In 10th week of pregnancy, two fetuses with two hearts and an attached thorax were observed. A diagnosis of thoracopagus was made, and the pregnancy was terminated. Conclusion(s): Conjoined twins conceived through assisted reproduction are extremely rare. This case, which occurred after transfer of cleavage-stage embryos, suggests that ovulation induction, ICSI, and assisted hatching may also play roles in addition to other factors commonly proposed to be responsible for conjoined twining, such as in vitro culture condition, culture time, and blastocyst-stage transfer. (Fertil Steril 2011;96:e111–4. 2011 by American Society for Reproductive Medicine.) Key Words: Conjoined twins, assisted reproduction, intracytoplasmic sperm injection, IVF
Assisted reproductive technologies (ART) are associated with an increase in the incidence of both heterozygotic and monozygotic multifetal pregnancies (MZT). Monozygotic twinning occurs in 0.40% to 0.45% of all births and in 2.2% after single-embryo transfer (1, 2). Conjoined twins constitute 1% of monozygotic twins, and they occur in 1 per 100,000 to 200,000 spontaneous pregnancies (3). It has been reported that the incidence of monochorionic pregnancies increases by eight times in ART cycles (4). Several factors have been proposed in the etiology of monozygotic pregnancies including ovulation induction (5), intracytoplasmic sperm injection (ICSI) (6), blastocyst-stage transfer (7), culture conditions (8), assisted hatching (9), and the experience of the embryologist (10). Conjoined twins (11) are considered a variant of monozygotic twinning. Two mechanisms have been proposed in the etiology of conjoined twins. Fission theory proposes the incomplete separation of embryonic discs at around 13 to 15 days after fertilization at the end of the twinning spectrum (12). Fusion theory postulates that
Received December 6, 2010; revised May 31, 2011; accepted June 1, 2011; published online July 1, 2011. R.M. has nothing to disclose. O.O. has nothing to disclose. Z.S. has nothing to disclose. A.N. has nothing to disclose. B.B. has nothing to disclose. B.U. has nothing to disclose. Reprint requests: Ramazan Mercan, M.D., Vehbi Koc Foundation American Hospital, Women’s Health Center, Assisted Reproduction Unit, Guzelbahce sokak no. 20, 34365 Nisantasi, Istanbul, Turkey (E-mail: [email protected]).
0015-0282/$36.00 doi:10.1016/j.fertnstert.2011.06.002
secondary fusion occurs between two embryos that were initially separated (13). The prognosis depends on the type of intertwin connection and the associated malformations. In this report, we present a case of conjoined twins in a twin pregnancy after ICSI and transfer of three eight-cell embryos on day 3.
CASE REPORT A 32-year-old nulliparous woman presented with 4 years of primary infertility. The couple’s infertility work-up was unremarkable except for oligomenorrhea. She had several cycles of ovulation induction with clomiphene citrate and intrauterine insemination followed by one fresh IVF cycle and one frozen embryo transfer cycle without success. In a second fresh IVF cycle using recombinant follicle-stimulating hormone and a long protocol, 12 oocytes were harvested; and nine of them were mature, and ICSI was performed 2 hours after oocyte pick up. Three good-quality, eight-cell embryos were transferred on the third day (Fig. 1). Vaginal progesterone gel was administered for luteal support beginning on the day of oocyte retrieval. The b-human chorionic gonadotropin (b-hCG) level was 309 mIU/mL and 773 mIU/mL at 12 and 14 days after embryo transfer, respectively. Transvaginal ultrasound was performed at week 6, day 4 of pregnancy, and one embryo measuring 7 weeks was observed, which was relatively big in size and bizarre in appearance with a single heartbeat. Repeat ultrasound 2 weeks later revealed two fetuses with a common heart. In the 10th week of pregnancy, two fetuses with two hearts, attached at the thorax, were observed,
Fertility and Sterility Vol. 96, No. 2, August 2011 Copyright ª2011 American Society for Reproductive Medicine, Published by Elsevier Inc.
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FIGURE 1 The images of eight-cell embryos transferred.
Mercan. Conjoined twins after IVF-ICSI. Fertil Steril 2011.
and a diagnosis of thoracopagus was made (Fig. 2). After a consultation with the pediatric surgeon, the family elected termination of the pregnancy.
DISCUSSION Monozygotic twinning after IVF was first reported in 1984 (14), and since that time several studies have demonstrated an increased occurrence of monozygotic twins associated with ART procedures (1). According to the first and most extended theory, monozygosity is caused by a breach in the integrity of the zona pellucida, herniation of the blastomeres, and splitting of the embryo (9). In this scenario, it is expected that ICSI and assisted hatching should increase the incidence of monozygotic twinning. Indeed, a higher MZT rate has been reported after ICSI cycles compared with IVF treatment (6). Assisted hatching also has been associated with MZT (9). However, recent studies failed to confirm an association between ICSI and/or assisted hatching and monozygosity (15, 16). Although ovulation induction itself has also been proposed in the etiology of MZT, the mechanism is unknown (5).
Previous studies have shown that the incidence of monozygotic twinning is increased after blastocyst transfer compared with cleavage-stage embryos (7, 10, 15). In 2006, the American Society for Reproductive Medicine Practice Committee noted that, based on the available literature, blastocyst transfer ‘‘results in an increased incidence of MZT varying between 2.7% and 13.2%,’’ and thus MZT remains a major drawback to routine blastocyst transfer for all ART patients (17). In a recently published retrospective study, the incidence of MZTwas found to be 1.57% in the blastocyst-stage transfer group compared with 0 in the cleavage-stage transfer group, and the difference was statistically significant (18). In a recent meta-analysis Chang et al. (19) reviewed the published literature and found that the incidence of MZT is indeed increased in blastocyst-stage transfer compared with cleavage-stage cycles. They also found that with studies published after 2002 there was no increase in the incidence of MZT compared with cleavage-stage cycles (odds ratio 1.00; 95% confidence interval, 0.43–2.32). This meta-analysis included only two studies, and one of them had only a small number of patients. They concluded that separate patient-specific underlying factors rather than the ART technique
FIGURE 2 Ultrasonography images of conjoined twins as (A) conventional and (B) four dimensional.
Mercan. Conjoined twins after IVF-ICSI. Fertil Steril 2011.
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Conjoined twins after IVF-ICSI
Vol. 96, No. 2, August 2011
Mercan. Conjoined twins after IVF-ICSI. Fertil Steril 2011.
2 1 0 2 þ NA NA þ 11 w, 3 d 8w 9w 11 w 4 3 2 4 3 2 1 NA 38 34 30 22 8 9 10 11
1 2 1 1
0 1 0 0
Day 3 Day 5 Day 2 NA
Fresh Fresh Fresh NA
ICSI ICSI ICSI OI
þ ND ND NA
3 2 1 NA
0 1 0 NA þ þ 10 w 11 w, 3 d 10 w 2 4 3 3 4 2 36 37 20 5 6 7
0 2 ND
0 1 ND
Day 3 and 5 Fresh ND FET ND Fresh
IVF ICSI IVF
ND
1 3 2
1 1 þ NA 8 w, 4 d 28 w 3 2 2 1 3 2 ICSI ICSI Fresh Fresh ND ND 0 0 1 2 28 30 3 4
Note: Cases 1, 2, 3, 6, 8, and 11 were quadruplet or triplet pregnancy. Cases 7 and 9 were in two gestational sacs. Cases 4, 5, and 10 were single gestational sac. CS ¼ cesarean section; FET ¼ frozen-thawed embryo transfer; ICSI ¼ intracytoplasmic sperm injection; NA ¼ not applicable; ND ¼ not documented; NVD ¼ vaginal delivery; OI ¼ ovulation induction.
Allegra et al. (30) Hirata et al. (31) Poret at al. (32) Mendilcioglu and Simsek (33)
Shimizu et al. (27) Maymon et al. (28) Charles et al. (29)
Goldberg et al. (25) Fujimori et al. (26)
Boulot et al. (23) Skupski et al. (24)
NVD Ongoing in third trimester NVD (37 w) CS (30 w neonatal death) Termination (11 w) Elective CS (38 w) Premature delivery (21 w) Elective CS (38 w) NVD (39 w) Termination (11 w) CS (36 w) 1 1 þ þ 10 w 12 w 3 3 2 2 2 4 þ IVF IVF Fresh Fresh ND Day 3 0 2 ND ND 27 35 1 2
Study Result No. of No. of Gestational IVF Assisted embryos gestational No. of age at Elective No. of cycle Treatment hatching transferred sacs fetuses diagnosis termination fetuses Day of ET Case Age Gravity Parity
TABLE 1
The reported cases of conjoined twins occurring after assisted reproduction.
Fertility and Sterility
used could predispose particular patients to MZT. In contrast, in the study by Papanikolaou et al. (20) there were no cases of MZT in 73 blastocyst-stage pregnancies compared with 3.4% in the cleavagestage group. Also, in another recently published retrospective study, the incidence of MZT was found to be 1.8% in the blastocyst group and 2.6% in the cleavage-stage group in patients undergoing singleembryo transfer (2). Thus, the role of blastocyst transfer in the increased MZT rate is still in question. Another factor proposed to be associated with monozygosity is prolonged embryo culture (9, 10). Prolonged in vitro culture might harden the zona pellucida, contributing to the formation of MZT (8). On the contrary, other researchers argue that it is not prolonged culture time but in vitro culture conditions, such as high levels of glucose in the medium (8), responsible for the increased incidence of MZT. Steinman et al. (21) proposed that the long exposure time of a blastocyst to lower calcium levels in culture predisposes the blastocyst to inner cell mass division as the intracellular bonds are destabilized. Moayeri et al. (22) have described a decrease in the incidence of MZT with blastocysts over an 8-year period, which they attributed to the improvement of blastocyst culture. The decrease in MZT incidence also could be related to an increase in embryologists’ experience over the time (22). To our knowledge, 11 cases of conjoined twins have been reported in the literature: six cases with ICSI, one with assisted hatching, three with both ICSI and assisted hatching, and one with IVF (23–33) (Table 1). Almost all cases were associated with zona manipulation either with ICSI or assisted hatching. Seven of cases were reported as a part of a triplet pregnancy, but three of them had only conjoined twins. A case of conjoined twins was been reported after ovulation induction with only clomiphene citrate (33). We report a case of conjoined twins after a cleavagestage transfer. We perform 1,000 to 1,200 ICSI cycles per year, and we have observed our first case of conjoined twins, which suggests that in vitro culture condition, culture time, or blastocyst-stage transfer was not responsible in our case. In our case, ovulation induction, ICSI, and assisted hatching could be considered in the etiology. Although genetic factors have been suggested in the etiology of MZT (34), the family history in our case was unremarkable. Conjoined twins are classified by taking into account the most prominent site of connection. The most common varieties are thoracoomphalopagus (28%), thoracopagus (18.5%), and omphalopagus (10%) (35). The prognosis depends on the type and severity of the connection and the associated malformations, but usually it requires extensive surgery. The role of ultrasonography is not restricted to the diagnosis of the conjunction; it can also help in defining the prognosis of the conjoined twins by determining the degree of the union. Previous studies reported ultrasonographic diagnosis as early as the 8th week of pregnancy. In our case, we suspected an anomaly as early as 6 weeks, 4 days of pregnancy, and we confirmed the diagnosis at 8 weeks of pregnancy, comparable with the case reports of others. All reported cases have demonstrated that ultrasound diagnosis is possible in the first trimester of pregnancy. Although we confirmed the diagnosis week 8, the severity of connection was confirmed at week 10 of the pregnancy. Both fetuses had separate organs, but a long segment of thorax was attached. In conclusion, MZT and conjoined twins should be kept in mind in all ART cycles, irrespective of the possible etiologic factors, including the day of transfer, assisted hatching, culture conditions, the embryologist’s experience, and family history.
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