Human Reproduction, Vol. 15, No. 6, 1413-1415,
June 2000
© 2000 European Society of Human Reproduction and Embryology
First trimester diagnosis of conjoined twins in a triplet pregnancy after IVF and ICSI: Case report
Department of Obstetrics and Gynecology, HaEmek Medical Center, Afula and the Rappaport School of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
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Abstract |
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A case of conjoined twins in a triplet pregnancy after in-vitro fertilization and intracytoplasmic sperm injection is described. The diagnosis was made by high-resolution vaginal sonography, as early as the eighth week of gestation. The third fetus, of different chorionicity, was normal. Selective termination was successfully done at 12 weeks. The possible association between assisted reproduction and conjoined twinning is discussed. The importance of expert early vaginal sonography of pregnancy resulting from assisted reproduction technology is emphasized.
Key words: assisted reproduction/chorionicity/fetal malformation/twins conjoined/twins monozygotic
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Introduction |
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Assisted reproductive techniques are widely used all over the world, and have raised the occurrence of multifetal pregnancies. Most of these pregnancies are multizygotic arising from separate ova, but there is also a definite rise in the rate of monochorionic twinning. Intracytoplasmic sperm injection (ICSI) has lately become the most common technique used in most assisted reproductive units, solving the majority of problems of severe male infertility. Concerns had been raised over the possible increase in the occurrence of birth defects associated with micromanipulation, and with monochorionic twinning, one of which is conjoined twins (Cohen et al., 1990
). Conjoined twinning is a rare condition, reported at a rate of 1 in 2800 to 1 in 200 000 pregnancies (Rees et al., 1993). It is even more rare in the situation of triplet pregnancy (Koontz et al., 1985; Shalev and Zuckerman, 1987; Apuzzio et al., 1988; Boulot et al., 1992). Conjoined twins were previously reported IVF and assisted hatching (Skupski et al., 1995) but not after ICSI. Here we report a case of conjoined twins in a triplet pregnancy conceived after ICSI. The diagnosis was made at the eighth week of gestation by early transvaginal sonography. The early diagnosis allowed selective termination of the conjoined twins. This case raises again the need for early and expert sonographic evaluation of pregnancies achieved after ICSI, as this enables accurate diagnosis and adequate counselling.
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Case report |
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A gravida 1, para 0, 28 year old patient was referred for regular sonographic evaluation at 37 days after the transfer of three embryos, and positive ß-human chorionic gonadotrophin (HCG) in the blood test. The embryos were the result of ICSI procedure. The first sonographic examination revealed two gestational sacs with positive heartbeats but one of the embryos seemed bigger than expected. A week later (44 days post-embryo transfer), repeated scan showed clearly one sac with an apparently normal living fetus, with crown–rump length (CRL) corresponding to 8 weeks and 4 days. In the other sac, two embryos were seen, joined at the thorax and abdomen, with a common heart (Figure 1
). The finding of a common heart was clearly demonstrated using colour Doppler.
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Fetal size (CRL) was adequate for gestational age in both concepti. Different chorionicity of the two gestational sacs was diagnosed based on the `lambda sign' (Dalton and Dudly, 1989
). In view of the expected poor outcome for conjoined twins and different chorionicity, the couple was offered and accepted selective termination of the conjoined twins. The operation was deferred to the 12th week of gestation according to the couple's request. The couple signed an informed consent form.
At the 12th week of gestation, selective termination was done by a transabdominal approach. A 22-gauge needle was directed into the sac of the conjoined twins, and intracardiac injection of potassium chloride was performed, as described previously (Evans et al., 1990). Immediate cessation of heartbeat of the conjoined twins was seen, with normal heartbeat of the single fetus. The pregnancy is ongoing, with an apparently normal singleton fetus of 26 weeks gestation.
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Discussion |
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Most of the multifetal pregnancies after assisted reproduction are multichorionic. However, from several reports, the rate of monochorionic pregnancies, most of them twins, was raised eight-fold above the background rate (Wenstrom et al., 1993
). After assisted reproduction, early serial sonographic evaluation of pregnancies is usually performed. This is done to detect cases of multiple fetuses, non-viable or ectopic pregnancies. In most cases of multifetal pregnancies, chorionicity can be diagnosed with appreciable accuracy, when done early (Dalton and Dudly, 1989; Wood et al., 1996).This in turn is most important in later obstetric care of these pregnancies (Fisk and Bryan, 1993).
It has been argued that delayed ovum transport, delayed implantation and the manipulation of the egg might raise the rate of monochorionic and conjoined twins (Edwards et al., 1986; Cohen et al., 1990). According to this assertion, both mono-amniotic and diamniotic monochorionic twins are created during hatching, when embryos may be trapped in a gap in the zona pellucida. The twins can continue to develop when the inner cell mass splits in half. This may happen either when the trophoblast splits, or when it remains intact. The latter possibility may lead to monochorionic mono-amniotic twinning, with a possibility of conjoined twins. The formation of conjoined twins probably indicates incomplete separation of the inner cell mass.
Another possibility of conjoined formation is incomplete cleavage of the embryonic disk at 13–15 days after conception. Yet another possibility is formation of heteropagus, that appears like conjoined twins but results from an incomplete fusion of two embryos, which could even be dizygotic (Logrono et al., 1997). Conjoined twins had been reported after IVF and assisted hatching (Skupski et al., 1995), but not with ICSI.
Early diagnosis of conjoined twins was previously reported, but not before the 10th week of gestation (Koontz et al., 1985; Shalev and Zuckerman, 1987; Boulot et al., 1992, Skupski et al., 1995; Hubinot et al., 1997). On careful transvaginal sonography and serial scanning there appears to be an inability to separate between the anatomical parts of the fetuses. Use of colour Doppler can help in making the diagnosis, especially in revealing the exact nature of the blood circulation, as was done in the current case.
The early diagnosis of conjoined twins associated with a normal singleton permits the option of selective termination of the abnormal fetuses, and this can be offered to the women if there is certainty in the diagnosis of chorionicity. Selective termination can only be offered if the fetuses are of different chorionicity. Clinical experience with second trimester selective termination shows that the earlier the procedure is done, the lower the loss rates are. In addition, the gestational age at delivery is greater with early procedure as compared with later procedures (Berkowitz et al., 1988; Wapner et al., 1990).
In conclusion, we report the first case of conjoined twins in a triplet pregnancy achieved after IVF and ICSI. This case was diagnosed at the eighth week of gestation, earlier than other cases reported before, emphasizing again the importance of early expert sonographic evaluation of pregnancies conceived after assisted reproduction. In this case diagnosis of different chorionicity permitted selective reduction of the abnormal pregnancy, which was done successfully at the 12th week. The pregnancy is ongoing with an apparently normal fetus of 26 weeks.
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The patient went through an uneventful pregnancy and delivered vaginally a healthy male baby on the 37th week.
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Notes |
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1 To whom correspondence should be addressed at: Department of Obstetrics and Gynecology, HaEmek Medical Centre, Afula 18101, Israel. E-mail: shaleve{at}tx.technion.ac.il
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References |
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Submitted on November 22, 1999; accepted on February 28, 2000.
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