University of Bristol Divisions of 1 Obstetrics and Gynaecology, St Michaels Hospital, Bristol BS2 8EG, 2 Child Health, Southmead Hospital, Bristol BS10 5NB and 3 The Cotswold Centre, Southmead Hospital, Bristol BS10 5NB, UK
4 To whom correspondence should be addressed at: Level D, University of Bristol Division of Obstetrics and Gynaecology, St Michaels Hospital, Bristol BS2 8EG, UK. Email: d.j.cahill{at}bris.ac.uk
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Abstract |
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Key words: chorionicity/quadruplet pregnancy/zygosity
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Introduction |
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Case report |
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Ovarian stimulation was undertaken using down-regulation with a long protocol luteal phase GnRH agonist (Buserelin; Shire, Basingstoke, Hants, UK), gonadotrophin stimulation, and, following menstruation, a recombinant FSH product (Gonal F; Serono, Feltham, Middlesex, UK). Final oocyte maturation was undertaken with hCG (Profasi; Serono). Two days later, a vaginal ultrasound-guided oocyte collection was undertaken. At oocyte recovery, of the five mature follicles (17 mm) on the right, oocytes were collected from two follicles. From the six mature follicles on the left, six oocytes were collected. The embryologists evaluated all eight oocytes as being mature based on the appearance of the surrounding cumulus oophorus and all were inseminated. After 19 h, they were evaluated. Of the eight oocytes, five showed pronucleate development. The remaining three were still unfertilized. These were discarded. The five pronucleate oocytes were maintained in culture. They were further evaluated the following day, 44 h after oocyte recovery. Of the five, two had developed to the 4-cell stage, two to the 2-cell stage, and one was a 6-cell embryo. The two 4-cell embryos were considered most appropriate for embryo transfer and this was undertaken later that day at 49 h post-oocyte recovery. Embryo transfer was undertaken without difficulty using a one piece Frydman catheter (Rochford Medical, Oxford, UK). The remaining three embryos were further evaluated on day 3 at 69 h. As none of them had achieved the criteria for cryopreservation, they were all discarded.
Three weeks later, the patient reported a positive pregnancy test and at 5 weeks and 2 days from oocyte recovery, an ultrasound was performed. At this initial ultrasound scan, a multiple pregnancy was diagnosed and two intrauterine sacs, with fetuses each measuring 11 mm were seen (appropriate for the equivalent menstrual age). A normal heartbeat was noted in both fetuses. One week later, she presented to the local early pregnancy clinic with vaginal bleeding. Here, the pregnancy was noted to be ongoing, but four intrauterine gestational sacs were noted, each with a fetus, showing a normal heart rate and each appropriately grown for the gestational age. Not surprisingly, the woman was shocked and surprised by this news and she was referred back to the treating IVF unit for further discussion and counselling. This counselling took the form of an outline of the risks of high order multiple pregnancy, the possible treatment options open to her at that time including selective reduction, the supervision and management of the pregnancy should she choose to continue and the likely options for, and the gestational age at which, delivery might occur.
At 11 weeks, she was seen in the fetal medicine unit when the crownrump length measurements were 30, 25, 24 and 35 mm respectively. The nuchal translucency measurement were 0.8, 0.8, 0.7 and 1 mm respectively and so were all low risk. Chorionicity was examined by looking at the intersac membranes and they appeared to be quatro-chorionic. After extensive counselling about the risks of a quadruplet pregnancy, given the encouraging nuchal translucency and chorionicity results, the woman and her husband chose to continue with the pregnancy without reduction.
At 34 weeks gestation the woman had a transvaginal scan of her cervix which showed a shortened cervical length and a dilated internal cervical os. Delivery was advised and undertaken by semi-elective Caesarean section the following day. At this, she was delivered of four healthy infants, three boys and one girl. Their weights were 2052, 2258, 1144 and 1660 g respectively. The neonatal period was complicated by mild to moderate respiratory distress syndrome in all babies, moderate in the third boy and the girl. In addition, she subsequently required mechanical ventilation because of necrotizing enterocolitis (which did not require surgery) and a patent ductus arteriosus (which did require surgical ligation). In total, they stayed for 154 days in the neonatal intensive care unit.
Because of the clear indication that these quadruplets did not arise from a monozygotic twinning of the embryos replaced, blood was taken from the parents and from the three boys for zygosity testing. Using 11 different probes, examination of parental allele combinations on chromosomes 4, 7 and 19 showed that the three boys originated from independent zygotes. Permission was sought and obtained from the couple to publish this report.
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Discussion |
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The presence of two fetuses and sacs at the first scan and four at the next deserves some comment. The first scan was undertaken 5 weeks and 2 days post-oocyte recovery. Not all the sacs were seen but all were sufficiently grown a week later to be seen. At 11 weeks, the crownrump lengths were in two distinct groups, but the possibility of spontaneous conception was still not seriously considered. One explanation for the difference in size was that the two putative fetuses which had undergone monozygotic twinning were of different sizes. In retrospect, it is easier to see that the difference in size was related to the difference of several days gestation between the two sets of twins, one from spontaneous and one from assisted conception.
Despite the intentions of the IVF unit to provide this couple with a minimal risk of a multiple pregnancy, they ended up with a quadruplet pregnancy. It appears that this multiple pregnancy came about because of the natural fertilization of oocytes left behind at oocyte recovery by sperm that were introduced 4 days prior to oocyte collection. The practice of a couple having intercourse during a treatment cycle was not discouraged by the IVF unit at the time and is advocated by some as being safe (Tremellen and Norman, 2001) and conferring an improved implantation rate (Tremellen et al., 2000
). However, and this is the main message of this case report, such a practice carries a risk of multiple pregnancy in a couple with patent Fallopian tubes and normal sperm function. There is a well established risk of 12% of conception occurring in an IVF cycle prior to oocyte collection in association with the use of GnRH agonists (Cahill et al., 1994
; Cahill, 1998
). However, reports of spontaneous pregnancies occurring following oocyte collection are rarely reported. Most twin and triplet pregnancies are assumed to result from the transfer of two or three embryos. When two embryos are replaced the normal likelihood of a multiple pregnancy should be far lower (0.5% triplets and 10% twins; unpublished data). When a twin pregnancy occurs after a transfer of two embryos, this is assumed to result from the implantation of both embryos, though embryo studies may refute this. When triplets or higher order pregnancy occurs after the transfer of two embryos, monozygotic twinning is assumed to have occurred in at least one of the embryos replaced. In one published case, a quadruplet pregnancy (and delivery) resulted from a two embryo transfer. In that case, it appears that monozygotic twinning occurred in one transferred embryo, a third gestation sac resulted from a second transferred embryo and a fourth sac arose from the fertilization of a residual oocyte (not collected at oocyte recovery) (Milki et al., 2001
). In a second published case, quintuplets resulted from monopaternal superfecundation following the transfer of two embryos with subsequent selective reduction to two fetuses at 12 weeks (Amsalem et al., 2001
). Despite the outcome, Amsalem et al. advised that couples should have intercourse after retrieval to increase their chances for a pregnancy, although only in selected cases where the likelihood of success is suboptimal. In our report, monozygotic twinning of the two replaced embryos was ruled out by the zygosity testing of the three male infants. Consequent to the information we gained from this case and the previous case reports, we have changed our policy in the IVF unit to advise couples not to have intercourse without contraception during their stimulation cycle. We suggest that in young couples with no sperm disorder and patent tubes, this policy would prevent further undesired multiple pregnancies following assisted reproductive technology.
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References |
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Cahill, D.J. (1998) Risks of gonadotrophin releasing hormone agonist administration in early pregnancy In Filicori, M. and Buletti, C. (eds) Ovulation Induction Update 1998. Parthenon Publishing, Camforth, UK, pp. 97105.
Cahill, D.J., Fountain, S.A., Fox, R., Fleming, C.F., Brinsden, P.R. and Hull, M.G. (1994) Outcome of inadvertent administration of a gonadotrophin-releasing hormone agonist (buserelin) in early pregnancy. Hum. Reprod., 9, 12431246.[Abstract]
Milki, A.A., Hinckley, M.D., Grumet, F.C. and Chitkara, U. (2001) Concurrent IVF and spontaneous conception resulting in a quadruplet pregnancy. Hum. Reprod., 16, 23242326.
Tremellen, K.P. and Norman, R.J. (2001) The effect of intercourse on pregnancy rates during assisted human reproduction. Hum. Reprod., 16, 20302031.
Tremellen, K.P., Valbuena, D., Landeras, J., Ballesteros, A., Martinez, J., Mendoza, S., Norman, R.J., Robertson, S.A. and Simon, C. (2000) The effect of intercourse on pregnancy rates during assisted human reproduction. Hum. Reprod., 15, 26532658.
Submitted on August 12, 2002; accepted on October 30, 2002.