The incidence of multiple pregnancy followed by In Vitro Fertilisation procedure is 24% (1). We would like to report a case of management of a twin pregnancy complicated by discordant fetal anomaly after IVF.
A 37 year old primigravida with a long history of infertility and conceived a dichorionic diamniotic twin pregnancy after IVF. Her first trimester dating scan raised the possibility of a major fetal anomaly in Twin 1. She was reviewed in the Tertiary Fetal Medicine Centre which confirmed Twin 1 had anencephaly and was small for gestational age. Twin 2 was confirmed as anatomically normal.
The patient was counselled regarding her two options: continuation of the pregnancy or Selective Fetal Termination, either in the Second or Third Trimester. The benefits and risks of selective termination were discussed and the patient consented for second trimester selective termination. The procedure was performed at 15 weeks. Amniocentesis and Chorionic Villous Sampling were performed on both twins prior to the procedure. Following injection of intracardiac lignocaine, follow-up scans confirmed cardiac standstill of Twin 1 and the wellbeing of Twin 2. Karyotype of both Twins was subsequently shown to be normal. Serial growth scans every four weeks confirmed the continued growth of the remaining fetus.
The pregnancy then progressed uneventfully to 34 weeks. At 34+2 weeks the patient presented with spontaneous rupture of the membranes. She progressed into labour and achieved a normal vaginal delivery of a 2040g male with good Apgar scores. He had an uneventful postnatal course and was discharged home from the SCBU at age 12 days
Management of Twin Pregnancy Discordant for Fetal Anomaly
1. Continue the Pregnancy
2. Selective Fetal Termination
3. Terminate the pregnancy
Selective fetal termination (SFT) is an invasive ultrasound-guided procedure. The first report was in 1978 in order to prolong the pregnancy and improve the outcome and survival the existing normal fetus.(2).Common indications are chromosomal anomalies, major structural anomalies and genetic disorders. The preferred route of fetal entry is transabdominal. Complications include pregnancy loss (6-12%), preterm delivery (8%), chorioamnionitis, placental abruption, bleeding, maternal coagulopathy, psychological stress and depression. The risk to the normal fetus is of extreme preterm delivery, neurodevelopment delay as a result of the death of its co-twin (much lower in dichorionic than monochorionic twins) and intrauterine death. Routine monitoring of cervical length, maternal platelets and clotting factors have not shown to be helpful. Serial scans are required to monitor the wellbeing of the surviving fetus.
Termination may be granted if ‘there is a substantial risk that if the child were born it would suffer from such physical or mental abnormalities as to be seriously handicapped’ (UK Abortion Act 1967, amended 1991, clause E). The risk of stillbirth after the procedure is 6-12%, similar to the risk of stillbirth in multifetal gestation (12.3%). The ongoing presence of the anomalous fetus potentially increases the complications in the antenatal period to those of a twin pregnancy, thereby putting the normal fetus at risk. Thus SFT, by reducing the ongoing risks of the pregnancy, is beneficial to the mother in improving the chances of having at least one normal child.
Selective Fetal termination is a reasonable alternative to expectant management or termination of the whole pregnancy in cases of twin pregnancy discordant for major fetal anomaly (3). In most experienced hands, it can be performed in all three trimesters with good outcome in >90% of cases(4)
1.National Collaborating Centre for Women’s and Children’s Health. Multiple Pregnancy-the management of twin and triplet pregnancies in the antenatal period (NICE clinical guideline 129). National Institute for Health and Clinical Excellence, London September 2011.
2. Aberg, A., Metelman, F., Cantz, M. et al. (1978) Cardiac puncture of fetus with Hurler’s disease avoiding abortion of unaffected co-twin. Lancet, ii, 990–991.
3. Selective termination in dichorionic twins discordant for congenital defect.,Fetal Medicine Unit, Madrid, Spain. European Journal of Obstetrics and Gynaecology. 2012 Mar;161(1):8-11
4. Selective termination for structural, chromosomal, and mendelian anomalies: international experience. American Journal of Obstetrics and Gynaecology. 1999 Oct;181(4):893-7.