Cephalopagus twins diagnosed at 7 weeks gestational age following IVF/ICSI

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A patient in her 30s who was a G0 proceeded with in vitro fertilisation (IVF) for a history of male factor infertility. Following single embryo transfer, the patient was diagnosed with a conjoined twin pregnancy. During her IVF cycle, the patient was stimulated with an antagonist protocol for 13 days followed by a gonadotropin-releasing hormone agonist trigger. 13 eggs were retrieved, 9 were mature and 5 fertilised with intracytoplasmic sperm injection. Of those, two were cryopreserved. She had a successful frozen blastocyst embryo transfer. The patient’s 7-week ultrasound demonstrated a single gestational sac, yolk sac and fetal pole. However, the crown-rump length appeared visually abnormal and two heartbeats were visualised. She was referred to maternal–fetal medicine (MFM) for a first-trimester ultrasound. Her ultrasound with MFM was notable for a fluid-filled chest, foreshortened limbs and early sacral agenesis. She was subsequently diagnosed with cephalopagus twins and underwent an induced abortion following consultation with MFM.