A 37-year-old woman with four previous caesarean sections presented with lower abdominal discomfort the day after her embryo transfer. Her ovaries were hyperstimulated with minimal ascites on ultrasound scan. Subsequently, she developed severe ovarian hyperstimulation syndrome with severe ascites for which supportive treatment was given and paracentesis was performed. On transvaginal sonography ( Figure 1) after 25 days of embryo transfer, a dichorionic twin pregnancy was diagnosed. The first gestational sac was situated at the fundus and the other was lower down, immediately over the caesarean section scar. Both the sacs had a fetal pole each of 2 mm, with visible fetal heart beats. A diagnosis of heterotopic caesarean scar pregnancy was made.At this stage, both pregnancies had a reasonable chance of progressing, although there was a risk of spontaneous miscarriage. The findings and options of expectant management, termination of both the pregnancies and selective termination of scar pregnancy were discussed with the couple. Selective embryo reduction was performed 2 days later at a gestational age of 6 weeksþ3 days, by transvaginal needle aspiration of the pregnancy implanted in the caesarean scar under ultrasound guidance. At the end of the procedure there was no embryonic cardiac activity in the scar pregnancy and the other pregnancy in the uterus appeared intact.A follow-up scan at 12 weeks showed a single viable gestation sac located in the uterine fundus ( Figure 2). Unfortunately, the scan at 12 weeks' gestational age showed that the remaining viable fetus had a cystic hygroma. A chorionic villus sampling diagnosed trisomy 13, and a suction termination of pregnancy was performed without further complications.