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Ultrasound‐guided, intra‐abdominal laser to treat acardiac pregnancies

A 19 year old woman in her first pregnancy at 18 weeks of gestation was referred to the fetal medicine unit because of an abnormal twin pregnancy in which it was believed that one of the fetuses had died. At ultrasound examination, there was one live fetus whose measurements were consistent with gestational age by her last menstrual period, with no obvious fetal abnormalities except a single umbilical artery. There were no signs of hydrops although the umbilical artery Doppler pulsatility index was elevated at 1.73, and there was a full bladder with a moderate increase in the amniotic fluid volume (amniotic fluid index 1⁄4 25.2 cm). No heart action was present in the other fetus, which was extremely hydropic and the lower body was more developed than the upper body. No face, neck or arms could be identified and the body consisted of a chest, abdomen and relatively well-developed legs, which showed movements. The diagnosis of an acardiac twin pregnancy was made. Perfusion at the cord insertion was demonstrated and using colour Doppler it was possible to identify that the blood was moving away from the acardiac twin via the umbilical vein and towards it in the umbilical arteries. The woman was told of the findings and the overall poor prognosis of this condition. She was given the options of either doing nothing with a high risk of preterm delivery, having laser coagulation of the acardiac fetal circulation or having a termination of pregnancy. She chose laser ablation, which was performed a week later. After infiltration of local anaesthetic into the maternal abdomen, a 17-gauge chorion villus sampling needle was passed into the abdomen of the acardiac twin under ultrasound guidance (Aspen, Acuson, Mountain View, California, USA) until its tip was in close proximity to the superior vesical arteries, as identified by colour Doppler. A laser fibre of 1.05 mm diameter (Surgical Laser Technologies, Philadelphia, Pennsylvania, USA) connected to a neodymium yttrium aluminium garnet laser (Surgical Laser Technologies, Philadelphia, Pennsylvania, USA) was then passed through the needle under ultrasound-guidance and the superior vesical arteries on both sides of the bladder were coagulated using pulses of 20 W to 30 W lasting three to five seconds until there was no visible flow on colour Doppler. The entire procedure lasted twenty minutes and the fetal heart rate of the other twin remained normal throughout the procedure. Subsequent serial scans showed normal growth, umbilical artery pulsatility index and amniotic fluid volume in the sac of the surviving fetus. In addition, no abnormalities of the brain were detected. Although the acardiac twin remained visible, it did not grow and no blood flow could be demonstrated within it at any time. Labour was induced at 38 weeks of gestation, and the woman had a vaginal delivery of a 3.52 kg well baby boy. Postnatal cranial ultrasound and magnetic resonance imaging of the brain of the baby were normal and at 18 months of age the child is developmentally normal. Postmortem examination of the acardiac twin, which was severely macerated, confirmed the ultrasound findings and in addition, the foot length was consistent with 17–18 weeks of gestation. It was not possible to identify the ablated superior vesical arteries during the internal examination or the site of insertion of the umbilical cord of the acardiac fetus into the placenta.