The first human fetal surgery, performed in the 1950s, were fetal blood transfusions for Rh-positive babies whose red blood cells were under attack by theRh-negative mother's immune system. Attempts to improve this technique via direct access to the fetus through an open uterus were unsuccessful, and open-womb fetal surgery was abandoned. The development of real-time ultrasound imaging in 1977 made intrauterine fetal surgery feasible: visual imaging permitted surgeons to accurately guide needles similar to those used for amniocentesis without the risk of damage to placenta or fetus. In the early 1980s, surgeons at several medical centers attempted closed-womb surgery to relieve fetalhydrocephalus (abnormal accumulation of fluid around the brain) by drainingexcess fluid. Although fluid could be drained, most babies were born with severe neurological defects. In 1981, pediatric surgeon Michael Harrison of theUniversity of California at San Francisco developed a closed-womb shunting procedure to correct a urinary tract obstruction which afflicts one in every 2,000 male fetuses. In this defect, a blocked bladder damages or destroys the unborn baby's kidneys and, because the presence of the baby's urine in the amniotic fluid is vital for its lung development, the absence of urine is fatal.Although this technique is now widely used, it remains high-risk.
Harrison performed the first successful major open-womb surgery on a fetus onJune 15, 1989 when he repaired a hole in the diaphragm of a 24-week-old fetus. In this pioneering operation, the unborn baby's arm was lifted out of hismother's womb through an incision in her abdomen and uterus, exposing the left side. The baby's misplaced internal organs were repositioned and the diaphragm and abdominal incisions patched with Gortex. The baby was born seven weeks later, premature but healthy. Harrison and his team successfully performedthe same operation on a second fetus soon after. These successes were preceded by minor surgery on fetuses either inside or partially removed from the womb, although six previous procedures on humans had failed. Harrison prepared for human prenatal surgery by performing more than a thousand intrauterine operations on animals--the first successful animal fetal operations being carried out in the 1920s.
Prenatal surgery is still in its earliest stages and the success rate is notyet high, even though it is higher for some closed-womb procedures such as the bladder shunt. Risk remains high for both fetus and mother, and prenatal surgery is recommended for only a few conditions. One technique that has exciting possibilities is fetal stem-cell transplantation in which stem cells, thesource of all blood cells, from a dead fetus are injected into a living fetus, providing healthy genetic material in an effort to overcome defective genesin the recipient fetus.