Open surgery is highly experimental. As of 1994, medical researchers had reported only about 55 operations in the previous 14 years. The vast majority of these were performed by pediatric surgeon Michael R. Harrison and his team at the Fetal Treatment Center at the University of California, San Francisco. Harrison's team has performed open surgery, at least once, for seven or eight different birth defects. Three types of open surgery have proved most promising: removing lung tumors, treating a blocked urinary tract, and repairing a hole in the diaphragm. Prompt treatment of these conditions early in pregnancy prevent a cascade of other problems in fetal development. A hole in the diaphragm, for instance, allows the stomach and intestines to migrate through the diaphragm and press against the lungs. This condition, known as a diaphragmatic hernia, halts the development of the lungs. Most babies with diaphragmatic hernias are unable to breathe at birth and die.
In open surgery, the pregnant woman is placed under anesthesia. The anesthetic, which crosses the placenta, puts the fetus to sleep as well. The surgeon then cuts through the abdomen and uterus to reach the fetus. This part of the operation is like a cesarean section. Once revealed, the tiny fetus is gently turned, so that the desired body part is exposed to the surgeon's hands. At 24 weeks, a typical age for surgery, the fetus weighs about 1 lb (0.5 kg) and has arms smaller than a surgeon's fingers.
When lung cysts are removed, an incision is made in the fetus's chest, and the abnormal growth is sliced off. Only solid cysts require open surgery. Other types of cysts can be treated without opening the uterus. In a closed-womb procedure, the surgeon uses a hollow needle to install a shunt that drains the cyst into the amniotic sac.
Blockages in the urinary system can also be relieved with either open or closed surgery. When blockages occur, the bladder fills with urine and balloons to immense proportions, sometimes growing larger than the fetus's head. The grotesque size and pressure of this organ disturbs the normal growth of the kidneys and lungs. In open surgery, the fetus is gently pulled, feet first, out of the uterus until its abdomen is exposed and the blockage can be surgically corrected. In closed-womb procedures, surgeons install a shunt that permits the fetal urine to flow from the bladder into the amniotic sac.
To repair a diaphragmatic hernia, the surgeon makes two incisions into the fetus's left side: one into the chest and one into the abdomen. Next the surgeon pushes the stomach and intestines back down into their proper place. Then he or she closes the hole in the diaphragm with a patch of waterproof Gore-Tex, the fabric used in outdoor gear. Rather than close the abdominal incision, the surgeon places a Gore-Tex patch over the cut in order to allow the abdomen to expand and accommodate its newly returned organs. At birth, this patch is removed. The internal patch remains for life.
After the surgery on the fetus is finished, the mother's uterus and abdomen are closed. She can usually leave the hospital after eight days of careful monitoring. To prevent premature labor, a common problem after open surgery, the woman must stay in bed and take drugs to quell uterine contractions.
Babies who have successfully undergone surgery are born without scars, a happy and unexpected by-product of operations performed in the womb. They are usually born early, however. Thus, in addition to their original medical problem, they face the problems of any premature infant. Surgery also has a long-term effect on the mother. Since her uterus has been weakened by the incisions made during surgery, normal labor and delivery is no longer safe. To prevent uterine rupture, she must deliver this baby (and all future babies) by cesarean section, before active labor begins, to prevent uterine rupture.
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