What is fetal surgery?

Indications and Procedures

As early as the 1960s, some unborn infants suffering from progressive anemia caused by antibodies that drew away their strength were saved by receiving blood transfusions in utero. These early procedures marked the beginnings of invasive medical intervention in dealing with fetal problems.

Not until the technical advances of the 1970s and beyond, however, was it possible to observe human fetuses in the uterus. With the development of ultrasound imaging, it became possible to examine in considerable detail the size, growth, and contour of fetuses. The use of ultrasound enabled physicians to assess with considerable accuracy the age of fetuses, their probable date of birth, and a number of congenital abnormalities, such as spina bifida.

Laparoscopes with diameters of less than 0.1 inch make it possible to examine the fetal stomach. The use of lasers and tiny instruments guided by computers has allowed methods of fetal surgery that were inconceivable in the mid-twentieth century. These instruments greatly reduce blood loss in all types of surgery, including fetal surgery, and greatly improve the prognosis in such procedures. They are used to repair ruptured membranes in fetuses, to install shunts to relieve blockages, and, with the laser excision of placental vessels, to equalize osmotic pressure in twin-twin transfusion
syndrome.

It has become possible for obstetricians to observe all significant fetal organs. Whereas physicians earlier could barely hear the beat of the fetal heart, they now can monitor all four of its chambers in the unborn to detect defects early, and, in some cases, to repair them surgically. Ultrasound enables physicians to observe fetal movement within the uterus and to monitor fetal breathing and swallowing.

Because physicians can now gather specific information about the fetus and its health, abnormalities and life-threatening physical problems can be detected several months prior to delivery. Whereas neonatologists have regularly encountered such problems as intestinal and urinary tract obstructions, heart defects, protrusions of the wall of the stomach into the thorax (diaphragmatic hernia) or into the esophageal region (hiatal hernia), swelling of the kidney (hydronephrosis), tumors (sacrococcygeal teratomas), hydrocephalus (water on the brain), and defects of the chromosomes shortly after the birth of a child, it is now possible to detect and, in some cases, to treat these defects surgically in utero.

In cases where fetal surgery appears to offer the most reasonable solution to a difficult problem, the mother may be sent to one of the few centers in the United States where this highly specialized and controversial form of surgery is performed regularly. With the development of sophisticated computer-operated instrumentation, surgeons geographically distant from their patients can perform highly specialized surgery on them. Eventually, such surgery will likely be performed without uprooting mothers.

The current success rate of fetal surgery is not encouraging, although some remarkable outcomes have occurred through its use. Fetal surgical procedures often result in miscarriages and sometimes in the death of both the mother and the fetus.

Two conditions that frequently require fetal surgery are obstructions in the urinary tract that, if untreated until birth, may lead to kidney failure, and hydrocephalus, in which cerebral swelling makes it difficult or impossible for brain cerebrospinal fluid to circulate. Both conditions, which occur in 1 of every 5,000 to 10,000 births, require immediate attention to prevent long-term problems or death. Stents can overcome blockages. Instruments have been developed to drain fluid from the brain in instances of hydrocephalus.

When surgery is performed to allow fetal lungs to develop normally, the fetus, attached to the mother through the umbilical cord, exists in the most protective environment it is ever likely to know. If corrections are made in the uterus, then the fetal lungs are in the safest possible environment for becoming stronger before they are forced to function on their own.

In cases of obstructive urinopathy (obstruction of the urinary tract), surgery may help injured kidneys to recover and develop. Hypotonic urine found in fetal samples indicates that normal kidney function might be restored and suggests that surgery may permit the affected kidneys to gain strength within the uterus. On the other hand, the presence of isotonic urine in fetal samples indicates kidneys that are too badly compromised to regain normal function. Treatments currently available offer no solution to this problem.

One of the more routine procedures connected with pregnancy is amniocentesis, testing for chromosomal abnormalities through the analysis of amniotic fluid drawn through the abdominal wall of the mother and of blood drawn from the umbilical cord. This procedure is not without risks to mothers and fetuses. It is commonly used, however, because the benefits derived from it are generally thought to outweigh the risks.

Nevertheless, amniocentesis remains a controversial procedure, and major ethical questions surround its use. If the test reveals a chromosomal abnormality, the parents are left with the decision of whether to seek a therapeutic abortion to terminate the pregnancy, which in many jurisdictions would be considered a realistic option. With many such abnormalities, however, the fetus might be delivered alive and, although significantly handicapped, have a life expectancy of many years.

Fetal surgery is indicated when physicians are convinced that a fetus will not survive long enough to be delivered or when it appears certain that the newborn will be unable to survive long after its birth. For example, if it appears through ultrasound that a fetus suffers from a severe kind of congenital diaphragmatic hernia in which the liver is in the chest, then it is obvious that the development of the lungs will be seriously compromised without surgical intervention. Fetal surgery becomes a stopgap measure in such cases to lessen the severity of the problem so that the fetus can grow to term and be delivered, after which corrective surgery outside the uterus can be undertaken. This procedure involves substantial risk, however, because the liver can be destroyed in the process of trying to restore it to its normal position below the diaphragm.

Sometimes ultrasound reveals noncancerous sacrococcygeal tumors. Such tumors, if untreated, can become large enough in a fetus to put a strain on the heart sufficient to cause heart failure. This severely compromises the survival of the fetus. Guided by ultrasound imagery, surgeons can cut off the blood supply to such tumors and starve them before they do irreparable damage to the fetus. When this procedure is used, the destroyed tumor can be removed surgically after birth.

Another growing use of fetal surgery is in cases where spina bifida, usually identified through ultrasound around the sixteenth week of pregnancy, is present. This congenital defect involves a malformation in the vertebral arch, in which the neural tube connected to the brain and the spine is exposed. When this condition is diagnosed and treated early in the development of the fetus, considerable spinal cord function can be preserved. This makes postnatal treatment more effective than it would be were the condition not discovered until after delivery.

There are essentially two major forms of fetal surgery. The more drastic of these involves performing a cesarean section, after which the fetus is carefully removed from the uterus and treated. It is then returned to the uterus, which is closed with sutures. The umbilical cord is not cut, so that the fetus is still receiving oxygen and need not breathe on its own before its lungs have developed sufficiently. This procedure is indicated when some congenital defect, possibly a teratoma (tumor), blocks the airway. Clearing the fetal airway enables the baby to breathe independently upon delivery. The other form of fetal surgery is done without removing the fetus from the uterus and is made possible by the use of laparoscopes and other specialized instruments. This is the preferred method if a choice is offered.

Uses and Complications

As fetal surgery becomes more significant and more common in the treatment and elimination of many threatening prenatal conditions, numerous complications, both ethical and physical, necessarily arise. Any surgery involves risk, and in fetal surgery a dual risk exists: risk to the fetus and risk to the mother. Therefore, physicians who perform fetal surgery have simultaneously as patients both prospective mothers and fetuses. Because fetuses cannot speak for themselves or make their own decisions, fetal surgeons often find themselves in an ethical quagmire. Most physicians hesitate to recommend fetal surgery except in such extreme cases that fetal death or severe disability without such surgery seems inevitable.

Sometimes wrenching decisions must be made about whether to save the life of the mother or the life of the fetus. Questions also arise about whether to allow a fetus to come to term if it is obvious that it will suffer from birth defects that will either severely limit the length of its life or adversely compromise its quality of life, which in some cases may involve a normal life span. Many notable people who suffered from severe birth defects have made significant contributions to society and have led productive and rewarding lives.

One of the more significant uses of fetal surgery is in the treatment of twin-twin transfusion syndrome. In the United States, this syndrome occurs in about one thousand pregnancies each year. Twin-twin transfusion syndrome results in a pair of twins being of unequal size in the fetal state because of abnormal circulation of amniotic fluid between them within the placenta that they share. The larger of the two is surrounded by considerably more amniotic fluid than the smaller one. This disproportion can result in the death of one or both of the fetuses. Attempts can be made to equalize the amniotic fluid by inserting a hollow needle through the mother’s abdomen and drawing out excess fluid, a procedure that can threaten the viability of one or both of the fetuses.

Another more sophisticated treatment of twin-twin transfusion syndrome involves inserting a fetoscope into the uterus and using heat from a laser to seal off the blood vessels between the fetuses. This treatment is directed toward separating the circulation between the twins, which accounts for the condition. Regardless of which treatment is employed, the mortality rate is currently quite high in such cases, and premature delivery is a virtual certainty in them. Without intervention, however, these fetuses inevitably die in the uterus.

One of the greatest complications of fetal surgery is premature delivery. Fetuses were once thought to be viable only in the seventh month and beyond. Now the means are available to make survival outside the uterus possible earlier than that, although extraordinary care, attention, and equipment are required for extended periods following the delivery of a baby short of seven months and hospitalization in the neonatal intensive care unit (NICU) may continue for many months following such a birth.

When fetal surgery is performed, the mother is routinely medicated with drugs that will both reduce her pain and substantially decrease the possibility of miscarriage or premature delivery. As the field grows and becomes increasingly sophisticated, many of the current problems that it poses will surely be overcome.

Perspective and Prospects

The development of highly specialized instruments, including fiber-optic telescopes and instruments specially designed to enter the uterus through minute incisions, has made possible the field of fetal surgery. Obstetrical surgeons can now correct life-threatening defects and malformations through the smallest, least invasive of openings while the fetus remains within the protection of the mother’s body. This procedure, referred to as fetoscopic surgery, is the method preferred whenever it is possible because it reduces substantially the danger of bringing about premature labor at a time when the fetus cannot breathe on its own.

Because fetal surgery is in its infancy, relatively few surgeons specialize in it and the full range of its uses and promises has yet to be explored. The two major centers in the United States that have pioneered development in this field are the Children’s Hospital in Philadelphia and the University of California Hospital in San Francisco.

Considerable research in fetal surgery is being conducted at both of these institutions and in laboratories and hospitals throughout the country. It is a matter of time before improved technology will exist to eradicate some of the major barriers to more extensive fetal surgery. Surgery of all kinds is becoming less invasive, which reduces considerably the shock that it delivers to patients’ bodies, including blood loss and recovery time. Noninvasive fetal surgery is particularly important to ensure the physical welfare of both the fetus and the mother.

Bibliography

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Dickens, Bernard M., and Rebecca J. Cook. "Legal and Ethical Issues in Fetal Surgery." International Journal of Gynecology & Obstetrics 115, no. 1 (October, 2011): 80–83.

Harrison, Michael, et al. The Unborn Patient: The Art and Science of Fetal Therapy. 3d ed. Philadelphia: W. B. Saunders, 2001.

Hartmann, Katherine E., et al. "Evidence to Inform Decisions About Maternal-Fetal Surgery." Obstetrics & Gynecology 117, no. 5 (May, 2011): 1191–1204.

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Wise, Barbara, et al., eds. Nursing Care of the General Pediatric Surgical Patient. Gaithersburg, Md.: Aspen, 2000.

Vrecenak, Jesse, and Alan Flake. "Fetal Surgical Intervention: Progress and Perspectives." Pediatric Surgery International 29, no. 5 (May, 2013): 407–417.