Fetal surgery allows doctors to treat certain abnormalities of the fetus that might otherwise be fatal or cause significant problems if permitted to progress.
Approximately 3% of babies born in the United States each year have a complex birth defect. Parents are
Some of the fetal abnormalities that may be treated by fetal surgery are:
- Myelomeningocele. Also called spina bifida, myelomeningocele is a condition in which the spine fails to close properly during early fetal development. The spinal cord may protrude or be exposed through an opening in the lower back. Paralysis, neurological problems, bowel and bladder problems, and hydrocephalus (fluid buildup in the brain) may result. Myelomeningocele affects one out of every 1,000 babies born in the United States.
- Congenital diaphragmatic hernia (CDH). In babies with CDH, the diaphragm (the thin muscle that separates the chest from the abdomen) doesn't develop properly. The abdominal organs may enter the chest cavity through a hole (hernia) and cause pulmonary hyperplasia (underdeveloped lungs). CDH occurs in about one out of every 2,000 births.
- Urinary tract obstruction. The urethra (the tube that carries urine from the bladder to the outside of the body) may become obstructed in utero or fail to develop normally. When this happens, urine can back up into the kidneys and destroy tissue or cause the bladder to become enlarged. The amount of amniotic fluid also decreases because fetal urine is its major component. Pulmonary hypoplasia usually results because the lungs rely on amniotic fluid in their development.
- Congenital cystic adenomatoid malformation of the lung (CCAM). CCAM is a large mass of malformed lung tissue that does not function properly. As a result of its large size, it may put pressure on the heart and lead to heart failure. Lung development is also affected, and pulmonary hyperplasia may result.
- Twin/twin transfusion syndrome (TTTS). In some twin pregnancies, the two fetuses will share a placenta. TTTS occurs in approximately 15% of these twins when blood volume between the fetuses is unequal, causing abnormally low blood volume in the donor twin and abnormally high blood volume in the "recipient" twin. There is often a large difference in size between the twins. Approximately 70–80% of fetuses suffering from TTTS will die without intervention.
- Sacrococcygeal teratoma (SCT). This usually benign fetal tumor develops at the base of the spine (coccyx) and affects approximately one in 35,000 to 40,000 newborns in the United States. The tumor may become very large (sometimes as large as the fetus) and filled with blood vessels, causing stress on the heart.
What fetal surgical technique is used depends on the specific condition of the fetus and its severity. The fetoscopic temporary tracheal occlusion procedure is used to treat CDH. The trachea is temporarily blocked (occluded) by a small balloon to trap fluid in the lungs (that normally escapes into the amniotic fluid); buildup of the fluid enlarges the lungs and stimulates their growth, pushing any abdominal organs that have moved into the chest cavity back into the abdomen. The occlusion is removed immediately after birth of the baby. The procedure is performed endoscopically. Rather than make a large incision into the abdomen and uterus, the surgeon
Open fetal surgery is used for conditions that cannot be treated endoscopically. An incision is made through the abdomen and the uterus is partially removed from the body. Amniotic fluid is drained from the uterus and kept in a warmer for replacement after completion of the surgery. An incision is made in the uterus (called a hysterotomy). In order to minimize bleeding of the uterus, an instrument called a uterine stapler is used to make an incision while simultaneously placing staples around the perimeter of the incision to prevent bleeding. Surgery is then performed on the fetus through the opening in the uterus to locate the abnormality and remove or fix it. Open fetal surgery is used for CCAM (to remove the cystic mass), myelomeningocele (to close the exposed spine), and SCT (to remove the tumor). Because of the nature of open fetal surgery, delivery for this child and all subsequent children of this mother will have to be performed by cesarean section.
Detection of many birth defects is possible through the use of sophisticated imaging and diagnostic techniques such as:
- Ultrasound. This imaging technique uses a machine that transmits high frequency sound waves to visualize structures in the human body, including the uterus and fetus. Ultrasound is used to determine the size, position, and age of the fetus; to measure the amount of amniotic fluid; and to assess the fetus for any congenital abnormalities.
- Chorionic villus sampling (CVS). Cells are collected from the placenta with a thin plastic tube inserted through the cervix (opening to the uterus) or a needle inserted through the abdomen. The cells may then be analyzed for possible genetic disorders.
- Alpha-fetoprotein (AFP) testing. AFP is a protein made by the developing fetus. Large amounts of AFP in the mother's bloodstream may indicate certain fetal abnormalities.
- Amniocentesis. A needle is inserted through the woman's abdomen and into the uterus to procure a sample of amniotic fluid. Fetal cells in the fluid are then analyzed for possible genetic disorders.
Once a congenital abnormality has been diagnosed, the condition will be assessed to determine if the fetus is eligible for fetal surgery. Generally only the most severe conditions that are certain to cause fetal death or significant disability are treated with fetal surgery. If fetal surgery is indicated, the parents will meet with the team of health care providers that will be involved in the surgery.
To prepare for the surgery, the steroid betamethasone will be given in order to speed up the development of the fetus's lungs. A complete history and physical examination will be performed. A monitor will be used to track uterine contractions and fetal heart rate. The patient will be instructed to refrain from eating and drinking after midnight the day of surgery, and will sign a surgical consent. Blood samples may be taken for laboratory tests and to type match the patient's blood in case a blood transfusion is necessary. An intravenous (IV) catheter will be used to infuse fluids and/or medications to the patient.
Postoperative recovery generally takes from five to 10 days. The patient will be closely monitored to ensure that she does not go into premature labor. She may be put on bed rest to minimize this risk. Some signs of premature labor include contractions, cramping, lower back pain or abdominal pain or pressure, vaginal bleeding, and leaking of fluid from the vagina. Tocolytics are drugs given to delay or stop labor; some commonly administered tocolytics are terbutaline, indocin, and magnesium sulfate. Antibiotics will usually be administered to prevent postsurgical infection.
Some risks associated with fetal surgery include infection of the incision or lining of the uterus, premature
The results of fetal surgery depend on the reason for the procedures. Successful results of fetal surgery generally include halting the progression of the congenital malformation and perhaps reversing some of the potential complications that would arise without intervention.
Morbidity and mortality rates
One study of open fetal surgery used to repair myelomeningocele indicated that the risk of going into premature labor was significantly increased among women who had had the procedure (50% compared to 9% of similar cases with no fetal surgery performed). There was also an increased risk of oligohydramnios or low amniotic fluid (48% compared to 4% of similar cases with no fetal surgery performed). Because of the high risk of premature labor associated with fetal surgery, some fetuses have died during premature birth.
There are some alternative procedures that are offered for treating specific birth defects, depending on their severity. Fetal surgery is generally recommended only for the most severe defects. For example, myelomeningocele may be treated by closing of the lesion soon after delivery. SCTs and CCAMs may also be removed soon after the baby is born. Parents are often given the option of aborting the fetus (termed therapeutic abortion); or they may decide to refrain from medical intervention.
Bruner, Joseph, Noel Tulipan, Ray Paschall, Frank Boehm, William Walsh, Sandra Silva, Marta Hernanz-Schulman, Lisa Lowe, and George Reed. "Fetal Surgery for Myelomeningocele and Incidence of Shunt-Dependent Hydrocephalus." Journal of the American Medical Association 282, no. 19 (November 17, 1999): 1819–25.
Center for Fetal Diagnosis and Treatment, Children's Hospital of Philadelphia. 34th Street and Civic Center Boulevard, Philadelphia, PA 19104-4399. (800) IN-UTERO. <http://fetalsurgery.chop.edu>.
Fetal Diagnosis & Therapy, Vanderbilt University Medical Center. B-1100 Medical Center North, Nashville, TN 37232. (615) 343-5227.
Fetal Treatment Center, University of California at San Francisco. 513 Parnassus Ave., HSW 1601, San Francisco, CA 94143-0570. (800) RX-FETUS. <http://www.fetus.ucsf.edu>.
Spina Bifida Association of America. 4590 MacArthur Blvd., SW, Washington, DC 20007. (800) 621-3141. <http://www.sbaa.org>.
Danielpour, Moise, and Diana L. Farmer. "Fetal Surgery for Congenital CNS Abnormalities." Cedars-Sinai Net Journal. 2002 [cited February 28, 2003]. <http://www.cedarssinai.edu/mdnsi/images/fetalsurg.pdf>.
"The Fetal Treatment Center: Our Treatments." University of California at San Francisco. 2001 [cited February 28, 2003]. <http://www.fetus.ucsf.edu/ourtreatments.htm>.
Iannelli, Vincent. "Surgery Before Birth?" Pediatrics. January 29, 2000 [cited February 28, 2003]. <http://pediatrics.about.com/library/weekly/aa012900.htm>.
Stephanie Dionne Sherk
WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?
Fetal surgery is a highly specialized procedure that is offered at only a handful of hospitals around the United States. Among those health care providers who will have a role in the surgery are:
- a perinatologist (a medical doctor specializing in the care and treatment of the fetus/infant during the time shortly before and after birth)
- a pediatric surgeon (a surgeon specializing in the treatment of children)
- a fetal treatment coordinator (a nurse who will coordinate the patient's care, including communication with the medical team and arranging various tests)
- a sonographer (a person who is trained to perform ultrasounds and interpret their results)
- an anesthesiologist (a medical doctor specializing in the science and application of techniques to decrease or eliminate pain)
- operating room nurses
- clinical nurses
QUESTIONS TO ASK THE DOCTOR
- Why is fetal surgery recommended in my case?
- What alternatives to fetal surgery are available to me?
- What are the costs associated with fetal surgery? Will my insurance cover the procedure?
- What will happen if there is no medical intervention?
- Will my own obstetrician be able to care for me for the rest of my pregnancy or will I have to remain near the surgical center?