Pediatric Annals

Fetal Surgical Treatment

Michael R Harrison, MD; Mitchell S Golbus, MD; Roy A Filly, MD; Don K Nakayama, MD; Alfred A De Lorimier, MD

Abstract

Fetal anatomy, normal and abnormal, can now be accurately delineated by ultrasonography and other imaging techniques. Although some fetal malformations with a known pattern of inheritance may be specifically sought, many are identified serendipitously during obstetric ultrasonography. Until recently, the only question raised by the prenatal diagnosis of a fetal malformation was whether the fetus should be aborted, but other therapeutic alternatives are becoming available. The detection of a fetal abnormality may now lead to a change in the timing of delivery, a change in the mode of delivery, and even prenatal treatment. We have tentatively outlined the diagnostic and therapeutic alternatives for the management of specific fetal malformations that can be recognized in utero.1

MALFORMATIONS BEST TREATED AFTER TERM DELIVERY

Most correctable malformations that can be diagnosed in utero are best managed by appropriate medical and surgical therapy after delivery at term. The term infant is a better anesthetic and surgical risk than the preterm infant. Examples of such malformations that have been diagnosed in utero are given in Table 1. Although this list is not exhaustive, the majority of neonatal surgical disorders fall into this category. Knowing that a fetus has one of these anomalies may improve perinatal management by allowing preparation for appropriate postnatal care. Therapy for hydramnios and premature labor may be desirable to allow the fetus to remain in utero as long as possible. The delivery can be planned so that appropriate personnel (neonatologist, anesthesiologist, pediatrie surgeon) are available. When the neonate will require highly specialized services, transporting the fetus in situ (maternal transport) may be preferable to postnatal transport of the fragile newborn.

MALFORMATIONS USUALLY MANAGED BY SELECTIVE ABORTION

When serious malformations incompatible with normal postnatal life are diagnosed early enough, the family has the option of terminating the pregnancy. When these malformations are recognized too late for safe termination, the family can be counseled and appropriate postnatal management arranged. Table 2 lists examples of severe anatomic malformations that are considered indications for selective abortion. These anatomic abnormalities join a long list of inherited chromosomal and metabolic disorders that can be diagnosed in utero and may lead to selective abortion.

PRENATAL DIAGNOSIS LEADING TO EARLY DELIVERY

Early delivery may be indicated for certain fetal anomalies that require correction as soon as possible after diagnosis (Table 3). In each of these cases, the risk of premature delivery must be weighed against the risk of continued gestation. This approach has already proven beneficial in managing the fetus with hydrops fetalis and intrauterine growth retardation. Recent advances in stimulating fetal surfactant production with corticosteroids, and in ventilating small babies, have greatly improved the outcome for premature infants with respiratory distress syndrome.

Table

Congenital Obstructive Hydrocephalus

Another simple obstructive lesion with severe developmental consequences is obstructive hydrocephalus secondary to stenosis of the aqueduct of Sylvius. Here, obstruction to the flow of CSF produces back pressure that dilates the ventricles, compresses the developing brain, and eventually destroys neurological function. Decompressing the ventricles may reverse the adverse effects of high-pressure hydrocephalus and allow development to proceed normally.3 The obstructed CSF could be repeatedly aspirated or shunted into the amniotic fluid by means of a small one-way catheter placed by either surgical or sonographically guided percutaneous techniques.'7

There are significant problems in managing the fetus with ventriculo megaly discovered by ultrasonogram. First, the dilated ventricles may not be due to simple obstruction to the flow CSF, but instead may be one part of a more extensive intrinsic central nervous system malformation. Ventricular drainage would not be expected to benefit the fetus with non-obstructive ventricular dilation. Second, even for true obstructive hydrocephalus,…

Fetal anatomy, normal and abnormal, can now be accurately delineated by ultrasonography and other imaging techniques. Although some fetal malformations with a known pattern of inheritance may be specifically sought, many are identified serendipitously during obstetric ultrasonography. Until recently, the only question raised by the prenatal diagnosis of a fetal malformation was whether the fetus should be aborted, but other therapeutic alternatives are becoming available. The detection of a fetal abnormality may now lead to a change in the timing of delivery, a change in the mode of delivery, and even prenatal treatment. We have tentatively outlined the diagnostic and therapeutic alternatives for the management of specific fetal malformations that can be recognized in utero.1

MALFORMATIONS BEST TREATED AFTER TERM DELIVERY

Most correctable malformations that can be diagnosed in utero are best managed by appropriate medical and surgical therapy after delivery at term. The term infant is a better anesthetic and surgical risk than the preterm infant. Examples of such malformations that have been diagnosed in utero are given in Table 1. Although this list is not exhaustive, the majority of neonatal surgical disorders fall into this category. Knowing that a fetus has one of these anomalies may improve perinatal management by allowing preparation for appropriate postnatal care. Therapy for hydramnios and premature labor may be desirable to allow the fetus to remain in utero as long as possible. The delivery can be planned so that appropriate personnel (neonatologist, anesthesiologist, pediatrie surgeon) are available. When the neonate will require highly specialized services, transporting the fetus in situ (maternal transport) may be preferable to postnatal transport of the fragile newborn.

MALFORMATIONS USUALLY MANAGED BY SELECTIVE ABORTION

When serious malformations incompatible with normal postnatal life are diagnosed early enough, the family has the option of terminating the pregnancy. When these malformations are recognized too late for safe termination, the family can be counseled and appropriate postnatal management arranged. Table 2 lists examples of severe anatomic malformations that are considered indications for selective abortion. These anatomic abnormalities join a long list of inherited chromosomal and metabolic disorders that can be diagnosed in utero and may lead to selective abortion.

PRENATAL DIAGNOSIS LEADING TO EARLY DELIVERY

Early delivery may be indicated for certain fetal anomalies that require correction as soon as possible after diagnosis (Table 3). In each of these cases, the risk of premature delivery must be weighed against the risk of continued gestation. This approach has already proven beneficial in managing the fetus with hydrops fetalis and intrauterine growth retardation. Recent advances in stimulating fetal surfactant production with corticosteroids, and in ventilating small babies, have greatly improved the outcome for premature infants with respiratory distress syndrome.

Table

TABLE 1MALFORMATIONS DETECTABLE IN UTERO BUT BEST CORRECTED AFTER DELIVERY AT TERM

TABLE 1

MALFORMATIONS DETECTABLE IN UTERO BUT BEST CORRECTED AFTER DELIVERY AT TERM

Table

TABLE 2MALFORMATIONS USUALLY MANAGED BY SELECTIVE ABORTION

TABLE 2

MALFORMATIONS USUALLY MANAGED BY SELECTIVE ABORTION

The rationale for early correction is unique to each anomaly, but the principle remains the same: continued gestation would have a progressive ill effect on the fetus. In some cases, the function of a specific organ system is compromised by the lesion and will continue to deteriorate until the lesion is corrected. In congenital hydronephrosis, unrelieved urinary tract obstruction results in progressive deterioration of renal function. Preterm delivery for early decompression of the urinary tract should reverse the renal maldevelopment at the earliest possible time and thus maximize subsequent renal growth and development.2 In obstructive hydrocephalus, high intra ventricular pressure compresses the developing brain. Early delivery for ventricular decompression should maximize the opportunity for subsequent brain development and may avoid the difficult obstetric problem of delivering a baby with an abnormally large head.'

Anomalies associated with progressive organ ischemia should be corrected as soon as possible. Volvulus associated with intestinal malrotation or meconium ileus may lead to intestinal gangrene, perforation and meconium peritonitis. Eariy delivery for correction of this type of bowel lesion would be aimed at minimizing the amount of bowel lost to the ischemie process. In some malformations, the progressive ill effects on the fetus result directly from being in utero. In the amniotic band complex, a fetal part is compressed or strangulated by herniation through a defect in the fetal membranes, resulting in amputation or deformity. This simple mechanical restriction to growth and development should be relieved at the earliest possible time to prevent further deformity. In ruptured omphalocele or gastroschisis, the bowel exposed to amniotic fluid becomes coated with a thick, fibrous inflammatory peel that may hinder repair and delay resumption of function. Early delivery should minimize the damage by shortening the time the bowel is exposed to the amniotic fluid.

PRENATAL DIAGNOSIS LEADING TO CAESAREAN DELIVERY

Elective caesarean delivery rather than a trial at vaginal delivery may be indicated for the fetal malformations listed in Table 4. In most cases, this is because the malformation would cause dystocia. Another indication for elective caesarean delivery is a malformation requiring immediate surgical correction best performed in a sterile environment. Examples are a ruptured omphalocele or an uncovered meningomyelocele. In this circumstance, the baby can be resuscitated in an adjacent sterile operating room and undergo immediate surgical correction. Finally, a caesarean delivery may be required if preterm delivery of an affected fetus is elected but labor is inadequate or the fetus does not tolerate labor as determined by fetal monitoring.

PRENATAL DIAGNOSIS LEADING TO INTERVENTION BEFORE BIRTH

Fetal Deficiencies

Some fetal deficiency states may be alleviated by treatment before birth (Table 5). In respiratory distress syndrome, glu coco rt ico ids given to the mother increase deficient fetal pulmonary surfactant and alleviate the disease. Fetal anemia secondary to isoimmunizationinduced hemolysis can be treated by transfusing red blood cells into the fetal peritoneal cavity. We have treated severe hydrops by administering digitalis and diuretics along with the blood. A fetus with vitamin Bi2-responsive methylmalonic acidemia has been treated in utero by giving massive doses of Bi2 to the mother. A fetus with biotin-dependent multiple carboxylase deficiency has been treated by giving the mother pharmacologie doses of biotin during the last half of pregnancy.

Table

TABLE 3MALFORMATIONS WHICH MAY REQUIRE INDUCED PRE-TERM DELIVERY FOR EARLY CORRECTION EX UTERO

TABLE 3

MALFORMATIONS WHICH MAY REQUIRE INDUCED PRE-TERM DELIVERY FOR EARLY CORRECTION EX UTERO

Table

TABLE 4MALFORMATIONS WHICH MAY REQUIRE CAESAREAN DELIVERY

TABLE 4

MALFORMATIONS WHICH MAY REQUIRE CAESAREAN DELIVERY

Table

TABLE 5MALFORMATIONS WHICH MAY REQUIRE TREATMENT IN UTERO

TABLE 5

MALFORMATIONS WHICH MAY REQUIRE TREATMENT IN UTERO

Medications and nutrients injected into the amniotic fluid are swallowed and absorbed by the fetus. Intraamniotic thyroid hormone can be used to treat congenital hypothyroidism and goiter and to help mature the fetal lung. The intrauterine growth-retarded fetus might be fed orally by instilling nutrients into the amniotic fluid.4

Anatomic Malformations

Correcting an anatomic malformation in utero is more difficult than providing a missing substrate, hormone, or medication to the fetus. The only anatomic malformations that warrant consideration are those that interfere with fetal organ development and that, if alleviated, would allow normal fetal development to proceed. At present, only three anatomic malformations deserve consideration, although others (eg, some rare cardiopulmonary lesions) may become candidates as their path o physiology is unraveled.5

Congenital Hydronephrosis

Congenital hydronephrosis secondary to urethral obstruction is an excellent example of an anatomically simple lesion that has devastating consequences on the developing fetus that may be prevented by correction before birth. Fetal hydronephrosis is being recognized with increasing frequency because fluid-filled masses are particularly easy to detect by sonogram and because associated oligohydramnios is a common obstetric indication for sonography. We have now managed more than 24 fetuses with urinary tract malformations. From this experience we have developed an approach based on the predictable pathophysiological consequences of obstruction on renal and pulmonary development.2'6 The algorithm is presented in Figure 1.

If a renal cystic mass is suspected, it is important to distinguish multicystic dysplasia from hydronephrosis, because the renal functional damage associated with dysplasia is irreversible, while that secondary to obstruction is potentially reversible if the obstruction can be relieved. Although severe dysplasia associated with obstruction very early in fetal life may sometimes be difficult to distinguish from hydronephrosis, by the third trimester advanced dysplastic lesions can usually be distinguished by morphologic features and function from simple reversible hydronephrosis.

Figure 1. Suggested treatment of fetus with urinary tract malformation based on prenatal sonographic assessment of urinary tract anatomy and function: asterisk, renal function inferred from volume of amniotic fluid and volume of urine in fetal bladder; dagger, sonographic assessment of fetal urine production bladder-filling, amniotic fluid volume) after giving furosemide to mother.

Figure 1. Suggested treatment of fetus with urinary tract malformation based on prenatal sonographic assessment of urinary tract anatomy and function: asterisk, renal function inferred from volume of amniotic fluid and volume of urine in fetal bladder; dagger, sonographic assessment of fetal urine production bladder-filling, amniotic fluid volume) after giving furosemide to mother.

The most important clinical consideration is the effect of the malformation on renal function. We have found that fetal renal function can be inferred to some extent from the volume of amniotic fluid and the presence or absence of urine in the bladder. Oligohydramnios is probably the most important indicator of functional impairment. Since fetal urine is a major source of amniotic fluid in late pregnancy, it is not surprising that oligohydramnios accurately reflects decreased fetal urine excretion and that normaî amniotic fluid volume accurately predicts the presence of at least one functioning kidney. Fetal urine output can also be estimated from real-time sonographic assessment of bladder filling and emptying. Inability to visualize the bladder on a routine sonogram does not in itself mean that fetal urine output is reduced, since the fetus may have recently voided. However, failure to visualize the bladder over a period of hours, especially after provoking fetal diuresis by giving furosemide to the mother, strongly suggests absence of adequate functioning* renal tissue. More detailed functional and anatomic information can be obtained by aspiration of fetal urine under sonographic guidance. Urine production might then be measured directly, urine composition determined and a fetal cystogram or pyelogram obtained.

When the findings suggest a unilateral multicystic kidney with adequate contralateral function, the fetus can be followed to term, for intervention even after birth is not urgent. When the prenatal findings suggest a severe bilateral dysgenetic or agenetic malformation that is incompatible with normal postnatal life, the family can be counseled and the pregnancy terminated or the neonate allowed to die without emotionally and financially draining family members.

When the prenatal findings suggest urinary tract obstruction, intervention may be necessary because unrelieved urinary tract obstruction interferes with fetal development, and the severity of damage depends on the degree and duration of obstruction. Although children born with partial obstruction may have only mild hydronephrosis, which is reversible with decompression after birth, children born at term with high-grade obstruction may already have advanced hydronephrosis (type IV cystic disease) that is incompatible with life. In addition, oligohydramnios secondary to fetal urinary tract obstruction is associated with pulmonary hypoplasia as well as skeletal, facial, and abdominal wall deformities. The pulmonary hypoplasia may be severe enough to prevent survival.2,6,7

In advanced cases with severe oligohydramnios, it may be necessary to relieve the obstruction as early as possible to avert the progressive destructive consequences of obstruction and to allow normal development to proceed.2'6 There are several alternatives for decompressing the obstructed fetal urinary tract. The fetal bladder or renal pelvis can be aspirated percutaneously under sonographic guidance, but this offers only temporary relief, since the fetus makes a large amount of urine (greater than 5 ml/ kg/ hr) and will refill the bladder within hours. Early delivery can be electively induced so the urinary tract can be decompressed ex utero. Preterm delivery for early decompression would maximize the opportunity for further renal development and minimize the adverse effects of oligohydramnios. The disadvantage of preterm delivery, fetal pulmonary immaturity, can be ameliorated by administration of corticosteroids to the mother before delivery. The efficacy of this approach has now been demonstrated in ten of our cases.

Physiologically, the ideal management of fetal urinary tract obstruction is early decompression of the urinary tract and continued gestation. Transurethral or suprapubic drainage of urine from the bladder into the amniotic fluid would not only decompress the urinary tract and allow renal development to proceed, but would also restore normal amniotic fluid dynamics and thus prevent oligohydramnios and its severe sequelae.

In utero correction is feasible. We have developed techniques for sonographically guided percutaneous placement of fetal shunt catheters and for surgical exteriorization of the fetal urinary tract. After we had studied the pathophysiology in a fetal lamb model,8'9 and established efficacy, feasibility, and safety in the more rigorous fetal monkey model,10 we began to apply these techniques clinically in a few highly selected cases. In a male fetus (one of twins) with urethral obstruction, an indwelling suprapubic catheter was placed percutaneously under sonographic control' ! (Figure 2). This technique has been refined and used for diagnosis and treatment of a wide variety of fetal urinary tract obstructions at the Fetal Treatment Program at UCSF.6 Open surgical decompression (bilateral fetal ureterostomies via hysterotomy) has also proven feasible.12 This more formidable technique requires extensive preparation in the non-human primate.

Congenital Diaphragmatic Hernia

Another fetal malformation that may require correction before birth is congenital diaphragmatic hernia. Although this simple defect is easily correctable in the neonatal period by removing the herniated viscera from the chest and closing the defect in the diaphragm, 50% to 90% of these infants die of pulmonary insufficiency because the lung compressed by the herniated viscera is hypoplastic." To allow the lung to grow and develop enough to support life at birth, the pulmonary compression must be relieved before birth. We have demonstrated in fetal lambs that compression of the fetal lung during the last trimester results in fatal pulmonary hypoplasia and that removal of the compressing lesion allows the lung to grow and develop sufficiently to reverse the fatal pulmonary hypoplasia and allow survival at birth.14'15 Congenital diaphragmatic hernia can be diagnosed in utero, and a technique for successful surgical correction in utero has been developed experimentally. lfi This is illustrated in Figure 3. Correction of diaphragmatic hernia is by far the most difficult of all procedures contemplated to date. It should not be attempted until the necessary skill is developed and success achieved in a rigorous animal model.

Figure 2. Artist's rendition ot catheter placement technique. The catheter is pushed off the needle so that the curled end is in the fetal bladder and the flared end is in the amniotic cavity.

Figure 2. Artist's rendition ot catheter placement technique. The catheter is pushed off the needle so that the curled end is in the fetal bladder and the flared end is in the amniotic cavity.

Figure 3. Technique developed in lambs for correction of CDH in utero. (A) Surgical exposure through a stapled hysterotomy. A screw-in fetal scalp electrode monitors heart rate and variability during surgery. (B) The herniated viscera are reduced, the air in the chest replaced with warm Ringers'lactate, and the diaphragm closed with a single layer of nonabsorbable sutures. (C) The abdomen is enlarged by silastic abdominoplasty, and the uterus closed with staples. Fetal operating time is less than 30 minutes.

Figure 3. Technique developed in lambs for correction of CDH in utero. (A) Surgical exposure through a stapled hysterotomy. A screw-in fetal scalp electrode monitors heart rate and variability during surgery. (B) The herniated viscera are reduced, the air in the chest replaced with warm Ringers'lactate, and the diaphragm closed with a single layer of nonabsorbable sutures. (C) The abdomen is enlarged by silastic abdominoplasty, and the uterus closed with staples. Fetal operating time is less than 30 minutes.

Congenital Obstructive Hydrocephalus

Another simple obstructive lesion with severe developmental consequences is obstructive hydrocephalus secondary to stenosis of the aqueduct of Sylvius. Here, obstruction to the flow of CSF produces back pressure that dilates the ventricles, compresses the developing brain, and eventually destroys neurological function. Decompressing the ventricles may reverse the adverse effects of high-pressure hydrocephalus and allow development to proceed normally.3 The obstructed CSF could be repeatedly aspirated or shunted into the amniotic fluid by means of a small one-way catheter placed by either surgical or sonographically guided percutaneous techniques.'7

There are significant problems in managing the fetus with ventriculo megaly discovered by ultrasonogram. First, the dilated ventricles may not be due to simple obstruction to the flow CSF, but instead may be one part of a more extensive intrinsic central nervous system malformation. Ventricular drainage would not be expected to benefit the fetus with non-obstructive ventricular dilation. Second, even for true obstructive hydrocephalus, the pathophysiologic rationale that decompression will allow improved brain development, although reasonable, has not been tested in an appropriate animal model.

For these reasons, we will continue to manage fetal hydrocephalus conservatively until we have sufficient clinical experience to be confident of the natural history of the disease and our ability to distinguish obstructive hydrocephalus from other forms of ventriculomegaly, and until we can study the pathophysiology in an appropriate animal model. Fetal hydrocephalus continues to be an area of intense experimental and clinical investigation at our Fetal Treatment Program.3'18

THE IMPACT OF FETAL THERAPY ON PRENATAL DIAGNOSIS

The potential for correction of some fetal malformations gives new importance to the rapidly developing field of prenatal diagnosis. Many fetal malformations are detectable in utero. In some cases, prenatal diagnosis will not alter management; some cannot be corrected, and most of the correctable lesions are best treated after normal term delivery. However, a few are amenable to treatment before term. Since their recognition will influence management of the pregnancy, prenatal diagnosis of these disorders assumes practical clinical importance.

Therapeutic decisions will require a thorough evaluation of the fetus beyond accurate anatomic definition of the malformation being considered for therapy.1 Since it is known that malformations often occur as part of a syndrome, a search for associated abnormalities is necessary to avoid delivering a neonate with one corrected anomaly but other unrecognized disabling or lethal abnormalities. Real-time sonographic evaluation may yield important information on fetal breathing, movements, and vital functions. Amniocentesis allows culture of amniotic fluid cells for detection of chromosomal defects and inherited metabolic abnormalities, evaluation of fetal pulmonary maturity from lecithinsphingomyelin analysis, and detection and quantitation of fetal hemolysis. Fetoscopy allows direct fetal visualization, fetal skin biopsy, and fetal blood sampling for diagnosis of hemoglobinopathies and other hematologic diseases. Amniography affords further definition of fetal anatomy, including the fetal GI tract. Finally, fluid collections in the fetus (including blood, urine, ascites, CSF) can be aspirated under real-time sonographic guidance for both diagnosis and therapy. The technique, in our experience, has proven safe and relatively simple.

In considering the ethical problems raised by fetal therapy, one clearly positive aspect is that prenatal diagnosis of a fetal malformation may now lead to treatment rather than abortion. However, the possibility of diagnosing and treating fetal disorders raises important questions about the rights of the mother and fetus as patients.19 Who makes decisions for the fetus? How can the risk of intervention be weighed against the burden of the malformation itself?

ASSESSING RISK AND BENEFIT

Fetal therapy raises complex medical and ethical issues. The first problem is defining the benefits and risks of fetal diagnosis and treatment. For the fetus, the risk of the procedure is weighed against the possibility of correction or amelioration of the malformation. The benefit to be derived from correction depends on the severity of the malformation and its predictable consequences on survival and quality of life (ie, on the natural history of the disease). Assessing the risks and benefits for the mother is more difficult. Most fetal malformations do not directly threaten the mother's health, yet she must bear some risk from the procedure. She may choose to accept the risk to aid her unborn baby and increase his prospects for a normal life and alleviate her own burden in carrying and preparing to raise a child with a severe malformation.

The risks involved in fetal diagnosis and treatment are generally greater for the fetus than the mother and vary greatly according to the magnitude and invasiveness of the procedure.1 Sonography carries no known risk. Amniography poses an increased risk of radiation exposure. Puncture of the amniotic cavity poses a small risk of fetal injury or loss. With appropriate equipment and expertise, fetoscopy, fetal blood sampling, and puncture of the fetal abdomen for intrauterine transfusion can be performed with acceptable risk. We have experience with sonographically guided aspiration of fetal ascites, pleural fluid, urine, and CSF, but insufficient experience to judge risk adequately. The risk to fetus and mother of more extensive manipulation, such as placement of shunt catheters using sonographically guided percutaneous techniques or direct surgical exposure of the fetus by hysterotomy, is not known. Until recently, experience with surgical exposure of the human fetus was limited to catheterization of fetal vessels for exchange transfusion.20 The greatest known risk of any fetal manipulation is induction of preterm labor and delivery. Although this remains the principal deterrent to fetal intervention, the pharmacologie control of uterine contractility with betamimetic drugs and prostaglandin synthetase inhibitors is improving. The electrophysiology of uterine muscle and the role of hormones, prostaglandins, and various tocolytic agents in preventing or controlling labor are areas of active investigation. 10

THE FUTURE OF FETAL TREATMENT

The pathophysiologic arguments for fetal intervention are compelling, but extreme caution must be exercised in undertaking any new fetal manipulation. Extensive experience with fetal surgery in laboratory animals may not be readily translatable to the human. Survival after fetal surgery is easy to achieve in sheep but much more difficult in primates, where premature labor is often difficult to control. Certainly, repair of human fetal malformations should not be undertaken until competence and a high degree of success are achieved in a primate model. Recent advances in anesthetic and surgical technique and pharmacologie control of labor may soon make this feasible.

Since the more invasive diagnostic and therapeutic procedures involve significant risks, a great deal of clinical and laboratory experience will be required to establish which are truly safe and feasible. In the meantime it is important to maintain a healthy skepticism about fetal treatment. Because a procedure can be done does not mean that it should be done. At this very early stage, fetal intervention should be pursued only in centers committed to research and development as well as (and prior to) responsible clinical application. Presently, the minimum requirements for fetal intervention include the cooperative efforts of an obstetrician experienced in prenatal intervention, a sonographer experienced and skilled in fetal diagnosis, a surgeon experienced in operating on tiny preterm infants and in performing fetal procedures in the laboratory, a perinatologist working in a high-risk obstetrical unit associated with a tertiary intensive care nursery, a reasonable and compassionate bioethicist, and uninvolved professional colleagues who will monitor such innovative therapy (ie, a committee on human research). Since there is considerable potential for doing harm, a fetal abnormality of any type should never be treated simply "because it is there," and never by someone unprepared for this fearsome responsibility. The responsibility of those undertaking fetal therapy includes an obligation to report to the medical profession all results, good or bad, so that the merits and liabilities of fetal treatment can be established as soon as possible.

Our ability to diagnose fetal birth defects has achieved considerable sophistication. Treatment of several fetal disorders has proven feasible, and treatment of more complicated lesions will undoubtedly expand as techniques for fetal intervention improve.

REFERENCES

1. Harrison MR, Golbus MS. Filly RA: Management of lhe fetus with a correctable congenital defect. JAMA 1981; 246:774-777.

2. Harrison MR, Filly RA, Parer JT, et at: Management of the fetus with a urinary iracl malformation. JAMA 1981; 246:635-639.

3. Nakayama DK, Harrison MR, Edwards MS, et al: Management of t he fetus with a CNS malformation, unpublished data.

4. Harrison MR, Villa R: Trans-amniotic fetal feeding. I. Development of an animal model: Continuous amniotic infusion in rabbits. J Pediatr Surg 1982; 17:376-380.

5. Turley K, V Ia hakes GJ. Harrison MR, et al: Intrauterine card io thoracic surgery: The fetal lamb model. Ann Thorac Surg. to be published.

6. Harrison MR. Golbus MS, Filly RA, el al·. Management of the ielus with congenital hydronephrosis. J Pediair Surg. to be published.

7. Nakayama DK, Harrison MR. de Lorimier AA: Fetal urethra! obstruction: The hidden mortality, unpublished data.

8. Harrison MR. Ross NA, Noall R, et al: Correction of congenital hydronephrosis in utero. 1. The model: Fetal urethral obstruction produces hydronephrosis and pulmonary hypoplasia in fetal lambs. J Pediatr Surg, to be published.

9. Harrison MR, Nakayama DK, Noall R, et al: Correction of congenital hydronephrosis in utero. II. Decompression reverses the effects of obstruction on the fetal lung and urinary tract. J Pediatr Surg, to be published.

10. Harrison MR, AndersonJ, Roseti MA, et al: Fetalsurgery in the primate. L Anesthetic, surgical and tocolytic management to maximize fetal- neo natal survival. J Pediair Surg 1982; 17: 1 15-122.

11. Golbus MS, Harrison MR, Filly RA. et al: In utero treatment of urinary tract obstruction. Am J Obsiet Gynecol 1982; 142:383-388.

12. Harrison MR, de Lorimier AA: Congenital diaphragmatic hernia. Surg hydronephrosis. ?1 Eng I J Med 1982; 306:591-593.

13. Harrison MR. de Lorimier AA: Congenital diaphragmatic hernia. Surg Clin North Am 1981:61:1023-1035.

14. Harrison MR, Jester JA, Ross NA: Correction of congenital diaphragmatic hernia in utero. L The model: lntrathoracic balloon produces fatal pulmonary hypoplasia. Surgery 1980; 88:174-182.

15. Hairison MR, Bressack MA. Chvug AM, et al: Correction of congenital diaphragmatic hernia in utero. IL Simulated correction permits fetal lung growth with survival at birth. Surgery 1980; 88:260-268.

16. Harrison MR, Ross NA. de Lorimier AA: Correction of congenital diaphragmatic hernia in utero. III. Development of a successful surgical technique using abdominoplasty to avoid compromise of umbilical blood now. J Pediair Surg 1981; 16:935-942.

17. Clewell WH, Johnson ML, Meier PR, et al: A surgical approach io the treatment of fetal hydrocephalus. N Engt J Med 1982; 306:1320-1325.

18. Nakayama DK, Harrison MR1 Berger MS. et al: Correction of congenital hydrocephalus in utero. I. The model: I nt racist er nal Kaolin produces hydrocephalus in fetal lambs. J Pediatr Surg, to be published.

19. Fletcher JC: The fetus as pattern: Ethical issues. JA MA 1981; 246:772-773.

20. Harrison MR: Unborn: Historical perspective of the fetus as a patient. Pharos 1982; 45:19-24.

TABLE 1

MALFORMATIONS DETECTABLE IN UTERO BUT BEST CORRECTED AFTER DELIVERY AT TERM

TABLE 2

MALFORMATIONS USUALLY MANAGED BY SELECTIVE ABORTION

TABLE 3

MALFORMATIONS WHICH MAY REQUIRE INDUCED PRE-TERM DELIVERY FOR EARLY CORRECTION EX UTERO

TABLE 4

MALFORMATIONS WHICH MAY REQUIRE CAESAREAN DELIVERY

TABLE 5

MALFORMATIONS WHICH MAY REQUIRE TREATMENT IN UTERO

10.3928/0090-4481-19821101-08

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