Biomedical Ethics and Fetal Therapy

2. Fetal Therapy: State of the Art

2 FETAL THERAPY: STATE OF THE ART Carl Nimrod, Alan Cameron, Dawn Davies, Joyce Harder, Stuart Nicholson The relative impact of congenital disease on perinatal mortality has increased rapidly over the last few years as the standard of perinatal care and neonatal resuscitative events improve. Imaging techniques such as x-rays and amniograms have been useful in the evaluation of fetal anatomy. Currently ultrasound provides visual access to the fetus and this window allows an assessment of fetal structure and in a more limited sense fetal function and behaviour (thumb-sucking, eye movements, and swallowing)1. Information previously unavailable is now "seen" ultrasonically and filtered through an observer and interpreted with varying degrees of accuracy . There is potential for a substantial number of problems to occur and several areas of concern must be addressed as the impact of this new technology is being assessed. These include: 1. How accurate is the scan? a. This must be judged in the context of the test-retest reliability . b. What are the positive and negative predictive values? 2. Patient benefit a. Does it result in improved function, lessened disability or better survival? b. Does it allow better monitoring of a specific therapy, such as cardiac arrhythmias? c. Is the mother more satisfied or reassured? 3. Risk Both maternal and fetal risks must be assessed. U. Influence on physician decision-making and confidence in decisionmaking . 5. Availability of the special skill in terms of its relative magnitude of need. 6 Biomedical Ethics and Fetal Therapy However, the significant improvements in imaging have led to an escalation in the number of fetal anomalies diagnosed by high resolution ultrasound. In addition to this, an overwhelming desire has arisen in well-meaning physicians to intervene and alter the course of the pregnancies. Lessons have had to be learned about the need to be certain about the diagnosis, about the possibility that some "conditions" might spontaneously disappear, and about the possibility that treatment may sometimes do more harm than good. It is also of historical significance that the first reports of fetal 2 transfusion by Liley and of steroid therapy for lung maturation by Liggins, both milestones in fetal therapy, were made at scientific meetings and faced the scrutiny of the scientific community rather than the lights of prime-time network television. It is also now apparent that the concept of fetal therapy cannot be ignored, and more precisely it means maternal-fetal therapy. There are maternal rights which must be recognized before the patient and her fetus can be subjected to treatment. This chapter will focus on four fetal conditions requiring therapy with particular emphasis on the establishment of the diagnosis, natural history of the disorder, therapeutic options, and maternal-fetal risks. A flow diagram is also presented (Figure 1) as a guide to decision-making when a particular case is under consideration for therapy. Fetal Urinary Tract Obstruction Diagnosis Fetal urinary tract malformations are being recognized with increasing frequency because fluid-filled masses are particularly easy to detect with ultrasound. Most fluid-filled abdominal masses in the fetus and neonate involve the urinary tract. Other cystic lesions (ovarian cysts, meconium pseudocyst, dilated bowel loops) can usually be distinguished by their location and the identification of normal renal anatomy. The major entities causing fetal hydronephrosis (dilatation of the urinary tract) include ureteropelvic junction obstruction, posterior urethral valves, and ectopic ureterocele. Ureteropelvic junction (UPJ) obstruction is the commonest cause of neonatal hydronephrosis. If it is unilateral, a normal amount of amniotic fluid is usually seen and the ureters are non-dilated and therefore not visualizable. The fetal urinary bladder should be easily Nimrod et al. / Fetal Therapy: State of the Art 7 visualized as it fills and empties appropriately. Bilateral UPJ obstruction which occurs in approximately 30 percent of affected n infants is a much more severe condition in which the renal pelvis is dilated bilaterally and amniotic fluid volume is decreased. Posterior urethral valves (PUV) are the second leading cause of neonatal hydronephrosis. The condition occurs exclusively in males. 54 Severely affected fetuses are readily detected by ultrasound and show several or all of the following symptoms: oligohydramnios, dilated and thick-walled urinary bladder, hydroureter, hydronephrosis, fetal ascites, and abdominal wall distention. Demonstration of male gender is important since massive urinary tract dilatation in a female fetus would suggest a caudal regression abnormality or urethral stenosis. An obstructed ectopic ureterocele is the third leading cause...