|Screening for Down's Syndrome|
William I. Cohen, MD
Peer Review Status: n/a
As you read this review, I want you to understand my bias from the outset. As a Developmental-Behavioral Pediatrician who directs the Down Syndrome Center of Western PA (Pittsburgh), I am extremely sensitive to assumptions regarding the worth of individuals with disabilities. Having been involved in the care of over 500 infants, children, adolescents and adults with Down Syndrome (DS), the fundamental premise of this work, articulated in Chapter 1, is abhorrent to me. EB Hook discusses the impact of the disorder upon society, posing the question: 'why should society screen?' The answer is as follows: DS makes a major contribution to the proportion of the population with mental retardation. In addition to mental retardation, the author notes that other malformations and conditions such as leukemia place 'a disproportionate burden on medical delivery systems.' Medical advances and social changes have resulted in individuals receiving more intensive and effective medical and surgical therapy, which has had the effect of prolonging life and changing the life span. He warns that the "economic impact of those affected who are born with the condition is likely to increase." (p 2)
Hook quotes a 1985 study which estimates that the excess cost to society of each DS child "over and above that of a normal child' to be $ 144,000. This leads to the calculation that in the USA, 'society could justify (economically) spending up to $180 of such (1985) dollars for each pregnancy screened to detect and prevent a case."(2)
This book is described as an "essential source of information for all those involved in prenatal diagnosis and the provision of obstetric care." However, the editors appear to believe society should undertake the detection of fetuses with DS in order to terminate these pregnancies. "The objective of the public health professional is to reduce the prevalence of Down's Syndrome in a cost effective manner that is acceptable to society.....AII studies have softened their end points by referring to detection and not termination rates. Some 8% of women would decide to continue the pregnancy in the knowledge that they have a Down's syndrome fetus." (27)
In Chapter 2, Mary Macintosh discusses the perception of risk. She seems to perceive that the birth of a child with DS is invariably negative, and consequently appears unable to understand why parents may not choose to selectively abort a fetus with DS. This, then, would seem to reflect the difference between obstetrician-gynecologists, geneticists, and biochemists, on the one hand, and my pediatric colleagues, on the other, who serve in positions similar to mine around the world. Meeting families of children with DS, watching these children grow from infants to adolescents can not help but have a profound effect on one's understanding of human potential. DS does not seem like a problem that needs to be solved, once and for all, but rather, a condition that needs to be dealt with on an ongoing lifelong basis.
The various chapters review the current state of biochemical screening methods, and discuss newly emerging techniques such as first trimester transvaginal ultrasonography. The possibility of isolated fetal cells from the maternal blood offers the possibility of identifying sex chromosome abnormalities, as well as trisomies 13, 18, and 21.
Buried at the back of the this volume in Chapter 20, is a description of the training necessary for obstetricians and midwives in order to appropriately offer serum screening for DS. TM Marteau has studied this area extensively, and appreciates the dilemmas. "Technical competence at prenatal screening for DS has outstripped our knowledge of how best to provide such services." (282) "No matter how good a test, screening of uninformed patients by unprepared staff is a recipe for confusion or sometimes disaster. This is potentially avoidable." (283)
Marteau's studies have documented differences in outcome of counseling. "Obstetricians are more likely to counsel directly, particularly in the direction of terminating the pregnancy. With DS, for example, a marked discrepancy was evident between the approaches taken by obstetricians, geneticists, and genetic counselors: 32% of obstetricians, 57% of geneticists and 94% of genetic counselors reported counseling non-directively, defined in this study as presenting positive and negative aspects of the condition equally." (278)
Furthermore, Marteau documents the significant psychological morbidity that occurs when parents terminate a pregnancy because the fetus is malformed or abnormal: the grief reaction is prolonged and much more severe than when the pregnancy is terminated for nonmedical reasons. This explains why some parents chose to carry infants to term with anencephaly, rather than terminate the pregnancy.
Screening for Down's Syndrome needs to be read in conjunction with Michael Bérubé's recently published description of Jamie, his son with DS. Life as We Know It: A Father, a Family and an Exceptional Child (Pantheon, 1996) eloquently describes the emotions of an educated couple who confront DS, not through abstract notions of risk, but in the person of their premature infant son with DS. As we watch Jamie grow, and learn to walk, and attend preschool with typical children, we share Bérubé's musings on how he, his wife, and his older son make sense of this event.
Dealing as we do with children and their families, in all their variations, readers of this Newsletter will doubtless be moved and delighted by Jamie's trials, false starts, and triumphs. I fear, however, that few of the authors of Screening for Down's Syndrome would experience these emotions. Rather, they would likely wonder how more effective screening protocols would have precluded Michael Bérubé's need to tell his story.