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Question 63: Under what conditions may surgeons attempt to separate Siamese twins?

As a resident in pediatric surgery, I am fascinated by the problem of separating Siamese twins. Eventually, I may have the opportunity to participate in such operations. There seems to be no moral problem in the less challenging cases. The connection between the babies is limited, separating them promises similar benefits to both, the likelihood of success is high, and the risks are minimal. But in many of the more interesting cases, there are moral problems.

Take, for example, the case of Amy and Angela Lakeberg, who were born 29 June 1993 at Loyola University Medical Center in Chicago. Joined at the chest, the babies shared a single liver and an abnormal, six-chambered heart. Because of the way they were joined, they could not breath normally and were soon put on a ventilator. Had they remained together and been given optimum care—an option apparently not thought worth considering by the Loyola ethics consultation committee—it seems they would have had to remain on the respirator and died before long of congestive heart failure. The babies were transferred to Philadelphia Children’s Hospital for surgery to separate them. Though Angela was expected to survive the operation, her prospects were poor. It was doubted that she would ever be able to do without the ventilator and thought likely that she would die without ever leaving the hospital. Amy, the weaker twin, was to die in the operation, since it would deprive her entirely of the shared heart and liver. The surgery was carried out 20 August 1993. After that, Angela’s mother visited her only three times and held her only once; the baby never left the hospital or breathed without the ventilator, and she died 9 June 1994 of pneumonia and cardiorespiratory failure.220

Many other problematic cases differ in various ways from that of the Lakeberg babies. I would be interested in knowing what you think about that case, but my question is more general: How can surgeons identify cases in which they may try to separate Siamese twins?


This question calls for specific norms by which to judge the moral acceptability of surgery to separate conjoined twins. At least three norms apply. First, an attempt to separate conjoined twins is unreasonable unless it is fair to everyone concerned. Second, the attempt is unjust to the babies if the prospective benefits to them are not sufficient to ground the argument for proceeding. Third, an attempt to separate conjoined twins that holds out different prospects for the two babies is unfair to the one whose prospects are poorer unless the detriment to that baby is slight and the benefit to his or her twin considerable. Applied to the case of the Lakeberg twins, each of these three norms would, in my judgment, have been sufficient to exclude the attempt to separate them.

The reply could be along the following lines:

In general, whether it is reasonable to undertake and/or continue a health care measure depends on a consideration of its prospective burdens and benefits. Individuals able to make decisions for themselves rightly refuse health care when they consider the prospective benefits to themselves inadequate to offset the expected burdens to themselves and others; and they unfairly choose measures whose prospective burdens on others they would not judge to be offset by their prospective benefits to themselves if it were a question of burdens on themselves and benefits to strangers. For the sake of prospective benefits to others, individuals may choose out of merciful love of neighbor to undergo experimental measures upon themselves that they could rightly reject as too burdensome. However, nobody may rightly choose experimental measures for a noncompetent person unless the prospective benefits to that very person seem adequate to offset the burdens, including the risks, to him or her.

The preceding general norms can be specified to guide decisions about surgery to separate conjoined twins. First, a surgeon cannot reasonably undertake such an operation unless the prospective benefits to the babies and others are sufficient to offset the burdens to everyone concerned. Second, a surgeon cannot justly try to separate conjoined twins unless the prospective benefits to the babies themselves are sufficient to offset the burdens imposed on them.

Since the prospective benefits and burdens of surgery to separate conjoined twins (like any other sort of health care) are diverse in kind and subject to no common measure, one cannot rationally commensurate them. Norms that seem to require doing that actually call for something else, namely, conscientious judgment, which presupposes excluding unreasonable motives and appraises the cases that can be made for each option.

The application of the two norms stated above in decisions about surgery to separate conjoined twins, therefore, requires that two things be clarified: the unreasonable motives likely to be operative and the intelligible goods, to which one can be rightly committed, involved in the peculiar benefit to the twins of their being separated rather than remaining conjoined.

Saying you are “fascinated by the problem of separating Siamese twins” and characterizing difficult cases as “challenging” and “interesting” point to one possible unreasonable motive that must be excluded. Since surgery requires special gifts and great skill, surgeons, like many other skilled people, take special interest in projects allowing them to innovate, perform outstandingly, improve their professional status, and/or increase their future income. Unlike people who work on subhuman materials, however, surgeons work on human persons and should put their skill entirely at their patients’ service. So, though surgeons are likely to be tempted to treat challenging cases as other creative people treat challenging projects involving subhuman material, the professional commitment to serve patients and patients’ personal dignity both require that surgeons’ interest in professional accomplishment be excluded as an unreasonable motive when considering whether to undertake an operation.

Another motive possibly operative is the prospect of developing surgical technique by experimentation so as to improve the prospects for other pairs of conjoined twins. Insofar as it bears on a genuine benefit, this motive could legitimately be taken into account as offsetting burdens to others (for example, costs to the public), but it cannot legitimately affect the estimation of burdens and benefits to the children themselves, which the second norm stated above requires. Being incapable of self-sacrifice, no pair of conjoined babies may be treated as an opportunity to experiment for others’ eventual benefit.

Surgery to separate conjoined twins sometimes offers a prospect of prolonged survival or improved functioning for both of them or at least one. It also usually enables the two persons to live independently of each other, a genuine benefit inasmuch as remaining conjoined is likely to impede (if not prevent) their efforts to pursue and enjoy various authentic goods, including the intimate communion of marriage and other friendships—not least, that with each other based upon their relationship as brothers or sisters. But the benefit of separation should not be absolutized. Like other serious handicaps, remaining a conjoined twin does not detract from an individual’s personal dignity and need not prevent him or her from living a good and holy life.

With the preceding clarifications in mind, the two norms stated above can be applied to the case of the Lakeberg twins. The burdens of the surgery included the immediate death of the weaker twin, the risk of shortening the life of the stronger twin, suffering for the children and their family, and the use of considerable resources at great expense. The prospective benefits were a slight possibility of significantly prolonging the life of the stronger twin and, perhaps, experience that might be helpful for dealing with similar future cases. The value of the experience was limited, however, for there are very few similar cases in which even the most successful technique could ever be applied.221 Thus, the prospective benefits to everyone concerned were not, in my judgment, sufficient to offset the whole set of burdens, as the first norm requires. I suspect that the decision to proceed partly hinged on a mistaken absolutizing or, at least, overestimation of the benefit of separation and/or an inappropriate interest of the surgeons in this challenging case. Even if the decision did not violate the first norm, however, I think it clearly violated the second, which excludes consideration of prospective benefits except to the babies themselves. There was no prospect of benefit to the weaker baby and very little prospect of benefit to the stronger. The weaker was certain to lose her life at once, the stronger certain to suffer greatly and unlikely to ever enjoy health or leave the hospital.

Besides the general norms for decisions regarding health care, norms of fairness govern actions affecting two persons. In general, apart from cases in which one person has some special duty to sacrifice himself or herself for another’s benefit, it often is unfair to subordinate one person’s interests to those of another—that is, to seek benefits for one at the cost of detriments to the other. How is the judgment of fairness to be made? As usual, by applying the Golden Rule. If one were in the place of one of the persons but did not know which, would one think it plainly reasonable to seek the benefit regardless of whose place one turned out to be in? One very likely would say no unless the prospective benefit to one individual is substantial and the detriment to the other negligible.

So, in a case of conjoined twins, where neither baby can have any duty to the other or be capable of self-sacrifice, a third norm for any attempt to separate them is: If the surgery will not be beneficial to both, it will be unfair to the baby whose prospects are poorer unless the detriment to that baby is slight and the benefit to his or her twin considerable. Therefore, in my judgment, if one baby certainly or probably will not survive the surgery, the attempt will be unfair to that one unless two conditions are met: (1) without the surgery, the abnormality of the babies’ shared organ(s) is likely to result soon in the death of both, and (2) with the surgery, the prospective survivor’s prospects are greatly improved. Since the second condition apparently was not met in the Lakeberg case, I believe that this norm, too, was violated.

Some who commented on the attempt to separate the Lakeberg twins held that it was intrinsically wrong.222 One argument for this view was that, since cutting the shared heart away from the weaker twin deprived her of her blood supply and immediately killed her, killing her was a means to provide an adequate heart for her sister. So, the argument concluded, the attempt to separate these twins involved the intrinsically wrong act of directly killing an innocent person.

I hold that directly killing an innocent human being is always wrong, provided direct killing is understood as killing intended as an end or chosen as a means to some other end (see LCL, 475–79). I also grant that the attempt to separate the Lakeberg twins involved the physically immediate causing of the weaker twin’s death, so that the surgeon directly killed her in the sense that the surgery of itself straightaway brought about her death. However, there is no reason to think the surgeon intended the weaker twin’s death as an end and there was no need to choose her death as a means. The shared heart and liver were not exclusively the organs of either twin; the chosen means to fashion an adequate heart for the stronger was to cut away the shared heart from the weaker and the chosen means to provide a liver from the stronger was to cut it away from the weaker. That, of course, resulted in her death, but her death was an effect of chosen means that in no way contributed to the end sought.223 Therefore, in my judgment, the operation was not intrinsically wrong as it would have been had it involved a choice to kill the weaker twin. Nevertheless, as explained above, the surgery did involve the wrongful killing of the weaker twin inasmuch as the surgeon should not have accepted her death, there being little chance the operation would significantly benefit her sister.

To challenge my view that the operation to separate the Lakeberg twins did not involve the intrinsically wrong choice to kill the weaker, someone might propose the following argument. Suppose identical twins who were not conjoined were born afflicted with similar heart defects, so that neither was likely to survive without heart surgery, and suppose the surgeon removed the weaker twin’s heart and used it to fashion a more adequate heart for the stronger. Since the weaker baby’s death, though an effect of removing his or her heart, would in no way contribute to the end sought, even this operation would not involve the intentional killing of an innocent human being. Yet, the argument would proceed, removing the weaker baby’s heart surely would be intrinsically wrong; if not, there would be nothing wrong in transplanting vital organs from dying persons without waiting for them to die. So, the argument would conclude, the attempt to separate the Lakeberg twins did involve a choice to kill the weaker.

I concede that on my analysis removing the weaker twin’s heart and transplanting vital organs from dying persons would not necessarily involve intentional killing. But I maintain that such operations would be intrinsically wrong, since they would involve an intentional violation of functional bodily integrity. The surgery would involve two distinct procedures: (1) to take from certain persons organs needed for some function, and (2) to give those organs and their functioning to others. The first procedure would be chosen as a means, and the choice would include depriving persons of a function. By contrast, separating the Lakeberg twins involved only a single procedure: cutting away the stronger twin, together with the heart and liver both babies had shared, from her weaker sister. So, it seems to me, the operation did not involve intending the violation of the weaker twin’s bodily integrity, but only accepting her being deprived of her share in organs that had been parts of both her sister and herself.224

In sum, the attempt to separate the Lakeberg twins involved, in my judgment, neither intentional killing of the weaker baby nor intentional violation of her bodily integrity, and was not intrinsically wrong. However, the operation failed to satisfy three other relevant norms, largely because there was little prospect of benefit even to the stronger baby. Therefore, I think similar surgery could be morally acceptable in a case in which, without it, both children probably would soon die, while with it one of them probably would survive indefinitely.

220. The history of the case is drawn from David C. Thomasma et al., “The Ethics of Caring for Conjoined Twins: The Lakeberg Twins,” Hastings Center Report, 26:4 (July–Aug. 1996): 4–12. This article is not well written, and I cannot recommend the ethical analysis attempted in it.

221. Ibid., 5.

222. See, e.g., Albert S. Moraczewski, O.P., “What Nature Has Misjoined Together,” Ethics and Medics, 18:11 (Nov. 1993): 1–2, who asserts (2) what I deny: “In effect, the heart is taken from one individual and given to another,” and proceeds by (what I will argue is an unsound) analogy with taking a vital organ from one nonconjoined twin and giving it to another.

223. See LCL, 470–74. William B. Smith, “A Single Heart?” Homiletic and Pastoral Review, 94:6 (Mar. 1994), 68, says: “That death is perhaps not directly intended as an ‘end,’ but it is surely foreseen and intended as a ‘means,’ as a necessary and causative condition of the hoped-for outcome here.” However, had a suitable heart and liver been available and been transplanted to the weaker twin, she might have survived; if so, that would have had no effect whatsoever on the hoped-for outcome for the stronger twin. Therefore, though no such transplant was attempted, the death of the weaker twin was not a necessary and causative condition of the operation’s success.

224. Moraczewski, op. cit., 1, says: “But in that very same procedure, the other twin is deprived of her rightful share of the single heart”; Smith, op. cit., 68, says: “But, this causal act does deprive the other twin of her rightful share of the single heart, and the same act does cause her death.” But precisely the point at issue is whether the weaker twin had a rightful share of a single heart inadequate to sustain both persons and whether causing her death was intended or only accepted as a side effect.