Antenatal diagnosis of a severe congenital malformation leads to grief, sadness, and anger. Conditions with the poorest prognosis are often described as “lethal,” a term used to convey the seriousness of the condition of the fetus. The term is used similarly to “futile treatment” in end-of-life decisions or for heterogeneous conditions to imply an ethical conclusion rather than to represent a clear prognosis. It obscures communication and counseling and generally should be avoided. This review analyzes the concept of lethality as applied to fetal or congenital malformations.
MEDLINE was searched for cohort studies, case series, reviews, or commentaries that discussed diagnosis, counseling, or management for conditions described as lethal. For malformations most frequently included in lists, a separate search strategy used the condition name in combination with “outcome” or “survival.” The search yielded 1717 papers; 75 full-text papers were reviewed. No agreed definition of a “lethal fetal or congenital malformation” (LM) was found, nor was an agreed list of conditions fitting this category apparent.
Lethal is used to describe something that causes death. The description of a perinatal condition as being lethal could mean one that invariably leads to fetal death in utero, one that invariably leads to death in utero or in the newborn period regardless of attempted supportive treatment, one that usually leads to death in utero or in the newborn period, or a condition that has been associated with death in utero or in the newborn period. The most straightforward understanding of LM is probably a condition incompatible with survival beyond the newborn period.
The diagnosis of an LM has ethical and legal implications. These malformations may be triggers for the involvement of perinatal palliative care services. Lethal fetal or congenital malformations may require different obstetric management, with interventions focused mostly or only on maternal not fetal well-being. It has been argued that termination of pregnancy in the third trimester would be justifiable in the presence of a certain diagnosis of an LM because the presence of this particular LM precludes any benefit to the fetus from the pregnancy continuing or exempts the decision from legal clauses that prevent late abortion on the grounds of viability.
A large number of individually rare conditions have received the lethal label. Lists differ among studies, although some conditions are more frequently cited than others. Some of the more commonly cited LMs include renal agenesis, anencephaly, thanatophoric dysplasia, trisomy 13 and 18, holoprosencephaly, triploidy, and hydranencephaly. Postnatal survival figures are imprecise, and none of the malformations that are most commonly described as being lethal are actually lethal in the strict sense.
The concept of a lethal fetal/congenital malformation has some similarities to the concept of futile treatment. Medical futility was a response to a perceived increase in conflicts between doctors and patients, especially for life-sustaining treatment. If futile treatments could be identified, doctors would be ethically justified in refusing to provide them. However, the concept of futility has several problems. One is the definition. Treatment is considered quantitatively futile if it has a very low chance of success, but how low the chance is a subject of disagreement. Qualitative futility is mentioned when treatment might sustain life but offers no benefit to the patient. These problems also apply to LM because no agreement has been reached on the probability of death that would justify describing a condition as lethal, nor is there agreement about just how much function loss would justify this label.
The second major problem with futility and lethality is the difficulty in determining whether treatment meets a given definition. The problem of self-fulfilling prophecies makes it difficult to know how often survival would be possible if all treatment were provided. The third challenge for futility is that although it is possible to define subgroups of patients who meet strict criteria for the futility of treatment, this actually applies to a relatively narrow set of cases.
No published reports indicate how often “lethal” is used in counseling after a prenatal diagnosis of a specific condition. Although some practitioners may avoid it, a significant number use this or related terminology. Practitioners may believe that certain conditions are not compatible with survival beyond the newborn period. A second potential reason is discomfort with uncertainty or a desire to make decision-making simpler. Women might more easily come to terms with termination of pregnancy or with palliative care if they are told survival is impossible, and it may be easier for professionals to make and rationalize such decisions. A third possibility is that practitioners are aware that death is not inevitable but believe that a survivor will not have a life worth living. Finally, it may be thought that using lethal is an effective way of communicating the grave nature of the fetus’ prognosis. However, the use of LM is not clear, which can hamper communication.
Doctors discuss a wide range of medical decisions with patients. They provide information about medical diagnoses, treatment options, and offer guidance about which course of action they feel would be best. Counseling after a prenatal diagnosis is different because health professionals are told to avoid making value judgments or offering explicit recommendations. One of the important ways to enhance the autonomy of women is to use language that avoids hidden/unstated value judgments.
If the term lethal is avoided, then women should be counseled using 5 key questions for understanding the fetus’ prognosis. (1) What is the diagnosis and how certain is it? (2) What is the likelihood of survival beyond the newborn period if life-sustaining treatment is offered? (3) What is the likely duration of survival if life-sustaining treatment is provided? (4) What is the range of possible physical or cognitive impairments if the newborn survives? (5) What is the burden of treatment required to keep the baby alive? Although each of these questions is challenging with uncertain answers, physicians have a professional responsibility to provide the best available evidence to address them. Acknowledging the limits of available data and genuine uncertainties in prognosis is important to respect a woman’s autonomy. Defining LMs carries serious conceptual and practical challenges. Unless lethal is clearly defined and consistently applied, it should be avoided in perinatal guidelines and counseling after a prenatal diagnosis because it can mislead the parents about the prognosis for a neonate with severe abnormalities. Counselors must be clear about the prognosis and implications of treatment. Acknowledging this uncertainty is often required.