Conjoined twins: bioethics, medicine and the law.

VIEWPOINT Conjoined twins are fused twins resulting from incomplete division of a single blastocyst, 13 to16 days post fertilization (1). Complete division of a human zygote within seven days of fertilization yields identical monozygotic twins (1). Fused body components, overlapping visceral components and impaired organogenesis characterize this anomaly (1–5). Classification of conjoined twins is based on, anatomical site of fixation, with the Greek suffix pagus (meaning, that which is fixed) being employed to indicate head (craniopagus), abdominal (omphalopagus) or pelvic (ischiopagus) fixation (1, 2). Conjoined twins are rare, occurring at rates ranging from 1 in 50 000 to 1 in 200 000 births (3). Clinicians managing conjoined twins find themselves at a crossroad where bioethics, medicine and the law converge (6–9). Surgical separation often places one twin at greater risk of death than the other and clinical decisions often conflict with parental wishes. A recent case of conjoined twins managed at the University Hospital of the West Indies (UHWI) presented such a dilemma to clinicians. Conjoined twins Jane and Luisa weighing 3.9 kg were transferred from a rural hospital, after being delivered by emergency Caesarian section after " failure to progress " during normal vaginal delivery. Mother, a 19-year-old primi-gravida, received no antenatal ultrasound imaging. The twins, born at term, were joined from the xiphisternum to the pelvis. They had four upper limbs, but only three lower limbs (tripus), because one deformed lower limb was a fused appendage. These xipho-omphalo-ischiopagus tripus twins had what appeared to be a cloacal deformity and no anal orifice. Jane the bigger and more active twin had a normal face. Luisa however had left facial hypoplasia, cleft palate, gasping respiration and generalized cyanosis. Jane had a simple atrial septal defect but Luisa had an uncorrectable cardiac defect, including transposition of the great vessels and a thick inter-ventricular septum. The twins shared one liver situated almost entirely in Jane's abdominal cavity. By physician's assessment, Luisa was dying because of a poor circulatory system. She was being kept alive only because her circulation was augmented by the pump action of Jane's heart. Eventually toxins accumulating in Luisa's circulation would cause Jane's heart to arrest because of mixing of the twins' circulations. Emergency separation surgery was therefore indicated to save Jane, but this surgery would precipitate Luisa's demise. This was the moral dilemma facing surgeons aware of the Hippocratic maxim, primum non nocere: first do no harm (10). …