bicephaly

Bicephaly is a rare congenital condition in which a single individual has two heads. It is a form of conjoined twinning that results from incomplete division of the embryonic disc early in pregnancy, leading to two brains and skulls that are connected to one body. The anatomical arrangement is highly variable; in many cases the two heads share portions of the upper body, while the extent of shared organs, limbs, and circulation differs from case to case.

Two common structural patterns have been described: two heads on a single torso with a common trunk, and two heads with their own necks connected to a shared chest. The brains are typically separate and may have some degree of coordinated function, but communication between the two nervous systems is limited. Other vital organs may be shared or separate, influencing prognosis.

Diagnosis is usually made prenatally by ultrasound, with further assessment by fetal MRI. After birth, imaging studies help map anatomy for care planning. The condition is life-threatening in many cases; survival is rare and often depends on how much organ sharing occurs and the functionality of critical systems.

Management requires a multidisciplinary team and is guided by the individual anatomy and prognosis. In most instances, treatment focuses on comfort and supportive care; surgical separation of two heads is rarely feasible and is undertaken only in carefully selected cases with favorable anatomy and without prohibitive risk.