Review: Fetal acardia: Aetiology, pathology and management

Neuropathological features of the brain in acardius acormus

Acardia is the most severe complication in monozygotic twinning. Acardius acormus is an uncommon phenotype among acardias. We report on an acardius acormus using thorough gross and light microscopic examination of the brain. Neuropathological examination revealed a severely disorganized cerebral cortex, agenesis of cerebellum and brain stem, and undeveloped basal ganglia and thalamus. In particular, the cerebral cortex was characterized by no clear lamination, almost complete loss of neurons, extensive gliosis, angiogenesis and focal mineralization. Neurohistology of the acardius acormus clearly demonstrated two types of lesions: developmental arrest of the brain and hypoxic-asphyxic damage to the brain with reactive gliosis and angiogenesis. Both types of lesions may be induced by the same teratogen: early onset of persisting hypoxia due to a reversed arterial perfusion. The quality of the description contributes valuably to a better understanding of the basic mechanism underlying the acardius phenotype.

Acardius acephalus after induced ovulation: a case report

An excess of structural defects occurs in monozygotic twins compared to dizygotic twins or singletons. Among these defects the acardius acephalus or chorangiopagus parasiticus is one of the most rare and severe and a possible cause of pathology to the other twin. Ovulation induction by clomiphene causes an increased frequency of multiple gestation and possibly of monozygotic multiple pregnancy. In the present report, we describe a prenatally diagnosed and autopsied case of acardius acephalus from a pregnancy established after ovulation induction by clomiphene. Approximately 1.4% of pregnancies are accomplished after use of ovulation inducing medication in the Netherlands. A possible etiological role of clomiphene justifies close monitoring of future cases.

Prenatal ultrasonographic diagnosis of acardiac twin

Acardiac twinning is a rare complication of monozygotic twin gestation occurring in 1/35,000 pregnancies or in 1% of all monozygotic twins. This condition is characterized by partial or complete lack of development of the heart in one of the twins, and requires that the normal twin (pump twin) provides circulation for itself as well as the acardiac sibling (perfused twin) by means of reverse circulation through large artery-to-artery and vein-to-vein anastomoses. The acardiac anomaly is uniformly fatal for the perfused twin, and the perinatal mortality for the normal twin is about 50%, usually as the result of congestive heart failure, polyhydramnios, and preterm delivery. In this report we present two cases of acardiac twin prenatally diagnosed by ultrasound. The principal sonographic features for prenatal diagnosis and the clinical management are briefly discussed.