2005-10-31-11 Twin, acardiac, acephalus © Lacaze www.thefetus.net/
Twin, acardiac, acephalus
Lacaze S. MD*, Cuillier F.*, MD, Rivière J.P., MD**
* Department of Gynecology, Hôpital Félix Guyon, 97400 Saint-Denis, Ile de la Réunion, France.
* Department of Anatomo-pathology, Hôpital Félix Guyon, 97400 Saint-Denis, Ile de la Réunion, France.
The present case describe an acardiac, acephalic fetus, diagnosed at 17 weeks and confirmed after miscarriage. The patient had a long history of primary infertility. The first scan at 13 weeks demonstrated one sac with one fetus. Near the placenta, there was an uncalcified mass. The umbilical cord was not visible. The Doppler analysis did not show umbilical vascularization, but an anarchic circulation was seen.
The presumed diagnosis was "teratoma". A chorioangioma seemed not possible, as was a severely macerated fetus. The patient refused amniocentesis. There was a polyhydramnios too. At 17 weeks, the same formless mass near the placenta was seen and inside, calcifications were seen. The calcifications appeared as an anarchic spinal column and perhaps limbs. Doppler velocimetry was not contributive, because the second twin was dead.
An interruption of pregnancy and the expulsion of the twin was done at 17 weeks. The diagnosis was confirmed by autopsy. Indeed pathological examination showed a 20g macerated fetus without cephalic extremity (acardiac-acephalic fetus). The left superior limb was absent. The right superior limb was seen partially and the inferior ones were curved without fingers in each foot . The internal organs exam revealed absent of heart, major vessels and lungs. The liver, pancreas and gastrointestinal tract were seen. The kidneys, adrenal and bladder were observed in their usual positions. Radiography shows abnormal characteristics of the skeleton and of the rostral end of the spine. The placenta study revealed velamentous insertion of the umbilical cord of the normal fetus and the umbilical cord of the acardiac fetus presented two vessels. Vascular anatomises was identified over corial disk.
At 13 weeks, the view of the mass without calcification.
At 17weeks, the view of the mass with calcifications.
The anatomic-pathological exam showing the normal fetus and the acardiac-acephalic fetus.
The acardiac-acephalic fetus with both inferior limbs and only the right limb.
The placenta study showing the velamentous insertion of the umbilical cord of the normal fetus and the vascular anastomoses over corial disk.
The radiography shows abnormal characteristics of the skeleton superior pole and of the spine.
Acardiac fetus is a rare lethal fetopathy encountered in monozygous pregnancies. It is a rare anomaly in which one twin has an absent, rudimentary of non functioning heart. Acardiac fetus occurs in less than 1 % of multiple pregnancies and can develop in single pregnancies too. The acardiac, acephalic fetus is a rare congenital malformation observed during the monozygotic twin pregnancy. The prevalence is 1:35,000 deliveries. The incidence of acardia is higher in monoamniotic than in diamniotic monochorionic twin pairs and is more common in monozygotic triplets than in monozygotic twins.
Twin reversed arterial perfusion has been recognized as necessary for development of the perfused fetus. Twin pregnancy with acardiac results from an artery-to-artery placental anastomosis in which the pump twin, morphologically normal, perfuses the abnormal acardiac in a reversed circulation. Clinical management depends on the spontaneous development of the acardiac fetus and the deleterious consequences for the healthy twin resulting from heart failure, anasarca or prematurity. Ultrasound prenatal diagnosis has enabled an increasing number of observations. The spontaneous prognosis for the healthy twin is unfavorable in half of case.