[Placental villous stem vessel occlusions. Studies of a twin placenta retained in utero following selective sectio parva].

During a twin pregnancy of a 41-year old woman, a selective sectio parva was performed, without removing the placenta, in the 23rd week of gestation. An amniotic fluid examination after routine amniocentesis showed a free trisomy 21 in only one of the twins. The twin with normal caryotype was delivered in the 28th week. His placenta was well developed, whereas the placenta of the other child showed severe obliterations of the stem arteries with partial avascularity of the villi. The histological aspect was that of a so-called "endarteritis obliterans". Since the twin delivered via sectio parva showed no signs of dystrophy, we presume that at the time of delivery his placenta had developed regularly. The changes of the placenta, demonstrated by histological examinations, seemed to be caused by the stopping of the foetal blood circulation. We suggest that the intrauterine death is not caused by "endarteritis obliterans" only as often described previously. Obviously, the morphological picture of endarteritis obliterans can be the result of cessation of foetal blood circulation. Obliteration of stem arteries might be the main reason for the stillbirth with significant signs of dystrophy. The similar histological picture in placentae of normally developed stillbirths is obviously caused by discontinuation of foetal blood circulation.