[A case report of collision in twin pregnancy].
A parturient who had never been examined during pregnancy was admitted to the maternity ward at the end of the first phase of labour. Owing to a stoppage in the expulsion of the regularly rotated head, the forceps was applied. The extraction of the head was followed by the collision of the shoulders. Behind the fetus's neck, in the uterine canal, there was the head of the other fetus. The attempt of the reposition of the head of the other twin in general anesthesia was a failure. Since auscultation revealed no heart tones in any of the twins, the perforation of the head of the other fetus was performed, and in this way the extraction of the first and then of the second fetus was possible. The authors emphasize the importance of the echographic detection of the position and site of the fetuses in twin pregnancy.