[Congenital arteriovenous malformation of the internal iliac artery discovered during pregnancy].

We report a case found at the start of labour because of the presence of a "tumour praevia". Ultrasound, Doppler and tomodensitometric examination carried out after caesarean section confirmed the vascular origin of this lesion. Arteriography made it possible to decide the pattern of this arteriovenous malformation which was occurring in several branches of the left internal iliac artery. It was not possible to obliterate it completely by selective arterial embolisation, so it was removed surgically a few months later. Little is known about the complications that occur because of these arteriovenous malformations in pregnancy and during delivery. There is the theoretical risk that spontaneous rupture will occur in pregnancy but this does not justify terminating the pregnancy. It is better to carry out caesarean section because the tumour can obstruct delivery and may rupture as well as causing delay in labour. The treatment for these lesions is sometimes difficult and complex and one has to decide whether to preserve the uterus or not. Selective embolisation and pre-operative embolisation followed by surgical removal of dysplasic tissue are the therapies of choice.