A sporadic case of delayed implantation after in-vitro fertilization in the human?

A possible case of delayed implantation after in-vitro fertilization(IVF) is described. The patient was sterilized in 1981, andmade fertile again by tubal anastomosis in 1988. In 1990 and1992 the patient had two right-sided tubal pregnancies, thefirst was treated with prostaglandin instillation, the secondwith salpingectomy. In connection with the salpingectomy in1992, the left tube was observed to be constricted in the middlepart and with phimosis of the ostium. In 1994 three IVF embryoswere transferred, but 15 days after the transfer, serum humanchorionic gonadotrophin (HCG) was negative (<10 IU/ml). Sevenweeks after the embryo transfer, menstruation was still missing,and the serum HCG was now positive (329 IU/ ml). Subsequentultrasound scans were compatible with an intrauterine pregnancy,progressing normally, but 5 weeks delayed compared with theoocyte aspiration. The pregnancy was successfully carried toterm. Such a long delay in detection of HCG, in associationwith a normal pregnancy, has not been described in the literaturebefore.