Caesarean section scar ectopic pregnancy: a new problem or new name for an old one?

Until recently, only a few of us had heard of a Caesarean section scar ectopic pregnancy. However, with new case reports being published in medical journals almost every day, it feels as if we are witnessing a global epidemic of a previously unknown form of ectopic pregnancy. Is this a true challenge for all of us or are we being offered a new fancy medical diagnosis of questionable clinical significance? Several factors have contributed to the rise of this new medical phenomenon. It is fairly obvious that the implantation of early pregnancy into a lower segment scar cannot occur without a woman previously undergoing a lower segment Caesarean section. In recent years, the number of Caesareans has been increasing steadily worldwide. Although lower uterine segments usually heal well after the operation, in a significant number of cases there is a substantial loss of both myometrium and the endo-metrium at the scar site. These defects typically communicate widely within the cervical canal, creating a characteristic " niche " in which pregnancy may implant 1,2. Despite a relatively large number of women with deficient Caesarean scars in the population, implantation of pregnancy in this defect is relatively rare 3.4. This may be explained by the location of defects. They are so distant from the uterine fundus that only a few early blastocysts venture so far in searching for a suitable implantation site. A majority of those that reach a deficient scar are likely to fail as support for trophoblast development is poor due to the lack of decidua 5. Only a few very resilient pregnancies can survive the harsh climate of " the uterine Arctic ". However, with the increasing number of Caesareans being performed it is inevitable that the number of pregnancies implanting in the scar is also increasing, leading to an increase the number of both sub-clinical and clinically detectable pregnancies. Another important factor contributing to the perceived increase in the number of scar pregnancies is the liberal use of ultra-sound for the assessment of women with suspected early pregnancy complications. High resolution transvaginal ultrasound has substantially improved the quality of ultrasound diagnosis in gynaecology and it has also helped us to learn more about subtle morphological features of uterine anatomy such as the appearance of Caesarean section scars. 6 In addition, in most women we are now also able to ascertain the exact site of pregnancy implantation. Such diagnostic …