Ectopic pregnancy is a well known and an undesirable risk of IVF. IVF is often carried out in patients with pelvic pathology such as pelvic inflammatory disease (PID) or previous tubal surgery. These mechanical factors increase the risk of subsequent ectopic pregnancy following IVF. The proportion of ectopic pregnancies after IVF ranges from 4–11% of pregnancies.1
OEP is a rare form of extrauterine ectopic pregnancy, accounting for only 1–3% of all ectopic pregnancies.2,3
There has been only one prior case report of an OEP in a patient who had undergone bilateral salpingectomy before IVF-ET to improve pregnancy rate.4
Specific risk factors for an OEP differ slightly from tubal ectopics in that PID and previous tubal damage are not seen as being important, but intrauterine device (IUD) use remains important.5
Due to its rarity, no definite mechanism has been established for the development of an OEP. It has been hypothesised that the most likely reason is due to reverse migration6
of one of these embryos from an IVF-ET procedure towards the fallopian tube and subsequent implantation in the ovary.7
It was also suggested that increased volume and pressure of culture medium injected into the uterus or the tilt-down position of the patient at the time of ET could be contributory factors for the development of OEP.7
It has also been noted that fifth day blastocyst transfer has been associated with increased incidence OEP in women with no other predisposing factors for ectopic pregnancy.8
Difficult embryo transfers have also been postulated for OEP as these are thought to promote strong junctional zone contractions.9
Perforation of the uterus at the time of the embryo transfer could also result in an OEP due to the transabdominal migration of the embryos.
The only previous case report on OEP in a patient with previous laparoscopic bilateral salpingectomies suggested that a cornual fistula was the likely aetiology.4
The authors suggested that use of electrocauterisation for dissection of fallopian tubes can result in reduced blood supply and poor healing at the utero-cornual region, leading to tissue necrosis and the formation of a cornual fistula.4
As most salpingectomies are either partial or segmental with the possible aim of future tubal reconstructive surgery in mind, this unfortunately is increasing the risk of subsequent ectopic pregnancies including ovarian from IVF. In our case the right sided tubal stump had formed a fistulous communication with the right ovary by becoming adherent to it and this probably resulted in the ovarian pregnancy.
First line management of OEP is surgical. If possible, ovarian wedge resection is preferred in order to maintain ovarian tissue and function. Occlusion of the cornual ends and removal of any tubal attachment from the ovary are possible ways of decreasing the incidence of OEP.10
A high index of suspicion for ectopic pregnancy including OEP is warranted in patients undergoing IVF-ET despite bilateral salpingectomies. Despite only one similar case being previously reported, the increase in use of IVF is likely to lead to increased and unusual ectopic pregnancy presentations; it is therefore vital to consider the diagnosis early to prevent subsequent morbidity and possible mortality. Reverse migration along with a fistulous communication could be the combined aetiological cause for such unusual ectopic pregnancy sites.11
- Ectopic pregnancy is still a leading cause of maternal mortality.
- A high index of suspicion is warranted for an ectopic pregnancy following an IVF-ET procedure despite bilateral salpingectomies.
- Early diagnosis, prompt resuscitation, including early surgical intervention, decreases maternal mortality in a ruptured ectopic pregnancy.