A major increase in the rate of ectopic pregnancies has been recorded at Dublin's three maternity hospitals over the past 25 years, according to new research.

However, the researchers say there is evidence emerging of over-treatment of ectopic pregnancies, with some women undergoing unnecessary operations, despite the fact that some of these cases can resolve spontaneously.

They say there is a need for better diagnostic tools to differentiate those ectopic pregnancies that require surgical intervention from those that are likely to resolve themselves without surgery.

Ectopic pregnancy is where the embryo implants somewhere other than the uterus, such as in the fallopian tubes. Ectopic pregnancies are usually not viable and can pose a risk to the health of the mother.

The study, carried out by doctors at Dublin's Rotunda Hospital, found that rates of ectopic pregnancy have risen on average five to sixfold across all the Dublin maternity hospitals between the late 1980s and 2011.

It found that the average number of ectopic pregnancies from 2007 to 2011 was 349 cases per year in the three hospitals, compared with 56.8 twenty years earlier.

The researchers found that the number of ectopic cases and the rate of increase in these cases were similar in all three hospitals over the period studied.

They say the increase in cases may be due to a true increase in ectopic pregnancy numbers, the fact that ectopic cases are now treated almost exclusively in maternity hospitals or because of the use of new coding systems to improve the reporting of ectopic pregnancies.

The researchers say, however, that the main contributing factor to the increase may be the early diagnosis and over-treatment of ectopic pregnancy.

According to the research paper, some experts claim that 15% of ectopic pregnancies will resolve spontaneously without treatment.

"The clinical dilemma is that no investigative tool exists to differentiate which ones will need treatment and which can be treated conservatively," the Dublin researchers say.

They add that early access to ultrasonography and blood testing have led to the increased diagnosis of 'pregnancy of unknown location' (which can include ectopic pregnancy).

According to the research paper, while between eight and 42% of these pregnancies may prnogress to ectopic pregnancy, 44-69% will resolve themselves.

The researchers, Drs Aoife Doyle and Peter McKenna, say that until newer investigations are available to differentiate ectopics that will regress from those that need active treatment, unnecessary salpingectomies (removal of a fallopian tube) will continue to occur.

Women who have one fallopian tube removed are still able to become pregnant and carry a pregnancy to term.

The research on ectopic pregnancies was presented at a recent major obstetrics meeting at the Royal College of Physicians of Ireland.

Find out more about ectopic pregnancy here