Women with pelvic inflammatory disease (PID) have a high occurrence of ectopic pregnancy. This results from the build-up of scar tissue in the fallopian tubes, causing damage to cilia. However, if both tubes were completely blocked, so that sperm and egg were physically unable to meet, then fertilization of the egg would naturally be impossible, and neither normal pregnancy nor ectopic pregnancy could occur. Intrauterine adhesions (IUA) present in Ashermans syndrome can cause ectopic cervical pregnancy or, if adhesions partially block access to the tubes via the ostia, ectopic tubal pregnancy. Ashermans syndrome usually occurs from intrauterine surgery, most commonly after D&C. Endometrial/pelvic/genital tuberculosis, another cause of Ashermans syndrome, can also lead to ectopic pregnancy as infection may lead to tubal adhesions in addition to intrauterine adhesions.Tubal ligation can predispose to ectopic pregnancy. Reversal of tubal sterilization (tubal reversal) carries a risk for ectopic pregnancy. This is higher if more destructive methods of tubal ligation (tubal cautery, partial removal of the tubes) have been used than less destructive methods (tubal clipping). A history of a tubal pregnancy increases the risk of future occurrences to about 10%. This risk is not reduced by removing the affected tube, even if the other tube appears normal. The best method for diagnosing this is to do an early ultrasound. Other
Although some investigations have shown that patients may be at higher risk for ectopic pregnancy with advancing age, it is believed that age is a variable which could act as a surrogate for other risk factors.
This may help in identifying failing PUL that are at low risk and thereby needing less follow-up. Inhibin A may also be useful for predicting spontaneous resolution of PUL, but is not as good as progesterone for this purpose. Mathematical models
There are various mathematical models, such as logistic regression models and Bayesian networks, for the prediction of PUL outcome based on multiple parameters. Mathematical models also aim to identify PULs that are low risk, that is, failing PULs and IUPs. Dilation and curettage
Dilation and curettage (D&C) is sometimes used to diagnose pregnancy location with the aim of differentiating between an EP and a non-viable IUP in situations where a viable IUP can be ruled out. Specific indications for this procedure include either of the following:
No visible IUP on transvaginal ultrasonography with a serum hCG of more than 2000 mIU/mL. An abnormal rise in hCG level. A rise of 35% over 48 hours is proposed as the minimal rise consistent with a viable intrauterine pregnancy. An abnormal fall in hCG level, such as defined as one of less than 20% in two days. Classification
Tubal pregnancy
The vast majority of ectopic pregnancies implant in the fallopian tube. Pregnancies can grow in the fimbrial end (5% of all ectopic pregnancies), the ampullary section (80%), the isthmus (12%), and the cornual and interstitial part of the tube (2%). Mortality of a tubal pregnancy at the isthmus or within the uterus (interstitial pregnancy) is higher as there is increased vascularity that may result more likely in sudden major internal bleeding.