How much of the fallopian tube must be removed for it to be a partial salpingectomy? Hardly any. And, anyway, if the baby is implanted in the tube, you’ll certainly have to remove some of the tube that it is connected to – if you didn’t, you’d be leaving in the extra blood vessels formed, and various other structures that begin to form, causing trouble later on.

A partial salpingectomy is a removal of a part of the mother, risking (towards 100%, admittedly) the life of the baby. The intent here is to repair the proximate part that’s going to kill her – a licit good. If she had a cyst and a surgeon cut it out, it would be fine – it’s an ordered end and a good work to save the mother’s life.

Abortion is murder: the intentional killing of a human being. The desired result is a dead human baby. The means to do it is to kill the baby first, then clean up the mess left by them trying desperately to cling on to life. Any other positive results are secondary to that grave evil.

Abortifacient “birth control” is abortion: the end here is to kill a human embryo if it’s around, and prevent one forming if it’s not.

“Birth Control” has as it’s end the avoidance of the good result of human sexuality: a child. Thus, it is a “disordered use of a good”, taking something which is full and complete, beautiful and perfect (as human sexuality is), and making it less than what it is, for selfish, often stupid purposes, and usually outside of marriage at that.

Utilizing NFP in most cases (you can use NFP like birth control, but most people don’t) is open to life, does honor both goods in being open to the possibility of children while putting no barrier to the intimacy of the spouses.

So, the reality is that this question attempts to present yet another false case in order to find some reason why one abortion might be acceptable, so by extension all abortions are acceptable for people who do not regard the ‘end’ of an act as something objective, but as subjective intent. But that’s BS: intent counts, but the objective facts of the matter are what are to be adjudicated. And, all such cases people have tried are truly false. (This is what irritates me about protestant and pseudo-Catholics when they try to do theology. They aren’t cute in their ignorance, they are damaging, blind-leading-the-blind stuff, and it is from these sorts of canards why we have ~60 million humans dead.)

As a Catholic philosopher with a background in moral theology, I’d suggest one step further: try transplanting the embryo to the uterine wall. That would be the best option, even if it doesn’t work, it shows you tried. Everybody’s happy, and only good things were done.