…continuing…
Methotrexate
An even simpler procedure, one that is especially effective if bleeding has not yet occurred, involves the use of methotrexate (MTX).9 MTX is a drug that, because it inhibits cell multiplication, is often used in very high doses as chemotherapy for the treatment of cancer. The drug, which can be either oral or intramuscular, interferes with a cell’s ability to synthesize DNA.10 Trophoblastic cells are extremely sensitive to the action of MTX.
The problem with methotrexate, as with salpingostomy, is that the death of the fetus follows upon the action which inhibits the destructive implantation process of the trophoblast. Can the principle of double effect be applied to the use of MTX? Some would say no, maintaining that the cells of the trophoblast and the cells of the fetus are so intimately connected as to form one entity.11
Others, using the analogy of normal childbirth — in which the result of the trophoblast, the placenta, is definitely separate from the developing fetus — maintain that MTX may be used because the directly intended effect, the treatment of the pathology by inhibiting the trophoblastic cells, is distinct from the unintended effect, the death of the fetus.
Given that in an ectopic pregnancy the fallopian tube is pathological (e.g., will bleed or rupture) because of the manner in which the trophoblast has imbedded itself in the tube’s inner wall, it seems well within moral probity for the obstetrician to intend the removal of the trophoblast and to employ the means to fulfill the intention, even though that means the death of the fetus will result. It seems this opinion has an intrinsic probability — that is, a probability founded on the physical facts of fetal development in an ectopic pregnancy.