I found this article that might help you. At least, I hope it helps.
uffl.org/vol12/bowring12.pdf
Here is an excerpt to answer your question. :
**In extrauterine pregnancy the affected part of the mother (e.g., cervix, ovary, or
fallopian tube) may be removed, even though fetal death is foreseen, provided that
(a) the affected part is presumed already to be so damaged and dangerously affected
as to warrant its removal, and that (b) the operation is not just a separation of the
embryo or fetus from its site within the part (which would be a direct abortion from
a uterine appendage) and that (c) the operation cannot be postponed without notably
increasing the danger to the mother.41
About this statement, Dr. May concludes, “This directive clearly authorizes as morally
licit the use of partial salpingectomy or total salpingectomy in order to safeguard the
mother’s life when there is grave danger of hemorrhaging from the fallopian-tube
pregnancy. But it also clearly excludes use of a salpingostomy. At the time this directive
was written, the management of tubal pregnancies by methotrexate was not known.”42
The more recent 1994 U.S. Bishops’ directive states more simply as follows: “In the
case of extrauterine pregnancy, no intervention is morally licit which constitutes a direct
abortion.”43 On the other hand, the document continues, “Operations, treatments and
medications that have as their direct purpose the cure of a proportionately serious
pathological condition of a pregnant woman (i.e., a salpingectomy) are permitted when
they cannot be safely postponed until the unborn child is viable, even if they will result in
the death of the unborn child” (47, italics added). In a section on emergency
contraception, the new directive also states, “It is not permissible, however, to initiate or
to recommend treatments that have as their purpose or direct effect the removal,
destruction, or interference with the implantation of a fertilized ovum” (36).
Reference:
41 National Conference of Catholic Bishops, Ethical and Religious Directives for Catholic Health Care Facilities (Washington, D.C., NCCB, 1971), 16.
42 William E. May. Catholic Bioethics and the Gift of Human Life (Huntington: OSV, 2000), 183. 43 National Conference of Catholic Bishops. Ethical band Religious Directives for Health Care Services (Washington, D.C.: NCCB, 1994), 28.**