Treatment Options and Outlook
Abortifacient medications (drugs that cause ABOR-
TION, or loss of a pregnancy) such as methotrexate
may terminate an ectopic pregnancy detected very
early, avoiding the need for surgery and minimiz-
ing the risk for damage to the fallopian tubes and
other structures. Such medications work by stop-
ping cell division, affecting rapidly dividing cells
such as those of the zygote. These medications
were first developed, and are still used, to treat
cancer, in which cells also rapidly divide.
Ectopic pregnancy that becomes at all advanced
requires surgery that terminates the pregnancy
and removes the tissues that have developed to
support it. There may be damage to the structure
where the pregnancy implanted, such as the fal-
lopian tube or less commonly the CERVIXor ovary,
that requires surgical repair. With prompt treat-
ment most women recover fully from ectopic
pregnancy though the experience of an ectopic
pregnancy is often emotionally traumatic because
the pregnancy cannot survive. Damage to or loss
of the involved fallopian tube or ovary, if it occurs,
may subsequently impair FERTILITY.
Risk Factors and Preventive MeasuresEctopic pregnancy occurs when there is a
mechanical or hormonal impediment that pre-
vents or slows the zygote’s movement through the
fallopian tube to the uterus after fertilization as is
the normal process in establishing pregnancy. Risk
factors for ectopic pregnancy include
- PELVIC INFLAMMATORY DISEASE(PID), which often
results in scarring and blockage of the fallopian
tubes - congenital abnormalities of the fallopian tubes
- progesterone-only contraceptives, which work
by impeding the implantation process - TUBAL LIGATIONin which the fallopian tube par-
tially reopens and allows SPERMto escape into
the abdominal cavity, or surgical reversal of
tubal ligation to restore fertility - use of an intrauterine device (IUD) for contra-
ception - ENDOMETRIOSIS
- abdominal adhesions (SCAR tissue), resulting
from abdominal surgery such as APPENDECTOMY,
that pull the fallopian tubes out of their normal
positions- previous ectopic pregnancy
Though there are no measures to prevent
ectopic pregnancy, prompt medical attention to
early symptoms of ectopic pregnancy allows treat-
ment before life-threatening complications arise.
Early treatment also helps preserve fertility.
See also CHEMOTHERAPY; CONTRACEPTION; OVA.ejaculation The forceful contractions that expel
SEMEN from the erect PENIS during the male
ORGASM. Though ejaculation occurs as a result of
sexual stimulation, the muscular contractions that
produce ejaculation are not within voluntary con-
trol. Ejaculation moves semen (SPERMand seminal
fluid) from the seminal vesicles, VAS DEFERENS, and
PROSTATE GLANDinto the URETHRA, and then ejects it
from the urethra. In a man who has had a VASEC-
TOMY, the semen does not contain sperm. A tiny
valve at the urethral entrance to the BLADDER
closes across the bladder opening, directing the
flow of semen through the urethra to the outside
of the penis. In a man who has had a PROSTATEC-
TOMY(surgery to remove the prostate gland), ejac-
ulation is retrograde (the semen enters the
bladder instead of exiting through the urethra)
because the OPERATION also involves removal of
this valve.
For further discussion of ejaculation within the
context of the structures and functions of repro-
duction and sexuality, please see the overview sec-
tion “The Reproductive System.”
See also RETROGRADE EJACULATION.embryo The stage of prebirth development from
the 15th day after CONCEPTIONto 8 weeks of gesta-
tional age. The embryo arises from the three germ
layers of the ZYGOTE:- The ectoderm is the outermost layer. It is the
foundation for the SKIN and mucous mem-
branes, the TEETH, and the structures of the
nervous system. - The mesoderm is the middle layer. It is the
foundation for the organs and structures of the
musculoskeletal, cardiovascular, pulmonary,
272 The Reproductive System