ECTOPIC PREGNANCY
II—RUPTURE, ABORTION
Very rarely does a tubal pregnancy develop longer than into the fourth or fifth month without symptoms and signs that ultimately lead to the diagnosis. The most frequent outcome of tubal pregnancy is abortion through the tube into the peritoneal cavity. It usually occurs between the middle of the second and the end of the third month, but it may come earlier. A partial or total separation of the trophoblast from the tubal walls occurs, leading to death of the embryo. Blood extravasation and later extrusion of the embryo with blood clots into the peritoneal cavity follow, where they may slowly be absorbed, provided the hemorrhage was slight. The uterine decidua may sometimes separate as a whole and be eliminated as a decidual cast of the uterine cavity. Passage of the decidual cast can be confused with an early spontaneous abortion, and hence the passed tissue should be carefully examined.
In many cases of tubal pregnancy,
the trophoblast erodes the tubal wall. This leads to a tubal rupture, which is
almost always accompanied by a serious, catastrophic clinical picture of acute
shock due to extensive hemorrhage into the peritoneal cavity. The time of tubal
rupture varies with the site of implantation. If the embryo develops in the
interstitial portion of the tube, rupture occurs relatively late, whereas
nidation in the isthmic part results in rupture in the very early weeks because
of the difference in the mass of musculature in the two parts of the tube.
Rupture may take place spontaneously but may also occur following defecation,
coitus, and vaginal examination. The consequences of a rupture after
interstitial implantation are more serious because of the major vessels in this
area.
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In a few cases, rupture has taken
place through the lower margin of the tube, where it is not covered by
peritoneum and where the two folds of the broad ligament meet only loosely. In
such instances, the tubal contents empty into the connective tissue of the
mesosalpinx, that is, between the two peritoneal sheets. Here hematoma may
develop, and the embryo will die, or a broad ligament pregnancy, also called
intraligamentary or extraperitoneal pregnancy, may continue, depending upon the
degree of placental separation.
Although rupture of a tubal
pregnancy or a tubal abortion with hemorrhage is a surgical emergency treated
by laparoscopy or laparotomy, when an ectopic pregnancy is diagnosed early,
medical therapy may be appropriate. Medical therapy may be considered for asymptomatic
or mildly symptomatic patients. Methotrexate is generally used for chemical
management of these patients. Methotrexate should not be used if the β-hCG
level is higher than15,000 mIU/mL, the adnexal mass is greater than 3 cm, or
the patient’s hemodynamic status is unstable. Patients with a
history of active hepatic or renal disease, fetal cardiac activity demonstrated
in the ectopic gestation, active ulcer disease, or significant alterations in
blood count (white blood cell count <3000,
platelet count of <100,000)
are not candidates for this therapy.
All Rh-negative, unsensitized women
with ectopic pregnancies should receive Rh immunoglobulin at a dosage of 50 µg
if the gestation is of less than 12 weeks’ duration and 300 g if it is beyond
12 weeks.
Termination of tubal pregnancy by
death of the embryo and its transformation into a lithopedion is a very rare
event. Such a process may go on completely asymptomatically, with slow
dehydration and mummification. This “missed tubal abortion,” as it has been
called, may be found only incidentally during laparotomy.
Hydatid mole formation and
choriocarcinoma development have been observed in ectopic pregnancy but are extremely rare.
