Cervical Ectopic Pregnancy
|Cervical Ectopic Pregnancy, Placenta (arrows)
||Cervical Ectopic Pregnancy Trophoblastic Flow (arrows)
||Twins with one non-viable aborting twin in the cervix (arrow)
A cervical ectopic pregnancy is identified extending into the
lower and mid-uterine segments. The placenta is identified in
the cervical area and lower uterine segment (arrows). Trophoblastic
flow (arrows) characterized by a high diastolic component (arrows)
is clearly seen. This in addition to embryonic cardiac activity
differentiates this from a spontaneous inevitable abortion.The
second case is that of a twin gestation with one twin in the body
of the uterus (arrowhead) and the other, a non-viable aborting
twin in the cervix (arrow).
Cervical pregnancy is a rare form of ectopic pregnancy reported
to occur between one in 1,000 and 1 in 50,000 pregnancies and
in 0.15% of all ectopic pregnancies. It occurs when the fertilized
ovum implants in the cervical mucosa distal to the internal cervical
os. Several predisposing factors reported are: multiparity, prior
abortion or instrumentation of the cervix or endometrial cavity.
Most patients terminate spontaneously in the first trimester due
to the unfavorable site of implantation. Patients often present
with painless vaginal bleeding. If ultrasound is not fortuitously
done the correct diagnosis may not be made until the time of a
procedure. Patients may bleed profusely from the site of uterine
implantation. This may occur even after removal of the products
of conception because cervical tissue is predominantly fibrous
connective tissue with only 15% of the cervix being smooth muscle.
Relatively conservative measures such as KCl injection into the
cervical pregnancy, maternal systemic methotrexate therapy and
iliac vessel ligation have all been shown to be relatively sucessful
at preventing life-threatening hemorrhage. However, the use of
hysterectomy still remains high.
The first ultrasound description of a cervical pregnancy was in
1978. The abnormally low postion of the gestational sac is relatively
easy to recognize sonographically. The difficult task is differentiating
cervical pregnancy from a cervical stage of a spontaneous abortion.
Several features of a cervical pregnancy will help make this distinction
possible. In a cervical pregnancy, the uterine cavity above the
cervix is often relatively small and the enlarged empty uterus
may have an hourglass configuration with the lower uterine segment.
In addition, the sac of a cervical pregnancy will be smooth and
round or oval, with a yolk-sac or embryo inside. One can often
identify the trophoblastic (placental) tissue with its characteristic
doppler spectral pattern or of a high end-diastolic flow.
Yankowitz J, Leake J, Huggins G, Gazaway P, Gates E. Cervical
ectopic pregnancy: review of the literature and report of a case
treated by single-dose methotrexate therapy. Obstet Gynecol Survey
Rosenberg RD, Williamson MR. Cervical ectopic pregnancy: avoiding
pitfalls in the ultrasonographic diagnosis. J Ultrasound Med 11:365-367,
Frates MC, Benson CB, Doubilet PM, DiSalvo DN, Brown DL, Laing
FC et al. Cervical ectopic pregnancy:results of conservative treatement.
Radiology 191:773-775, 1994
Zarabi M, Butkiewicz BL, Mazer J. Diagnosis of cervical pregnancy
by ultrasonography. J Ultrasound Med 2:333-335, 1983
Sheldon RS, Aaro LA, Welch JS. Conservative management of cervical
pregnancy. Am J Obstet Gynecol 87:504, 1963
Werber J, Prasadarao PR, Harris VJ. Cervical pregnancy diagnosed
by ultrasound. Radiology 149:279-280, 1983
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