Cervical pregnancy
Encyclopedia
Cervical pregnancy refers to an ectopic pregnancy
that has implanted in the uterine endocervix. Such a pregnancy typically aborts within the first trimester
, however, if it is implanted closer to the uterine cavity - a so-called cervico-isthmic pregnancy - it may continue longer. Placenta
l removal in a cervical pregnancy may result in major hemorrhage.
Pregnancies involving the isthmus - the segment of the uterus
between the cervix and the fundus - are more common than true cervical pregnancies. While in many situations the cause of the abnormal implantation remains unclear, there is evidence to link the development of cervical pregnancy to uterine instrumentation, specifically repeated D&Cs (dilatation and curettage). Cervical pregnancies are to be distinguished from pregnancies that start from an implantation in a scar of a previous cesarean section, so-called scar pregnancies.
or, more commonly, by obstetric ultrasonography
. A typical non-specific symptom is vaginal bleeding
during pregnancy. Ultrasound will show the location of the gestational sac
in the cervix, while the uterine cavity is "empty". Cervical pregnancy can be confused with a miscarriage
when pregnancy tissue is passing through the cervix.
Histologically the diagnosis has been made by Rubin’s criteria on the surgical specimen: cervical glands are opposite the trophoblast
ic tissue, the trophoblastic attachment is below the entrance of the uterine vessels to the uterus or the anterior peritoneal reflection, and fetal elements are absent from the uterine corpus. As many pregnancies today are diagnosed early and no hysterectomy is performed, Rubin's criteria can often not be applied.
, and/or by uterine artery embolization
, a more advanced pregnancy may require a hysterectomy
to control bleeding. The more advanced the pregnancy the higher the risk for a major bleeding necessitating a hysterectomy.
On a very rare occasion, a cervical pregnancy results in the birth of a live baby, typically the pregnancy is in the upper part of the cervical canal and manages to extend into the lower part of the uterine cavity.
A cervical pregnancy can develop together with a normal intrauterine pregnancy; such a heterotopic pregnancy will call for expert management as to not to endanger the intrauterine pregnancy.
Ectopic pregnancy
An ectopic pregnancy, or eccysis , is a complication of pregnancy in which the embryo implants outside the uterine cavity. With rare exceptions, ectopic pregnancies are not viable. Furthermore, they are dangerous for the parent, since internal haemorrhage is a life threatening complication...
that has implanted in the uterine endocervix. Such a pregnancy typically aborts within the first trimester
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
, however, if it is implanted closer to the uterine cavity - a so-called cervico-isthmic pregnancy - it may continue longer. Placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
l removal in a cervical pregnancy may result in major hemorrhage.
Incidence
The incidence has been reported to be about 1:1,000 to 1: 16,000 pregnancies.Pregnancies involving the isthmus - the segment of the uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
between the cervix and the fundus - are more common than true cervical pregnancies. While in many situations the cause of the abnormal implantation remains unclear, there is evidence to link the development of cervical pregnancy to uterine instrumentation, specifically repeated D&Cs (dilatation and curettage). Cervical pregnancies are to be distinguished from pregnancies that start from an implantation in a scar of a previous cesarean section, so-called scar pregnancies.
Diagnosis
The diagnosis is made in asymptomatic pregnant women either by inspection seeing a bluish discolored cervixCervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
or, more commonly, by obstetric ultrasonography
Obstetric ultrasonography
Obstetric sonography is the application of medical ultrasonography to obstetrics, in which sonography is used to visualize the embryo or foetus in its mother's uterus...
. A typical non-specific symptom is vaginal bleeding
Vaginal bleeding
Vaginal bleeding refers to bleeding in females that is either a physiologic response during the non-conceptional menstrual cycle or caused by hormonal or organic problems of the reproductive system. Vaginal bleeding may occur at any age, but always needs investigation when encountered in female...
during pregnancy. Ultrasound will show the location of the gestational sac
Gestational sac
The gestational sac is the only available intrauterine structure that can be used to determine if an intrauterine pregnancy exists, until the embryo is identified....
in the cervix, while the uterine cavity is "empty". Cervical pregnancy can be confused with a miscarriage
Miscarriage
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...
when pregnancy tissue is passing through the cervix.
Histologically the diagnosis has been made by Rubin’s criteria on the surgical specimen: cervical glands are opposite the trophoblast
Trophoblast
Trophoblasts are cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg...
ic tissue, the trophoblastic attachment is below the entrance of the uterine vessels to the uterus or the anterior peritoneal reflection, and fetal elements are absent from the uterine corpus. As many pregnancies today are diagnosed early and no hysterectomy is performed, Rubin's criteria can often not be applied.
Management
True cervical pregnancies tend to abort, if, however, the pregnancy is located higher in the canal and the placenta finds support in the uterine cavity it can go past the first trimester. With the placenta being implanted abnormally extensive vaginal bleeding can be expected at time of delivery and placental removal. While early cervical pregnancies may abort spontaneously or can be managed with excision, D&C, suturing , electrocautery, and tamponading, by medication such as methotrexateMethotrexate
Methotrexate , abbreviated MTX and formerly known as amethopterin, is an antimetabolite and antifolate drug. It is used in treatment of cancer, autoimmune diseases, ectopic pregnancy, and for the induction of medical abortions. It acts by inhibiting the metabolism of folic acid. Methotrexate...
, and/or by uterine artery embolization
Uterine artery embolization
Uterine artery embolization is a procedure where an interventional radiologist uses a catheter to deliver small particles that block the blood supply to the uterine body...
, a more advanced pregnancy may require a hysterectomy
Hysterectomy
A hysterectomy is the surgical removal of the uterus, usually performed by a gynecologist. Hysterectomy may be total or partial...
to control bleeding. The more advanced the pregnancy the higher the risk for a major bleeding necessitating a hysterectomy.
On a very rare occasion, a cervical pregnancy results in the birth of a live baby, typically the pregnancy is in the upper part of the cervical canal and manages to extend into the lower part of the uterine cavity.
A cervical pregnancy can develop together with a normal intrauterine pregnancy; such a heterotopic pregnancy will call for expert management as to not to endanger the intrauterine pregnancy.