Ectopic Pregnancy and its Types

Ectopic Pregnancy

Is a condition during which fertilized ovum implants outside of the endometrial lining of the uterus. There are many factors which lead to such kinds of implantations amoung which inflammation of pelvic cavity, prior ectopic pregnancy, assisted reproductive techniques such as ovulation induction and in vitro fertilization. It is the leading cause of maternal death. The clinical representation of ectopic pregnancy is non-specific and includes vaginal bleeding, adnexal mass in a patient with positive pregnancy test. In more complicated cases evaluation of intrauterine and extrauterine findings helps sonographers to confirm an ectopic pregnancy.

Intrauterine Findings

An endometrial lining and uterus exhibit a wide variety of appearance in a patient with ectopic pregnancy. An endometrial cavity appears normal, thickened, or heterogeneous and it may contain fluid-filled structures pseudogestational sac or decidual cysts. A pseudogestationl sac is a collection of fluid or other materials due to blood or debris that accumulates in the endometrial cavity in the setting of some ectopic pregnancy. A decidual cyst is a tiny cyst in the endometrium and is associated with higher risk of ectopic pregnancy in the setting of positive pregnancy test and no identifiable intrauterine pregnancy.

Extrauterine Findings

Identification of an embryo with cardiac activity in the extrauterine pseudogestationl sac is the most reliable ultrasound appearance of the ectopic pregnancy. In the appropriate clinical setting of a positive pregnancy test and failure to identify intrauterine, ultrasound identification of an adnexal ring sign, characterized by extraovarian and extrauterine mass with a peripheral hyperechoic rim of trophoblastic tissue and central fluid corresponding to the gestational sac, is highly likely to represent an ectopic pregnancy.  

Unusual Forms of Ectopic Pregnancy

• Interstitial Ectopic Pregnancy

Also known as cornual ectopic pregnancy, is a condition during which a fertilized egg implants in the intermural section of the fallopian tube, that is, in the segment of the fallopian tube that joins the uterine cavity wall. The pregnancy tends to grow larger and ruptures later in pregnancy than ectopic pregnancies in the ampullary or isthmic portion of the tube due to their location and abundant blood supply. In such kind of cases, ultrasound reveals a presence of pseudogestational sac in the superolateral aspect of the uterine fundus. There is absence or asymmetric thinning of the myometrium surrounding the gestational sac.

• Cervical Ectopic Pregnancy

Is a rare form of ectopic pregnancy which involves implantation of the gestation into the cervical tissue. Factors which leads to cervical ectopic pregnancy are more frequent use of assisted reproductive techniques, abortions and cervical instrumentation. In a patient with cervical ectopic pregnancy, ultrasound reveals an embryo with cardiac activity, prominent peri trophoblastic flow on Doppler evaluation, eccentric location of the gestational sac with the visualization of the endocervical canal separate from the pregnancy and lack of endometrial thicking in the upper uterus

• Abdominal Pregnancy

Abdominal pregnancy refers to implantation of the gestation in the abdominal cavity. It is also a rare form of ectopic pregnancy which occurs following tubal abortion, rupture of a tubal pregnancy into the abdomen, and can be found in a wide variety of locations such as the liver, cul-de-sac, and spleen and along the uterine wall, broad ligament or diaphragm. The ultrasound diagnosis of abdominal pregnancy relies on the identification of the uterus separate from the pregnancy.