After fertilization, the embryo normally nests in the uterus. However, in one to two out of every hundred cases, the embryo nests in the fallopian tube, ovary, cervix or abdominal cavity. Doctors refer to this as extrauterine pregnancy (EUG) or ectopic pregnancy. If an ectopic pregnancy is not detected early enough, life may be at risk. The diagnosis of an ectopic pregnancy is usually an unexpected and painful one. Many women are already dealing with planning their pregnancy and delivery when the surprise diagnosis is made. Other women with an ectopic pregnancy did not know they were pregnant until then and are suddenly faced with the need for surgery.
Ectopic pregnancy (tubal pregnancy)
Ectopic pregnancy is the most common type of pregnancy outside of the uterus, accounting for 96% (Hucke 2005). In a normal pregnancy, the egg is fertilized by the sperm in the fallopian tube. The resulting embryo is transported through the fallopian tube and into the uterine cavity within 3 to 4 days with the help of cilia in the mucosa of the fallopian tube. However, if the fallopian tubes are blocked or damaged and thus the embryo cannot be transported to the uterus, the embryo will nest in the fallopian tube resulting in an ectopic pregnancy. Reasons for blocked fallopian tubes can be: previous inflammations, endometriosis lesions, previous ectopic pregnancies, an abortion or adhesions after abdominal surgery in the abdominal cavity. Also, if an IUD is or has been in the uterus, it can promote the development of an extrauterine pregnancy. Previous tubal sterilization is also a risk factor. However, tubal pregnancy can occur even in women who do not have these risk factors.
Ovarian pregnancy (ovarian gravidity)
Implantation in or on the ovary is very rare and is estimated to occur in only 1 in 40,000 pregnancies (Lermann 2009). It is usually manifested by severe abdominal pain about 2 weeks after the absence of menstruation.
Cervical pregnancy (cervical pregnancy)
With 0.2-0.5% of ectopic pregnancies, cervical pregnancy is very rare (Lermann 2009). In a cervical pregnancy, the embryo nests in the narrow neck of the uterus.
Abdominal pregnancy (abdominal gravidity)
About 1% of extrauterine pregnancies are localized in the abdominal cavity (Lermann 2009). Since the ovary and fallopian tube are not firmly connected, the embryo can also enter the abdominal cavity and settle on the peritoneum. Since it initially has room to grow here, it is not uncommon for such a pregnancy to go unnoticed for several weeks or for atypical symptoms to occur. Because of the often minor symptoms, abdominal pregnancies are therefore sometimes only recognized at a late stage.
Early symptoms in extrauterine pregnancy may be very mild or absent altogether. Clinically, an ectopic pregnancy presents between the 5th and 8th week after the onset of the last menstrual bleeding. Because extrauterine pregnancy initially develops like a normal pregnancy, the usual accompanying signs of a normal pregnancy such as fatigue, nausea, vomiting, and breast tenderness also occur initially. As the ectopic pregnancy progresses, the surrounding tissue becomes invaded by the growing embryo or placenta. Sooner or later, this results in sometimes life-threatening bleeding – the main symptom of extrauterine pregnancy.
Warning signs of an ectopic pregnancy that is not quite so acute include severe, cramp-like or stabbing pain in the abdomen that usually occurs on only one side, possibly combined with spotting that resembles menstrual bleeding. A non-intact or ectopic pregnancy is also noticeable by a barely rising or even suddenly falling hCG level. In the acute form of ectopic pregnancy, shock symptoms are found as a result of internal bleeding: These include pallor, sweating, attacks of weakness, malaise, nausea, dizziness and even fainting, as well as a weak pulse and falling blood pressure. For this reason, extrauterine pregnancy is a very serious complication that may require emergency medical treatment because internal bleeding can be life-threatening.
Diagnostics and Therapy
Due to improved diagnostic possibilities, extrauterine pregnancies can be detected very early today. Extrauterine pregnancy must be assumed in any woman with abdominal pain or vaginal bleeding with a positive pregnancy test. An ultrasound examination showing a fetal sac with fetal parts and cardiac actions outside the uterus is conclusive of extrauterine pregnancy. Treatment of an ectopic pregnancy usually consists of surgical removal of the pregnancy, now usually by laparoscopy. However, especially in developing countries with poor prenatal care, extrauterine pregnancies are often a cause of maternal mortality despite improved diagnostics.
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Hucke J and Füllers U. 2005. extrauterine pregnancy. In: Gynecolog. 38, 535-552. doi:10.1007/s00129-005-1705-1.
Lermann J et al. 2009. extrauterine pregnancy. In: gynecology. update 3, 383-402. doi:10.1055/s-0029-1224626.
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Kiel University Hospital: ectopic pregnancy. https://www.uksh.de/frauenklinik-kiel/F%C3%BCr+patients/your+surgery/information+on+various+surgeries/abdominal+surgery/ectopic+pregnancy+-p-696.html Accessed: 12 Nov. 2019.