Condition in which a fertilized egg is imbedded outside the uterus (see fertilization). Early on, it may resemble a normal pregnancy, with hormonal changes, amenorrhea, and development of a placenta. Later, most patients have pain as the growing embryo stretches the structure it is attached to. Rupture may cause life-threatening bleeding. A tubal pregnancy may result from obstruction of the egg's passage through the fallopian tube. In an ovarian pregnancy, the egg is fertilized before it leaves the ovary. Implantation elsewhere in the abdomen is an abdominal pregnancy.
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An ectopic pregnancy is a complication of pregnancy in which the fertilized ovum is implanted in any tissue other than the uterine wall. Most ectopic pregnancies occur in the Fallopian tube (so-called tubal pregnancies), but implantation can also occur in the cervix, ovaries, and abdomen. The fetus produces enzymes that allow it to implant in varied types of tissues, and thus an embryo implanted elsewhere than the uterus can cause great tissue damage in its efforts to reach a sufficient supply of blood.
In a normal pregnancy, the fertilized egg enters the uterus and settles into the uterine lining where it has plenty of room to divide and grow. About 1% of pregnancies are in an ectopic location with implantation not occurring inside of the womb, and of these 98% occur in the Fallopian tubes.
In a typical ectopic pregnancy, the embryo does not reach the uterus, but instead adheres to the lining of the Fallopian tube. The implanted embryo burrows actively into the tubal lining. Most commonly this invades vessels and will cause bleeding. This intratubal bleeding (hematosalpinx) expels the implantation out of the tubal end as a tubal abortion. Some women thinking they are having a miscarriage are actually having a tubal abortion. There is no inflammation of the tube in ectopic pregnancy. The pain is caused by prostaglandins released at the implantation site, and by free blood in the peritoneal cavity, which is a local irritant. Sometimes the bleeding might be heavy enough to threaten the health or life of the woman. Usually this degree of bleeding is due to delay in diagnosis, but sometimes, especially if the implantation is in the proximal tube (just before it enters the uterus), it may invade into the nearby Sampson artery, causing heavy bleeding earlier than usual.
If left untreated, about half of ectopic pregnancies will resolve without treatment. These are the tubal abortions. The advent of methotrexate treatment for ectopic pregnancy has reduced the need for surgery; however, surgical intervention is still required in cases where the Fallopian tube has ruptured or is in danger of doing so. This intervention may be laparoscopic or through a larger incision, known as a laparotomy.
There are some speculative specific causes or associations. Smoking, advanced maternal age and prior tubal damage of any origin are well known risk factors for ectopic pregnancy.
The early signs are:
Patients with a late ectopic pregnancy typically experience pain and bleeding. This bleeding will be both vaginal and internal and has two discrete pathophysiologic mechanisms.
The differential diagnosis at this point is between miscarriage, ectopic pregnancy, and early normal pregnancy. The presence of a positive pregnancy test virtually rules out pelvic infection as it is rare indeed to find pregnancy with an active Pelvic Inflammatory Disease (PID). The most common misdiagnosis assigned to early ectopic pregnancy is PID.
More severe internal bleeding may cause:
Free fluid which is non-echogenic is a normal finding in the late menstrual cycle and early normal pregnancy. This is a transudate and is not presumptive evidence of bleeding. Echogenic free fluid suggests the presence of blood clot and is suggestive of free blood in the peritoneum.
A laparoscopy or laparotomy can also be performed to visually confirm an ectopic pregnancy. Often if a tubal abortion has occurred, or a tubal rupture has occurred, it is difficult to find the pregnancy tissue. A laparoscopy in very early ectopic pregnancy rarely shows a normal looking fallopian tube.
A less commonly performed test, a culdocentesis, may be used to look for internal bleeding. In this test, a needle is inserted into the space at the very top of the vagina, behind the uterus and in front of the rectum. Any blood or fluid found there likely comes from a ruptured ectopic pregnancy.
Cullen's sign can indicate a ruptured ectopic pregnancy.
While a fetus of ectopic pregnancy is typically not viable, very rarely, a live baby has been salvaged from an abdominal pregnancy. In such a situation the placenta sits on the intraabdominal organs or the peritoneum and has found sufficient blood supply. This is generally bowel or mesentery, but other sites, such as the renal (kidney), liver or hepatic (liver) artery or even aorta have been described. Support to near viability has occasionally been described, but even in third world countries, the diagnosis is most commonly made at 16 to 20 weeks gestation. Such a fetus would have to be delivered by laparotomy. Maternal morbidity and mortality from extrauterine pregnancy is high as attempts to remove the placenta from the organs to which it is attached usually lead to uncontrollable bleeding from the attachment site. If the organ to which the placenta is attached is removable, such as a section of bowel, then the placenta should be removed together with that organ. This is such a rare occurrence that true data are unavailable and reliance must be made on anecdotal reports. However, the vast majority of abdominal pregnancies require intervention well before fetal viability because of the risk of hemorrhage.
On 19 April 2008 an English woman, Jayne Jones (age 37) who had an ectopic pregnancy attached to the omentum, the fatty covering of her large bowel, gave birth. The baby was delivered by a laparotomy at 28 weeks gestation. The surgery, the first of its kind to be performed in the UK, was successful, and both mother and baby survived.
On May 29, 2008 an Australian woman, Meera Thangarajah (age 34), who had an ectopic pregnancy in the ovary, gave birth to a healthy full term 6 pound 3 ounce (2.8 kg) baby girl, Durga, via Caesarean section. She had no problems or complications during the 38 week pregnancy.
Although rare, with the continual increase of IVFs, heterotopic pregnancies are becoming more and more common. However, these pregnancies are still considered moderate to high risk. The survival rate of the uterine fetus of an ectopic pregnancy is around 70%.
This link describes a case of a burst tubal pregnancy continuing by the placenta implanting on the outside of the uterus, plus intra-uterine twins; laparotomy rescued three live babies. The intra-uterine twins were removed first.
Surgeons use laparoscopy or laparotomy to gain access to the pelvis and can either incise the affected Fallopian and remove only the pregnancy (salpingostomy) or remove the affected tube with the pregnancy (salpingectomy). The first successful surgery for an ectopic pregnancy was performed by Robert Lawson Tait in 1883.
The most common complication is rupture with internal bleeding that leads to shock. Death from rupture is rare in women who have access to modern medical facilities. Infertility occurs in 10 - 15% of women who have had an ectopic pregnancy.