What is an ectopic pregnancy?
Ectopic pregnancy is when a fertilized ovum implants outside of the uterine cavity. This is a life threatening condition that can lead to maternal morbidity and mortality if it is not diagnosed early.
The common sites of ectopic pregnancy include:
- The fallopian tube (95%) – In the fallopian tube, over 70% of the ectopic pregnancies occur in the ampulla and about 10% in the isthmus. 10% in the fimbrial ends and nearly 2% in the interstitial part of the fallopian tube.
- Ovaries (3%)
- Peritoneal cavity (1%)
The other possible sites of ectopic include:
- Broad ligament
Sometimes it is possible for a combined pregnancy or a heterotropic pregnancy to occur at the same time. This means that one pregnancy occurs in the fallopian tube and at the same time a second pregnancy occurs in the uterine cavity. Therefor when confirming a pregnancy it is important that the radiologist looks at other sites such as the fallopian tubes to exclude a heterotropic pregnancy.
What are the causes of an ectopic pregnancy?
Although the exact cause for ectopic pregnancy is not known, there are many risk factors identified which may lead to an ectopic pregnancy. The major risk factors for ectopic pregnancy include:
- Pelvic inflammatory disease – This refers to the inflammation of the female genital tract which is usually accompanied by fever and lower abdominal pain. The most common organism that may lead to pelvic inflammatory disease is Chlamydia trachomatis. It is a very slowly damaging infection. During an infection, adhesion formation also takes place and this will affect the mobility of the tubes thus leading to entrapment of the fertilized ovum within the tube and resulting in an ectopic pregnancy.
- During infection of the fallopian tubes, known as salphingitis, the cila (hair like structures that propels the fertilized ovum into the uterine cavity) gets damaged and hence hinders the propulsion of the fertilized ovum towards the uterus.
- Previous ectopic pregnancy.
- Previous tubal surgery such as ligation and resection of the tubes – Ligation and resection of the tubes is a permanent female sterilization method. However, sometimes there can be recanalization of these resected tubes allowing the sperm to travel through and fertilizing the ovum, eventually leading to ectopic pregnancy.
- Pregnancies following treatment for subfertility such as in vitro fertilization (IVF) – The incidence of ectopic are increased in this case because of the increased number of ova inseminated.
- Pregnancies despite having an intrauterine contraceptive device in-situ.
How is an ectopic pregnancy diagnosed?
In the past, ectopics have been diagnosed only on post mortem examination. However, now, advances in the diagnostic techniques have made it possible to diagnose ectopic pregnancies very early. A good history, examination and diagnostic investigations are necessary for the diagnosis of an ectopic pregnancy.
The presentation of each patient will vary. The 3 most common symptoms that patients with an ectopic pregnancy may present include:
- Period of amenorrhea – This means they will have a time period without any menstruation or they may have already been diagnosed to be pregnant.
- Lower abdominal discomfort
- Blood stained discharged through the vagina.
In such cases, a physical examination should be done to confirm the diagnosis. On abdominal examination, there may be lower abdominal tenderness. Vaginal examination may reveal cervical excitation pain (Pain on cervical motion) and tenderness of the fornices.
- A serum Beta HCG can be done to confirm the pregnancy.
- Full blood count – To assess the haemoglobin levels.
- Blood grouping and cross matching – This is necessary if there is continuous bleeding which may necessitate the need for a blood transfusion.
- Transvaginal ultrasound scan – A transvaginal ultrasound scan is useful in making the diagnosis of an ectopic pregnancy. On the scan , the obstetrician may notice and empty uterine cavity with no gestational or yolk sac, an ectopic sac may be located in a site outside the uterine cavity such as in the fallopian tubes. There may also be some blood collected in the pouch of Douglas and some free fluid within the abdominal cavity.
What is the management of an ectopic pregnancy?
The management of an ectopic pregnancy can be medical or surgical.
Medical management is considered in all unruptured ectopic pregnancies in the following situations:
- Patients with one fallopian tube and have future fertility wishes.
- Patients who refuse surgery or has a higher risk with surgical management.
- A corneal pregnancy – This is when the pregnancy takes place in one of the two upper horns of a bicornuate uterus.
- Persistent trophoblastic disease – This is a group of pregnancy related tumours.
Methotrexate is given to these patients. Methotrexate is a folic acid antagonist which inhibits the synthesis of the trophoblastic cells. Methotrexate is given as an intramuscular injection according the patient’s body surface area. These patients should be followed up with serial beta HCG levels and transvaginal ultrasound scans.
Some of the common side effects of using methotrexate include nausea, vomiting, and photosensitive skin rash. Therefore these patients should be advised to avoid exposure to sunlight. They should also be advised to use some form of contraception for 3 months after treatment with methotrexate.
Surgical management should be considered in all patients who present with a ruptured ectopic pregnancy. If the patient is stable, the best option is a laparoscopic surgery. If the fallopian tubes have been ruptured, then the fallopian tube has to be removed and this procedure is known as salpingectomy. However, if the fallopian tube is not ruptured, then the treatment option depends on the contralateral tube. If the opposite tube is normal, then the affected tube can be removed (salpingectomy) but if the opposite tube is absent or diseased, the affected tube should be incised and the products of conception should be removed followed by suturing back the incision. This method reserves the fallopian tube and is known as salphingostomy. However, the disadvantage of a salphingostomy is that there is a chance of recurrence of an ectopic pregnancy.