Ectopic pregnancy
 
Ectopic pregnancy was first described in the 11th century and since then continued to be the most frequent cause of first trimester maternal mortality. The word ectopic has be driven from the Greek word Ektopos which means out of place. It is diagnosed when a fertilised egg implants outside the uterine cavity. Its incidence increased lately most probably because of the increased incidence of sexually transmitted diseases especially chlamydia. 95% of all ectopic pregnancies occur along the fallopian tubes but could also occur in the ovaries or even the cervix. The ampullary part of the tube is the most common site but involvement of the narrow and muscular Isthmic part usually has a more dramatic effects.

 

Currently arround 2% of all pregnancies are ectopic and the rate of heterotopic pregnancies also increased with the more available IVF treatment. In this case one sac would be in the uterine cavity and the other one sited in one of the tubes, ovaries or cervix. Historically heterotopic pregnancies were quoted to occur 1 in 30000 pregnancies. However the natural current incidence is quoted as 1 in 4000 but came down to 1 in 35 -100 with clinical pregnancies following IVF.
 
The first successful surgical treatment of ectopic pregnancy took place in 1759 and was performed by John Bard in New York. Since then improvement in the managment of ectopic pregnancy improved the survival rate despite the dramatic increase in the incidence of the condition.

 

In most cases development of ectopic pregnancies could not be related to any specific cause. However certain risk factors have been identified over the years including the following factors: 

  • Previous pelvic inflammatory disease which brings the issue of safe intercourse and early diagnosis with efficient treatment of such episodes to the forefront of primary care and community gynaecology. A risk of 13%, 35% and 75% has been reported after one, two and three PID episodes respectively.
  • History of pelvic surgery leading to adhesions formation. Examples include appendectomy, ovarian cystectomy and myomectomy. Laparoscopic surgery is expected to cause fewer and less dens adhesions in comparison to open surgery.
  • History of tubal ligation or tubal reconstructive surgery is also a risk factor. Such risk is higher 2 years after tubal ligation with electocautery due to formation of tubal / peritoneal  fistulae.
  • Previous ectopic pregnancy increases the risk 10 times. This is mostly because the other tube might have been involved with the same pathology which contributed to the first one. Accordingly women who conceive for the second time after an ectopic pregnancy should seek early gynaecological care for transvaginal scan examination to exclude the possibility of another one. It is important to mention that up to 15% of women who had an ectopic pregnancy in the past might have future fertility problems.
  • Use of an intrauterine contraceptive device when conceived increases the risk of ectopic pregnancy to 15%  with medicated or progesterone loaded devices compared to 5% for non-medicated devices. However previous use of the coil does not predispose to ectopic pregnancy unless it was complicated by clinical or subclinical pelvic infection.

Some studies related ectopic pregnancy and tubal dysfunction to smoking and regular vaginal douching. On the other hand women who conceive despite using progestogen only pills or the morning after pill are  5 and 10 times more at risk respectively.

Presentation

 

A high degree of suspicion should be exercised to help with diagnosing ectopic pregnancies. They are mostly diagnosed between 6-7 weeks but could be seen at an earlier gestational age. Lower abdominal pain is the most common presentation. It could be acute in cases of ruptured ectopic with significant intra-abdominal bleeding or subacute with or without some vaginal bleeding. With recent advances in medical care the acute presentation is not frequently seen these days. Most patients present with:

  • Amenorrhoea of 5-7 weeks duration.
  • Persistent or intermittent lowerabdominal pain which is mostly unilateral.
  • Abnormal uterine bleeding which is usually mild to moderate in amount.
  • Positive pregnancy test though home kits might give a negative result.  

Management

 

The main objectives in the management of patients with ectopic pregnancies are pateints' safety, high dectection rate and avoiding the need to use laparoscopy for  the sole reason of diagnosis.
 
In recent years we became more conservative in treating ectopic pregnancies. Asymptomatic women and those with a small ectopic pregnancy on ultrasound examination and low  βhCG le  vel could be treated conservatively with or without intramuscular or tubal methotrexate injections. Accordingly a good clinical assessment should be followed by blood tests for FBC and  βhCG which should be repeated every 2 –3 days.  In approximately 85% of normal intrauterine pregnancies the level of βhCG is expected to double or at least show a 1.66 fold increase.  

 

As well progesterone could prove to be a useful parameter in the management of ectopic pregnancies as its level is constant during the first trimester. A blood level of 25 ng/ml during natural cycles is diagnostic of a normal intrauterine pregnancy and excludes ectopic pregnancy with 97.4% certainity. However a level < 15 ng/ml is seen in 81% of ectopic pregnancies, 93% of abnormal intrauterine pregnancies but could as well be seen in 11% of normal intrauterine pregnancies.

 

The role of transvaginal ultrasound examination
 
Transvaginal scanning proved to be an important tool in the diagnosis and management of ectopic pregnancies. It could give a very high positive predictive value and helps with the diagnosis in 90% of the cases when performed by experienced personnel. An empty uterus with ßhCG level of 1500-2000 IU/ml could indicate an ectopic pregnancy as at least an intrauterine sac should be seen at such levels. Alternatively a gestational sac could be seen to the side of the uterus with or without a yolk sac, fetal pole with or without fetal heart activity. Depending on the stage at diagnosis variable amount of fluid with floating particles could be seen in the pouch of Douglas indicating some intra-peritoneal leak of blood from the ectopic pregnancy.
 
The most common ultrasound finding is the presence of a mass 'in the ectopic angle' between the uterus and the ovary harbouring the corpus luteum, in almost 80% of the cases, but viable ones with fetal heart activity are the least common type.
 
The presence of tubrid fluid in the pouch of Douglas is an important but not a universal finding in all ectopic pregnancies. The amount of fluid usually reflects how much blood has leaked through the fimbrial end of the tube. Major haemoperitoneum would be seen in complicated or ruptured ectopic pregnancies. With a positive pregnancy test and an empty uterus, the presence of intraperitoneal fluid is almost 70% sensitive in diagnosing an ectopic. This sensitivity could rise up to > 90% if the fluid was echogenic.

 

 

 

The first picture above shows an ectopic pregnancy ring lateral to the uterus. The second picture shows a heterotopic pregnancy with one sac in the uterus and the other one in the dilated right tube. The third picture shows a heterotopic pregnancy with one intrauterine and one cornual or interstitial in location. Both heterotopic pregnancies followed IVF treatment. Note the echogenic band joining the two gestational sacs in the last picture. It could be thinner than what is shown in this picture in case of a cornual pregnancy without a concomitant intrauterine one. Such thin echogenic line extending into the cornual region and merging with the gestational sac is known as the interstitial line and has been found to be higly specific for intertitial pregnaqncies. Also a cornual sac would be surrounded by a thin layer of myometrium. Both of these characteristics are best seen in rendered coronal views after capturing a 3D volume. The presence of fluid collection or pseudosac in the uterine cavity could be seen with tubal pregnancies and should not be confused with intrauterine gestation. A pseudosac is usually seen within the cavity rather than towards one side or the other of the central uterine echo which is characteristic of normal ones. Futhermore it would not show a yolk sac or fetal pole.
  

Failure to see a gestational sac within the uterus or in one tube or the other with a positive ßhCG blood test does not rule out the presence of a pregnacny somewhere in the pelvis. This is now given the term Pregnancy of Unknown Location or PUL.

 

Patients with unstable cardiovascular system and those with acute onset of pain are better treated surgically. As well a patient with a large ectopic pregnancy and identifiable fetal heart activity should be treated surgically.

 

Laparoscopy has already taken over as the standard method for treating ectopic pregnancies needing surgical intervention. Patients could usually go home on the same day or at most the following morning after the procedure. The tube could be easily excised and removed in a retrieval bag as shown below. This is especially done when:

  • There is significant hemorrhage
  • The tube has ruptured
  • The tube is significantly distorted
  • Future fertility is not an issue.

However in certain cases the tube could be slit on top of the ectopic pregnancy which is removed without damaging the whole tube (salpingostomy). In such cases however there is 5-10% risk of persistent ectopic with viable chorionic villi continuing to grow. The ßhCG level will stay high and patients might become symptomatic again within 10 days of surgery. This could lead to subsequent rupture of the tube unless treatment with methotrexate is given or salpingectomy is done.

 

Methotrexate is an anti metabolite which is usually used for treating some forms of cancer. It inhibits rapidly growing cells hence used to block the growth of ectopic trophoblasts. It is usually used for small ectopic pregnancies  less than 3-4 cm in diameter in haemodynamically stable patients who have no significant intra-abdominal haemorrhage. Depending on the selection criteria more than 70% of medically treated ectopic pregnancies resolve with confirmed tubal patency in 70% of the cases and a similar repeat ectopic incidence compared to conservative surgery. The usual dose is 50 mg per square metre intramuscularly though direct injection into the ectopic site is used frequently as well. Strict follow up of these patients is necessary for a long time till the ßhCG level returns back to the non pregnant level. However there might be an initial transient rise in the level of ßhCG as well as lower abdominal pain. Furthermore it is also important to note that a mass could be seen at the ectopic site with transvaginal scanning for many months following medical treatment.
 
 
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