Ectopic pregnancy
Updates to Article Attributes
Ectopic pregnancy refers to the implantation of a fertilised ovum outside of the uterine cavity.
Epidemiology
The overall incidence has increased over the last few decades and is currently thought to affect 1-2% of pregnancies. There is an increased incidence with in-vitro fertilisation pregnancies (IVF).
Clinical presentation
Presentation is often with abdominal pain or bleeding. If unrecognised haemorrhage can be life threatening.
Pathology
Location of ectopics
-
tubal ectopic: 93-97%
- ampullary ectopic: most common ~70% of tubal ectopics and ~65% of all ectopics
- isthmal ectopic: ~12% of tubal ectopics and ~11% of all ectopics
- fimbrial ectopic: ~11% of tubal ectopics and ~10% of all ectopics
-
atypical ectopic pregnancies
- interstitial ectopic/cornual ectopic: 3-4%; also essentially a type of tubal ectopic
- ovarian ectopic: ovarian pregnancy; 0.5-1%
- cervical ectopic: cervical pregnancy; rare <1%
- scar ectopic: site of previous Caesarian section scar; rare
- abdominal ectopic: rare; ~1.4%
Risk factors
- in vitro fertilization (IVF)
- prior EP
- tubal injury
- pelvic inflammatory disease
- prior tubal surgery
- salpangitis isthmica nodusa
- endometrial injury or congenital anomalies
- use of intrauterine contraceptive devices 5
Markers
- serum beta HCG levels tend to increase at a slower rate
- serum progesterone levels can be not as elevated as for an intrauterine pregnancy 6; 5-25 ng/ml range although not absolute reference required
Radiographic features
It is useful to know a quantitative beta HCG prior to scanning as this will guide what you expect to see. At levels <1000 IU, a normal early pregnancy may well not be visible, and therefore should the scan prove negative, a repeat scan in a couple of days (along with a repeat beta HCG) is necessary (beta HCG should normally double approximately every two days during the first 8 weeks).
Ultrasound
The ultrasound exam should be performed both transabdominally and transvaginally. The transabdominal component provides a wider view of the abdomen to assess for potential free fluid.
Positive findings in a beta HCG positive (>1000 IU) patient include:
-
uterus
- empty uterine cavity or no evidence of intrauterine pregnancy
-
pseudogestational sac or decidual cyst: may be seen in 10-20% of ectopic pregnancies
- current evidence suggests that one should not initiate treatment for an ectopic pregnancy in a haemodynamically stable woman on the basis of a single hCG value 10
- decidual cast
-
tube and ovary
- simple adnexal cyst: 10% chance of an ectopic
- complex extra-adnexal cyst/mass: 95% chance of a tubal ectopic (if no IUP)
- an intra-adnexal cyst/mass is more likely to be a corpus luteum
- solid hyperechoic mass is possible, but nonspecific
-
tubal ring sign
- 95% chance of an tubal ectopic if seen
- described in 49% of ectopics and in 68% of unruptured ectopics
- ring of fire sign: can be seen on colour Doppler in a tubal ectopic, but can also be seen in a corpus luteum
- absence of colour Doppler flow does not exclude an ectopic
- live pregnancy: 100% specific, but only seen in a minority of cases
-
peritoneal cavity
- free pelvic fluid or haemoperitoneum in the pouch of Douglas
- the presence of free intraperitoneal fluid in the context of a positive beta HCG and empty uterus is
- ~70% specific for an ectopic pregnancy 4
- ~63% sensitive for ectopic pregnancy 4
- not specific for ruptured ectopic (seen in 37% of intact tubal ectopics)
- the presence of free intraperitoneal fluid in the context of a positive beta HCG and empty uterus is
- live pregnancy: 100% specific, but only seen in a minority of cases.
- free pelvic fluid or haemoperitoneum in the pouch of Douglas
In patients receiving in vitro fertilisation (IVF), it is important not to be completely reassured by the presence of a live intrauterine pregnancy 8, as there is a possibility of a coexisting ectopic pregnancy in ~1:500 (i.e. heterotopic pregnancy). In patients not receiving IVF, the risk of heterotopic pregnancy is miniscule (1:30,000).
Complications
Complications somewhat depend on the type of ectopic. General complications for a typical (tubal) ectopic pregnancy include:
- tubal rupture: 15-20%
Management
No single strategy can be employed as preferred management depends on the location of the ectopic pregnancy. In general, the options are:
- surgical: (in the case of tubal ectopics with open or laparoscopic salpingectomy or salpingotomy)
- medical
- methotrextate (a folate antagonist) either administered systemically or by direct ultrasound guided injection or potassium chloride (direct injection only obviously)
- usually considered if size small (e.g <4 cm) and if no concurrent complication
- the gestational mass can paradoxically increase in size following methotrexate on subsequent scanning and does not necessarily imply failure of methotrexate therapy 3
- conservative or expectant management is being recognised as an option for those ectopics where rupture has not occurred (i.e. no haemoperitoneum) and fetal demise has already taken place
Differential diagnosis
The differential diagnosis of abdominal pain in a pregnant patient is broad. An ectopic pregnancy must be excluded with ultrasound. Other common diagnoses in this setting include:
- ruptured corpus luteum
- appendicitis (negative beta hCG)
In a clinically suspected ectopic pregnancy that is not confirmed on ultrasound, the differential is frequently that of a pregnancy of unknown location, with the alternative possibilities being of a very early pregnancy or a completed miscarriage.
- +</ul><h5>Risk factors</h5><ul>
- +<li>in vitro fertilization (IVF)</li>
- +<li>prior EP </li>
- +<li>tubal injury </li>
- +<li>pelvic inflammatory disease</li>
- +<li>prior tubal surgery</li>
- +<li>salpangitis isthmica nodusa</li>
- +<li>endometrial injury or congenital anomalies</li>
- +<li>use of intrauterine contraceptive devices <sup>5</sup>
- +</li>
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