Ectopic pregnancy

An ectopic pregnancy occurs when the products of conception implant outside the endometrial cavity (1). The most common site is the fallopian tube - 17.4% in the fimbria, 55% in the ampulla, 25% in the isthmus and 2% in the interstitial portion. Less commonly, a pregnancy implants in the ovary (0.5%), in cervix, scar from a cesarean section or the abdominal cavity (0.1%) (1).

Non-tubal ectopic pregnancy is the term used to describe implantation of an embryo at a site lying outside the uterine cavity or fallopian tubes - there has been an increasing trend in the occurrence of these rare conditions, especially caesarean scar pregnancy (CSP) (2)

• ectopic pregnancy makes up 80% of maternal deaths that occur in the first trimester, of which non-tubal ectopic pregnancy deaths account for a higher rate than tubal pregnancy deaths

It is estimated that there are around 10,700 ectopic pregnancies in the UK each year, with an incidence of 11.1 in every 1000 pregnancies (3,4)

• there is a maternal mortality of 0.2 per 1000 estimated ectopic pregnancies. About two thirds of these deaths are associated with substandard care (4)

It is usually associated with a period of amenorrhoea followed by bleeding and pain.

A heterotrophic pregnancy is when an intrauterine and an extrauterine pregnancy occur together in a woman (5).

Note though that the advice from the CEMD report (1) states "it is essential that GPs and other clinicians, including staff in A and E departments, consider the diagnosis of ectopic pregnancy in any woman of reproductive age who complains of abdominal pain. It is important to recognise that the clinical presentation is not often "classical". BhCG (pregnancy) testing should be considered in any woman of reproductive age with unexplained abdominal pain whether or not she has missed a period or had abnormal vaginal bleeding."

Some women (around 8 to 31%) with suspected ectopic pregnancies may present without any signs of an extra- or intra-uterine pregnancy on initial transvaginal ultrasound scan (TVS). These women are categorized as having a pregnancy of unknown location (PUL).

• around 25-50% of women with an ectopic pregnancy initially presents as PUL
• approximately 7 to 20% of women with a PUL will eventually be given a diagnosis of an ectopic pregnancy (1)

Risk of ectopic pregnancy with different homornal contraceptivs:

• a study (n=963,964 followed up for 7.8m person-years) found use of any levonorgestrel IUS linked to significantly increased risk of ectopic pregnancy vs other hormonal contraceptives, with highest risk for 13.5-mg IUS, including when compared with other doses (6)
  • adjusted absolute rate (per 10,000 person-years) of ectopic pregnancy was 2.4 with other hormonal contraceptives, 7.7 with 52-mg (difference, 5.3), 7.1 with 19.5-mg (difference, 4.8), and 15.7 with 13.5-mg levonorgestrel IUS (difference, 13.4)
  • corresponding relative rate ratios were 3.4 (95% CI, 2.4-4.8), 4.1 (95% CI, 2.9-5.9), and 7.9 (95% CI, 6.3-10.1). Ectopic pregnancy rate for each levonorgestrel IUS dose also increased with duration of use

Notes:

• the Levonorgestrel system is classified as an intra-uterine system (IUS) and not a IUCDhttps://jamanetwork.com/journals/jama/article-abstract/2802628

Reference:

• (1) Barnhart KT. Clinical practice. Ectopic pregnancy. N Engl J Med. 200923;361(4):379-87
• (2) LongY et al. Interventions for non-tubal ectopic pregnancy. Cochrane Database of Systematic Reviews 2020, Issue 7. Art. No.: CD011174. DOI: 10.1002/14651858.CD011174.pub2
• (3) Confidential Enquiry into Maternal and Child Health (CEMACH) 2007. Saving mothers’ life:Reviewing maternal deaths to make motherhood safer - 2003-2005
• (4) NICE (September 2023).Ectopic pregnancy and miscarriage: diagnosis and initial management
• (5) Lin EP, Bhatt S, Dogra VS. Diagnostic clues to ectopic pregnancy. Radiographics. 2008;28(6):1661-71
• (6) Meaidi A et al.Ectopic Pregnancy Risk in Users of Levonorgestrel-Releasing Intrauterine Systems With 52, 19.5, and 13.5 mg of Hormone. JAMA. 2023;329(11):935–937. doi:10.1001/jama.2023.0380