An ectopic pregnancy is defined as the presence of a pregnancy outside the uterine cavity, the commonest location being the fallopian tube. They account for 1-2% of pregnancies in the UK and may be as high as 4% with assisted conception.

Abstract: An ectopic pregnancy is defined as the presence of a pregnancy outside the uterine cavity, the commonest location being the fallopian tube. They account for 1-2% of pregnancies in the UK and may be as high as 4% with assisted conception. Ectopic pregnancy remains the leading cause of maternal death related to an early pregnancy cause, with an estimated maternal mortality of 0.2/1000 ectopic pregnancies. Transvaginal ultrasound technology remains the mainstay of diagnosis. Once the diagnosis of an ectopic pregnancy has been made, the management options are expectant, medical or surgical.

Key words: ectopic pregnancy, transvaginal ultrasonography

Authors: Shabnam Bobdiwala1, Jessica Farren1, 2, Tom Bourne1,3,4

1. Tommy’s National Centre for Miscarriage Research, Imperial College,Queen Charlottes and Chelsea Hospital, London, UK

2. Department of Gynaecology, St Mary’s Hospital, London, UK

3. KU Leuven, Department of Development and Regeneration, Leuven, Belgium

4. Department of Obstetrics and Gynecology, University Hospitals Leuven, Leuven, Belgium

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An ectopic pregnancy is defined as the presence of a pregnancy outside the uterine cavity and could be in any of  the following locations:

  • fallopian tube
  • ovary
  • cervix
  • myometrium (interstitial ectopic)
  • caesarean section scar
  • elsewhere in the abdominal cavity

The commonest location of an ectopic pregnancy is in the fallopian tube, and accounts for approximately 95% of all ectopic pregnancies.


The incidence varies depending on the population. In the UK, ectopic pregnancy affects 11/1000 pregnancies.3 and can be as high as 4% in assisted conception patients.2 Importantly, the condition has an estimated maternal mortality of 0.2/1000 ectopic pregnancies.3 In the developing world it has been estimated that “10% of women admitted to hospital with a diagnosis of ectopic pregnancy ultimately die from the condition”4

Rick Factors4

Over half of women with ectopic pregnancies will have no risk factors but important contributing factors include:

  • Tubal damage (caused by previous tubal/ pelvic surgery (including caesarean section and ovarian cystectomy), previous abdominal surgery (including appendicectomy and bowel surgery) and/or a confirmed genital infection/ pelvic inflammatory disease, commonly by Chlamydia trachomatis)
  • Subfertility (particularly that which is associated with documented tubal disease, the use of assisted reproductive technology techniques, endometriosis and unexplained infertility)
  • Contraceptive failure(including the presence of an intrauterine contraceptive device at the time of conception and/ or use of the emergency ‘morning after pill’/ progestogen-only contraception)
  • Previous ectopic pregnancy
  • Age >35 years
  • Smoking


Clinical symptoms

The clinical symptoms of ectopic pregnancy5 includes unilateral pelvic pain, vaginal bleeding, gastrointestinal symptoms such as diarrhea and rectal pressure and/or shoulder tip pain. Women may also be asymptomatic, where the ectopic pregnancy is noted at a scan performed for another reason (e.g. previous ectopic pregnancy)

Ultrasound characteristics of tubal ectopic pregnancy

Transvaginal ultrasound is the gold standard investigation for the diagnosis of an ectopic pregnancy.6 The adnexal mass seen may have one of several different appearances:

  • ‘Blob sign’: a descriptive term used to describe the commonest (60%) appearance of a tubal ectopic pregnancy. This is an inhomogenous mass seen in the adnexa.1 This sign has been found to be the most effective non-invasive way to diagnose an ectopic pregnancy, with a meta-analysis reporting a specificity of 98.9%, a positive predictive value of 96.3%, a sensitivity of 84.4% and a negative predictive value of 94.8%.8
  • ‘Bagel sign’: a descriptive term used to describe the ultrasound appearance of 20% tubal ectopic pregnancies. This is an inhomogenous mass containing a gestation sac seen in the adnexa1
  • An extrauterine gestation sac with a yolk sac +/- a fetal pole that may have fetal cardiac activity

‘Pseuodosac’ is a term used to describe a collection of fluid in the endometrial cavity that is not an early intrauterine gestation sac (IUGS). It tends to have a central location within the endometrial cavity (whereas an IUGS tends to be eccentrically placed). It may also be transient and change shape during scanning or when pressure is exerted. It does not have a hyperechoic decidual reaction as would be expected with an IUGS and has been described as often having a ‘pointy edge’ and complex fluid within it.9

Importantly, it should be noted that “any round or oval fluid collection in a woman with a positive pregnancy test most likely represents an intrauterine gestational sac”.10 In fact, in the absence of an adnexal mass, a fluid filled structure within the uterus has a “0.02% probability of ectopic pregnancy” (and 99.98% probability of IUP).9 Therefore, the presence of a ‘pseudosac’ by no means confirms the presence of an extrauterine pregnancy and caution must be taken before intervening and inadvertently terminating a potential intrauterine pregnancy.



Following the definitive diagnosis of an ectopic pregnancy via transvaginal ultrasound, management options can be discussed with the patient. This includes expectant, medical or surgical management.

Success rates of 48-100%11 have been reported with expectant management. The main benefit is that it avoids the potential risk avoided with medical or surgical intervention and can be performed on an outpatient basis.

Medical management involved the use of the folate antagonist Methotrexate, usually at a dose of 50mg/m2. Overall success rates of 65-95% have been reported11,12, with two doses demonstrating a higher success rate (84%) when compared to a single dose (68%).13 Advantages are that it can also be  performed on an outpatient basis and avoids the risks of surgery, with <10% women treated this way requiring surgical intervention as a secondary treatment.14,15 The main disadvantages relate to the side effects of the drug, which can include abdominal pain (found in 75%), conjunctivitis, stomatitis and gastrointestinal upset. 14% women will require ≥ 1 dose and 7% will experience tubal rupture during follow-up.16

Both expectant and medical management carry an increased risk of unplanned admissions and interventions compared to surgical management.

Surgical intervention can be open, although a laparoscopic approach is by far the preferred method due to shorter operation times, less intra-operative blood loss, shorter hospital stays, lower costs, lower analgesic requirements and a reduced risk of adhesion formation.

 Either a salpingectomy (where the entire fallopian tube containing the ectopic pregnancy is removed) or a salpingotomy (where an incision is made in the fallopian tube, the ectopic trophoblast tissue removed and the incision made is left to heal by secondary intention) can be performed. A salpingectomy is related to lower rates of persistent trophoblast and subsequent ectopic pregnancy rates but a salpingotomy may be a preferable option for women with contralateral tubal damage as it is associated with a higher subsequent intrauterine pregnancy rate compared to a salpingectomy in these women17. There appears to be a minimal difference in tubal patency rate and subsequent intrauterine pregnancy rate overall in women who have a healthy contralateral tube.18 It should be noted that more robust studies are needed to assess these issues in detail. The main advantage of surgical treatment is that it is a definitive, one-stop form of treatment. If a salpingectomy is performed there is no prolonged follow-up and may therefore reduce the time until the next conception can occur, although serum hCG follow-up is usually necessary post-salpingostomy. The main disadvantages relate to the complications of pelvic surgery which include bladder/ bowel or ureteric injuries and the formation of adhesions which at a later date cause pelvic pain or subfertility.


  1. Kirk E, Bourne T. Diagnosis of ectopic pregnancy with ultrasound. Best Prac & Res Clinl Obst and Gynaecol 2009;23:501–8
  2. Kirk E, Bottomley C, Bourne T. Diagnosing ectopic pregnancy and current concepts in the management of pregnancy of unknown location. Hum Reprod Update 2014;20(2):250–61
  3. Tubal Pregnancy, Management (RCOG Green-top Guideline No. 21), 2004
  4. Sivalingam VN, Duncan WC, Kirk E, Shephard LA, Horne AW. Diagnosis and management of ectopic pregnancy. J Fam Plann Reprod Health Care 2011;37(4):231-40
  5.  Ayim F, Tapp S, Guha S, Ameye L, Al Memar M, Sayasneh A, Bottomley C, Gould D, Stalder C, Timmerman D, Bourne T. Do risk factors, clinical history and symptoms predict the risk of ectopic pregnancy in women attending an early pregnancy assessment unit? (in press)
  6. Kirk E, Papageorghiou AT, Condous G, Tan L, Bora S, Bourne T. The diagnostic effectiveness of an initial transvaginal scan in detecting ectopic pregnancy. Hum Reprod 2007;22(11):2824–28
  7.  Condous G, Van Calster B, Kirk E, Haider Z, Timmerman D, Van Huffel S, Bourne T. Prediction of ectopic pregnancy in women with a pregnancy of unknown location. Ultrasound Obstet Gynecol 2007;29:680–87
  8. Brown DL, Doubilet PM. Transvaginal sonography for diagnosing ectopic pregnancy: positivity criteria and performance characteristics. J Ultrasound Med. 1994;13:259–66
  9. Benson CB, Doubilet PM, Peters HE, Frates MC. Intrauterine Fluid With Ectopic Pregnancy. A Reappraisal. Ultrasound Med 2013;32:389–93
  10. Doubilet PM, Benson CB, Bourne T, Blaivas M. Diagnostic Criteria for Nonviable Pregnancy Early in the First Trimester. N Engl J Med 2013,369(15):1443-51
  11. Kirk E, Van Calster B, Condous G, Papageorghiou AT, Gevaert O, Van Huffel S, De Moor B, Timmerman D, Bourne T. Ectopic pregnancy: using the hCG ratio to select women for expectant or medical management. Acta Obstet Gynecol Scand. 2011;90(3):264-72
  12. Kirk E, Condous G, Van Calster B, Haider Z, Van Huffel S, Timmerman D, Bourne T. A validation of the most commonly used protocol to predict the success of single-dose methotrexate in the treatment of ectopic pregnancy. Hum Reprod 2007;22(3); 858–63
  13. Kirk E, Condous G, and Bourne T. The non-surgical management of ectopic pregnancy. Ultrasound Obstet Gynecol 2006;27:91–100
  14. Lipscomb G, Bran D, McCord M, Portera J, Ling F. Analysis of three hundred fifteen ectopic pregnancies treated with single-dose methotrexate. Am J Obstet Gynecol 1998;178:1354–8
  15.  Lipscomb G, McCord M, Stovall T, Huff G, Portera S, Ling F. Predictors of success of methotrexate treatment in women with tubal ectopic pregnancies. N Engl J Med 1999;341:1974–8
  16. Yao M, Tulandi T. Current status of surgical and nonsurgical management of ectopic pregnancy. Fertil Steril 1997;67:421–33
  17. Mol B, Matthijsse H, Tinga D, Huynh T, Hajenius P, Ankum W, Bossuyt PM, van der Veen F. Fertility after conservative and radical surgery for tubal pregnancy. Hum Reprod 1998;13:1804–9.
  18. Silva P, Schaper A, Rooney B. Reproductive outcome after 143 laparoscopic procedures for ectopic pregnancy. Fertil Steril 1993;81:710–5

This article should be cited as: Bobdiwala S, Farren J, Bourne T: Ultrasound assessment of ectopic pregnancy, Visual Encyclopedia of Ultrasound in Obstetrics and Gynaecology,,  June 2016

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