Masterclass – Ultrasound Study of the Tubal Ectopic Pregnancy

The incidence of ectopic pregnancy is about 2%. The mortality connected with ectopic pregnancies in the united states is about 0.50 deaths per 100,000 live births (Creanga AA et al., 2011). This shows exactly how important it is to set the proper diagnosis in time.

Risk Factors

  • previous ectopic pregnancy
  • previous chlamydia trachomatis infection
  • history of infertility
  • treatment with IVF for tubal infertility
  • previous adnexal surgery including sterilization
  • previous or current use of IUDs
  • smoking
  • poor education and poor occupation (Li C et al., 2015)
  • endometriosis (Yong, PJ et al., 2020).
ectopic pregnancy chlamydia
Tubal ectopic pregnancy and pelvic adhesions after infection with chlamydia trachomatis.
ectopic pregnancy iud
An adequate frontal plane of the anteverted uterus can usually be achieved transabdominally. This patient has an intrauterine device (IUD) and an ectopic pregnancy in the right fallopian tube. Sometimes combining transvaginal and transabdominal ultrasound may help the diagnosis.
Endometriosis may be associated with increased incidence of tubal ectopic. In this case a small endometriotic nodule can be seen on the isthmus of the left salpinx.

Approximately half of all women with an ectopic pregnancy present without known risk factors.

(Creanga AA et al., 2011).

Diagnosing a Tubal Ectopic

#1 – The Blob Sign

Tubal ectopic pregnancies should be identified by visualising an adnexal mass that is separate from the ovary (Elson CJ et al., 2016). The presence of this inhomogeneous mass which is clearly not a part of the ipsilateral ovary or of the uterus is called the blob sign (Nadim B. et al, 2017).

tubal ectopic pregnancy blob sign
The salpinx as a “blob”, or adnexal mass next to the ovary.
#2 – The Bagel Sign

The empty gestational sac and the decidualized tubal epithelium around it create an image similar to a bagel, or bagel sign (Nadim B. et al, 2017).

tubal ectopic pregnancy bagel sign
The thickened, decidualized tubal epithelium surrounds a small anechoic sac, giving the impression of a bagel.
Beside the corpus luteum of pregnancy (blue) the blob and bagel sign can be recognized in a small, still asymptomatic ectopic pregnancy (red).
#3 – Adnexal Mass Mobility

The ovary and ipsilateral tube are anatomically very close to one-another.

Ovary and tubal ectopic being adjacent to one another transvaginal ultrasound and intraoperative image of the same case.

Thus, when a tubal ectopic is suspected and a para-ovarian mass is seen consider testing for adnexal mass mobility:

  1. Place the endovaginal transducer as a wedge between the para-ovarian mass and the ovary.
  2. Apply gentle pressure either with your free hand transabdominally, or with the endovaginal transducer itself.

This maneuver may demonstrate obvious movement of each structure in different directions, aiding in the differential between ovarian cyst and tubal ectopic.

Be cautious however:

  1. Adhesions may prevent separate movement of the tube and the ipsilateral ovary.
  2. Mobile para-ovarian mass is not always an ectopic; do not forget that parovarian cysts (Morgagni’s hydatid cysts) are also very mobile.
Identification of an adnexal mass suspicious for tubal ectopic and testing its mobility with gentle pressure of the transvaginal transducer. The mass is mobile, indicating tubal ectopic.
Another adnexal mass suspicious for tubal ectopic. Here, gentle transabdominal pressure is applied with the examiner’s free hand, creating the same effect as above, the adnexal mass and the ovary move in different directions, indicating tubal ectopic.
#4 – Color Doppler

Color doppler signals may help in the diagnosis of the tubal ectopic pregnancy as they are clearly separated from ovarian tissue (Alkatout, I et al., 2013).

Keep in mind that both the corpus luteum cyst and the tubal ectopic may have similar appearance and both demonstrate ring-like color flow patterns (Fukami, T et al., 2006).

#5 – 3D Ultrasound

3D-ultrasound has not yet been proven to actually improve the diagnostic accuracy in tubal ectopic pregnancy (Infante, F et al., 2018). Still the power to create custom imaging planes may facilitate the diagnostic procedure.

tubal ectopic pregnancy 3d
Plane reconstructed after transabdominal 3d volume acquisition.

You might also find interesting other articles on ectopic pregnancy:


  • Creanga AA, Shapiro-Mendoza CK, Bish CL, Zane S, Berg CJ, Callaghan WM. Trends in ectopic pregnancy mortality in the United States: 1980-2007. Obstet Gynecol. 2011 Apr;117(4):837-43. doi: 10.1097/AOG.0b013e3182113c10.
  • Li C, Zhao WH, Zhu Q, Cao SJ, Ping H, Xi X, Qin GJ, Yan MX, Zhang D, Qiu J, et al. Risk factors for ectopic pregnancy: a multi-center case–control study. BMC Pregnancy childbirth. 2015;15:187. doi: 10.1186/s12884-015-0613-1.
  • Elson CJ, Salim R, Potdar N, Chetty M, Ross JA, Kirk EJ on behalf of the Royal College of Obstetricians and Gynaecologists. Diagnosis and management of ectopic pregnancy. BJOG 2016;. 123:e15–e55.
  • Nadim, B., Infante, F., Lu, C., Sathasivam, N. and Condous, G. (2017), The morphological ultrasound types known as ‘blob’ and ‘bagel’ signs should be reclassified from probable to definite ectopic pregnancy. Ultrasound Obstet Gynecol. Accepted Author Manuscript. doi:10.1002/uog.17435
  • Blaivas, M., & Lyon, M. (2005). Reliability of adnexal mass mobility in distinguishing possible ectopic pregnancy from corpus luteum cysts. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine24(5), 599–605.
  • Yong, P. J., Matwani, S., Brace, C., Quaiattini, A., Bedaiwy, M. A., Albert, A., & Allaire, C. (2020). Endometriosis and Ectopic Pregnancy: A Meta-analysis. Journal of minimally invasive gynecology27(2), 352–361.e2.
  • Alkatout, I., Honemeyer, U., Strauss, A., Tinelli, A., Malvasi, A., Jonat, W., Mettler, L., & Schollmeyer, T. (2013). Clinical diagnosis and treatment of ectopic pregnancy. Obstetrical & gynecological survey68(8), 571–581.
  • Fukami, T., Emoto, M., Tamura, R., & Kawarabayashi, T. (2006). Sonographic findings of transvaginal color Doppler ultrasound in ectopic pregnancy. Journal of medical ultrasonics (2001)33(1), 37–42.
  • Infante, F., Espada Vaquero, M., Bignardi, T., Lu, C., Testa, A. C., Fauchon, D., Epstein, E., Leone, F., Van den Bosch, T., Martins, W. P., & Condous, G. (2018). Prediction of Tubal Ectopic Pregnancy Using Offline Analysis of 3-Dimensional Transvaginal Ultrasonographic Data Sets: An Interobserver and Diagnostic Accuracy Study. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine37(6), 1467–1472.

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