Clinica de Diagnostico por Imagem (CDPI), Rio de Janeiro, Brazil

The risk of ectopic pregnancy is increased in specific conditions such as pelvic inflammatory disease, previous tubal surgery, endometriosis, previous ectopic pregnancy and in vitro fertilization. Transvaginal scan plays an important role in the early diagnosis. The diagnosis can be suspected when the patient has a positive pregnancy test with pain, bleeding or presence of adnexal mass. 80% of the ectopic pregnancies are in the ampullary portion of the fallopian tube,10 to 15% in the isthmic or interstitial portion, 5% in the fimbrial end, 2% to 4% in the interstitial end (also called cornual ectopic) and 0.5% in the ovary.

Because the tube is the most common site for ectopic pregnancies, it is important to scan above and below the ovaries and between the uterus and ovaries to exclude adnexal mass. The location of the corpus luteum is not helpful in directing the examination because contralateral implantation occurs in up to 1/3 of cases.
Abdominal and cervical pregnancies are very rare. They represent approximately 1% of all ectopic pregnancies.

Transverse scan of the left adnexa in a patient with an ectopic pregnancy. There is an adnexal ring containing a yolk sac (red arrow). Note a small amount of free fluid adjacent to the ovary (blue arrow).

Tubal ring in a patient with left ectopic pregnancy. The color Doppler shows peritrophoblastic flow. Note the corpus luteum cyst ipsilateral to ectopic pregnancy (arrow).

Power Doppler shows the peritrophoblastic flow. 3D scan shows the left ovarium whith the corpus luteum (red arrow) and the tubal ring (blue arrow)

Sagittal view of the uterus shows an empty cavity. Note the tubal ring (arrow).

Longitudinal transvaginal sonogram of a patient with an ectopic pregnancy. A large ectopic gestation is located superior to the fundus of the uterus. A fetus (12 weeks) can be easily identified. Note the empty uterus (arrow).

The gestational sac and fetus

Sagittal transvaginal scan shows a sac in the cervix (arrow) and the embryo (8 weeks) placed in the cervix (arrow)

References:

• Breen JL.: A 21 year survey of 654 ectopic pregnancies. Am J Obstet Gynecol 106: 1004, 1970. 
• Nyberg et al.: Extrauterine findings of ectopic pregnancy at transvaginal US. Radiology 1991; 178: 823.
• Werner H et al.: Abdominal pregnancy – Report of case. J Bras Ginec 108 (11/12): 413-416, 1998.