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2007-03-21-10 Ectopic tubal interstitial pregnancy © Werner

Ectopic tubal interstitial pregnancy

Heron Werner, MD, Adriana M. Tostes, MD.

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


Ectopic pregnancy is an implantation of the gestational sac outside the uterine cavity. The risk of ectopic pregnancy is increased in conditions that alter normal tubal function such as pelvic inflammatory disease, previous tubal surgery, previous ectopic pregnancy, endometriosis and pregnancies from in vitro fertilization.

The majority of ectopic pregnancies occur within the extrauterine portion of the fallopian tube: ampullary (93%), isthmic (4%), interstitial (2,5%), ovarian (0,5%), cervical (0,1%) and abdominal.

In the interstitial pregnancy (pregnancy occurring in interstitial portion of fallopian tube), myometrium surrounds the gestational sac, allowing it to enlarge painlessly for a relatively long time. That is why it can grow to a larger size than tubal ectopics. The diagnosis can be suggested when an intrauterine pregnancy is visualized high in the fundus that is not surrounded in all planes by 5 mm of myometrium.

Systemic Methotrexate or sac injection via laparoscopy or ultrasound guidance can be used as treatment. Rupture may require hysterectomy.

Case report

We present ultrasound images of interstitial pregnancy diagnosed in the 6th week. The empty gestational sac with hyperechoic ring of trophoblastic tissue was placed within the right corner of the myomatous uterus.

Images 1, 2: 6th week of gestation. Axial endovaginal ultrasound showing ectopic gestational sac in the myometrium of the right uterine corner surrounded by thin layer of myometrium (red arrow - left image); and axial power Doppler ultrasound showing rich vasculature around the ectopic gestational sac in the interstitial part of the right uterine tube (right image).


Images 3, 4: Axial endovaginal ultrasound showing myoma of the uterus (left image); and sagittal view of the uterus showing thick endometrium (right image).


Images 5: 6th week of gestation. 3D coronal views showing ectopic gestational sac in the myometrium of the right uterine corner (black arrow)




Nyberg DA et al.: Ectopic pregnancy: diagnosis by sonography correlated with quantitative hCG levels. J Ultrasound Med 1987; 6:145-150.


Tulandi T et al: Interstitial pregnancy: results generated from the society of Reproductive Surgeons Registry. Obstet Gynecol 2004; 103(1): 47-50.


Sagiv R et al.: Three conservative approaches to treatment of interstitial pregnancy. J Am Assoc Gynecol Laparosc 2001; 8(1): 154-158.


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