Descriptively correct, as interstitial portion of fallopian tube does transverse uterine wall
Not technically accurate, as blastocyst implants in tube not myometrium
Cornual pregnancy(least preferred term)
Often used interchangeably with IEP, but recent literature urges avoiding this term altogether
HIstorically used to refer to pregnancy in 1 horn of duplication anomaly (septate or bicornuate uterus)
Angular pregnancy (AP) is different diagnosis
Key difference from IEP is that AP is intrauterine
Pregnancy implants at lateral angle of uterine cavity medial to uterotubal junction
Near ostia of fallopian tube
Located medial to round ligament
IMAGING
General Features
Ultrasonographic Findings
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Microscopic Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Selected References
Jensen KK et al: Imaging of acute pelvic pain: pregnant (ectopic and first-trimester viability updated). Radiol Clin North Am. 58(2):347-61, 2020
Khan Z et al: In pursuit of understanding interstitial pregnancies: a rare yet high-risk ectopic pregnancy. Fertil Steril. 112(2):246-7, 2019
Di Tizio L et al: Interstitial pregnancy: from medical to surgical approach-report of three cases. Case Rep Obstet Gynecol. 2018:2815871, 2018
Marfori CQ et al: Angular vs. interstitial pregnancy: a case report highlighting diagnostic nuances with stark management differences. Case Rep Womens Health. 19:e00068, 2018
Chukus A et al: Uncommon implantation sites of ectopic pregnancy: thinking beyond the complex adnexal mass. Radiographics. 35(3):946-59, 2015
Tanaka K et al: Management of interstitial ectopic pregnancy with intravenous methotrexate: An extended study of a standardised regimen. Aust N Z J Obstet Gynaecol. 55(2):176-80, 2015
Arleo EK et al: Cornual, interstitial, and angular pregnancies: clarifying the terms and a review of the literature. Clin Imaging. 38(6):763-70, 2014
Hiersch L et al: Effectiveness of medical treatment with methotrexate for interstitial pregnancy. Aust N Z J Obstet Gynaecol. 54(6):576-80, 2014
Nezhat CH et al: Laparoscopically-assisted, hysteroscopic removal of an interstitial pregnancy with a fertility-preserving technique. J Minim Invasive Gynecol. 21(6):1091-4, 2014
Pedroso C et al: Interstitial pregnancy rupture at 15 weeks of pregnancy. BMJ Case Rep. 2014, 2014
Tanaka Y et al: Three-dimensional sonography in the differential diagnosis of interstitial, angular, and intrauterine pregnancies in a septate uterus. J Ultrasound Med. 33(11):2031-5, 2014
Rheinboldt M et al: Atypical presentation of a large interstitial pregnancy. Emerg Radiol. 20(3):251-4, 2013
Sagiv R et al: Interstitial pregnancy management and subsequent pregnancy outcome. Acta Obstet Gynecol Scand. 92(11):1327-30, 2013
Cucinella G et al: Laparoscopic management of interstitial pregnancy: the "purse-string" technique. Acta Obstet Gynecol Scand. 91(8):996-9, 2012
Tamarit G et al: Combined use of uterine artery embolization and local methotrexate injection in interstitial ectopic pregnancies with poor prognosis. Fertil Steril. 93(4):1348, 2010
Mavrelos D et al: Ultrasound diagnosis of ectopic pregnancy in the non-communicating horn of a unicornuate uterus (cornual pregnancy). Ultrasound Obstet Gynecol. 30(5):765-70, 2007
Deruelle P et al: Management of interstitial pregnancy using selective uterine artery embolization. Obstet Gynecol. 107(2 Pt 1):427-8, 2006
Klemm P et al: Sonographic monitoring of systemic and local methotrexate (MTX) therapy in patients with intact interstitial pregnancies. J Perinat Med. 34(2):149-57, 2006
Tang A et al: A medical management of interstitial ectopic pregnancy: a 5-year clinical study. Aust N Z J Obstet Gynaecol. 46(2):107-11, 2006
Cassik P et al: Factors influencing the success of conservative treatment of interstitial pregnancy. Ultrasound Obstet Gynecol. 26(3):279-82, 2005
Deruelle P et al: Management of interstitial pregnancy using selective uterine artery embolization. Obstet Gynecol. 106(5 Pt 2):1165-7, 2005
Filhastre M et al: Interstitial pregnancy: role of MRI. Eur Radiol. 15(1):93-5, 2005
Lee GS et al: Diagnosis of early intramural ectopic pregnancy. J Clin Ultrasound. 33(4):190-2, 2005
Coric M et al: Laparoscopic approach to interstitial pregnancy. Arch Gynecol Obstet. 270(4):287-9, 2004
Jermy K et al: The conservative management of interstitial pregnancy. BJOG. 111(11):1283-8, 2004
Tarim E et al: Angular pregnancy. J Obstet Gynaecol Res. 30(5):377-9, 2004
Ackerman TE et al: Interstitial line: sonographic finding in interstitial (cornual) ectopic pregnancy. Radiology. 189(1):83-7, 1993
Related Anatomy
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Related Differential Diagnoses
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References
Tables
Tables
KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
Clinical Issues
TERMINOLOGY
Definitions
Terminology in literature is mixed, confusing, and inconsistently applied
Interstitial ectopic pregnancy (IEP) or interstitial pregnancy are preferred terms
Blastocyst implants in interstitial segment of fallopian tube
Descriptively correct, as interstitial portion of fallopian tube does transverse uterine wall
Not technically accurate, as blastocyst implants in tube not myometrium
Cornual pregnancy(least preferred term)
Often used interchangeably with IEP, but recent literature urges avoiding this term altogether
HIstorically used to refer to pregnancy in 1 horn of duplication anomaly (septate or bicornuate uterus)
Angular pregnancy (AP) is different diagnosis
Key difference from IEP is that AP is intrauterine
Pregnancy implants at lateral angle of uterine cavity medial to uterotubal junction
Near ostia of fallopian tube
Located medial to round ligament
IMAGING
General Features
Ultrasonographic Findings
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Microscopic Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Selected References
Jensen KK et al: Imaging of acute pelvic pain: pregnant (ectopic and first-trimester viability updated). Radiol Clin North Am. 58(2):347-61, 2020
Khan Z et al: In pursuit of understanding interstitial pregnancies: a rare yet high-risk ectopic pregnancy. Fertil Steril. 112(2):246-7, 2019
Di Tizio L et al: Interstitial pregnancy: from medical to surgical approach-report of three cases. Case Rep Obstet Gynecol. 2018:2815871, 2018
Marfori CQ et al: Angular vs. interstitial pregnancy: a case report highlighting diagnostic nuances with stark management differences. Case Rep Womens Health. 19:e00068, 2018
Chukus A et al: Uncommon implantation sites of ectopic pregnancy: thinking beyond the complex adnexal mass. Radiographics. 35(3):946-59, 2015
Tanaka K et al: Management of interstitial ectopic pregnancy with intravenous methotrexate: An extended study of a standardised regimen. Aust N Z J Obstet Gynaecol. 55(2):176-80, 2015
Arleo EK et al: Cornual, interstitial, and angular pregnancies: clarifying the terms and a review of the literature. Clin Imaging. 38(6):763-70, 2014
Hiersch L et al: Effectiveness of medical treatment with methotrexate for interstitial pregnancy. Aust N Z J Obstet Gynaecol. 54(6):576-80, 2014
Nezhat CH et al: Laparoscopically-assisted, hysteroscopic removal of an interstitial pregnancy with a fertility-preserving technique. J Minim Invasive Gynecol. 21(6):1091-4, 2014
Pedroso C et al: Interstitial pregnancy rupture at 15 weeks of pregnancy. BMJ Case Rep. 2014, 2014
Tanaka Y et al: Three-dimensional sonography in the differential diagnosis of interstitial, angular, and intrauterine pregnancies in a septate uterus. J Ultrasound Med. 33(11):2031-5, 2014
Rheinboldt M et al: Atypical presentation of a large interstitial pregnancy. Emerg Radiol. 20(3):251-4, 2013
Sagiv R et al: Interstitial pregnancy management and subsequent pregnancy outcome. Acta Obstet Gynecol Scand. 92(11):1327-30, 2013
Cucinella G et al: Laparoscopic management of interstitial pregnancy: the "purse-string" technique. Acta Obstet Gynecol Scand. 91(8):996-9, 2012
Tamarit G et al: Combined use of uterine artery embolization and local methotrexate injection in interstitial ectopic pregnancies with poor prognosis. Fertil Steril. 93(4):1348, 2010
Mavrelos D et al: Ultrasound diagnosis of ectopic pregnancy in the non-communicating horn of a unicornuate uterus (cornual pregnancy). Ultrasound Obstet Gynecol. 30(5):765-70, 2007
Deruelle P et al: Management of interstitial pregnancy using selective uterine artery embolization. Obstet Gynecol. 107(2 Pt 1):427-8, 2006
Klemm P et al: Sonographic monitoring of systemic and local methotrexate (MTX) therapy in patients with intact interstitial pregnancies. J Perinat Med. 34(2):149-57, 2006
Tang A et al: A medical management of interstitial ectopic pregnancy: a 5-year clinical study. Aust N Z J Obstet Gynaecol. 46(2):107-11, 2006
Cassik P et al: Factors influencing the success of conservative treatment of interstitial pregnancy. Ultrasound Obstet Gynecol. 26(3):279-82, 2005
Deruelle P et al: Management of interstitial pregnancy using selective uterine artery embolization. Obstet Gynecol. 106(5 Pt 2):1165-7, 2005
Filhastre M et al: Interstitial pregnancy: role of MRI. Eur Radiol. 15(1):93-5, 2005
Lee GS et al: Diagnosis of early intramural ectopic pregnancy. J Clin Ultrasound. 33(4):190-2, 2005
Coric M et al: Laparoscopic approach to interstitial pregnancy. Arch Gynecol Obstet. 270(4):287-9, 2004
Jermy K et al: The conservative management of interstitial pregnancy. BJOG. 111(11):1283-8, 2004
Tarim E et al: Angular pregnancy. J Obstet Gynaecol Res. 30(5):377-9, 2004
Ackerman TE et al: Interstitial line: sonographic finding in interstitial (cornual) ectopic pregnancy. Radiology. 189(1):83-7, 1993
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