Interstitial Ectopic Pregnancy

interstitial ectopic pregnancy

This patient presented with abdominal pain, 7 weeks and 5 days since the last menstrual period. The beta-hCG was elevated. An off-midline sagittal transvaginal ultrasound image of the uterus demonstrates an echogenic rounded structure in the region of the uterine cornu (towards fundus and eccentrically placed). The distance from the edge of the echogenic area to the serosal surface of the uterus is 1.4mm.

Interstitial ectopic pregnancy (sometimes called cornual) occurs in the interstitial portion of the fallopian tube. It accounts for 2% – 4% of all ectopics. The morbidity and mortality are higher due to later presentation, and the tendancy to massive haemorrhage. The diagnosis is suggested by visualisation of an intrauterine gestational sac or decidual reaction located high in the fundus, that is not surrounded by more than 5mm of myometrium in all planes. An interstitial line sign – an echogenic line from the mass to the endometrial echo complex reportedly has high sensitivity (80%) and specificity (98%).
Management of interstitial ectopic includes methotrexate (either systemic or local), potassium chloride injection, conservative laparoscopic surgery, uterine artery embolisation, cornuectomy or hysterectomy. The latter two are usually reserved for the emergency case or for failure of other methods.
References:
Callen PW. Ultrasonography in Obstetrics and Gynaecology. 4th edition. WB Saunders, 2000
Ackerman TE, et al. Interstitial line: sonographic finding in interstitial (cornual) ectopic pregnancy. Radiology 189; 83-87. 1993

Credit: Dr Laughlin Dawes