On a routine first trimester ultrasound at 6 weeks, gestational sac is seen separate from the endometrium and >1 cm away from the most lateral edge of the uterine cavity. "Interstitial line sign" is seen. What is your diagnosis?

An interstitial pregnancy is one that implants within the proximal tubal segment that lies within the muscular uterine wall.Incorrectly, they may be called cornual pregnancies, but this term describes a conception that develops in the rudimentary horn of a uterus with a mullerian anomaly.Criteria that may aid differentiation include an empty uterus, a gestational sac seen separate from the endometrium and >1 cm away from the most lateral edge of the uterine cavity, and a thin, <5-mm myometrial mantle surrounding the sac (Timor-Tritsch, 1992). An echogenic line, known as the "interstitial line sign," extending from the gestational sac to the endometrial cavity most likely represents the interstitial poion of the fallopian tube and is highly sensitive and specific Distinct from interstitial pregnancy, the term angular pregnancy describes implantation within the endometrial cavity but at one cornu and medial to the uterotubal junction and round ligament. An angular pregnancy displaces the round ligament upward and outward, whereas an interstitial tubal pregnancy does not see itSurgical management with either cornual resection or cornuectomy may be performed laparotomy or laparoscopy, depending on patient hemodynamic stability and surgeon expeiseReference: William's Obstetrics; 25th edition; Chapter 19; Ectopic pregnancy