- Most common
- Adnexal mass ± gestational sac
- May demonstrate peripheral vascularity
- Ectopic angle is the most common site (between the uterus and ovary).
Non-tubal ectopic pregnancy
- Interstitial/cornual ectopic: mass or gestational sac in the cornual region of the uterus, outside the endometrial cavity
- Scar ectopic: mass or gestational sac related to the caesarean section scar
- Cervical ectopic: mass or gestational sac within the endocervical canal
- Ovarian ectopic: mass or gestational sac within the ovary. This is a rare condition (less than 1 percent of ectopics) and needs to be differentiated from the much more common corpus luteum (see below)
- Abdominal and intramural ectopics are rare.
- A rare condition of co-existing intrauterine and ectopic pregnancy
- Rare (0.6–2.5 per 10,000 pregnancies)
- Increased incidence in women undergoing IVF or ovulation induction
- If suspected sonographically, then specialist opinion is required.
Corpus luteum of pregnancy
- Seen within the ovary in early pregnancy
- May be single or multiple
- Appearances may be those of a thin- or thick-walled cyst or solid isoechoic nodule with peripheral ring vascularity
- An exophytic corpus luteum on the periphery or surface of the ovary may mimic an ectopic pregnancy. It may be difficult to differentiate a corpus luteum from an ectopic pregnancy.
Helpful sonographic features include:
- no internal yolk sac or embryo
- isoechoic to the ovary
- moves with the ovary on probe pressure.
If there is an empty uterus and indeterminate ultrasound findings, a follow-up scan should be recommended (in 5–7 days, or earlier if there is interval clinical concern regarding ectopic pregnancy). An ectopic pregnancy or a normal intrauterine pregnancy may often become visible on the follow-up scan.