Synopsis
Choose transvaginal or transabdominal pelvic ultrasound, identify pregnancy location and viability safely, manage pregnancy of unknown location, and escalate symptoms that suggest ectopic rupture despite uncertain imaging.
- Offer transvaginal ultrasound to identify pregnancy location and fetal pole or heartbeat; use transabdominal imaging when transvaginal scanning is declined or unsuitable and explain its limitations.
- Describe an empty uterus with a positive pregnancy test as pregnancy of unknown location until follow-up establishes intrauterine or ectopic location.
- In pregnancy of unknown location, prioritise changing symptoms over hCG values and give written twenty-four-hour emergency access advice.
Key red flags
Pregnancy of unknown location can be ectopic until location is determined; a reassuring single hCG result cannot exclude rupture.
New or worsening pain, dizziness, syncope, shoulder-tip pain, pallor or heavy bleeding overrides a planned routine repeat scan.
Do not diagnose miscarriage from gestational age by last menstrual period alone or from measurements below validated conservative thresholds.
Adnexal mass separate from the ovary, extrauterine yolk sac or embryo, or substantial free fluid requires urgent specialist interpretation.
An adnexal mass separate from the ovary, especially with yolk sac or embryo, strongly supports an extrauterine pregnancy.
Positive pregnancy testing with no pregnancy seen on transvaginal ultrasound remains potentially ectopic until location is established.
Moderate or large pelvic fluid, especially echogenic blood with pain or instability, raises concern for rupture.
Investigation priorities
Identify early pregnancy location, embryo, heartbeat, adnexa and pelvic fluid.
Management branches
A stable patient has pelvic pain, a positive pregnancy test and no pregnancy identified on transvaginal ultrasound.
- Context: assess haemodynamics, bleeding, shoulder-tip pain, syncope, previous ectopic risk, gestational history and consent for scanning.
- Reasoning: classify pregnancy of unknown location, examine adnexa and free fluid and avoid inferring location from one hCG value.