Early pregnancy pain and bleeding, including pregnancy of unknown location

It is Saturday morning in the early pregnancy assessment unit. Your first patient is 25, six weeks by dates, bleeding lightly and aching low on the left. She looks well. The scan shows an empty uterus, a normal left ovary and no free fluid. Her hCG is 940 IU/L. You now hold the single most dangerous label in gynaecology — a pregnancy you cannot find — and the whole of this topic is how you hold it safely.^[1][4]

Overview and definition

Pain and bleeding in the first trimester is the commonest reason a woman meets a gynaecologist. Most of those pregnancies are fine, some are miscarrying, and a small but lethal minority are ectopic. Your job is not to guess which; it is to run a protocol that makes guessing unnecessary.^[1][4]

The word "unknown" is doing real work. It does not mean "probably fine". In the largest prospective implementation cohort, 320 of 2625 women classified as PUL (roughly 12%) ultimately had an ectopic pregnancy.^[6]

References21ShowHide

1. [1]Royal College of Obstetricians and Gynaecologists Diagnosis and Management of Ectopic Pregnancy: Green-top Guideline No. 21 BJOG, 2016.PMID 27813249
2. [2]American College of Obstetricians and Gynecologists' Committee on Practice Bulletins—Gynecology ACOG Practice Bulletin No. 193: Tubal Ectopic Pregnancy Obstet Gynecol, 2018.PMID 29470343
3. [3]Barnhart K, van Mello NM, Bourne T, et al. Pregnancy of unknown location: a consensus statement of nomenclature, definitions, and outcome Fertil Steril, 2011.PMID 20947073
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5. [5]Van Calster B, Bobdiwala S, Guha S, et al. Managing pregnancy of unknown location based on initial serum progesterone and serial serum hCG levels: development and validation of a two-step triage protocol Ultrasound Obstet Gynecol, 2016.PMID 26776599
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18. [18]Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Miscarriage, Recurrent Miscarriage and Ectopic Pregnancy (C-Gyn 38), Clinical Guideline, Version 1. RANZCOG, 2025.Source
19. [19]National Institute for Health and Care Excellence Ectopic pregnancy and miscarriage: diagnosis and initial management NICE guideline NG126, 2026.Source
20. [20]Everett C Incidence and outcome of bleeding before the 20th week of pregnancy: prospective study from general practice. BMJ, 1997.PMID 9233324
21. [21]Principi G, Salvatori MM, Ficarola F, et al. Management of heterotopic cervical pregnancy: a case report and review of the literature. J Med Case Rep, 2026.PMID 41486141