Ectopic pregnancy

Overview

An ectopic pregnancy occurs when a fertilised ovum implants outside the uterine cavity. It is a leading cause of first-trimester maternal death in the UK, affecting ~11 in 1000 pregnancies.

Risk factors

~1/3 of women with ectopic pregnancy have NO identifiable risk factors - absence of risk factors does not exclude the diagnosis.

Previous ectopic pregnancy
Previous pelvic/tubal surgery
Pelvic inflammatory disease / STIs (esp. Chlamydia)
IUD in situ
Assisted reproductive technology (IVF)
Endometriosis
Smoking
Increasing age

Presentation

•Classic triad - amenorrhoea (4-8 weeks), pelvic pain (unilateral, colicky), vaginal bleeding (light, dark brown)

•Shoulder-tip pain - referred pain from subdiaphragmatic blood irritating phrenic nerve; implies haemoperitoneum

•Dizziness, syncope, collapse - signs of significant haemorrhage

•GI/urinary symptoms - nausea, diarrhoea, dysuria; can mislead to appendicitis or UTI diagnosis

•Examination - adnexal tenderness, cervical motion tenderness, adnexal mass; in rupture: peritonism, guarding, tachycardia, hypotension

🚨
Haemodynamic instability (tachycardia, hypotension, pallor, collapse) in a woman of reproductive age = ruptured ectopic until proven otherwise. Call for senior help immediately - do not delay for imaging if the patient is unstable.

Investigations

🥇 First-line

•Urine pregnancy test - rapid; positive from ~3-4 weeks gestation

•Serum beta-hCG (serial, 48 h apart) - viable IUP rises >63% in 48 h; plateau or slower rise = ectopic/failing pregnancy

•Transvaginal ultrasound (TVS) - empty uterus + positive pregnancy test + adnexal mass = highly suspicious; offer to all women with suspected ectopic (NICE)

•FBC, group and save (crossmatch if unstable), U&E, LFTs (essential before methotrexate)

🏆 Gold standard

•Diagnostic laparoscopy - direct visualisation and simultaneous surgical treatment; used when diagnosis uncertain or patient haemodynamically unstable

💡
Discriminatory zone - serum hCG ~1500-2000 IU/L above which a viable IUP should be visible on TVS. If hCG is above this level with an empty uterus on TVS, ectopic pregnancy must be strongly suspected.

Differential diagnosis

Key differentials
DiagnosisKey distinguishing features
MiscarriageIntrauterine pregnancy visible on TVS
Corpus luteum cysthCG not elevated; no trophoblastic tissue
AppendicitisRIF pain, fever, raised inflammatory markers; pregnancy test negative
PIDBilateral tenderness, fever; negative pregnancy test
Ovarian torsionSevere acute pain, adnexal mass; negative pregnancy test
UTI/pyelonephritisUrinary symptoms, positive dipstick; negative pregnancy test

Diagnosis	Key distinguishing features
Miscarriage	Intrauterine pregnancy visible on TVS
Corpus luteum cyst	hCG not elevated; no trophoblastic tissue
Appendicitis	RIF pain, fever, raised inflammatory markers; pregnancy test negative
PID	Bilateral tenderness, fever; negative pregnancy test
Ovarian torsion	Severe acute pain, adnexal mass; negative pregnancy test
UTI/pyelonephritis	Urinary symptoms, positive dipstick; negative pregnancy test

Management

All women with confirmed or suspected ectopic pregnancy should be referred to secondary care (EPAU or emergency gynaecology if unstable). Management depends on haemodynamic stability, ectopic size/location, hCG level, and patient preference.

First · assess haemodynamic status
1Haemodynamically unstable → emergency surgical management (laparoscopy/laparotomy)
↓
Haemodynamically stable - expectant management
Selected cases: small ectopic, low/falling hCG (<1500 IU/L), no fetal cardiac activity, asymptomatic. Serial hCG monitoring until undetectable. Advise immediate return if pain worsens.
Haemodynamically stable - medical management
Methotrexate IM (single-dose) - folate antagonist, inhibits trophoblast proliferation. Criteria: hCG <5000 IU/L, no fetal cardiac activity, ectopic <35 mm, no rupture. Check LFTs before administration. Avoid pregnancy for ≥3 months post-treatment.
Haemodynamically stable - surgical management
Laparoscopic salpingectomy (preferred) or salpingotomy. Salpingotomy: risk of persistent trophoblast ~8% vs <1% after salpingectomy - requires hCG follow-up. Indicated if medical criteria not met, or patient preference.
↓
Then · anti-D
1Anti-D immunoglobulin 250 IU IM - offer to all rhesus-negative women undergoing surgical management

Follow-up

•After methotrexate - serum hCG on days 4 and 7; failure to fall >15% between days 4-7 = treatment failure, requires further intervention; weekly hCG until undetectable

•After salpingotomy - hCG monitoring to exclude persistent trophoblast (~8% risk)

•Fertility counselling - ~65% achieve subsequent IUP; advise early TVS in future pregnancies to confirm intrauterine implantation

•Recurrence risk - ~10% after one ectopic, ~25% after two

•Psychological support - grief, anxiety, depression common; refer to counselling as appropriate

Complications

•Tubal rupture and haemoperitoneum - life-threatening; remains a cause of maternal death (MBRRACE-UK)

•Subfertility - tubal damage, especially after bilateral ectopics or salpingectomy with single tube

•Methotrexate side effects - stomatitis, nausea, bone marrow suppression, hepatotoxicity (check LFTs before use)

⚠️
A heterotopic pregnancy (simultaneous IUP + ectopic) is rare in natural conception (~1:30,000) but significantly more common with IVF (~1:100 cycles). The IUP can provide false reassurance on ultrasound - always examine the adnexae in ART pregnancies.