Ectopic Pregnancy
Summary
An ectopic pregnancy is the implantation of a fertilized ovum outside the endometrial cavity. >95% occur in the Fallopian tube (Ampulla). It is a life-threatening emergency, remaining the leading cause of maternal death in the first trimester. Early diagnosis via ultrasound (TVUSS) and serum hCG tracking has shifted management from life-saving laparotomy to conservative medical/ laparoscopic options. [1,2]
Key Locations
- Ampulla (70%): Most common.
- Isthmus (12%): Narrowest part -> Early rupture (6-8 weeks).
- Fimbria (11%).
- Interstitial/Cornual (2%): Myometrial vascularity -> Catastrophic haemorrhage later in gestation (10-14 weeks).
- Scar / Cervical / Ovarian / Abdominal: Rare (less than 1%).
Clinical Pearls
The "Classic Triad" is Poor: Only 50% of patients present with the classic triad of (1) Amenorrhoea, (2) Abdominal Pain, and (3) PV Bleeding. Always perform a pregnancy test in ANY woman of reproductive age with abdominal pain or collapse, regardless of "normal periods" (bleeding can be mistaken for a period).
Diarrhoea and Dizziness: Blood in the Pouch of Douglas irritates the rectum (causing loose stools/tenesmus) and causes vagal stimulation (dizziness/syncope). This combination in early pregnancy suggests rupture.
Heterotopic Pregnancy: The coexistence of an intrauterine AND ectopic pregnancy. Historically rare (1:30,000), but in the era of IVF (transferring multiple embryos), the risk is 1 in 100. Seeing a pregnancy in the uterus does NOT exclude an ectopic in an IVF patient.
Risk Factors
- Tubal Damage: Previous PID (Chlamydia - most common), Endometriosis, Previous Tubal Surgery.
- Previous Ectopic: Recurrence risk is ~10-15%.
- Assisted Conception (IVF).
- Cigarette Smoking: Impairs ciliary motility.
- Contraceptive Failure:
- Progesterone Only Pill (POP): Slows tubal transport.
- IUCD (Coil): Very effective at preventing intrauterine pregnancy, less effective at preventing tubal pregnancy. If a woman on a coil gets pregnant, it is much more likely to be ectopic.
Mechanism
- Normally, the fertilized ovum travels down the tube over 3-4 days to implant in the uterus.
- Any delay (structural blockage or functional ciliary stasis) causes the blastocyst to implant within the tube wall.
- The tube lacks a submucosa and cannot distend -> Erosion into blood vessels -> Rupture -> Intraperitoneal Haemorrhage.
Symptoms
Signs
- Speculum: Check os (closed in ectopic/threatened miscarriage, open in incomplete/inevitable).
- Bimanual: Gentle. Vigorous examination can rupture an ectopic mass.
- Urine: Positive Pregnancy Test.
1. Transvaginal Ultrasound (TVUSS)
- Diagnostic Criteria:
- "Blob Sign": Inhomogeneous adnexal mass (most common).
- "Bagel Sign": Hyperechoic ring around gestational sac.
- Fetal Heart: Visible heartbeat in adnexa (Gold standard diagnosis).
- Haemoperitoneum: Free fluid in Pouch of Douglas or Morrison's Pouch.
- PUL (Pregnancy of Unknown Location): Positive test + Empty Uterus + Normal Adnexa.
2. Serum Beta-hCG
- Discriminatory Zone: >1500 IU/L.
- If hCG is >1500 and uterus is empty -> Ectopic until proven otherwise.
- Serial Tracking (0hr and 48hr):
- Intrauterine: Doubles every 48h (+66%).
- Failing (Miscarriage): Drops >50%.
- Ectopic: Suboptimal rise (less than 63%) or plateau.
3. Bloods
- Group and Save: Immediate. Crossmatch if unstable.
- Progesterone: Low (less than 20 nmol/L) suggests failing pregnancy (ectopic or miscarriage). High (>60) suggests viable.
Management Algorithm
ECTOPIC PREGNANCY CONFIRMED
↓
HEMODYNAMICALLY STABLE?
┌───────────┴───────────┐
NO YES
(Tachy/Hypotensive) ↓
↓ DOES IT MEET CRITERIA?
EMERGENCY SURGERY ┌───────┴───────┐
(Lap Salpingectomy) LOW RISK MOD RISK
↓ (hCGless than 1000) (hCGless than 1500)
GIVE ANTI-D ↓ ↓
EXPECTANT MEDICAL
(Monitor) (Methotrexate)
1. Expectant Management
- Criteria: Clinically stable, No pain, hCG less than 1000 and falling, Mass less than 35mm, No heartbeat.
- Protocol: Monitor hCG every 48h until negative.
- Success Rate: ~70% (if criteria met).
2. Medical Management (Methotrexate)
- Criteria: Stable, Mild pain, hCG less than 1500 (NICE) or less than 5000 (RCOG), No heartbeat, No intrauterine pregnancy.
- Protocol: Single dose IM Methotrexate (50mg/m2).
- Follow-up: Check hCG on Day 4 and Day 7. Must drop by >15%.
- Contraindications: Liver/Renal disease, Active infection, Breastfeeding.
- Advice: Stop folate. Avoid pregnancy for 3 months (teratogenic).
3. Surgical Management
- Laparoscopic Salpingectomy: Removal of the tube. Gold standard.
- Laparoscopic Salpingotomy: Opening the tube to remove pregnancy (preserves tube). Only usually done if the other tube is absent/damaged, as it carries risk of persistent trophoblast (need to track hCG) and recurrent ectopic.
- Laparotomy: If patient is in profound shock (faster access).
- Rupture: Hypovolaemic shock.
- Tubal Factors: Infertility (though normal pregnancy rate is nearly same with 1 tube vs 2).
- Persistent Trophoblast: After salpingotomy, retained tissue continues to grow (hCG doesn't fall). Requires Methotrexate.
- Recurrence: 10% risk in next pregnancy.
- Fertility: 65% of patients achieve a future intrauterine pregnancy.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| NG126: Ectopic & Miscarriage | NICE (2019) | Ectopic diagnosis and management pathways. Prefer Salpingectomy over Salpingotomy. |
| GTG 21: Ectopic Pregnancy | RCOG (2016) | Methotrexate protocols and surgical standards. |
Landmark Evidence
1. ESEP Study (Lancet)
- Comparisons of Salpingectomy vs Salpingotomy showed similar future fertility rates, but Salpingotomy had higher rates of persistent trophoblast/reintervention. Hence Salpingectomy is standard unless only one tube remains.
What is an ectopic pregnancy?
Normally, the egg is fertilised in the tube and travels down to the womb to grow. In an ectopic pregnancy, it gets stuck in the tube and starts to grow there.
Can the baby survive?
No. The tube is a thin pipe and cannot stretch like the womb. As the pregnancy grows, it will eventually burst the tube, causing life-threatening internal bleeding.
Can you move it to the womb?
No, transplanting the pregnancy is not medically possible. We treat it by either giving an injection to stop the growth (Methotrexate) or keyhole surgery to remove the tube.
Will I be able to have children?
Yes. Even with only one tube, your fertility is almost normal. The other ovary can release an egg that travels down the remaining tube. You should take a pregnancy test early next time, as there is a small risk (1 in 10) of it happening again.
Primary Sources
- Elson J, et al. Diagnosis and management of ectopic pregnancy: Green-top Guideline No. 21. BJOG. 2016.
- NICE Guideline [NG126]. Ectopic pregnancy and miscarriage: diagnosis and initial management. 2019.
- Mol F, et al. Salpingotomy versus salpingectomy in women with tubal pregnancy (ESEP study). Lancet. 2014.
Common Exam Questions
- Diagnosis: "Shouldier tip pain?"
- Answer: Haemoperitoneum irritating diaphragm (C3/4/5).
- Management: "Single dose Methotrexate Criteria?"
- Answer: hCG less than 1500 (NICE), No heartbeat, No pain, Unruptured.
- Advice: "Post-Methotrexate?"
- Answer: Use contraception for 3 months (drug causes birth defects).
- Physiology: "Discriminatory Zone?"
- Answer: The level of hCG (>1500) where an intrauterine sac SHOULD be visible on scan.
Viva Points
- Anti-D: Who needs it?
- Surgery: YES (all rhesus negative women).
- Medical: Recommended (Kleihauer test not helpful as fetal cells minimal).
- Expectant: Usually not required.
- Arias-Stella Reaction: Histological finding in the endometrium (hypersecretory glands) due to progesterone stimulation, even though the pregnancy is extra-uterine. Proves pregnancy, but not location.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.