Obstetrics and Gynaecology chapters
Ectopic pregnancy
Implantation outside the uterine cavity: sites, risk factors, the classic and the subtle presentations, how transvaginal scan and serial hCG make the diagnosis, and when to choose expectant, methotrexate or surgical treatment.
- An ectopic pregnancy implants outside the uterine cavity, over 98% in the fallopian tube (commonest site the ampulla); risk factors are tubal damage (PID, previous ectopic, tubal surgery), smoking, IVF and IUD failure.
- Suspect it in any woman of reproductive age with pain or bleeding and a positive pregnancy test; shock with a positive test = ruptured ectopic until proven otherwise. Diagnose with TVUSS (empty uterus, adnexal mass, fluid) and serial hCG.
- Unstable: resuscitate and operate (laparoscopic salpingectomy). Stable and small: expectant or methotrexate (50 mg/m2 IM) if hCG is under 5,000 IU/L, mass under 35 mm and no heartbeat.
On this page
Overview
An ectopic pregnancy is a pregnancy implanted outside the uterine cavity. It occurs in about 1 in 80 pregnancies and remains an important cause of maternal death, especially in low-resource countries (10-30% of maternal deaths there, against 9-13% in the West), where women present late with rupture.
Golden rule: every woman of reproductive age with abdominal pain, vaginal bleeding, collapse or even bowel or urinary symptoms needs a pregnancy test. A positive test with pain or bleeding means ectopic must be excluded.
Sites
| Site | Notes |
|---|---|
| Fallopian tube (over 98%) | Ampulla is the commonest site; then isthmus, fimbrial end |
| Interstitial (cornual) | The part of the tube within the uterine wall; surrounded by myometrium, so it can grow larger before rupture with heavy bleeding |
| Ovary | Rare |
| Cervix | Rare; heavy bleeding |
| Caesarean section scar | Implantation in the old scar; increasing as caesarean rates rise |
| Abdominal cavity | Rare |
| Heterotopic | Intrauterine and ectopic at the same time: about 1 in 25,000-30,000 naturally, but about 1% after IVF with two embryos |
The ampulla is the commonest site; the narrow isthmus tends to rupture earlier; an interstitial pregnancy ruptures later but bleeds more.
Risk factors
- Tubal damage:
- Pelvic inflammatory disease (chlamydia, gonorrhoea): the most important cause in practice.
- Previous ectopic pregnancy (recurrence about 8-18%).
- Previous tubal surgery (sterilisation, tubal reconstruction).
- Altered tubal function: smoking, older maternal age.
- Others: previous abdominal surgery (appendicectomy, caesarean section), subfertility and IVF, conception with an IUD in place, endometriosis, conception while on the progestogen-only or emergency pill.
An IUD lowers the overall chance of any pregnancy, so it lowers the absolute risk of ectopic too; but if a woman conceives with an IUD in place, the pregnancy is more likely to be ectopic.
"PID, Previous ectopic, Pipe surgery, Puffing (smoking)": the four Ps of tubal damage.
Clinical presentation
Subacute (most common)
- Amenorrhoea, typically around 6 weeks (may be absent or confused with a period).
- Lower abdominal pain, usually one-sided.
- Vaginal bleeding or brown spotting (from shedding decidua).
- Non-specific symptoms: diarrhoea, urinary symptoms, pain on defecation, rectal pressure.
- Signs: adnexal tenderness, cervical motion tenderness; uterus slightly enlarged or normal.
Acute (rupture)
- Sudden severe pain, collapse, fainting.
- Shoulder-tip pain (blood under the diaphragm irritating the phrenic nerve) and an urge to defecate (blood in the pouch of Douglas).
- Hypovolaemic shock: tachycardia, hypotension, pallor; abdominal guarding and rigidity; abdomen may be distended.
Bradycardia and shock in early pregnancy may come from products in the cervix (cervical shock), but tachycardia, hypotension and a positive test is a ruptured ectopic until the abdomen is opened or it is excluded. Do not wait for a scan in an unstable woman.
Differential diagnosis
Miscarriage, corpus luteum cyst rupture or haemorrhage, ovarian torsion, PID, appendicitis, urinary infection or stones. Remember that bleeding and pain also occur with a normal intrauterine pregnancy.
Investigations
Transvaginal ultrasound (first-line)
- Intrauterine gestational sac with yolk sac (± fetal pole): effectively excludes an ectopic (except the rare heterotopic pregnancy).
- Empty uterus + adnexal mass separate from the ovary (sometimes containing a fetal pole and heartbeat): sensitivity 87-99% and specificity 94-99.9% for ectopic.
- Fluid (blood) in the pouch of Douglas or abdomen: suggests rupture.
- A fluid collection in the uterus without a yolk sac may be a pseudosac (blood in the cavity), not a pregnancy.
Serum hCG
- In a normal intrauterine pregnancy, hCG rises by more than 63% in 48 hours.
- In an ectopic pregnancy the rise is usually suboptimal (or it plateaus or falls slowly).
- Values vary widely, so two measurements 48 hours apart are compared.
- Discriminatory level: with hCG above about 1,500 IU/L, a normal intrauterine pregnancy should be seen on TVUSS; an empty uterus above this level strongly suggests ectopic.
Day 0 hCG 1,000 IU/L. A normal rise needs over 63%: 1,000 × 1.63 = 1,630 IU/L.
Day 2 hCG 1,200 IU/L: rise of only 20%, suboptimal, so an ectopic or failing pregnancy is likely; correlate with TVUSS.
Pregnancy of unknown location (PUL)
- Positive pregnancy test with no pregnancy seen in or outside the uterus on TVUSS.
- Up to 40% of ectopics are labelled PUL at the first visit.
- It is a working label, not a diagnosis; ectopic has not been excluded.
- Managed with serial hCG (and repeat scans) until the location is found or hCG becomes negative.
Other tests
- Haemoglobin, group and save / cross-match, Rhesus status.
- Laparoscopy is both diagnostic and therapeutic when doubt remains.
- Older methods (culdocentesis to find blood in the pouch of Douglas) are rarely needed where ultrasound is available.
Management
Haemodynamically unstable (ruptured)
- ABC: two large-bore cannulae, IV fluids, bloods (FBC, cross-match), activate the major haemorrhage protocol, nil by mouth, call seniors.
- Immediate surgery: laparoscopy if the team is skilled and she can tolerate it, otherwise laparotomy; remove the affected tube (salpingectomy).
Haemodynamically stable: three options
| Option | Criteria | Follow-up / notes |
|---|---|---|
| Expectant | No symptoms, stable; mass under 35 mm; no heartbeat; hCG under 1,000 IU/L (up to 1,500 with senior input); willing to return | Serial hCG until undetectable (under 20 IU/L); many resolve on their own |
| Medical (methotrexate) | Minimal pain; mass under 35 mm; no fetal heartbeat; hCG under 5,000 IU/L; able to attend follow-up | Single IM dose 50 mg/m2; hCG on days 4 and 7, must fall over 15% between them, then weekly to negative |
| Surgical (laparoscopy) | Pain, larger mass, fetal heartbeat, high hCG, failed medical treatment, or patient choice | Salpingectomy is standard; salpingotomy only if the other tube is absent or damaged |
Methotrexate is a folic acid antagonist that blocks DNA synthesis in the rapidly dividing trophoblast.
- Contraindications: chronic liver, kidney or blood disease, active infection, immunodeficiency, breastfeeding, haemodynamic instability, ruptured ectopic, intrauterine pregnancy.
- Side effects: abdominal pain (in about two-thirds), stomatitis, conjunctivitis, gastrointestinal upset, photosensitivity.
- Advice: avoid intercourse during treatment, avoid alcohol and strong sunlight, avoid conceiving for 3 months (teratogenic).
- About 15% need a second dose, and a similar number end up needing surgery. The higher the starting hCG, the more likely it is to fail.
Body surface area 1.6 m2: dose = 50 × 1.6 = 80 mg IM.
hCG day 4 = 2,000 IU/L, day 7 = 1,600 IU/L: fall = (2,000 − 1,600) / 2,000 = 20%, which is over 15%, so continue weekly hCG; under 15% would need a second dose or surgery.
Methotrexate is the medical treatment of choice, but only for a stable woman with a small, non-viable ectopic and a low hCG. A visible fetal heartbeat is a reason to operate.
Surgery: salpingectomy or salpingotomy?
| Operation | What is done | When |
|---|---|---|
| Salpingectomy | Remove the tube with the ectopic | Operation of choice when the other tube is healthy |
| Salpingotomy (or salpingostomy) | Open the tube, remove the pregnancy, keep the tube | Other tube absent or damaged and fertility is wanted; higher rate of repeat ectopic; hCG must be followed to make sure all trophoblast has gone |
If the other tube is normal, future pregnancy rates are good, because an egg from either ovary can be picked up by the remaining tube.
Anti-D and aftercare
- Rh-negative women having surgery: anti-D 250 IU (50 micrograms) within 72 hours. After methotrexate, guidance varies and it is often given.
- In a future pregnancy, offer an early transvaginal scan to confirm the site.
- Offer bereavement support; many women grieve for the lost pregnancy.
Expect: the ampulla as the commonest site and over 98% being tubal; risk factors (PID, previous ectopic, tubal surgery, smoking, IVF, IUD failure); the triad of amenorrhoea, pain and bleeding; shoulder-tip pain and shock in rupture; TVUSS findings and the meaning of an empty uterus with a raised hCG; the 63% rise in 48 hours and the discriminatory hCG level; pregnancy of unknown location; methotrexate as the drug of choice with its criteria (hCG under 5,000, mass under 35 mm, no heartbeat), dose, monitoring and contraindications; salpingectomy versus salpingotomy; recurrence risk; heterotopic pregnancy after IVF; anti-D after surgery.
Quick revision
- Ectopic = outside the uterine cavity; 1 in 80 pregnancies; over 98% tubal, ampulla commonest.
- Risk: PID, previous ectopic, tubal surgery, smoking, age, IVF, IUD failure, endometriosis.
- Classic: amenorrhoea, one-sided pain, spotting; rupture = collapse, shoulder-tip pain, shock.
- Intrauterine sac with yolk sac on TVUSS excludes ectopic (except heterotopic).
- hCG should rise over 63% in 48 hours; empty uterus above about 1,500 IU/L suggests ectopic.
- PUL = positive test, nothing seen; follow hCG.
- Methotrexate 50 mg/m2 IM if stable, hCG under 5,000, mass under 35 mm, no heartbeat; check hCG days 4 and 7 (over 15% fall).
- Unstable: resuscitate and do salpingectomy; salpingotomy only if the other tube is bad.
- Anti-D 250 IU within 72 hours after surgery if Rh-negative.
Written by The House Job from standard references (Gynaecology by Ten Teachers; Obstetrics by Ten Teachers).
FAQ
Does an empty uterus on scan with a positive test always mean an ectopic pregnancy?
No. It may be a very early intrauterine pregnancy, a complete miscarriage or an ectopic; serial hCG and repeat scans decide, unless she is unstable.
Why is salpingectomy preferred to saving the tube?
When the other tube is healthy, removing the affected tube still gives good future pregnancy rates, while keeping a damaged tube raises the chance of another ectopic.
Why must pregnancy be avoided for 3 months after methotrexate?
Methotrexate is a folate antagonist that can harm a developing baby, so conception is delayed until the drug's effect has passed.
Can a woman have an ectopic pregnancy and an intrauterine pregnancy at the same time?
Yes, this is a heterotopic pregnancy; it is very rare naturally but much commoner after IVF, so a seen intrauterine sac does not fully exclude ectopic in IVF patients.