Lucan · Conditions

Ectopic pregnancy

Australian guidance: RANZCOG C-Gyn 38 Miscarriage / Ectopic Pregnancy 2025

1. Definition and epidemiology

An ectopic pregnancy is any pregnancy implanting outside the uterine cavity, with the fallopian tube accounting for approximately 95% of all cases. In Australia, ectopic pregnancy complicates roughly 1 to 2% of all pregnancies and remains a leading cause of first-trimester maternal mortality due to the risk of tubal rupture and intraperitoneal haemorrhage. Non-tubal sites include the cervix, caesarean scar, interstitial segment of the tube, and ovary, each carrying distinct management challenges.

2. Pathophysiology

Normal implantation requires the blastocyst to reach the endometrial cavity by day five to six post-fertilisation. In ectopic pregnancy, impaired tubal transport allows implantation before this migration is complete. The trophoblast invades the muscular wall of the fallopian tube, which lacks the distensibility and decidualised stroma of the endometrium. As trophoblastic tissue proliferates and the conceptus enlarges, the tube distends and its thin muscularis is progressively eroded. Invasion of the spiral arterioles within the tubal wall produces haemorrhage into the tubal lumen (haematosalpinx) or peritoneal cavity. Rupture typically occurs between six and ten weeks of gestation when vascular erosion exceeds the structural capacity of the tube. Risk factors that impair tubal transport include prior pelvic inflammatory disease, previous tubal surgery, endometriosis, assisted reproductive technology, smoking, and prior ectopic pregnancy. The underlying molecular mechanism involves defective tubal ciliary beating and delayed expression of embryo-receptive signals, consistent with Robbins Ch 22 which emphasises trophoblastic invasion as the proximate cause of haemorrhage and rupture.

3. Clinical presentation and diagnostic criteria

The classic triad of amenorrhoea, lower abdominal pain, and vaginal bleeding occurs in fewer than half of presentations. Pain is typically unilateral, colicky, and may radiate to the shoulder tip if diaphragmatic irritation from haemoperitoneum is present. Vaginal bleeding is usually light and does not reflect the degree of internal haemorrhage. On examination, cervical excitation and adnexal tenderness are characteristic; a haemodynamically unstable patient with peritonism and a positive pregnancy test constitutes a surgical emergency until proved otherwise. An empty uterus on transvaginal ultrasound with a positive urine or serum beta-human chorionic gonadotrophin (beta-hCG) test establishes a pregnancy of unknown location, which must be presumed ectopic until ruled out. Reliable ultrasound diagnostic criteria include an adnexal mass containing a gestational sac (with or without yolk sac, foetal pole, or foetal heart), an empty gestational sac ("bagel sign"), or an inhomogeneous adnexal mass with a sliding sign ("blob sign").

4. Investigations and AU-specific cutoffs

Investigations proceed in a stepwise fashion.

First line: Urine hCG (qualitative) for bedside confirmation of pregnancy, then serum beta-hCG (quantitative). Transvaginal ultrasound is the primary imaging modality and should be performed urgently in any patient with a positive pregnancy test and pelvic pain or bleeding.

Serial serum beta-hCG: In a normal intrauterine pregnancy, serum beta-hCG rises by at least 35% every 48 hours in the first trimester; failure to rise appropriately or a falling level with an empty uterus strongly suggests ectopic or failing pregnancy.

Cutoffs guiding management: - hCG less than 1,500 IU/L with adnexal mass under 35 mm and no foetal heart activity: eligible for expectant management, methotrexate, or surgery - hCG 1,500 to less than 5,000 IU/L with adnexal mass under 35 mm and no significant pain or signs of rupture: eligible for methotrexate or surgery - hCG above 5,000 IU/L, adnexal mass over 35 mm, haemodynamic instability, or signs of rupture: surgical management required

Additional investigations: Full blood count (haemoglobin, platelet count), group and screen (Rh D status critical for anti-D decision), urea and electrolytes before methotrexate, and liver function tests given methotrexate hepatotoxicity risk.

5. Management

Management is stratified into expectant, medical, and surgical approaches based on haemodynamic stability, ultrasound findings, and serum hCG level.

Surgical management is indicated when the patient is haemodynamically unstable, shows signs of rupture, has hCG above 5,000 IU/L, an adnexal mass over 35 mm, or has contraindications to medical or expectant management. Salpingectomy is the preferred surgical procedure over salpingotomy because it achieves a higher likelihood of complete resolution with a single procedure (Recommendation 24, GRADE moderate). Salpingotomy may be considered on a case-by-case basis for women who wish to preserve the tube, are unable to access in vitro fertilisation, or have specific medical history considerations, but women must be counselled about the increased risk of treatment failure and the need for further intervention including methotrexate or repeat surgery.

Medical management with systemic methotrexate is appropriate for clinically stable women meeting the cutoffs above. One dose of systemic methotrexate is recommended when hCG is below 3,000 IU/L or adnexal mass is under 20 mm. Two doses given four to seven days apart are recommended when hCG is 3,000 to 5,000 IU/L or adnexal mass is 20 to 35 mm (Recommendation 21, GRADE moderate). Serial hCG monitoring after methotrexate is mandatory and further doses may be required. Women should be counselled that emergency surgical intervention may still be necessary if medical management fails.

Expectant management is an option for stable women with hCG below 1,500 IU/L and an adnexal mass under 35 mm without foetal cardiac activity, provided they understand the need for close follow-up and that emergency treatment may become necessary.

Non-tubal ectopic sites: Interstitial ectopic pregnancy in stable women is managed with systemic methotrexate or intra-sac methotrexate under ultrasound guidance; surgical options include laparoscopic cornuostomy or cornual resection with ipsilateral salpingectomy. Cervical ectopic pregnancy in stable women is treated with methotrexate; expectant management is avoided given the risk of severe haemorrhage.

Rh D immunoglobulin: Anti-D immunoglobulin should be offered to all Rh D negative women undergoing surgical management of ectopic pregnancy. For medically or expectantly managed ectopic pregnancy, anti-D should be considered after informed discussion about the uncertain evidence.

6. Pharmacology and AU PBS notes

Methotrexate (MTX): A folate antagonist that inhibits dihydrofolate reductase, preventing DNA synthesis in rapidly dividing trophoblastic cells. Systemic administration is intramuscular. There is no specific PBS streamlined code for ectopic pregnancy; it is used as an off-label indication in this setting. The AU brand name is Methofar or generic methotrexate (various manufacturers). Folinic acid (leucovorin) supplementation is not routinely co-administered in the single or two-dose ectopic protocols.

Contraindications to methotrexate include haemodynamic instability, immunodeficiency, active hepatic or renal disease, haematological abnormalities, breastfeeding, or patient inability to comply with follow-up.

Women must avoid conception for three months after methotrexate treatment due to teratogenicity; reliable contraception should be discussed at the time of treatment.

Anti-D immunoglobulin: Rh D immunoglobulin 250 IU (RhoGAM or Rhophylac, AU) administered intramuscularly to Rh D negative women at time of surgical management. PBS listed for prevention of Rh D sensitisation.

7. Complications and monitoring

Tubal rupture is the most immediately life-threatening complication, presenting with sudden severe abdominal pain, haemodynamic compromise, and signs of haemoperitoneum. It occurs in approximately 15 to 20% of ectopic pregnancies before diagnosis and mandates emergency laparoscopy or laparotomy.

Post-methotrexate monitoring: Serum beta-hCG should be checked on day four and day seven after the first dose, then weekly until below 20 IU/L. A rise in hCG between day one and day four is expected and does not indicate failure; failure is defined as a fall of less than 15% between days four and seven, warranting a second dose or surgical review.

Transient side effects of methotrexate include nausea, mucositis, abdominal pain (which may be a separation pain rather than rupture), and mildly abnormal liver function. Two-dose regimens carry a higher rate of these effects than single-dose regimens.

Future fertility: Intrauterine pregnancy rates are broadly comparable between medical and surgical management in the contralateral tube, though salpingectomy carries lower risk of repeat ectopic in the treated tube. Women should be informed that recurrent ectopic pregnancy risk is approximately 10 to 15% following a first ectopic.

Psychological support: Ectopic pregnancy constitutes a pregnancy loss and women should be offered appropriate counselling and referral, acknowledging the emotional impact alongside the medical urgency of management.

Written for Australian practice and grounded in the guidance named above. Study material only — not medical advice. Always check against current guidelines.