Miscarriage and ectopic pregnancy

Early Pregnancy Bleeding, Ectopic Pregnancy & Antenatal Screening

Vaginal bleeding in the first trimester occurs in approximately 20% to 25% of confirmed pregnancies and represents one of the most common acute presentations in Australian primary care and emergency departments. The primary clinical objectives are distinguishing viable intrauterine pregnancies from non-viable pregnancies (miscarriage) or life-threatening extrauterine gestations (ectopic pregnancy), assessing maternal haemodynamic stability, and implementing appropriate Rh(D) isoimmunisation prophylaxis.

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Clinical Classification of Miscarriage

Miscarriage is defined as the spontaneous loss of a pregnancy before 20 weeks of gestation. Clinical classification relies on symptoms (bleeding, pain), speculum examination of the external and internal cervical os, and transvaginal ultrasonography (TVS):

• Threatened Miscarriage: Characterized by light vaginal bleeding and mild suprapubic cramping in the presence of a closed internal cervical os. Transvaginal ultrasound confirms a viable intrauterine pregnancy with documented fetal cardiac activity. The vast majority of cases resolve spontaneously with a favorable outcome; management is expectant with reassurance and repeat clinical review.
• Inevitable Miscarriage: Characterized by open internal cervical os with active vaginal bleeding and progressive lower abdominal cramping. Spontaneous expulsion of products of conception (POC) has not yet occurred, but pregnancy loss is unavoidable. Ultrasound confirms non-viability or detachment of the gestational sac.
• Incomplete miscarriage: Some tissue has passed with ongoing bleeding/cramps and possible retained products. Interpret ultrasound with symptoms and prior confirmed pregnancy; an endometrial thickness alone does not mandate evacuation.
• Complete miscarriage: Symptoms settle after tissue passage in a previously confirmed IUP. If no IUP was previously confirmed, an empty uterus can still be PUL and requires follow-up; do not simply reassure from a thin stripe.
• Missed (Silent or Delayed) Miscarriage: The embryo or fetus has died or failed to develop (anembryonic pregnancy / blighted ovum), but the non-viable gestational tissue is retained in utero. The internal cervical os remains closed, and the patient may be asymptomatic or notice a gradual regression of early pregnancy symptoms. Definitive ultrasound criteria for missed miscarriage include:
  1. Crown-rump length (CRL) $\ge 7\text{ mm}$ with no visible fetal cardiac activity.
  2. Mean gestational sac diameter (MSD) $\ge 25\text{ mm}$ without an identifiable embryo.
  3. Absence of an embryo with a heartbeat $\ge 14\text{ days}$ after a scan showing an empty gestational sac without a yolk sac (or $\ge 11\text{ days}$ after a scan showing a gestational sac with a yolk sac).
• Septic Miscarriage: Any miscarriage subtype complicated by ascending intrauterine infection. Manifests with maternal fever, rigors, tachycardia, offensive or purulent vaginal discharge, exquisite uterine tenderness, and cervical motion tenderness. Requires immediate hospital admission, high-dose intravenous broad-spectrum antibiotics (ampicillin, gentamicin, and metronidazole), aggressive fluid resuscitation, and emergent surgical evacuation.

Management Strategies for Miscarriage

1. Expectant Management: First-line for stable, afebrile patients with incomplete or missed miscarriage $< 6\text{ weeks}$. Success rates range between 70% and 80% over 1 to 2 weeks. Follow-up includes serial clinical review and repeat TVS or urine pregnancy testing at 2 to 3 weeks.
2. Medical Management: Indicated for women seeking active expulsion without surgical intervention. The recommended regimen is oral or vaginal misoprostol ($800\text{ mcg}$ vaginally, or $600\text{ mcg}$ sublingually). Misoprostol induces myometrial contractions and cervical softening. Adequate analgesia (paracetamol, NSAIDs, or codeine) and antiemetics should be co-prescribed. If complete expulsion is not achieved, a second dose may be administered at 24 to 48 hours.
3. Surgical Management: Suction evacuation / curettage under general or local anaesthesia is indicated for haemodynamic instability, active uncontrolled uterine haemorrhage, clinical evidence of infection (septic miscarriage), suspected gestational trophoblastic disease, or patient preference. Preoperative cervical priming with misoprostol ($400\text{ mcg}$) is often employed.

• RhD prophylaxis: For a non-sensitised RhD-negative patient, the 2024 National Blood Authority guideline recommends 250 IU for first-12-week miscarriage, ectopic pregnancy, molar pregnancy or chorionic-villus sampling. Light threatened bleeding does not routinely require anti-D; repeated/heavy bleeding, pain or trauma may justify it. Abortion has separate newer guidance: RANZCOG 2025 does not require routine RhD testing for medical or surgical abortion up to 10 weeks. Later events require the gestation-specific guideline; after 12 weeks the usual dose is 625 IU.

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Ectopic Pregnancy

Ectopic pregnancy occurs when a blastocyst implants outside the endometrial cavity, with approximately 95% situated in the fallopian tube (ampullary 70%, isthmic 12%, fimbrial 11%, and interstitial/cornual 2% to 3%). Interstitial ectopic gestations implant in the myometrial segment of the fallopian tube and can expand unnoticed until 12 to 16 weeks, where catastrophic rupture leads to massive intraperitoneal exsanguination.

Risk Factors

• Prior ectopic pregnancy (highest relative risk, ~10-fold increase)
• History of pelvic inflammatory disease (salpingitis) or tubal infection (Chlamydia trachomatis)
• Previous tubal surgery (reconstructive surgery or sterilization reversal)
• Assisted reproductive technologies (in vitro fertilisation - IVF)
• Conception with an intrauterine device (IUD) in situ (the absolute pregnancy rate is low, but if conception occurs, up to 50% are ectopic)
• Endometriosis and maternal cigarette smoking

Clinical Presentation and Diagnosis

The classic triad of ectopic pregnancy comprises amenorrhoea, unilateral lower abdominal or pelvic pain, and abnormal vaginal bleeding (characteristically dark brown "prune juice" spotting). Ruptured ectopic pregnancy presents with acute haemoperitoneum: sudden severe peritoneal pain, diaphoresis, syncope, peritonism with rebound tenderness and cervical motion tenderness, subdiaphragmatic irritation producing referred unilateral shoulder tip pain (Kehr sign), and hypovolaemic shock.

• PUL: An empty uterus with positive hCG does not diagnose ectopic pregnancy, including above a traditional discriminatory range. Review symptoms, serial hCG and expert ultrasound; follow until location/outcome is established. Do not give methotrexate solely because a threshold was crossed.
• Definition: PUL means positive hCG with neither an intrauterine nor extrauterine pregnancy visible; it is not restricted to hCG below 1,500. Unstable pain, syncope or heavy bleeding requires immediate reassessment.
• hCG trends: A viable pregnancy may rise more slowly than a memorised doubling rule. A falling or suboptimal rise does not localise the pregnancy. Follow serial hCG and ultrasound until location/outcome is established, with immediate return for pain, syncope or heavy bleeding.
  • Non-viable intrauterine pregnancy / resolving miscarriage: serum $\beta$-hCG drops by $> 50\%$.
  • Falling or plateauing hCG can occur in different outcomes and does not localise the pregnancy. Continue follow-up and safety-net for rupture symptoms.
• Transvaginal Ultrasound Findings:
  • Empty uterine cavity with thickened decidualised endometrium
  • Pseudo-gestational sac: a central, homogeneous intrauterine fluid collection lacking the double decidual sac sign
  • Inhomogeneous, complex adnexal mass separate from the ovary
  • "Tubal ring sign" (bag of pearls): echogenic ring surrounding an extrauterine gestational sac
  • Free fluid in the pouch of Douglas or Morison pouch (echogenic fluid indicates haemoperitoneum)

Management Modalities

• Medical Management (Methotrexate): Single-dose intramuscular methotrexate ($50\text{ mg/m}^2$ body surface area) is an established alternative to surgery in strictly selected, stable patients. Criteria for medical therapy:
  1. Haemodynamically stable without severe pain or peritoneal irritation
  2. Serum $\beta\text{-hCG} < 5,000\text{ IU/L}$
  3. Unruptured ectopic mass $< 35\text{ mm}$ on TVS
  4. Absence of embryonic cardiac activity on TVS
  5. Normal baseline full blood count, renal function, and liver enzyme levels
  6. Reliable patient able to attend outpatient monitoring on day 4 and day 7
  • Monitoring Protocol: Serum $\beta$-hCG is measured on day 4 and day 7. An initial rise between day 1 and day 4 is normal. A reduction of $\ge 15\%$ between day 4 and day 7 indicates successful response, followed by weekly $\beta$-hCG until $< 5\text{ IU/L}$. If $< 15\%$ reduction occurs, a second dose of methotrexate or laparoscopic surgery is required.
• Surgical Management (Laparoscopy):
  • Laparoscopic salpingectomy is the gold standard in Australia. Preferred in women with haemodynamic instability, ruptured ectopic pregnancy, acute peritoneal irritation, serum $\beta\text{-hCG} \ge 5,000\text{ IU/L}$, adnexal mass $\ge 35\text{ mm}$, or visible fetal cardiac activity.
  • Laparoscopic salpingostomy (incising the tube and extracting the trophoblast) is reserved for women with a severely damaged or absent contralateral fallopian tube who desire future fertility. Requires postoperative weekly $\beta$-hCG monitoring to exclude persistent trophoblastic tissue (occurs in ~10% of cases).

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Primary references (checked 7 October 2026): ADIPS 2025 diagnostic recommendations; National Blood Authority anti-D guideline.