9.1 Early Pregnancy: Miscarriage & Ectopic Pregnancy

Early Pregnancy: Miscarriage & Ectopic Pregnancy

Early pregnancy complications represent one of the most common acute presentations in acute gynaecology and primary care. Rapid clinical evaluation in an Early Pregnancy Assessment Unit (EPAU) is critical to differentiate between benign physiological bleeding, spontaneous miscarriage, and life-threatening ectopic pregnancy.

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Classification & Clinical Features of Miscarriage

Miscarriage is defined as the spontaneous loss of a pregnancy before 24 completed weeks of gestation. Clinical classification depends on cervical os patency, presence of bleeding, abdominal cramping, and transvaginal ultrasound (TVUS) findings.

Diagnostic Ultrasound Thresholds for Non-Viability (NICE NG126)

When assessing early pregnancy viability on TVUS, strict empirical thresholds prevent accidental termination of viable pregnancies:

• Crown-Rump Length (CRL) Threshold: A fetal pole with a CRL ≥ 7 mm and no visible fetal heartbeat indicates miscarriage, but NICE NG126 requires a second opinion and/or a second scan at least 7 days later before the diagnosis is made.
• Mean Sac Diameter (MSD) Threshold: A gestational sac with a mean sac diameter ≥ 25 mm and no visible fetal pole indicates an anembryonic pregnancy; again, seek a second opinion and/or rescan at least 7 days later before confirming.
• Inconclusive Findings: If the CRL is < 7 mm without cardiac activity, or the MSD is < 25 mm without a fetal pole, the pregnancy is of uncertain viability. Repeat the transvaginal scan at least 7 days later before any diagnosis of non-viability.

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Stepped Management of Spontaneous Miscarriage

Once non-viability is confirmed, management options include expectant, medical, or surgical interventions:

1. Expectant Management

• First-line approach for women with confirmed miscarriage who are clinically stable, have minimal pain, and display no signs of infection or heavy haemorrhage.
• The patient is observed for 7 to 14 days to allow spontaneous expulsion of retained tissue.
• If bleeding and pain resolve, the patient takes a home urine pregnancy test at 3 weeks. If symptoms persist or worsen after 14 days, medical or surgical intervention is offered.

2. Medical Management

• Indicated if expectant management fails, is unacceptable to the patient, or if retained products are present without severe instability.
• NICE Regimen (missed miscarriage): A single oral dose of mifepristone 200 mg (a progesterone receptor antagonist that sensitises the myometrium), followed 48 hours later by misoprostol 800 micrograms (a synthetic prostaglandin E1 analogue given vaginally, orally or sublingually) to stimulate uterine contractions and cervical ripening.
• Incomplete miscarriage: misoprostol 600 micrograms alone (vaginal, oral or sublingual); mifepristone is not needed.
• Adequate oral analgesia (codeine, paracetamol, or NSAIDs) and antiemetics should be provided.
• A urine pregnancy test is performed 3 weeks later. Persistent positive tests or unresolved symptoms require hospital follow-up to exclude gestational trophoblastic disease or retained products.

3. Surgical Management

• Indications: Haemodynamic instability, severe intractable bleeding, clinical evidence of infection (septic miscarriage), or patient preference.
• Modality:
  • Manual Vacuum Aspiration (MVA): Outpatient procedure performed under local anaesthetic and paracervical block; suitable for pregnancies up to 10–12 weeks.
  • Surgical Evacuation (ERPC / SMM): In theatre under general anaesthesia using suction curettage.

Anti-D Rhesus Prophylaxis

• NICE NG126 (2023 update): offer anti-D immunoglobulin 250 IU within 72 hours to all rhesus D-negative women who have a surgical procedure to manage a miscarriage or an ectopic pregnancy.
• Do not offer anti-D to women who have solely medical management of a miscarriage or ectopic pregnancy, a threatened miscarriage, a complete miscarriage, or a pregnancy of unknown location. Do not use a Kleihauer test to quantify feto-maternal haemorrhage in early pregnancy.
• Some local haematology policies (based on British Society for Haematology guidance) still give anti-D for bleeding after 12 weeks; in an exam, follow NICE unless the question states otherwise.

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Ectopic Pregnancy

Ectopic pregnancy occurs when a blastocyst implants outside the normal uterine endometrial cavity. Over 95% occur in the fallopian tube, with the ampulla being the most frequent site (~70%), followed by the isthmus (~12%), fimbria (~11%), and interstitial/cornual segment (~2%).

Clinical Presentation

• Classic Triad: Amenorrhoea (typically 6–8 weeks), unilateral iliac fossa / lower abdominal pain, and abnormal dark brown vaginal spotting ("prune juice bleeding").
• Signs of Tubal Rupture & Haemoperitoneum:
  • Sudden-onset severe sharp pelvic pain progressing to generalized peritonism.
  • Shoulder tip pain: Referred pain from diaphragmatic irritation by free blood in the peritoneal cavity (innervated by the phrenic nerve, C3–C5).
  • Tenesmus or rectal pressure due to blood pooling in the rectouterine pouch (pouch of Douglas).
  • Haemodynamic collapse, pallor, syncope, tachycardia, and hypotension.

Diagnostic Evaluation

• Transvaginal Ultrasound (TVUS): Demonstrates an empty uterine cavity with thickened endometrium (decidual reaction / pseudo-gestational sac), an adnexal mass separate from the ovary (tubal ring or "doughnut sign"), and free fluid in the pelvis or pouch of Douglas.
• Serum Beta-hCG Dynamics:
  • In a normal viable intrauterine pregnancy, serum beta-hCG concentrations approximately double (increase by ≥ 63%) every 48 hours.
  • In ectopic pregnancy, serum beta-hCG characteristically displays a suboptimal rise (< 63% rise over 48 hours) or a plateau.
  • Discriminatory Zone: The serum hCG level (typically 1000–1500 IU/L) above which a viable intrauterine sac must be visualized on TVUS. An empty uterus with hCG above the discriminatory zone strongly suggests ectopic pregnancy.

Treatment Modalities for Tubal Ectopic Pregnancy

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Hyperemesis Gravidarum (HG)

Hyperemesis gravidarum is characterized by intractable, severe nausea and vomiting presenting before 16 weeks gestation, associated with ketonuria, dehydration, electrolyte derangements, and weight loss > 5% of pre-pregnancy weight.

Assessment & Severity Scoring

• Evaluated using the validated PUQE (Pregnancy-Unique Quantification of Emesis) score (assessing hours of nausea, episodes of vomiting, and retching).
• Typical biochemical profile: Hypokalaemic, hypochloraemic metabolic alkalosis, elevated urea/creatinine (prerenal azotemia), ketonuria (≥ 2+ on dipstick), and secondary mild transaminitis.

Clinical Management Protocol

1. Intravenous Fluid Resuscitation: Initial rehydration with 0.9% normal saline supplemented with potassium chloride. Potassium must be closely replaced to correct hypokalaemia.
2. MANDATORY THIAMINE (PABRINEX) RULE: Parenteral thiamine (vitamin B1 / Pabrinex) must be administered BEFORE any dextrose-containing intravenous infusions. Dextrose administration in a carbohydrate-depleted, thiamine-deficient state rapidly exhausts remaining thiamine stores during glycolysis, precipitating acute, irreversible Wernicke's encephalopathy (triad of ataxia, ophthalmoplegia/nystagmus, and acute confusion).
3. Antiemetic Stepping (RCOG):
   • First-line: Cyclizine (antihistamine) 50 mg TDS oral/IV/IM, prochlorperazine 5–10 mg TDS, or promethazine.
   • Second-line: Metoclopramide 10 mg TDS (max 5 days due to extrapyramidal / oculogyric crisis risk) or Ondansetron 4–8 mg BD/TDS.
   • Third-line: Oral or intravenous corticosteroids (prednisolone or hydrocortisone) in refractory cases.
4. Thromboprophylaxis: Severe dehydration and pregnancy-induced hypercoagulability produce high venous thromboembolism (VTE) risk. Prescribe prophylactic low molecular weight heparin (LMWH) and anti-embolism stockings during admission.