OG6.1 | Diagnosis of Pregnancy — Summary & Reflection

KEY TAKEAWAYS

Diagnosis of Pregnancy — Key Points:

• Three-tier classification of pregnancy signs:
• Presumptive (subjective): amenorrhoea, nausea, breast changes, urinary frequency, quickening
• Probable (objective): Hegar's sign (isthmus softening, 6–8 wks), Chadwick's sign (vaginal blueness), Goodell's sign (cervical softening), ballottement, uterine enlargement
• Positive (definitive): fetal cardiac activity on USS, fetal movements felt by examiner, fetal heart sounds by Doppler
• hCG-based pregnancy tests: detect β-hCG (unique subunit); qualitative urine test positive ~10–14 days post-fertilisation (≥25 mIU/mL); quantitative serum β-hCG doubles every ~48 hours in normal early pregnancy; failure to double suggests ectopic or failing IUP
• Discriminatory zone: serum β-hCG >1,500–2,000 mIU/mL with empty uterus on TVS = ectopic pregnancy until proven otherwise
• Ultrasound milestones: gestational sac (TVS 4.5–5 wks), yolk sac (5.5 wks), cardiac activity at CRL ≥5 mm (~6 wks); CRL most accurate for dating (6–13 wks, ±5 days)
• Naegele's rule: EDD = LMP − 3 months + 7 days; assumes 28-day cycle, ovulation day 14
• Differential of amenorrhoea: always test pregnancy first; then consider PCOS, hypothyroidism, hyperprolactinaemia, premature ovarian insufficiency
• MTP Act 2021: gestational age determines eligibility category; must be established by USS; PCPNDT prohibits sex determination
• Emergency rule: positive pregnancy test + pelvic pain = exclude ectopic before any other diagnosis

REFLECT

Return to the opening scenario — the young woman with an undiagnosed ectopic pregnancy who reached the emergency department at midnight and nearly died because no one ordered a pregnancy test. Now that you have completed this module, you can see exactly where the diagnostic chain failed: the triage nurse and the emergency doctor both anchored on 'period pain' without following the rule that any woman of reproductive age with pelvic pain must have a pregnancy test. Kolb's reflective cycle asks you to extract a durable lesson: what clinical rule will you commit to that prevents this error? Write it down and share it in your next clinical teaching session. The power of a simple, reflexive rule — 'urine pregnancy test first, in every woman of reproductive age with pelvic pain, before anything else' — is that it costs nothing and could save a life every time you apply it.