Obstetrics and Gynaecology: Two Patients, One Decision
Core concepts
Obstetrics requires simultaneous consideration of maternal and fetal wellbeing. Know the physiology of pregnancy - expanded plasma volume, dilutional anaemia, changes in cardiac output and renal filtration - and how these alter normal values. Master the hypertensive disorders: define chronic hypertension, gestational hypertension, pre-eclampsia with and without severe features, and eclampsia; know that pre-eclampsia is diagnosed after 20 weeks and that delivery is the definitive treatment. Learn the causes of postpartum haemorrhage in order of frequency (tone, tissue, trauma, thrombin) and the stepwise management. Understand fetal surveillance: cardiotocography interpretation, the significance of reduced fetal movements, and the timing of antenatal corticosteroids.
Gynaecology questions reward a clear framework for abnormal uterine bleeding by age, the approach to pelvic mass, and the diagnosis of ectopic pregnancy. Know contraceptive options by contraindication profile, and the staging principles of gynaecological malignancy.
Traps
Questions often present a patient who is 'not yet 20 weeks' to exclude pre-eclampsia, or who has a normal blood pressure but other severe features such as deranged liver enzymes. Beware of confusing hyperemesis with normal nausea, and of missing sepsis as a cause of maternal deterioration. In gynaecology, a positive pregnancy test changes every differential.
Rule of thumb
In pregnancy, when maternal and fetal interests appear to conflict, stabilise the mother first; delivery is the treatment for most severe pregnancy-specific disease.
Worked example
A woman at 34 weeks has blood pressure 150/100 mmHg, platelets 90 × 10⁹/L, and right upper quadrant pain. This is pre-eclampsia with severe features; the answer is admission, antihypertensives, magnesium sulphate for seizure prophylaxis, and planned delivery after steroids.