Diagnosing miscarriage

Miscarriage is the most common serious pregnancy complication affecting approximately 30% of biochemical pregnancies and 11–20% of clinically recognised pregnancies. The diagnosis of miscarriage is made most commonly by trans-vaginal ultrasound (TVS) assessment. Evidence-based criteria should be employed for the diagnosis of delayed and incomplete miscarriage. Complete miscarriage should not be diagnosed with TVS alone without serial biochemical confirmation (unless an intrauterine gestation sac has previously been visualised). After a clinical assessment suggesting complete miscarriage, 45% of women will have retained tissue on ultrasound, whilst women with an ultrasound scan showing an empty uterus with a history suggestive of miscarriage will be found to have an ectopic pregnancy in 6% of cases. Prediction of the diagnosis of miscarriage using maternal history and ultrasound features may be helpful in counselling women towards likely pregnancy outcome and planning appropriate further assessment. Use of three-dimensional ultrasound has not improved diagnosis of miscarriage. After a diagnosis of miscarriage, half the women undergo significant psychological effects, which may last for up to 12 months.