From the Guidelines
For suspected miscarriage at 6 weeks gestational age, the primary investigations should include quantitative serum beta-human chorionic gonadotropin (β-hCG) measurements and transvaginal ultrasound, as recommended by the most recent study 1.
Key Investigations
- Quantitative serum beta-human chorionic gonadotropin (β-hCG) measurements: Serial β-hCG levels should be obtained 48 hours apart to assess if they are rising appropriately (typically doubling every 48-72 hours in viable pregnancies) 1.
- Transvaginal ultrasound: Should be performed to confirm intrauterine pregnancy and assess for fetal cardiac activity, which may be visible by 6 weeks 1.
Additional Investigations
- Complete blood count: Should be ordered to evaluate for anemia if bleeding is present.
- Blood type and Rh status determination: Essential, as Rh-negative women with threatened miscarriage require RhoGAM (50 mcg) to prevent Rh sensitization.
- Progesterone levels: May be helpful as values below 5 ng/mL often indicate non-viable pregnancies.
Clinical Assessment
- Assessment of vital signs and pelvic examination: Necessary to rule out ectopic pregnancy or complete miscarriage if bleeding or pain is severe.
Importance of Accurate Diagnosis
These investigations are crucial because accurate diagnosis directs appropriate management and emotional support, while also identifying potentially life-threatening conditions like ectopic pregnancy that require immediate intervention 1.
From the Research
Investigations for Suspected Miscarriage at 6 Weeks GA
- Transvaginal ultrasound scan is considered the standard test to assess viability of the pregnancy 2, 3
- Assessment of the amount of vaginal bleeding experienced is best made in the context of time taken to saturate a sanitary pad 2
- Changing a pad soaked with blood and clots more than once an hour is an indication of heavy bleeding that requires immediate referral 2
- Handheld transabdominal ultrasound may be used to confirm first trimester viable intrauterine pregnancy, especially from gestational week 7 4
- Ultrasound markers such as fetal bradycardia can help predict miscarriage in women with viable intrauterine pregnancy 5
- Human chorionic gonadotropin (hCG) ratio may be used to predict the viability of intrauterine pregnancies of uncertain viability (IPUVs) 6
Additional Considerations
- A clinical assessment suggesting complete miscarriage should be confirmed with serial biochemical tests or an intrauterine gestation sac previously visualised 3
- 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 3
- 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 3