Which laboratory test is most useful for diagnosing spontaneous abortion?

The most useful laboratory test for diagnosing spontaneous abortion is the measurement of beta-human chorionic gonadotropin (beta-hCG) levels. This hormone is produced by the placenta shortly after a fertilized egg attaches to the uterine lining, and its levels can provide significant insights into the viability of a pregnancy.

In cases of normal early pregnancy, beta-hCG levels typically double every 48 hours. If a spontaneous abortion is occurring, these levels may rise inadequately or begin to decline, indicating that the pregnancy is not progressing as it should. Therefore, monitoring these hormone levels can help confirm the diagnosis of a spontaneous abortion, especially in the early stages of pregnancy.

While ultrasound examinations are also a critical tool in evaluating the status of a pregnancy and can provide visual confirmation of a miscarriage (by showing an empty uterus or signs of tissue loss), beta-hCG testing can often provide the initial indication of a potential problem before ultrasonography is utilized.

Cervical cultures and a complete blood count are not directly useful in diagnosing spontaneous abortion. Cervical cultures are primarily used to identify infections, and while a complete blood count may help in assessing overall health or detect anemia, it does not provide specific information about the viability of a pregnancy.