Threatened abortion: prediction of viability based on signs and symptoms

To examine the relationship between signs and symptoms associated with threatened abortion and viability of the pregnancy.

A prospective observational study

A university teaching hospital

One thousand consecutive women presenting with a threatened abortion.

A structured history and an examination were performed as initial clinical assessment. These were followed by transvaginal sonography to determine the status of the pregnancy.

The relationship between individual signs and symptoms and the status of the pregnancy was determined. Logistic regression was performed to determine which signs or symptoms were independent predictors of spontaneous abortion.

A history of having passed a tissue mass, the presence of products of conception in the vagina and an open cervix were the only sign or symptom associated with a greater than 90% chance that the pregnancy was non-viable. Logistic regression of signs and symptoms at presentation indicated that maternal age greater than 35 years, a history of passing clots vaginally, vaginal bleeding similar to normal menstruation, increasing vaginal bleeding and discrepancy of 4 or more weeks between the uterine size on examination and that which would have been expected by menstrual dates were significant predictors of nonviable pregnancy. A history of vomiting was predictive of a viable pregnancy.

The clinical assessment of threatened abortion is unreliable in most cases and should be superseded by ready access to sonographic assessment.