The algorithm consists of six criteria excluding pregnancy, all conditional upon a seventh ‘master criterion’ relating to pregnancy signs or symptoms. Few data exist on the specificity of pregnancy among family planning clients of long-accepted signs and pregnancy symptoms. The present study aimed to assess whether reported signs and symptoms of pregnancy add to an algorithm’s predictive value to rule out pregnancy.

Data from a previous observational study were used to assess the algorithm’s performance with and without the ‘signs and symptoms’ criterion. The study group comprised 1852 new, non-menstruating family planning clients from seven clinics in Kenya.

Signs and symptoms of pregnancy were rare as was pregnancy. Signs and symptoms were more common among the 22 clients who tested positive for pregnancy than among the 1830 clients who tested negative but did not add significantly to the predictive value of the algorithm. Most women with signs or symptoms were not pregnant and would have been unnecessarily denied a contraceptive method using the current criteria.

The study concluded that the ‘signs and symptoms’ criterion did not substantially improve the ability of the algorithm to exclude pregnant clients, but several reasons render it unlikely that the algorithm will be changed.