Probabilistic databases and database outsourcing are two recent and important applications of database systems. In this paper, we introduce authenticated query processing in outsourced probabilistic databases. We have proposed a novel authenticated data structure (ADS) called PH-tree, which is a combination of PDR-tree and MH-tree.We have also implemented k-means clustering as a preprocessor. We have compared our algorithm with an existing ADS called MR-tree and showed that PH-trees outperform MR-trees significantly.