Objective: The technique of conventional cell blocks is rather labor- and time-consuming. The purpose of this study was to generate a convenient and quick manual procedure using ultrasound processing which could be applied in most developing countries and to evaluate its efficacy in the cytopathologic diagnosis of cavity fluids. Study Design: We carried out a rapid cell block procedure using egg albumen as the pre-embedded adjuvant and using ultrasound to accelerate fixation, dehydration, clearing and waxing. The diagnostic efficacy was evaluated as compared with tissue blocks and liquid-based cytology tests (LCTs). Results: A total of 155 samples underwent rapid cell block detection, and 61 were diagnosed as malignancies. The method was able to produce high-quality formalin-fixed paraffin-embedded cell block sections and has similar diagnostic validity to the LCT. The immunohistochemistry and in situ hybridization staining patterns in rapid cell block sections were similar to those in their tissue block counterparts. Conclusions: The ultrasound-processed rapid cell block is a convenient and quick method for cytopathologic diagnosis. We consider it may serve as an effective adjuvant technique for most primary medical institutions.