###HUMAN: get the number of patients with diagnoses icd9 code 99662 who had ascitic fluid lab test done., ###ASSISTANT: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN lab ON demographic.hadm_id = lab.hadm_id WHERE diagnoses.icd9_code = "99662" AND lab.fluid = "Ascites"