Whereas conventional radiographs (x-rays) allow assessment of size, shape and position of internal organs, ultrasound allows evaluation of the inner character of these organs. Abnormal organ texture can alert the veterinarian to conditions such as liver disease, kidney disease, stones of the urinary bladder, abscesses, and cancer. If abnormal tissues are detected during the ultrasonographic examination, and if the patient is stable enough, tissue samples may be obtained by performing ultrasound guided fine needle aspirates. With this technique, a small needle is inserted into the organ of question, for example the urinary bladder, and fluid or tissue samples are collected. These can then be examined using specific laboratory analyses, and it may be possible to diagnose a disease process without putting the patient through a more invasive procedure.