The Ova / Cyst test is conducted to measure the level of parasites in the stool. The test also checks the presence of ova and cysts in the stool. Ova/s are the eggs of parasites and cysts are hard shells that protect the parasites when they reach a certain stage of their lifecycle. To do this test, a sample of stool is taken and analysed. The presence of these parasites can cause trouble in the lower digestive tract thus leading to symptoms such as diarrhoea. If you have such symptoms, your doctor would recommend you get the test done.