Sold in drugstores, ovulation testing kits detect the amount of luteinizing hormone (LH) in your urine, which increases one to two days before ovulation. Similar to over-the-counter pregnancy tests, these are digital devices with a testing stick to be held under your urine stream. There is another type of testing kit, using which you can test your dried saliva under a microscope for "fern" patterns that sometimes indicate a rise in estrogen levels in the few days leading up to ovulation. This is less reliable than the LH test, especially if you have poor eyesight. Very concentrated or very dilute urine throws off the results of this test. For best results, avoid caffeine and alcohol on the day of the test, avoid dehydration or excessive water consumption, and wait until your bladder is full. Urinate on the stick and wait for a new line to appear in the viewing window. A line that is about as dark as the existing control line means you are probably ovulating. A faint line is not a reliable indicator.  Ovulation tests accurately predict the level of LH in urine, but the surge in LH only lasts about 24–48 hours, giving you a short window to detect it. Using multiple methods to track ovulation is recommended. Some tests may work slightly differently, so check the instructions. For example, you may need to urinate into a cup and dip the test into it, or the fertility symbol may show up as as smiley face instead of a line. Test yourself daily during the most likely parts of your cycle, as described in the calendar section. If you have missed your ovulation in previous cycles and can afford additional tests, consider taking an ovulation test twice daily.

How would you rephrase that briefly using Vietnamese?
Mua một bộ kiểm tra rụng trứng. Duy trì lượng nước nạp vào cơ thể vài tiếng trước khi kiểm tra. Phân tích kết quả. Thử lại nếu cần thiết.