Doctor.. My Sister Has Pcos Problem N The Doc Whom

Doctor.. my sister has pcos problem n the doc whom she's consulting has asked to come for a scanning on day 3 of her date. She's worried abt this kind of day 3 test as she's unaware of wat kind of test the doc will be doing. As they've told her about scanning. I need to explain to her as wat kind of test Wil be done.