Hay, congrats! At 4 weeks, makikita mo na usually ang gestational sac sa ultrasound, pero honestly kung baguhan ka pa lang, parang tiny dot lang talaga siya on screen kaya don't be disappointed if di ka makita ng marami. A few of my mum friends were surprised how small it was compared sa expectations nila! Best talaga na i-ask mo directly sa OB mo kung ano exactly makikita niya sa 4-week scan, kasi bawat ultrasound machine at doctor may sariling approach.