Waalaikum assalam, sayang. I can feel how worried you are, and that's completely normal. First thing, please follow up closely dengan doctor yang detect ini, okay? They'll monitor baby carefully throughout your pregnancy and birth, and many babies dengan single umbilical artery lahir perfectly fine. A few of us mum friends have gone through unexpected findings during scans, and the anxiety is real, tapi most of the time baby okay je. Your doctor is the best person to reassure you and plan the next steps, don't hesitate to ask all your questions, no matter how small. Sabar ya, and lean on your support circle. Doa and regular checkups je yang you boleh do right now. Thinking of you and your little one.