Fluid in uterus?

Kelsie • Wife, Momma to 3 girls, expecting baby #4! 🤰

Has anyone has this happen? I went to a 6 week ultrasound today and they saw "fluid" next to the sac. I am a mom of fraternal twins already. Is this a vanishing twin? She said it could be or it could be just unexplainable fluid. Would love to hear from anyone else with similar sonograms!