Premature rupture of membranes refers to the rupture of the amniotic sac before labor begins. The diagnosis of premature rupture of membranes is mainly based on clinical symptoms, gynecological examination, and ultrasound assessment. Ultrasound can only serve as an auxiliary tool for diagnosing premature rupture of membranes. This is because, during premature rupture, an ultrasound might sometimes show a reduction in amniotic fluid due to significant fluid leakage, although amniotic fluid can also regenerate quickly. In such cases, an ultrasound done for premature rupture of membranes might still show the amniotic fluid level within the normal range. Therefore, the diagnosis of premature rupture of membranes heavily relies on clinical symptoms and gynecological examination. The presence of a large amount of fluid leaking from the vagina and a change in color on the amniotic fluid test strip during a gynecological examination are crucial for confirming the diagnosis. Ultrasound, in this context, serves only as a supplementary diagnostic method.