What is the main symptom of placenta previa?

The main symptom of placenta previa is bright red vaginal bleeding without pain. This condition occurs when the placenta is abnormally positioned in the lower segment of the uterus, either partially or totally covering the cervical opening.

In most cases, this bleeding occurs in the third trimester of pregnancy and is a result of the placental attachment disrupting the blood vessels in the lower uterine segment. Typically, this bleeding can be alarming for the patient when it occurs, yet it is often painless, which is a distinguishing characteristic of placenta previa compared to other conditions that might cause bleeding during pregnancy, such as placental abruption, which is usually accompanied by pain.

In contrast, other symptoms like severe abdominal cramps, amniotic fluid leakage, and increased fetal movement are not primarily associated with placenta previa. Abdominal cramps can be related to various conditions but do not specifically indicate placenta previa. Amniotic fluid leakage does not directly relate to this condition and could indicate other complications, such as premature rupture of membranes. Increased fetal movement is generally a sign of a healthy fetus and does not correlate with any specific pathology concerning placenta previa. Thus, the identification of bright red vaginal bleeding without pain as the main symptom is critical for timely diagnosis and intervention in cases of placenta previa.