The classic clinical presentation of placenta previa is sudden, painless, bright red vaginal bleeding in the second or third trimester. Upon abdominal examination, the uterus is typically soft, relaxed, and non-tender. This is because the bleeding originates from the separation of the placenta from the lower uterine segment, and the blood escapes vaginally without irritating the uterine muscle (myometrium). The absence of uterine tenderness and rigidity is a key diagnostic feature that helps differentiate placenta previa from abruptio placentae.

A. A rigid, boardlike abdomen: This is the hallmark sign of a moderate to severe abruptio placentae, where concealed bleeding irritates the myometrium, causing tetanic contractions.

B. Uterine atony: This refers to the failure of the uterus to contract effectively after delivery and is a primary cause of postpartum hemorrhage, not an antepartum finding.

D. Hypertonicity of the uterus: This finding, characterized by excessive uterine tone and contractions that do not fully relax, is characteristic of abruptio placentae.

1. Oyelese, Y., & Smulian, J. C. (2006). Placenta Previa, Placenta Accreta, and Vasa Previa. Obstetrics & Gynecology, 107(4), 927–941. In the section "Clinical Presentation and Diagnosis," the article states, "The classic presentation of placenta previa is painless vaginal bleeding... The uterus is usually soft and nontender." (p. 929). https://doi.org/10.1097/01.AOG.0000207559.15715.98

2. Cunningham, F. G., Leveno, K. J., Bloom, S. L., Dashe, J. S., Hoffman, B. L., Casey, B. M., & Spong, C. Y. (Eds.). (2018). Williams Obstetrics (25th ed.). McGraw-Hill Education. In Chapter 41, "Obstetrical Hemorrhage," the text differentiates the clinical findings, noting that with placenta previa, "uterine palpation does not typically elicit tenderness."

3. University of California, San Francisco (UCSF) School of Medicine. (n.d.). Obstetrics and Gynecology Clerkship: Third Trimester Bleeding. Course materials describe the physical exam for placenta previa as revealing a "soft, non-tender uterus," contrasting it with the "firm, tender uterus (often with contractions)" seen in placental abruption.