A nurse is caring for a female client who is at 30 weeks of gestation in the labor and delivery unit.

Exhibits

The nurse is reviewing the client's assessment data. For each assessment finding below, click to specify if the finding is consistent with placenta previa, preterm labor, or abruptio placenta. Each finding may be consistent with more than one condition

Vaginal bleeding

Bleeding occurs in placenta previa due to partial or total implantation of the placenta over the cervical os, leading to painless bright red bleeding from disrupted placental vessels. It also occurs in preterm labor when cervical effacement and dilation disrupt small cervical vessels, producing light bleeding or spotting. In abruptio placenta, bleeding is dark red and may be concealed or apparent, resulting from premature placental detachment and rupture of maternal vessels in the decidua basalis.

Uterine contractions

Regular uterine contractions every 2 to 3 minutes with cervical change are diagnostic of preterm labor, resulting from premature activation of uterine oxytocin receptors and prostaglandin release before 37 weeks. In abruptio placenta, contractions are often strong and sustained (hypertonic uterus) due to myometrial irritability from bleeding into the decidual layer. Placenta previa, however, typically presents with painless bleeding and a soft, relaxed uterus without contractions because the uterine muscle tone remains unaffected.

Cervical dilation

Cervical dilation indicates preterm labor, as biochemical changes in the cervix from increased prostaglandin and relaxin activity cause collagen breakdown and effacement before term. This process reflects uterine activation sequence initiation leading to potential preterm birth. In placenta previa, the cervix may remain closed despite bleeding because bleeding originates from placental implantation, not cervical change. Abruptio placenta rarely involves dilation unless labor progresses secondarily after placental separation, thus cervical dilation is not a key feature.

Abdominal tenderness

Abdominal tenderness is characteristic of abruptio placenta, caused by bleeding between the uterine wall and placenta leading to myometrial irritability, uterine rigidity, and ischemic pain. The trapped blood increases intrauterine pressure, stimulating pain receptors in the myometrium and stretching the uterine serosa. Placenta previa presents with a soft, nontender abdomen because bleeding is external and not associated with uterine muscle involvement. Preterm labor generally causes back discomfort or cramping, not localized abdominal tenderness.

Client report of low back pain

Low back pain is prominent in preterm labor, resulting from referred pain due to rhythmic uterine contractions transmitted through the lumbosacral plexus and pelvic nerves. It reflects early cervical change and uterine irritability. In abruptio placenta, the back pain may occur secondary to uteroplacental separation and posterior placental bleeding irritating the parietal peritoneum. Placenta previa typically lacks pain or back discomfort since bleeding occurs without uterine or peritoneal irritation.