## Distinguishing Placental Abruption from Preterm Labor ### Key Discriminating Feature **Key Point:** Vaginal bleeding with evidence of hemorrhage (concealed or revealed) is the hallmark of placental abruption and is NOT a typical feature of uncomplicated preterm labor. ### Comparative Clinical Features | Feature | Placental Abruption | Preterm Labor | |---------|-------------------|---------------| | **Vaginal bleeding** | Present (revealed or concealed) | Absent unless cervicitis/polyps | | **Uterine tenderness** | Marked (due to extravasated blood) | Mild to absent | | **Uterine contractions** | Present but irregular, tetanic | Regular, progressively stronger | | **Cervical changes** | Variable; may be dilated late | Progressive dilation and effacement | | **Fetal distress** | Often present early | May develop with progression | | **Maternal shock** | Can occur (concealed abruption) | Rare unless sepsis | ### Why This Matters **Clinical Pearl:** In placental abruption, the bleeding is the primary pathology — it triggers uterine irritability and contractions secondarily. In preterm labor, contractions are primary and bleeding is absent unless there is concurrent cervical pathology. **High-Yield:** Concealed abruption (no vaginal bleeding) can present with severe pain, uterine tenderness, and maternal shock out of proportion to visible bleeding — a classic NEET PG trap. The absence of vaginal bleeding does NOT exclude abruption; the presence of bleeding strongly favors abruption over preterm labor. ### Mnemonic: ABRUPTION vs LABOR - **A**bruption = **A**bnormal bleeding + **A**cute pain + **A**bsent cervical change (early) - **L**abor = **L**ower segment contractions + **L**ower segment dilation + **L**ess bleeding [cite:Williams Obstetrics 26e Ch 34]
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