A 28-year-old primigravida delivers a healthy 3.2 kg male infant vaginally after a 6-hour second stage. The third stage is prolonged (>30 minutes). Placenta is expelled with gentle cord traction and fundal massage. Within 15 minutes of delivery, the patient complains of severe lower abdominal pain and vaginal bleeding increases suddenly. On examination, the uterus is soft, boggy, and difficult to palpate. Lochia is heavy with clots. Vital signs: BP 100/62 mmHg, HR 110/min, RR 20/min. Hemoglobin is 8.2 g/dL (pre-delivery 11.5 g/dL). What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Uterine Atony **Key Point:** Uterine atony is the most common cause of postpartum hemorrhage (PPH), accounting for 70–80% of cases. It occurs when the myometrium fails to contract adequately after placental delivery, preventing compression of spiral arteries. ### Diagnostic Features in This Case | Feature | Finding | Significance | |---------|---------|---------------| | **Uterine consistency** | Soft, boggy, difficult to palpate | Hallmark of atony; loss of myometrial tone | | **Timing** | Within 15 min of placental delivery | Typical onset of primary PPH from atony | | **Lochia character** | Heavy with clots | Indicates ongoing venous ooze from placental bed | | **Vital signs** | Tachycardia (110), hypotension (100/62) | Compensatory response to acute blood loss | | **Hemoglobin drop** | 11.5 → 8.2 g/dL (3.3 g/dL loss) | Significant acute hemorrhage | ### Pathophysiology 1. Placental separation occurs normally 2. Myometrium fails to contract (atony) 3. Spiral arteries remain open → ongoing bleeding from placental bed 4. Uterus becomes distended with blood → further impairs contraction (vicious cycle) **Clinical Pearl:** A soft, boggy uterus is pathognomonic for atony. The uterus should feel firm and contracted (like a grapefruit) after delivery; if it is soft and enlarged, atony is present. ### Risk Factors for Uterine Atony - Prolonged labor (present: 6-hour second stage) - Multiparity - Polyhydramnios - Macrosomia - Uterine overdistension - Anesthesia (halothane, magnesium sulfate) - Rapid labor **High-Yield:** First-line management is **uterine massage** + **oxytocin** (10 IU IV or IM). If unresponsive, escalate to methylergonovine or misoprostol. ### Why NOT the Other Diagnoses - **Retained placental fragments:** Would present with persistent vaginal bleeding but uterus is typically firm initially; pain is less severe and localized. - **Uterine inversion:** Presents with severe shock out of proportion to bleeding, visible vaginal mass, and severe pain; uterus is not palpable abdominally. - **Cervical laceration:** Bleeding is steady and vaginal in origin; uterus is firm and well-contracted; no abdominal pain.