A 28-year-old primigravida delivers a healthy 3.2 kg male infant vaginally after 8 hours of labor. The third stage of labor lasts 35 minutes. Immediately after delivery of the placenta, the uterus is soft and boggy. Vaginal bleeding is brisk—approximately 800 mL in the first 15 minutes postpartum. Vital signs: BP 100/62 mmHg, HR 110/min, RR 22/min. Hemoglobin is 9.2 g/dL (pre-delivery was 11.5 g/dL). The cervix and perineum are intact. 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 bleeding vessels in the placental bed. ### Diagnostic Features in This Case | Feature | Finding | Significance | |---------|---------|---------------| | **Uterine tone** | Soft, boggy | Hallmark of atony | | **Timing of bleed** | Immediate (within 15 min) | Characteristic of atony | | **Volume** | 800 mL in 15 min | Brisk, continuous bleeding | | **Cervix/perineum** | Intact | Rules out lacerations | | **Vital signs** | Tachycardia, borderline BP | Early shock response | | **Hemoglobin drop** | 2.3 g/dL | Significant acute loss | **High-Yield:** The soft, boggy uterus immediately after placental delivery with brisk vaginal bleeding is pathognomonic for atony. This is a clinical diagnosis—no imaging or labs are needed to confirm. ### Pathophysiology After placental separation, myometrial contraction compresses spiral arteries and forms a "living ligature." Without adequate contraction: 1. Spiral arteries remain patent and bleed freely 2. Blood loss is continuous and can be massive 3. Shock develops rapidly if not managed ### Risk Factors for Atony **Mnemonic: TIRED** - **T**oo much fluid (polyhydramnios, macrosomia) - **I**nfection (chorioamnionitis, sepsis) - **R**apid labor (or prolonged labor—exhaustion) - **E**xhausted uterus (multiparity, grand multiparity) - **D**rugs (magnesium sulfate, nifedipine) **Clinical Pearl:** Primigravidas are generally at lower risk for atony, but prolonged labor (8 hours in this case) and a large baby (3.2 kg) are relative risk factors. ### Management Algorithm ```mermaid flowchart TD A[Soft, boggy uterus + PPH]:::outcome --> B[Uterine massage]:::action B --> C{Bleeding controlled?}:::decision C -->|Yes| D[Continue oxytocin infusion]:::action C -->|No| E[IV access × 2, cross-match blood]:::action E --> F[Oxytocin 10 IU IV/IM]:::action F --> G{Still bleeding?}:::decision G -->|Yes| H[Ergot alkaloid or misoprostol]:::action G -->|No| I[Observe, monitor vitals]:::action H --> J{Refractory?}:::decision J -->|Yes| K[Consider balloon tamponade or surgery]:::urgent J -->|No| I ``` **Tip:** The first-line treatment is **uterine massage** + **oxytocin**. Do not wait for investigations; start empirically if atony is suspected clinically.