What is the initial approach for investigating postpartum bleeding (PPB) more than 6 weeks post-delivery?

Initial Approach for Investigating Postpartum Bleeding Beyond 6 Weeks

Transvaginal ultrasound should be the first-line imaging modality for investigating postpartum bleeding that persists beyond 6 weeks post-delivery, with particular attention to detecting retained products of conception and vascular abnormalities. 1, 2

Diagnostic Algorithm

Step 1: Clinical Assessment

• Quantify bleeding volume and pattern
• Assess vital signs for hemodynamic stability
• Evaluate for signs of infection (fever, uterine tenderness)
• Review delivery details (vaginal vs. cesarean, complications)

Step 2: Initial Laboratory Tests

• Complete blood count to assess hemoglobin/hematocrit
• Coagulation studies (PT/INR, PTT, fibrinogen)
• Group and screen for potential transfusion
• Venous blood gas for rapid hemoglobin measurement and lactate level (>2 mmol/L indicates shock) 2

Step 3: First-Line Imaging

• Transvaginal ultrasound with color Doppler
  • Most sensitive for detecting retained products of conception (RPOC)
  • Look for echogenic endometrial mass with vascularity (most diagnostic combination) 1
  • Assess for vascular abnormalities (pseudoaneurysm, arteriovenous malformation)
  • Evaluate uterine involution and endometrial thickness

Step 4: Additional Imaging Based on Initial Findings

• If ultrasound is inconclusive and bleeding persists:
  • CT with IV contrast to:
    • Determine presence of active hemorrhage
    • Localize bleeding source
    • Identify hematomas (bladder flap, subfascial, perivaginal) 1
  • MRI may be considered but has limited ability to distinguish retained products from blood clots without contrast 2

Common Etiologies of Late Postpartum Bleeding

1. Retained Products of Conception (RPOC)

   • Most common cause after vaginal delivery
   • Ultrasound finding: echogenic endometrial mass with vascularity 1

2. Subinvolution of Placental Bed

   • Delayed healing at placental implantation site
   • Can be difficult to distinguish from acquired vascular uterine abnormalities 1

3. Infection/Endometritis

   • More common after cesarean delivery 1
   • Associated with fever, uterine tenderness

4. Vascular Abnormalities

   • Pseudoaneurysm (swirling or yin-yang pattern on Doppler) 1
   • Arteriovenous malformations

5. Cesarean Scar Complications

   • Dehiscence (disruption of endometrial and myometrial layers)
   • Bladder flap hematoma >5 cm should raise suspicion 1

Important Considerations and Pitfalls

• Doppler assessment pitfalls:

  • Absence of vascularity does not exclude RPOC (can be avascular) 1
  • Marked vascularity can mimic pseudoaneurysm
  • RPOC typically extends to endometrium, while pseudoaneurysm is restricted to myometrium 1

• Normal postpartum findings that may be misinterpreted:

  • Presence of debris and gas (common in up to 25% of early postpartum cases) 1
  • Thickened endometrial echo complex up to 2-2.5 cm can be normal in early postpartum period 1

• Timing considerations:

  • Secondary postpartum hemorrhage is defined as significant bleeding between 24 hours and 6 weeks postpartum 1, 2
  • Bleeding beyond 6 weeks requires thorough investigation as it falls outside the typical timeframe

• Risk factors to consider:

  • Primary postpartum hemorrhage is a risk factor for secondary postpartum hemorrhage 1
  • Cesarean delivery increases risk of endometritis 1
  • Peripartum or postpartum blood loss >1L increases risk of complications 2

By following this systematic approach to investigating postpartum bleeding beyond 6 weeks, clinicians can efficiently identify the underlying cause and initiate appropriate management to reduce morbidity and mortality associated with delayed postpartum hemorrhage.