What is the most common cause of 1000 cc of vaginal bleeding after an uneventful vaginal delivery with a firm uterus?

Genital Tract Laceration (Answer: C)

In a patient with 1000 cc of postpartum bleeding and a firm uterus after vaginal delivery, genital tract laceration is the most common cause, as uterine atony—which accounts for 70-75% of all postpartum hemorrhage cases—is effectively ruled out by the presence of a firm, well-contracted uterus. 1, 2

Clinical Reasoning

The key to this question lies in the physical examination finding of a firm uterus, which fundamentally changes the differential diagnosis:

Why Not Uterine Atony (Option A)?

• Uterine atony is indeed the most common cause of postpartum hemorrhage overall, accounting for 70.6% of all PPH cases and up to 80% in some series 1, 3, 2
• However, uterine atony presents with a soft, boggy uterus that fails to contract properly 1
• The clinical scenario explicitly states the uterus is firm, which by definition excludes atony as the diagnosis 1
• This is a critical clinical distinction that must guide your diagnostic approach

Why Genital Tract Laceration (Option C)?

• When postpartum hemorrhage occurs with a firm, well-contracted uterus, genital tract trauma becomes the leading cause 4
• Genital tract lacerations account for approximately 16.9% of all postpartum hemorrhage cases 2
• The ACR Appropriateness Criteria specifically identifies vaginal lacerations as causes of bleeding that can be elucidated by history and physical examination 4
• Lacerations of the cervix, vagina, or perineum can produce significant bleeding even when uterine tone is adequate 3, 5

Why Not the Other Options?

Coagulopathy (Option B):

• Accounts for only 2.7% of postpartum hemorrhage cases 2
• Typically develops following cardiovascular collapse from massive hemorrhage, not as a primary cause 1
• Would present with bleeding from multiple sites, not isolated vaginal bleeding with stable vitals 1

Retained Products of Conception (Option D):

• Accounts for approximately 16.4% of PPH cases 2
• The scenario states placental delivery was completed, making this less likely
• Would typically present with a soft, subinvoluted uterus, not a firm one

Clinical Approach Algorithm

When evaluating postpartum hemorrhage with 1000 cc blood loss:

1. First, assess uterine tone 1, 5

   • If soft/boggy → Uterine atony (most common overall)
   • If firm → Proceed to step 2

2. With firm uterus, thoroughly inspect the genital tract 1, 5

   • Examine cervix for lacerations
   • Inspect vaginal walls systematically
   • Assess perineum and any episiotomy sites
   • Look for paravaginal hematomas 6

3. Verify complete placental delivery 5

   • Inspect placenta for missing cotyledons
   • Consider ultrasound if concern for retained tissue

4. Assess for coagulopathy if bleeding persists 1, 5

   • Check fibrinogen, platelets, PT/PTT
   • Look for bleeding from IV sites or other locations

Common Pitfalls to Avoid

• Do not assume uterine atony is always the cause simply because it is statistically most common—the physical examination finding of uterine firmness excludes this diagnosis 1
• Inadequate visualization of the cervix and upper vagina is a frequent cause of missed lacerations; proper retraction and lighting are essential 1, 5
• Failing to recognize that multiple causes can coexist in 7.8% of cases, though this scenario presents with a single clear finding 2