What is the approach to investigating prolonged postpartum bleeding?

Investigation of Prolonged Postpartum Bleeding

Accurate measurement of blood loss and early detection of postpartum hemorrhage (PPH) are essential first steps in the investigation of prolonged postpartum bleeding, followed by systematic evaluation of the four main causes: uterine atony, trauma, retained tissue, and coagulopathy.

Initial Assessment

Blood Loss Measurement

• Every effort should be made to measure blood loss volumes cumulatively using volumetric and gravimetric techniques rather than estimation 1
• Abnormal bleeding is defined as >500 ml after vaginal delivery and >1000 ml after cesarean delivery 1, 2
• Early recognition of bleeding incorporated into a clear escalation plan reduces the use of blood components 1
• Use of a calibrated blood-collection drape for objective measurement is recommended for accurate assessment 3

Laboratory Assessment

• Immediate blood tests should include:
  • Full blood count (hemoglobin)
  • Coagulation studies (PT, APTT)
  • Group and screen
  • Venous blood gas for rapid hemoglobin measurement and lactate (>2 mmol/L indicates shock) 1
  • Fibrinogen level (critical parameter)

Systematic Evaluation of Causes (Four T's)

1. Tone (Uterine Atony - 70-80% of cases)

• Clinical examination to assess uterine tone and response to massage
• Ultrasound (transabdominal and transvaginal with Doppler) is the first-line imaging modality 1
• CT may detect hematoma within an enlarged uterine cavity suggesting atony 1

2. Trauma

• Thorough visual inspection and examination of the genital tract
• Digital rectal examination to detect obstetric anal sphincter injuries 2
• CT can identify:
  • Bladder flap, subfascial, or perivaginal space hematomas
  • Uterine dehiscence (>5 cm bladder flap hematoma should raise suspicion) 1
  • Uterine rupture (presence of gas in myometrial defect with hemoperitoneum) 1

3. Tissue (Retained Products)

• Ultrasound to identify retained placental tissue
• MRI may be useful but has limited ability to distinguish retained products from blood clots without contrast 1

4. Thrombin (Coagulopathy)

• Monitor fibrinogen levels - hypofibrinogenemia (<2 g/L) is the most common factor deficiency in PPH and most predictive of severe PPH 1, 2
• Point-of-care testing is preferred for monitoring coagulation status during obstetric hemorrhage 1, 2
• Viscoelastic coagulation testing (thromboelastography or rotational thromboelastometry) can provide rapid assessment of hypofibrinogenemia 1

Advanced Imaging for Persistent Bleeding

Contrast-Enhanced CT

• Indicated when conventional medical treatment has been unsuccessful 1
• Primary role is to:
  • Determine if active ongoing hemorrhage is present
  • Localize the bleeding
  • Identify the source 1

CT Angiography (CTA)

• Indicated for persistent hemorrhage after empiric embolization 1
• Excellent accuracy (97%) for detection of active extravasation 1
• Can identify feeding arteries of arteriovenous malformations for treatment planning 1
• Evaluates abdominopelvic vasculature including ovarian and inferior epigastric arteries 1

MRI

• Limited role in acute PPH due to time constraints
• Better than CT and ultrasound for detecting myometrial defects with intact serosal layer in uterine dehiscence 1
• Useful for distinguishing uterine dehiscence versus rupture when findings are confusing on ultrasound or CT 1

Management Considerations During Investigation

Blood Component Therapy

• If coagulation tests are not known, withhold FFP until four units of RBC have been given 1
• Target fibrinogen levels above 2 g/L with cryoprecipitate or fibrinogen concentrate if ongoing bleeding 1, 2
• If no coagulation results are available and bleeding is ongoing after four units of RBC, give four units of FFP and maintain 1:1 ratio of RBC:FFP until results are known 1

Pharmacological Management

• Tranexamic acid (1g IV over 10 minutes) should be administered within 3 hours of birth for all cases of PPH 2
• A second dose may be given if bleeding persists after 30 minutes 2, 4

Common Pitfalls and Caveats

• Estimating blood loss at delivery is notoriously inaccurate - use objective measurement techniques 1
• Hypofibrinogenemia can occur unexpectedly in association with any obstetric etiology - monitor levels closely 1
• CT can be falsely positive due to dilated tortuous hypertrophic uterine arteries mimicking extravasation 1
• In the immediate postpartum period, hypodense edema at cesarean incision site should not be misinterpreted as dehiscence 1
• Delayed diagnosis of PPH significantly increases risk of coagulopathy - early recognition is critical 1
• Patients should be kept warm as many clotting factors function poorly if body temperature is below 36°C 1