Postpartum Hemorrhage Definition and Classification

Definition and Types

• Postpartum hemorrhage (PPH) is defined as any hemorrhage associated with signs or symptoms of hypovolemia within 24 hours of delivery, regardless of the type of delivery, or quantitatively as blood loss ≥500 mL after vaginal delivery or ≥1000 mL following cesarean section, according to the American College of Radiology 1
• Primary (Early) PPH occurs within the first 24 hours after delivery and represents the most common and life-threatening form of postpartum hemorrhage, affecting 1% to 5% of all deliveries 1
• Secondary (Late/Delayed) PPH occurs from 24 hours up to 6 weeks (or 12 weeks by some definitions) postpartum and is less common than primary PPH but still clinically significant 1

Causes and Risk Factors

• Uterine atony is the most common cause of primary PPH, responsible for more than 75% of all primary PPH cases 2
• Trauma, including lacerations, uterine rupture, and hematomas, is the second most common category of primary PPH causes 2
• Retained products of conception (RPOC) with or without superimposed infection are additional causes of primary PPH 1, 2
• Coagulopathy, including DIC, amniotic fluid embolism, placental abruption, severe pre-eclampsia, or HELLP syndrome, can also contribute to primary PPH 3, 2

Complications and Management

• Coagulopathy development, including fibrinogen levels <2 g/L, can occur in 17% of cases with blood loss exceeding 2000 mL, indicating evolving coagulopathy 2
• Disseminated intravascular coagulation (DIC) can complicate the hemorrhage 2
• Surgical complications, including infection, poor wound healing, and adhesion formation, can arise from emergency procedures 4
• Uterine artery or internal iliac artery ligation complications, as well as embolization-related complications, including non-target embolization, can occur 1
• Increased risk of recurrent PPH in subsequent pregnancies (3.5-fold increased risk) is a long-term complication 5
• Thromboembolic complications from immobility and coagulopathy, particularly after cesarean section, can also occur 4
• Bronchospasm from prostaglandin F2α or ergometrine use, particularly in women with asthma, is a complication specific to treatment modalities 4
• Respiratory depression from opioid analgesia, especially problematic in women with underlying respiratory disease, can also occur 4
• Infection risk in women requiring uterine packing or balloon tamponade is another consideration 1

Critical Pitfalls to Avoid

• Do not wait for laboratory confirmation of DIC before initiating massive transfusion protocol when blood loss exceeds 1,500 mL - immediate blood product administration in fixed ratios is recommended while addressing the underlying cause, according to Praxis Medical Insights 2
• Avoid using prostaglandin F2α in women with asthma due to bronchoconstriction risk, as recommended by the European Respiratory Journal 4

Complications of Postpartum Hemorrhage

Early Complications (Within 24 Hours to 6 Weeks)

• Endometritis or abscess formation may occur, particularly with retained products of conception, according to the American College of Radiology 6
• Ovarian vein thrombosis is a potential vascular complication, as reported by the American College of Radiology 6
• Bladder flap, subfascial, or perivaginal space hematomas may require intervention, especially those larger than 5 cm, as noted by the American College of Radiology 7, 6
• Infected hematomas may require drainage, as indicated by the American College of Radiology 6

Delayed Complications (Beyond 6 Weeks)

• Vascular uterine abnormalities (VUA) or pseudoaneurysm formation may occur due to failure of placental bed vessel obliteration, according to the American College of Radiology 6
• Subinvolution of the placental bed can lead to persistent bleeding, as reported by the American College of Radiology 6
• Retained products of conception (RPOC) with or without superimposed infection may occur, as noted by the American College of Radiology 6

Post‑partum Bleeding on Day 9: Evidence‑Based Etiology and Imaging Recommendations

Etiology of Secondary Post‑partum Hemorrhage

• The American College of Radiology identifies retained products of conception (RPOC) and endometritis as the two most common causes of bleeding at 9 days postpartum; cesarean delivery predisposes to endometritis, whereas vaginal delivery is more frequently associated with RPOC. 8
• After vaginal delivery, RPOC are found in ≈ 32.8 % of secondary PPH cases compared with ≈ 10.8 % after cesarean delivery. 8
• Pelvic hematomas (e.g., bladder‑flap, subfascial, perivaginal) may become infected and present with delayed postpartum bleeding. 8
• Uterine scar dehiscence can occur after cesarean section and may be difficult to differentiate from a normal cesarean scar on imaging. 8
• Gestational trophoblastic disease (e.g., choriocarcinoma) is a rare cause; it appears as a hypervascular intra‑uterine mass and should be considered when β‑HCG is elevated. [8][9]

First‑Line Imaging for Suspected RPOC or Infection

Advanced Imaging When Ultrasound Is Inconclusive

• Contrast‑enhanced CT (in hemodynamically stable patients) can localize bleeding sources and detect vascular complications such as uterine‑artery pseudoaneurysm. [8][9]
• Multiphasic CT angiography (non‑contrast, arterial, portal‑venous phases) achieves ≈ 97 % accuracy for identifying active contrast extravasation. 8

Critical Diagnostic Pitfalls

• Relying solely on ultrasound to exclude a pseudoaneurysm is unsafe; serpiginous myometrial vessels on Doppler raise suspicion, but definitive confirmation requires CTA or angiography. [8][9]
• On multiphase CT, RPOC may mimic blood products; correlation with clinical context and, when needed, adjunctive imaging is essential. 8

All facts are derived from peer‑reviewed evidence published by the American College of Radiology.

Evaluation and Management of Late Post‑partum Hemorrhage After Cesarean Section

Definition

• Late postpartum hemorrhage (PPH) is defined as any clinically significant uterine bleeding occurring between 24 hours and 6 weeks after delivery. [American College of Radiology] 10

Common Etiologies on Day 14

• Endometritis is the leading infectious cause after cesarean delivery and typically appears on imaging as a thickened, heterogeneous endometrium containing fluid, gas, and debris. [American College of Radiology] 10
• Endometritis may be complicated by parametrial abscess formation or an infected postoperative hematoma that requires drainage. [American College of Radiology] 10
• Retained products of conception (RPOC) are difficult to separate from blood products on multiphase CT, necessitating careful interpretation. [American College of Radiology] 10
• Subinvolution of the placental bed—failure of normal obliteration of placental‑bed vessels—can produce persistent bleeding. [American College of Radiology] 10
• Uterine‑artery pseudo‑aneurysm may develop and present with delayed hemorrhage. [American College of Radiology] 10
• Large postoperative hematomas (>5 cm) in the bladder flap, sub‑fascial, or perivaginal spaces may become infected and act as a bleeding source. [American College of Radiology] 10
• A bladder‑flap hematoma larger than 5 cm should raise suspicion for uterine scar dehiscence (disruption of endometrial and myometrial layers with an intact serosa). [American College of Radiology] 10
• Edematous changes at the cesarean incision site can mimic dehiscence early postpartum; by day 14 the distinction becomes clinically relevant. [American College of Radiology] 10

First‑Line Sonographic Assessment

• Endometrial thickness greater than 8–13 mm on transvaginal ultrasound suggests RPOC, although normal early‑postpartum endometrium may be up to 2–2.5 cm thick. [American College of Radiology] 10
• The most specific sonographic sign of RPOC is a vascular, echogenic endometrial mass demonstrating intralesional flow on color Doppler. [American College of Radiology] 10
• In the early postpartum period, intra‑cavitary debris and gas are observed in roughly 20–25 % of patients and are nonspecific for pathology. [American College of Radiology] 10

Advanced Imaging When Ultrasound Is Inconclusive

• Contrast‑enhanced CT of the abdomen/pelvis can localize active bleeding sources and demonstrate contrast extravasation. [American College of Radiology] 10
• CT also identifies vascular complications such as pseudo‑aneurysms and large postoperative hematomas. [American College of Radiology] 10
• Additional CT findings include ovarian‑vein thrombosis, parametrial abscess, and infected hematoma. [American College of Radiology] 10

Multiphasic CT Angiography

• Multiphasic CTA attains approximately 97 % accuracy for detecting active contrast extravasation. [American College of Radiology] 10
• Active extravasation is visualized in 41–74 % of secondary PPH cases on CTA. [American College of Radiology] 10
• CTA enables precise localization of feeding arteries of arteriovenous malformations to guide endovascular therapy. [American College of Radiology] 10

Diagnostic Pitfalls

• CTA may produce false‑positive findings when dilated, tortuous hypertrophic uterine arteries mimic extravasation, and false‑negative results when uterine atony causes slow, intermittent bleeding. [American College of Radiology] 10
• On multiphase CT, RPOC can masquerade as blood products; correlation with clinical context and serum β‑hCG levels (elevated values suggest gestational trophoblastic disease) is essential. [American College of Radiology] 10

Management Recommendations

• For confirmed RPOC, surgical curettage is the definitive therapy. [American College of Radiology] 10
• Endometritis requires antibiotic therapy; however, antibiotics alone do not control hemorrhage and may need adjunctive surgical or mechanical intervention. [American College of Radiology] 10
• Vascular uterine lesions such as pseudo‑aneurysms are best treated with selective arterial embolization. [American College of Radiology] 10
• Infected postoperative hematomas should be drained when clinically indicated. [American College of Radiology] 10

Strength of evidence: The source does not specify a formal evidence grade; the statements reflect expert consensus and imaging‑based data reported in the cited radiology literature.