What are the causes of Disseminated Intravascular Coagulation (DIC) in the first trimester of pregnancy?

Causes of DIC in the First Trimester of Pregnancy

In the first trimester, DIC is exceedingly rare but can occur primarily with septic abortion, intrauterine infection, amniotic fluid embolism during pregnancy termination or amniocentesis, and retained products of conception following miscarriage. 1, 2, 3

Primary First-Trimester Causes

Septic Abortion and Intrauterine Infection

• Septic abortion is the most common cause of DIC in the first trimester, occurring when pregnancy termination (spontaneous or induced) becomes complicated by bacterial infection 2, 3
• Intrauterine infection releases endotoxins and tissue thromboplastin into maternal circulation, triggering systemic coagulation activation 4, 3
• Maternal sepsis can progress to death within 18 hours of symptom onset, making this a true obstetric emergency 5
• Look for maternal tachycardia, purulent cervical discharge, uterine tenderness, and fever—though never delay treatment waiting for fever if other infection signs are present 5

Amniotic Fluid Embolism

• Amniotic fluid embolism can occur during first-trimester pregnancy termination or amniocentesis, though this is extremely rare 1
• The clinical presentation is dramatic: anxiety, mental status changes, agitation, sensation of doom, followed by rapid progression to cardiac arrest 1
• Coagulopathy may have immediate or delayed onset following cardiovascular collapse 1
• The coagulopathy may be the only finding in very rare cases without cardiorespiratory compromise 1

Retained Dead Fetus/Products of Conception

• Coagulopathy after intrauterine fetal death typically develops in the second week following fetal demise, with approximately 3% of women developing coagulation abnormalities initially and 10% developing hypofibrinogenemia within 4 weeks 5
• Active evacuation is always indicated for confirmed intrauterine fetal demise rather than expectant management, specifically because infection and coagulopathy risks increase with time 5
• The second week after demise is the highest-risk period for both coagulopathy and sepsis 5

Less Common First-Trimester Causes

Acute Fatty Liver of Pregnancy

• While typically a third-trimester complication, acute fatty liver can rarely present in late first trimester and is associated with DIC 1, 3
• This represents a systemic disorder with both maternal and fetal manifestations requiring prompt recognition 3

Severe Pre-eclampsia/HELLP Syndrome

• Though uncommon in the first trimester, severe pre-eclampsia can rarely occur and lead to DIC 1, 2
• Women with elevated first-trimester CRP (>4.5 mg/dL) require more frequent blood pressure monitoring throughout pregnancy 6

Critical Diagnostic Approach

Laboratory Confirmation

• Check platelet count and coagulation studies immediately before any procedure in suspected cases 5
• Diagnosis requires demonstration of reduced fibrinogen and platelets, prolonged thrombin/prothrombin/partial thromboplastin times, and presence of fibrin/fibrinogen degradation products 4
• Serial assessment is necessary as coagulation parameters can deteriorate rapidly—never rely on previous values 5

Pregnancy-Specific Considerations

• The pregnancy-specific DIC score includes three components: fibrinogen concentrations, PT difference (patient's plasma vs. laboratory control), and platelet count 7
• At a cutoff of ≥26 points, this score has 88% sensitivity and 96% specificity 7
• Normal pregnancy is a procoagulant state with increased fibrinogen, factor VIII, and von Willebrand factor, making standard DIC criteria less applicable 1

Management Priorities

Immediate Actions

• Prompt removal of the source of procoagulant material is the linchpin to treatment—this means evacuation of uterine contents in first-trimester cases 2, 4
• Activate massive transfusion protocols where available 1
• Replace depleted clotting factors with appropriate blood product support 2, 4
• Consider heparin anticoagulation in select cases, though this remains controversial 4

Common Pitfall

• Do not delay evacuation waiting for coagulation parameters to normalize—the underlying cause must be removed first, with blood product support provided simultaneously 2, 4, 3