Postpartum Thrombocytopenia

Postpartum thrombocytopenia is a platelet count below 150 x 10^9/L after birth, mild at 100 to 149, moderate at 50 to 99 and severe below 50 x 10^9/L.

It results from consumption (preeclampsia, HELLP syndrome, disseminated intravascular coagulation, sepsis), immune destruction (immune thrombocytopenia, lupus, antiphospholipid syndrome), thrombotic microangiopathy (thrombotic thrombocytopenic purpura, atypical haemolytic uraemic syndrome), drug effect (heparin), infection (HIV, malaria) and dilution after massive transfusion. It matters because it causes bleeding and wound haematomas, and some causes are fatal if missed.

• Risk factors: preeclampsia, postpartum haemorrhage, sepsis, known immune thrombocytopenia, HIV, malaria, heparin exposure, massive transfusion.
• In HELLP syndrome the platelet count usually reaches its lowest point within the first 1 to 2 days after birth and then recovers.
• Heparin induced thrombocytopenia appears 5 to 10 days after starting heparin.

Women may have no symptoms, or have bruising, petechiae, gum and nose bleeding, heavy lochia, wound oozing and, in severe cases, intracranial or gastrointestinal bleeding. Features of the cause may be present: hypertension, right upper quadrant pain, fever, jaundice, confusion or kidney failure.

• Petechiae on the legs and mucosa; ecchymoses; bleeding from injection sites.
• Fever, neurological signs, kidney failure and haemolysis suggest thrombotic thrombocytopenic purpura.
• Differential diagnosis: HELLP syndrome, disseminated intravascular coagulation, immune thrombocytopenia, thrombotic thrombocytopenic purpura, atypical haemolytic uraemic syndrome, heparin-induced thrombocytopenia, sepsis, HIV, malaria, lupus, antiphospholipid syndrome, hypersplenism, vitamin B12 or folate deficiency.
• Complications: postpartum haemorrhage, wound or pelvic haematoma, intracranial haemorrhage, kidney failure, stroke, thrombosis in heparin-induced thrombocytopenia, maternal death.

The approach is to confirm the count, find the mechanism and exclude life-threatening causes.

• Repeat full blood count in a citrate tube to exclude clumping; blood film for fragmented red cells (schistocytes), malaria parasites and platelet size.
• Blood pressure, urine protein, liver enzymes, lactate dehydrogenase, bilirubin, creatinine, haptoglobin, reticulocyte count, fibrinogen, prothrombin time, activated partial thromboplastin time, D-dimer.
• HIV test, malaria rapid test, blood culture, antinuclear antibody and antiphospholipid antibodies, vitamin B12 and folate.
• Heparin history with timing; ADAMTS13 activity where available (below 10 percent confirms thrombotic thrombocytopenic purpura).

The principle is to treat the cause, protect against bleeding, and give platelets only for bleeding or a very low count.

• Supportive: admit if platelets are below 50 x 10^9/L or there is bleeding; avoid IM injections, aspirin and NSAIDs; monitor blood pressure, urine output and bleeding; check wound and lochia; stop heparin if the count has fallen by 50 percent after day 5.
• Pharmacological: preeclampsia or HELLP syndrome: magnesium sulphate 4 g IV over 20 minutes then 1 g/hour IV for 24 hours, labetalol 20 mg IV then 40 mg after 10 minutes and 80 mg every 10 minutes (maximum total 220 mg) or nifedipine 10 mg oral repeated after 30 minutes for blood pressure at or above 160/110 mmHg, dexamethasone 10 mg IV 12-hourly for 2 doses; immune thrombocytopenia with platelets below 30 x 10^9/L or bleeding: prednisolone 1 mg/kg oral once daily (maximum 80 mg) for 2 to 4 weeks then taper over 4 weeks, with IV immunoglobulin 1 g/kg IV once (repeat on the next day if needed) for severe bleeding; sepsis: ceftriaxone 2 g IV once daily plus metronidazole 500 mg IV 8-hourly; thrombotic thrombocytopenic purpura: prednisolone 1 mg/kg oral daily with plasma exchange in a specialist unit; heparin-induced thrombocytopenia: stop all heparin and give fondaparinux 7.5 mg subcutaneous once daily (weight 50 to 100 kg) under specialist advice; tranexamic acid 1 g oral 8-hourly for 3 days for heavy lochia.
• Procedures: platelet transfusion (one adult dose) for counts below 10 x 10^9/L, below 20 x 10^9/L with fever or mucosal bleeding, below 50 x 10^9/L with active bleeding or before surgery; plasma exchange for thrombotic thrombocytopenic purpura; drainage of an expanding haematoma.
• Special groups: women with lupus or antiphospholipid syndrome need anticoagulation decisions made with a haematologist once the count is above 50 x 10^9/L; women with HIV have the count rechecked 4 weeks after starting antiretroviral treatment.
• Red flags: platelets below 20 x 10^9/L, severe headache, confusion, haematuria, melaena, fever with kidney failure, expanding haematoma, falling haemoglobin.
• Follow-up: platelet count every 12 to 24 hours until rising on two readings, then weekly until above 100 x 10^9/L; review at 6 weeks; persistent counts below 100 x 10^9/L after 12 weeks need a haematology review; counselling on future pregnancy, with aspirin 150 mg oral at night from 12 weeks in any later pregnancy if preeclampsia was the cause.