Thrombocytopenia
at the bedside
- assess: active bleeding, hemodynamic instability, sepsis, new thrombosis
is it real?
- exclude pseudothrombocytopenia: check blood film for clumping
- clumping present → repeat CBC in citrate tube
- count still low → manual platelet count
escalate now if
- platelets <10
- active bleeding
- neurological symptoms
- rapid platelet fall (>50%)
- new thrombosis
focused check
HPI
- infection: fever, recent admission, known infection
- bleeding: epistaxis, gum bleeding, hematuria, GI bleeding
- thrombosis: limb swelling, chest pain, dyspnea, stroke symptoms
- meds: heparin, linezolid, piperacillin-tazobactam, TMP-SMX, valproate, chemotherapy
- background: liver disease, autoimmune, malignancy, previous thrombocytopenia
examination
- petechiae · purpura · ecchymosis
- mucosal bleeding
- hepatosplenomegaly
- signs of thrombosis
how to think
- platelets falling + sepsis → sepsis-associated thrombocytopenia
- falling + high INR + low fibrinogen → DIC
- falling 5–10 days after heparin → HIT
- thrombocytopenia + hemolysis → TTP / TMA
- isolated thrombocytopenia → ITP or drug-induced
- thrombocytopenia + splenomegaly → liver disease or hypersplenism
send now
- repeat CBC · blood film
- PT / APTT / INR · fibrinogen · D-dimer
- hemolysis: LDH, bilirubin, haptoglobin, reticulocytes
- LFT · blood cultures if infection suspected
treat
active bleeding
- IV access, group & screen
- correct coagulopathy
- transfuse platelets if indicated
- treat underlying cause
suspected HIT
- stop all heparin products
- calculate 4Ts score
- HIT antibody testing
- switch to a non-heparin anticoagulant: argatroban (hepatic dose adjustment), bivalirudin (preferred if critically ill or procedure planned, short t½), or fondaparinux (avoid if CrCl <30)
suspected DIC
- treat underlying cause
- monitor PT / APTT, fibrinogen, platelets
- blood-product support if bleeding or procedure planned
suspected TTP
- urgent hematology referral
- plasma exchange, do not delay
- avoid platelet transfusion unless life-threatening bleeding
calculator 4Ts score (HIT) · MDCalc ↗︎
platelet transfusion: prophylactic
- platelets <10 → transfuse regardless of bleeding
- platelets <20 → consider if febrile, septic, or added bleeding risk
before procedures
- ≥20 → central venous catheter
- ≥50 → LP, most procedures, surgery
- ≥100 → neurosurgery or ophthalmic surgery
active bleeding: transfusion target
- platelets <50 → transfuse
- intracranial / life-threatening bleeding → aim >100
caution
- avoid platelet transfusion in HIT unless major bleeding
- avoid platelet transfusion in TTP unless major bleeding or urgent procedure
recheck
- one adult platelet dose ≈ +20 to 40 ×10⁹/L
- recheck if result will change management
before leaving
- document: platelet value + trend, suspected cause, treatment + response
- pending: repeat CBC, HIT testing, hemolysis screen
- hand over: last count + trend, next recheck, escalation trigger
MOC pearl
rapid platelet drop? not real → sepsis → DIC → HIT → TTP before rarer causes.
evidence
| source | type |
|---|---|
| 4Ts score for HIT | common practice / validated tool |
| Platelet transfusion thresholds (procedural / bleeding) | common practice |
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
free the on-call checklist covers the whole shift on one printable page.
More clinical resources in the MOC+ Library →
reviewed Jun 2026updated Sep 2026file lab/cbc-platelet-count-drop