Blood disorders Flashcards
How does the haemostatic mechanism in newborns differ from that of older children?
In newborns, there is reduced activity of clotting factors, diminished platelet function, and suboptimal defense against clot formation.
causes of bleeding
- Deficiency of clotting factors / coagulopathy
- Platelet problems
- Vascular anomalies such as arterio-venous malformations and haemangiomas.
- Other
Deficiency of clotting factors / coagulopathy
- Vitamin K deficiency / lack of administration (note: Vitamin K dependent
factors II, VII, IX and X). - Maternal drugs (phenytoin, phenobarbitone, salicylates and warfarin).
- Disseminated intravascular coagulopathy / DIC secondary to infection, shock,
hypoxia, necrotising enterocolitis (NEC), renal vein thrombosis or use of
venous catheters. - Inherited abnormalities (haemophilia, Turner syndrome, von Willebrand
disease).
Platelet problems
- Decreased production.
- Increased destruction.
- Dysfunction.
Other causes of bleeding
- liver dysfunction.
- trauma.
What aspects should be covered in the history when evaluating a bleeding newborn infant?
The history should include inquiries about familial bleeding disorders, maternal illness (such as infection and HELLP syndrome), and maternal drug use.
What should be assessed during the physical examination of a bleeding newborn infant?
During the physical examination, it is important to assess whether the infant appears sick or well, check for signs of shock, anemia, or dysmorphism, examine bleeding sites, and determine the presence of hepatosplenomegaly and jaundice.
What are the essential investigations needed for diagnosing a bleeding disorder in a newborn infant?
The essential investigations include a full blood count, blood smear examination, and coagulation profile (including INR, PT, and PTT). These tests help in evaluating various aspects of blood composition and coagulation function.
If the patient is sick what is the differential diagnosis
-DIC
-Platelet consumption (infection,
NEC, renal vein thrombosis)
-Altered vascular integrity
(extreme prematurity, hypoxia,
acidosis)
-Liver disease, heparinisation
If the patient is well what is the differential diagnosis
Immune thrombocytopaenia,
occult infection or thrombosis,
abnormal bone marrow function
-Vitamin K deficient bleeding of
the newborn
-Haemophilia
-Bleeding due to trauma,
anatomical abnormalities,
dysfunctional platelet disorders
DIC laboratory investigations
Platelets: low
INR (PT): high
aPTT: high
Platelet consumption laboratory investigations
Platelets: low
INR (PT): normal
aPTT: normal
Altered vascular integrity laboratory investigations
Platelets: normal
INR (PT): normal
aPTT: normal
Liver disease, heparinisation Laboratory investigations
Platelets: normal
INR (PT): high
aPTT: high
Immune thrombocytopaenia,
occult infection or thrombosis,
abnormal bone marrow function laboratory investigations
Platelets: low
INR (PT): normal
aPTT: normal
Vitamin K deficient bleeding of
the newborn laboratory investigations
Platelets: normal
INR (PT): high
aPTT: high
Haemophilia laboratory investigations
Platelets: normal
INR (PT): normal
aPTT: high
Bleeding due to trauma,
anatomical abnormalities,
dysfunctional platelet disorders laboratory investigations
Platelets: normal
INR (PT): normal
aPTT: normal
How is thrombocytopenia defined?
Thrombocytopenia is defined as a platelet count of less than 150 X 10^9/L. It is considered mild if 100 to 150 X 10^9/L, moderate if 50 to 99 X 10^9/L, or severe if less than 50 X 10^9/L.
causes of thrombocytopenia , early onset in a well infant
- Fetal hypoxia.
- Immune-mediated: autoimmune (mother has thrombocytopaenia / ITP or SLE) or
alloimmune (mother has normal platelet count and there is passive transfer of
maternal alloantibodies directed against paternally derived platelet antigens).
What are the classifications of thrombocytopenia based on timing and the infant’s condition?
Thrombocytopenia is classified as early (within 72 hours of life) or late (after 72 hours of life), and its etiology can be determined by assessing the infant as ill or well.
causes of thrombocytopenia , early onset in a sick or dysmorphic infant
- DIC.
- Congenital infection.
- Genetic disorders or syndromes including (Trisomy 21, thrombocytopaeniaabsent-radii (TAR) syndrome, Wiskott-Aldrich syndrome and Fanconi anaemia)
- Tumour (Kasabach-Meritt syndrome).
- Thrombosis (renal vein).
Causes of thrombocytopenia , late onset
The most common cause is bacterial or fungal sepsis and NEC.
* Thromboses secondary to umbilical catheters.
* Drug-induced.
* Less common causes include inborn errors of metabolism and Fanconi anaemia.
What are the guidelines for platelet transfusion in newborn infants with thrombocytopenia?: If platelet count is less than 30 X 10^9/L
transfuse all newborn infants.
What are the guidelines for platelet transfusion in newborn infants with thrombocytopenia?: If platelet count is 30-49 X 10^9/L
transfuse if extreme low birth weight, less than one week of age, hypotensive requiring inotropic support, or with bleeding tendency (major or minor).
What are the guidelines for platelet transfusion in newborn infants with thrombocytopenia?: If platelet count is 50-99 X 10^9/L,
transfuse only if there is bleeding.
What are the guidelines for platelet transfusion in newborn infants with thrombocytopenia?: If platelet count is more than 99 X 10^9/L,
do not transfuse.
Why are newborn infants, especially preterm newborns, vulnerable to disseminated intravascular coagulopathy (DIC)?
Newborn infants, particularly preterm newborns, are vulnerable to DIC because anticoagulants such as antithrombin and protein C are normally low at this stage.
Main causes of DIC
- Sepsis.
- Perinatal hypoxia.
- Respiratory distress syndrome.
- Necrotising enterocolitis.
Clinical manifestations of DIC
- Ill looking.
- Petechiae.
- Gastrointestinal haemorrhage
- Oozing from puncture sites.
- Signs of infection
investigations of DIC
- Decreased platelet count.
- Increased INR / PTT.
- Fragmented red blood cells on blood smear.
- Decreased fibrinogen.
- Increased D-dimers.
What is the focus of management for disseminated intravascular coagulopathy (DIC)?
The focus of management for DIC is treating the underlying cause and ensuring that vitamin K has been given. Platelets, fresh frozen plasma, and cryoprecipitate should be considered as part of the treatment.
