PSYCH 1XX3 Lecture Notes - Lecture 8: Vitamin K Deficiency, Fanconi Anemia, Necrotizing Enterocolitis
19 May 2018
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1. Acquired coagulation/platelet disorders
Acquired haemostatic disorders in the newborn:
• haemorrhagic disease of the newborn (HDN)
• DIC
• liver disease
• Neonatal thrombocytopenia
HDN is due to vitamin K deficiency
• poor placental transfer of vitamin K
• low fetal vitamin K stores
• low vit K content of breast milk
• absent bacterial vit K synthesis in neonatal gut
• immaturity of fetal liver
HDN usually presents within a week
• Haemorrhages in the brain, GIT, post circumcision and excessive bruising/purpura
• Diagnose with prolonged PT
• Manage with prophylactic and/or episodic Vitamin K or FFP if bleeding is severe
HDN classification
Time of presentation
causes
early
within 1 day
maternal drugs
classic
within 1 week
physiological [see above]
late
2-12weeks
liver disease, breast feeding
The principle of treating neonatal DIC is the same as always – treat the cause
• Infection
• Necrotizing enterocolitis
• Asphyxia
• Meconium aspiration
• Placental abruption
• Retained dead second twin
• Diagnose with prolonged PT, APTT, TT, low Plt + high FDPs.
• Treat underlying cause and may need to give platelets/FFP if bleeding is severs
Neonatal thrombocytopenia is the commonest abnormality in newborn babies
• Reduced platelet production
o transient - maternal HTN/ DM and fetal IU growth restriction
o rare – BM failure, fanconi anaemia
• Increased platelet clearance
o immune mediated - maternal ITP, neonatal alloimmune thrombocytopenia
o non-immune mediated – DIC, infections (CMV, rubella)
The mechanism of NAITP involves HPa1a antibodies
• Mother is HPA1a negative
• Fetus inherits HPA1a from father
• Mother produces antibodies against fetus which can cross the placenta
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Document Summary
Liver disease immaturity of fetal liver: acquired coagulation/platelet disorders. Acquired haemostatic disorders in the newborn: haemorrhagic disease of the newborn (hdn, dic, neonatal thrombocytopenia. Hdn is due to vitamin k deficiency: poor placental transfer of vitamin k, absent bacterial vit k synthesis in neonatal gut. Time of presentation within 1 day within 1 week. 2-12weeks causes maternal drugs physiological [see above] liver disease, breast feeding. Neonatal thrombocytopenia is the commonest abnormality in newborn babies: reduced platelet production transient - maternal htn/ dm and fetal iu growth restriction rare bm failure, fanconi anaemia. Increased platelet clearance immune mediated - maternal itp, neonatal alloimmune thrombocytopenia: non-immune mediated dic, infections (cmv, rubella) Inherited haemostatic disorders in the newborn: haemophilia a/b, t3 vwd, rare coagulation factor deficiencies. Haemophilia is the commonest inherited coagulation disorder and is frequently diagnosed post circumcision: affected boys may present with excessive bleeding after circumcision, cephalohaemoatomas,
