Vitamin K deficiency bleeding

Overview

Vitamin K deficiency bleeding (VKDB), traditionally called haemorrhagic disease of the newborn, is a temporary clotting defect caused by a lack of vitamin K, which leads to spontaneous bleeding in an otherwise healthy baby. It is almost entirely preventable with a single dose of vitamin K at birth, so it is seen mainly in babies born at home or otherwise missed, and in infants with malabsorption.

Without prophylaxis it affects roughly 0.25-1.7% of newborns (Akbar; Nelson quotes 1-2% before routine vitamin K).

Vitamin K in coagulation

• The liver makes factors II (prothrombin), VII, IX and X as inactive precursors.
• Vitamin K is the cofactor for gamma-carboxylation of glutamic acid residues on these proteins. The carboxylated residues bind calcium, which the factors need to work on phospholipid surfaces.
• Without vitamin K, the precursors are released but cannot act. They are called PIVKA (proteins induced by vitamin K absence) and are a useful diagnostic marker.
• Proteins C and S (natural anticoagulants) are also vitamin K-dependent, as is the bone protein osteocalcin.
• Vitamin K comes from the diet (green vegetables) and from gut bacteria.

Why newborns are at risk

• Little vitamin K crosses the placenta, so stores at birth are low.
• The newborn liver is immature.
• The gut is sterile at birth, so bacteria do not yet make vitamin K.
• Breast milk contains little vitamin K.
• Most babies have a moderate fall in factors II, VII, IX and X by 48-72 hours, recovering by about 7-10 days; those with the deepest fall bleed.

Forms of vitamin K deficiency bleeding

Clinical features

• A well-looking baby who suddenly bleeds.
• Gastrointestinal bleeding: blood-stained vomit or stools (the commonest site in the classic form).
• Oozing from the umbilical cord, circumcision wound and injection sites.
• Cephalhaematoma or scalp bleeding, bruising, nosebleeds, vaginal bleeding or haematuria.
• Intracranial haemorrhage: seizures, drowsiness, shock; the fatal or disabling complication, especially in late VKDB.
• Pallor and shock if the loss is large.

Diagnostic evaluation

History

• Place of birth; was vitamin K given?
• Breastfed or formula fed.
• Maternal medicines (anticonvulsants, anti-tuberculous drugs, warfarin).
• Jaundice, pale stools and dark urine (cholestasis); diarrhoea; antibiotic use.

Laboratory findings

• Normal newborns already have a slightly longer PT and APTT than older children, so compare with neonatal reference ranges.
• In cholestasis, check conjugated bilirubin and liver function.

Differential diagnosis

Management

Treatment of a bleeding baby

• Give vitamin K immediately; do not wait for test results.
• Give it intravenously (slowly) or subcutaneously; avoid intramuscular injections in a bleeding infant. Nelson gives 1 mg IV; Akbar allows a somewhat higher range. Bleeding and the PT improve within a few hours.
• Serious bleeding, prematurity or liver disease: also give fresh frozen plasma (about 10 mL/kg, Akbar) to replace factors at once, or blood if there is major loss.
• Larger or repeated vitamin K doses may be needed in liver disease or after maternal warfarin or anticonvulsant exposure.
• Treat shock; manage intracranial haemorrhage with neurosurgical and supportive care.
• Treat the cause in late disease (biliary atresia surgery, cystic fibrosis care, fat-soluble vitamin supplements).

Prevention (vitamin K supplementation)

• Every newborn should receive vitamin K at birth: 1 mg intramuscularly is the method of choice.
• Oral vitamin K is less reliable; if used, it must be repeated (Akbar: at birth, at discharge and at 3-4 weeks), because one oral dose does not prevent the late form.
• Babies born at home are the group most likely to miss the dose; every contact (vaccination visit, first clinic) is a chance to check.
• Infants with cholestasis or malabsorption need ongoing vitamin K supplements.
• Mothers taking anticonvulsants or anti-tuberculous drugs should be identified antenatally so the baby is protected at birth.
• National newborn care guidance on vitamin K may be updated; check the current national guideline.

Vitamin K deficiency in older children

• Fat malabsorption: cystic fibrosis, coeliac disease, obstructive jaundice, pancreatic insufficiency.
• Long courses of broad-spectrum antibiotics (kill gut bacteria).
• Accidental warfarin or rat poison ingestion.
• Treat with vitamin K and the underlying cause.

Prognosis

Excellent when treated early and there is no intracranial bleed. Intracranial haemorrhage, especially in late VKDB, carries a high risk of death or long-term neurological disability.

Quick revision

• Vitamin K carboxylates factors II, VII, IX, X and proteins C, S.
• Newborn risk: low stores, immature liver, sterile gut, breast milk poor in vitamin K.
• Early (under 24 h): maternal anticonvulsants, warfarin, rifampicin, isoniazid.
• Classic (days 2-7): breastfed, no vitamin K; gut, cord, circumcision bleeding.
• Late (1-6 months): cholestasis, malabsorption; intracranial bleeding.
• PT prolonged (most sensitive), APTT prolonged; platelets, fibrinogen, BT normal.
• Prevention: 1 mg IM at birth to all; oral needs repeated doses.
• Treatment: IV vitamin K at once; FFP for serious bleeding.
• Apt test separates swallowed maternal blood.

Written by The House Job from standard references (Basis of Paediatrics by Pervez Akbar; Nelson Essentials of Paediatrics).

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