Hemorrhagic disease of newborn A. Prevent by giving IM Vitamin K after birth B. Classic disease occurs within 24hrs C. Risk isincreased with maternal phenobarbitone therapy D. Causesincrease prothrombin time E. Causes delayed separation of umbilical cord
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Hemorrhagic Disease of the Newborn (VKDB) - Answer Analysis
This is a question about Vitamin K Deficiency Bleeding (VKDB) of the newborn, formerly called "Hemorrhagic Disease of the Newborn." Let's evaluate each option:
A. Prevented by giving IM Vitamin K after birth - TRUE ✓
This is the correct, universally established intervention. As stated in multiple textbooks, "Administration of vitamin K intramuscularly at birth prevents hemorrhagic disease of the newborn." The American Academy of Pediatrics recommends IM vitamin K to all newborns. The IM route is preferred over oral because it provides reliable, sustained levels.
- Tietz Textbook of Laboratory Medicine, 7th Edition: "Bleeding from neonatal vitamin K deficiency is avoided by treating neonates with vitamin K."
- Bradley and Daroff's Neurology: "Administration of vitamin K intramuscularly at birth prevents hemorrhagic disease of the newborn."
B. Classic disease occurs within 24 hours - FALSE ✗
The classic form occurs in the first week of life (days 1-7), NOT within 24 hours. The form that occurs within 24 hours is actually the early form (which is rare and typically due to maternal drug use such as anticoagulants or anticonvulsants).
The three forms are:
| Form | Timing |
|---|---|
| Early | Within 24 hours (due to maternal drugs - warfarin, anticonvulsants) |
| Classic | Days 1-7 (first week of life) |
| Late | 2-12 weeks (up to 6 months) |
- Tietz Textbook of Laboratory Medicine: "The classic hemorrhagic disease of the newborn... occurs in the first week of life."
C. Risk is increased with maternal phenobarbitone therapy - TRUE ✓
Enzyme-inducing antiepileptic drugs, including phenobarbitone (phenobarbital), cause a transient deficiency of vitamin K-dependent clotting factors in neonates.
- Harrison's Principles of Internal Medicine 22E: "Enzyme-inducing drugs such as phenytoin, carbamazepine, oxcarbazepine, topiramate, phenobarbital, and primidone cause a transient and reversible deficiency of vitamin K-dependent clotting factors in ~50% of newborn infants."
- Bradley and Daroff's Neurology: "A deficiency of vitamin K-dependent clotting factors occurs in some neonates born to women who take phenobarbital, primidone, carbamazepine, ethosuximide, or phenytoin."
Phenobarbitone induces hepatic cytochrome P450 enzymes, which accelerates the breakdown of vitamin K, reducing its availability for clotting factor carboxylation.
D. Causes increased prothrombin time - TRUE ✓
Vitamin K is required for the carboxylation (activation) of clotting factors II (prothrombin), VII, IX, and X. Factor VII has the shortest half-life, so PT/INR (which depends on the extrinsic pathway including factor VII) is the first and most sensitive test to become abnormal in vitamin K deficiency.
- Tietz Textbook of Laboratory Medicine: "Vitamin K deficiency may manifest with bleeding or may be identified incidentally with an isolated prolongation of PT or combined prolongation of PT and aPTT."
- Tintinalli's Emergency Medicine: "A prolonged prothrombin time can result in neonatal bleeding" in VKDB.
- Dermatology 5e: "Elevated prothrombin time" is listed as a feature of hemorrhagic disease of the newborn.
E. Causes delayed separation of umbilical cord - FALSE ✗
Delayed separation of the umbilical cord is not a feature of VKDB/hemorrhagic disease of the newborn. Delayed cord separation is classically associated with Leukocyte Adhesion Deficiency (LAD), a disorder of neutrophil function. In VKDB, the clinical manifestations are bleeding - from the umbilical stump (oozing/hemorrhage), GI tract, intracranial, skin, or mucous membranes - but delayed separation is a distinct entity.
Summary Table
| Option | Statement | Verdict |
|---|---|---|
| A | Prevented by IM Vitamin K at birth | TRUE ✓ |
| B | Classic disease occurs within 24 hours | FALSE ✗ (Classic = days 1-7; Early = <24 hrs) |
| C | Risk increased with maternal phenobarbitone | TRUE ✓ |
| D | Causes increased prothrombin time | TRUE ✓ |
| E | Causes delayed umbilical cord separation | FALSE ✗ (feature of LAD, not VKDB) |
Correct answers: A, C, D
The most commonly tested "trap" here is option B - the classic form is days 1-7, not within 24 hours. The early form (<24 hrs) is the rare type caused by maternal drugs (warfarin, anticonvulsants like phenobarbitone). Ironically, C is true because phenobarbitone increases the early form risk, but phenobarbitone does NOT prevent it - it actually causes it.
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