A 3-day-old boy is brought to the emergency department due to bruising. The patient was born at 39 weeks gestation via vaginal delivery at home, and this is his first medical evaluation. He is breastfed exclusively. Vital signs are within normal limits. Several ecchymoses are visible on the extremities. Physical examination is otherwise unremarkable. Laboratory results are as follows: Which of the following is the most likely cause of this patient's condition?

Question

A 3-day-old boy is brought to the emergency department due to bruising.  The patient was born at 39 weeks gestation via vaginal delivery at home, and this is his first medical evaluation.  He is breastfed exclusively.  Vital signs are within normal limits.  Several ecchymoses are visible on the extremities.  Physical examination is otherwise unremarkable.  Laboratory results are as follows:  Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec25c8_d6b0_55d9_bc81_d947c1729ab0_MD0003_00 This neonate who has not received prior medical care has bruising and prolonged PT and PTT, findings concerning for vitamin K-deficient bleeding (VKDB). Vitamin K is essential for enzymatic carboxylation and activation of coagulation factors II (prothrombin), VII, IX, and X. Newborns are vitamin K deficient due to poor placental transfer, lack of intestinal flora to synthesize vitamin K, and immature liver function (ie, poor vitamin K utilization). Therefore, intramuscular vitamin K is given at birth to prevent spontaneous bleeding. Neonates who do not receive this injection, such as this patient, are at highest risk of VKDB, particularly if exclusively breastfed because breast milk contains insufficient vitamin K. Classic VKDB presents on day 2-7 of life with easy bruising, mucosal bleeding (eg, epistaxis), gastrointestinal hemorrhage, and/or intracranial hemorrhage. Late-onset disease can occur up to age 6 months. Because of reduced coagulation factor carboxylation, laboratory evaluation shows prolonged PT and, in severe deficiency, prolonged PTT. The diagnosis is confirmed by the reversal of laboratory abnormalities with vitamin K administration. (Choice A) Afibrinogenemia is a rare, autosomal recessive bleeding disorder characterized by absent fibrinogen production. Severe bleeding classically develops at the site of the umbilical cord after birth. Like PT and PTT, thrombin time is prolonged. (Choice B) Disseminated intravascular coagulation typically presents with bleeding (eg, bruising, intravenous site oozing) due to consumption of platelets and clotting factors. Laboratory findings include prolonged PT and PTT and thrombocytopenia. This patient's platelet count is normal. (Choices C and D) Severe von Willebrand disease (characterized by impaired synthesis of von Willebrand factor) and factor VIII deficiency (hemophilia A) can present with easy bruising and bleeding in the neonatal period. Both conditions have a prolonged PTT but normal PT. (Choice E) Impaired platelet function can be caused by medications (eg, aspirin), metabolic conditions (eg, uremia, liver disease), or congenital disorders (eg, Glanzmann thrombasthenia). Patients have mucocutaneous bleeding and petechiae; PT, PTT, and platelet count are normal. Educational objective: Vitamin K-deficient bleeding classically presents with bleeding in newborns (day 2-7 of life) who did not receive intramuscular vitamin K, which is essential in the enzymatic carboxylation and activation of coagulation factors II (prothrombin), VII, IX, and X. Symptoms include easy bruising, mucosal bleeding, gastrointestinal bleeding, and/or intracranial hemorrhage; laboratory evaluation reveals prolonged PT with or without prolonged PTT. References: Prevention of vitamin K deficiency bleeding in newborn infants: a position paper by the ESPGHAN committee on nutrition. (http://www.ncbi.nlm.nih.gov/pubmed/27050049) Vitamin K prophylaxis for prevention of vitamin K deficiency bleeding: a systemic review. (http://www.ncbi.nlm.nih.gov/pubmed/27109090)

A 3-Day-Old Boy Is Brought to the Emergency Department Due