A 61-year-old woman comes to the emergency department due to fever, chills, and left flank pain that began abruptly last evening. A month ago, the patient was treated for a urinary tract infection with a short course of ciprofloxacin. She otherwise has no medical problems and currently takes no medications. She has no history of hospitalizations or surgeries.
Temperature is 39.4 C (103 F) , blood pressure is 80/40 mm Hg, pulse is 120/min, and respirations are 24/min. Pulse oximetry shows 94% on room air. Mucous membranes are dry and jugular veins are flat. Cardiopulmonary auscultation reveals clear lung fields and normal heart sounds without murmurs. The abdomen is soft and nontender. Left costovertebral angle tenderness is present. Skin examination is normal. The extremities are warm with no edema. Neurologic examination is within normal limits.
Laboratory results are as follows:
Broad-spectrum antibiotics and intravenous fluids are initiated, and the patient is admitted to the intensive care unit. Enoxaparin is given for prophylaxis against deep vein thrombosis. On hospital day 2, urine and blood cultures are positive for Escherichia coli and antibiotics are narrowed based on culture sensitivities. Repeat laboratory testing is similar to admission, except platelet count has dropped to 105,000/mm³.
Which of the following is the most appropriate next step in management of this patient?

Question

A 61-year-old woman comes to the emergency department due to fever, chills, and left flank pain that began abruptly last evening. A month ago, the patient was treated for a urinary tract infection with a short course of ciprofloxacin. She otherwise has no medical problems and currently takes no medications. She has no history of hospitalizations or surgeries.
Temperature is 39.4 C (103 F) , blood pressure is 80/40 mm Hg, pulse is 120/min, and respirations are 24/min. Pulse oximetry shows 94% on room air. Mucous membranes are dry and jugular veins are flat. Cardiopulmonary auscultation reveals clear lung fields and normal heart sounds without murmurs. The abdomen is soft and nontender. Left costovertebral angle tenderness is present. Skin examination is normal. The extremities are warm with no edema. Neurologic examination is within normal limits.
Laboratory results are as follows:

Broad-spectrum antibiotics and intravenous fluids are initiated, and the patient is admitted to the intensive care unit. Enoxaparin is given for prophylaxis against deep vein thrombosis. On hospital day 2, urine and blood cultures are positive for Escherichia coli and antibiotics are narrowed based on culture sensitivities. Repeat laboratory testing is similar to admission, except platelet count has dropped to 105,000/mm³.
Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec193a_961c_7e4f_853d_87425d59859c_MD0002_00 This patient with likely Escherichia coli pyelonephritis had a decline in platelets on hospital day 2 after starting enoxaparin for prophylaxis against deep vein thrombosis. Platelet declines in patients on heparin should prompt a consideration of heparin-induced thrombocytopenia (HIT) type 2, a life-threatening condition. To evaluate for HIT type 2, the 4 Ts score (see the image above) is typically used. This patient has a score of 1 due to a platelet decline <30% (0 points), onset <5 days with no known heparin exposure (0 points), no evidence of thrombosis (0 points), and likely other causes of thrombocytopenia (1 point). As such, HIT type 2 is unlikely, and no change in therapy is required (enoxaparin may be continued). There are many potential causes for this patient's thrombocytopenia, including >1 of the following: Disseminated intravascular coagulation - presence of prolonged INR/PTT and low to normal fibrinogenAntibiotics - many antibiotics (eg, ceftriaxone) can result in thrombocytopeniaHIT type 1 - typically causes platelet nadir ~100,000/mm³ <2 days after heparin initiation Disseminated intravascular coagulation - presence of prolonged INR/PTT and low to normal fibrinogen Antibiotics - many antibiotics (eg, ceftriaxone) can result in thrombocytopenia HIT type 1 - typically causes platelet nadir ~100,000/mm³ <2 days after heparin initiation ³ (Choices B, C, and D) Patients with HIT type 2 require the immediate discontinuation of all heparin products (eg, enoxaparin), PF4 (HIT) antibody testing, and alternate anticoagulation (eg, argatroban). (Choice E) Tinzaparin is also a low-molecular-weight heparin; if HIT type 2 were suspected, this would not be a suitable alternate anticoagulant as all heparin products must be avoided. Educational objective: Patients who develop thrombocytopenia after initiation of heparin products should be evaluated for heparin-induced thrombocytopenia (HIT) type 2 with a 4 Ts score. Patients with low (<3) scores are unlikely to have HIT type 2 and can continue heparin therapy without additional testing or change in treatment. __________

A 61-Year-Old Woman Comes to the Emergency Department Due to Fever