A 35-year-old patient is brought into the emergency department post motor vehicle crash. Stabilization of the patient in the trauma bay requires endotracheal intubation. The patient has a laceration on the femoral artery from shrapnel and seems to have lost large quantities of blood. The patient is transfused with 13 units of packed red blood cells. His vitals are T 96.5, HR 150, BP 90/40. Even with the direct pressure on the femoral artery, the patient continues to bleed. Results of labs drawn within the last hour are pending. Which of the following is most likely to stop the bleeding in this patient?

Fresh frozen plasma and platelets

A 6-month-old male presents to the emergency department with his parents after his three-year-old brother hit him on the arm with a toy truck. His parents are concerned that the minor trauma caused an unusual amount of bruising. The patient has otherwise been developing well and meeting all his milestones. His parents report that he sleeps throughout the night and has just started to experiment with solid food. The patient’s older brother is in good health, but the patient’s mother reports that some members of her family have an unknown blood disorder. On physical exam, the patient is agitated and difficult to soothe. He has 2-3 inches of ecchymoses and swelling on the lateral aspect of the left forearm. The patient has a neurological exam within normal limits and pale skin with blue irises. An ophthalmologic evaluation is deferred. Which of the following is the best initial step?

Complete blood count and coagulation panel

Ensure the child's safety and alert the police

A 58-year-old cirrhotic man with ascites undergoes large volume paracentesis (6 liters removed). Four hours later, he becomes hypotensive (BP 80/50 mmHg) and tachycardic (HR 115/min). Labs show: Cr 2.1 mg/dL (baseline 1.0), Na+ 128 mEq/L, Hct 38%. What is the most appropriate immediate management?

5% albumin 6-8 grams per liter of ascites removed

Octreotide and midodrine for hepatorenal syndrome

Vasopressors to maintain blood pressure

Re-infusion of filtered ascitic fluid

A 42-year-old woman with prolonged vomiting from gastroparesis is admitted with weakness. Labs show: K+ 2.1 mEq/L, pH 7.51, HCO3- 42 mEq/L, Mg2+ 1.4 mg/dL. She receives 80 mEq of IV potassium chloride over 24 hours, but repeat K+ is 2.3 mEq/L. What explains the refractory hypokalemia?

Hypomagnesemia preventing potassium retention

Secondary hyperaldosteronism from volume depletion

Insufficient potassium replacement dose

Ongoing losses from continued vomiting

Metabolic alkalosis promoting intracellular potassium shift

A 65-year-old diabetic man with TURP syndrome presents with confusion, nausea, and seizures 2 hours post-operatively. Labs show: Na+ 115 mEq/L, serum osmolality 240 mOsm/kg. He weighs 70 kg. What is the target sodium correction rate and fluid management strategy?

3% saline to increase sodium by 4-6 mEq/L in first 2-4 hours, then slower correction

Conivaptan infusion for water diuresis

Normal saline infusion with fluid restriction

Rapid correction to 135 mEq/L with 3% hypertonic saline over 4 hours

Increase sodium by 6-8 mEq/L in first 24 hours with 3% saline boluses

A 50-year-old man is 5 days post-operative from a Whipple procedure. He has had high nasogastric output (1500 mL/day) and has been NPO. Labs show: Na+ 132 mEq/L, K+ 2.9 mEq/L, Cl- 88 mEq/L, HCO3- 38 mEq/L, pH 7.52. Urine chloride is 8 mEq/L. What is the appropriate management?

Normal saline with potassium chloride

Discontinue nasogastric suction only

Acetazolamide to promote bicarbonate excretion

Half-normal saline with potassium supplementation

Point-of-care coagulation testing for USMLE Step 1: High-Yield Surgery Lessons

POCT Coagulation - Clotting Snapshot

Provides a real-time, holistic view of hemostasis, from clot formation to lysis.
Key technologies: Thromboelastography (TEG) & Rotational Thromboelastometry (ROTEM).
Core Parameters:
- R-time / CT: Clot initiation (Factor-dependent).
- K-time / CFT & α-angle: Clot kinetics (Fibrinogen).
- MA / MCF: Max clot strength (Platelets).
- LY30 / ML: Fibrinolysis at 30 min.

⭐ Guides goal-directed transfusion in trauma, reducing blood product usage compared to standard labs.

TEG and ROTEM graphical output with parameter labels

Thromboelastography (TEG) - The Clot's Story

TEG provides a real-time, holistic view of the entire coagulation cascade, from clot formation to lysis. It helps guide transfusion therapy in trauma and major surgery.

Thromboelastogram (TEG) Interpretation Diagram tracing with parameters R, K, alpha-angle, MA, and LY30 labeled)

R (Reaction) time: Time to initial fibrin formation. Evaluates coagulation factors.
- Prolonged: Deficiency of factors. Treat with FFP.
K-time & α-angle: Speed of clot formation and strengthening. Evaluates fibrinogen.
- Prolonged K / low α-angle: Hypofibrinogenemia. Treat with Cryoprecipitate.
MA (Maximum Amplitude): Represents ultimate clot strength. Evaluates platelet number/function.
- Low MA: Thrombocytopenia or platelet dysfunction. Treat with Platelets.
LY30: Percentage of clot lysis 30 minutes after MA. Evaluates fibrinolysis.
- High LY30: Excessive fibrinolysis. Treat with antifibrinolytics (TXA).

⭐ A normal TEG in a bleeding patient may suggest a surgical (mechanical) cause rather than a coagulopathy.

Rotational Thromboelastometry (ROTEM) - Spinning a Clot

A viscoelastic point-of-care test that provides a holistic view of the coagulation cascade, from initiation to fibrinolysis, guiding targeted transfusion therapy.

ROTEM tracings with CT, CFT, Alpha-angle, MCF, ML parameters

Key Parameters & Targeted Interventions:
- CT (Clotting Time): Evaluates coagulation factors.
  - Prolonged: Factor deficiency → Treat with FFP.
- α-angle & CFT (Clot Formation Time): Assess fibrinogen function and polymerization.
  - Decreased α-angle / Prolonged CFT: Fibrinogen deficiency → Treat with Cryoprecipitate or fibrinogen concentrate.
- MCF (Maximum Clot Firmness): Indicates ultimate clot strength, primarily from platelets and fibrin.
  - Low MCF: Thrombocytopenia or platelet dysfunction → Treat with Platelets.
- LI30 (Lysis Index at 30 min): Measures clot stability.
  - High Lysis: Hyperfibrinolysis → Treat with Antifibrinolytics (e.g., Tranexamic Acid).

⭐ In trauma, ROTEM-guided algorithms are superior to conventional coagulation tests for predicting the need for massive transfusion and reducing mortality.

TEG & ROTEM are crucial for goal-directed transfusion in trauma and major surgeries, reducing blood product use.

Prolonged R time (TEG) or CT (ROTEM) indicates a clotting factor deficiency; treat with Fresh Frozen Plasma (FFP).

A low alpha-angle or K-time suggests a fibrinogen problem; administer cryoprecipitate.

Decreased Maximum Amplitude (MA) or MCF points to platelet dysfunction or thrombocytopenia; transfuse platelets.

Elevated LY30 signifies hyperfibrinolysis; give tranexamic acid (TXA).

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