Emergency medical personnel transport an 18-month-old boy to the emergency department due … — USMLE Step 2 CK

Emergency medical personnel transport an 18-month-old boy to the emergency department due to progressive lethargy and severe pallor over the past 12 hours. The patient has a known history of sickle cell disease (HbSS) and is currently prescribed daily penicillin prophylaxis. Upon arrival, his temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), heart rate is $172/\text{min}$ , respiratory rate is $44/\text{min}$ , and blood pressure is $65/35\text{ mm Hg}$ . Physical examination reveals a somnolent toddler with marked conjunctival pallor, delayed capillary refill of 4 seconds, and cool, clammy extremities. Abdominal examination demonstrates significant distension and a firm, tender mass extending $6\text{ cm}$ below the left costal margin. Laboratory studies reveal the following:

* Hemoglobin: $3.8\text{ g/dL}$ (baseline $8.2\text{ g/dL}$ )
* Reticulocytes: $16\%$
* Platelets: $45,000/\text{mm}^3$
* Leukocytes: $14,000/\text{mm}^3$

Which of the following is the most appropriate next step in the management of this patient?

Intravenous administration of isotonic crystalloids and packed red blood cellsCevap
B
Computed tomography of the abdomen with intravenous contrast
C
Emergent exploratory laparotomy and splenectomy
D
Bone marrow aspiration and biopsy
E
Observation with serial abdominal girth measurements

Cevap

Intravenous administration of isotonic crystalloids and packed red blood cells

This patient is presenting with acute splenic sequestration crisis, a life-threatening complication seen primarily in young children with sickle cell disease (typically between 6 months and 3 years of age, before the spleen auto-infarcts). The condition occurs when vaso-occlusion within the splenic vasculature causes massive pooling of red blood cells in the spleen. This results in acute splenomegaly, a precipitous drop in hemoglobin levels, and potentially fatal hypovolemic shock. The trapping of platelets also frequently causes mild to moderate thrombocytopenia. Crucially, the bone marrow responds appropriately to the severe anemia, leading to a marked elevation in reticulocytes. The immediate priority in management is the reversal of hypovolemic shock and severe anemia. Therefore, the rapid intravenous administration of isotonic crystalloids (to expand intravascular volume) and packed red blood cells (to restore oxygen-carrying capacity and correct the profound anemia) is the most appropriate next step.

Adım Adım Çözüm

Analyze the patient's vital signs and physical examination.

The patient has marked tachycardia (

172/\text{min}

), hypotension (

65/35\text{ mm Hg}

), delayed capillary refill, and altered mental status (somnolence), indicating severe uncompensated hypovolemic shock.

Recognizing the presence of shock dictates the urgency and direction of initial management.

Interpret the laboratory findings in the context of the physical examination.

The precipitous drop in hemoglobin (

3.8\text{ g/dL}

), concurrent thrombocytopenia (

45,000/\text{mm}^3

), and robust reticulocyte count (

16\%

) alongside massive splenomegaly confirm a diagnosis of acute splenic sequestration crisis.

Differentiating sequestration (high reticulocytes, large spleen) from aplastic crisis (low reticulocytes, no splenomegaly) is critical for targeted therapy.

Determine the most appropriate immediate intervention based on the primary pathophysiology.

The primary cause of imminent death is intravascular volume depletion due to red blood cell trapping in the spleen; therefore, rapid volume expansion and correction of severe anemia are required.

Immediate survival depends on reversing hypovolemia and restoring tissue oxygenation before pursuing definitive long-term treatments like splenectomy.

Anahtar Kavram

Acute splenic sequestration crisis is a life-threatening emergency in young children with sickle cell disease characterized by rapid splenic pooling of red blood cells, leading to severe anemia, hypovolemic shock, and compensatory reticulocytosis. Initial management requires immediate volume resuscitation and blood transfusion.

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