Should a patient with a visible spleen and a positive mononucleosis (mono) spot test be evaluated in the emergency room (ER)?

Management of Visible Spleen with Positive Mono Spot Test

A patient with visible splenomegaly and a positive mono spot test should be evaluated in the emergency room due to the risk of spontaneous splenic rupture, which occurs in 0.1-0.5% of infectious mononucleosis cases and can be life-threatening.

Rationale for Emergency Evaluation

Infectious mononucleosis (IM) with visible splenomegaly represents a significant clinical concern for several reasons:

1. Risk of splenic rupture: Spontaneous splenic rupture is the most feared complication of IM 1, 2

   • Occurs in 0.1-0.5% of IM cases
   • Potentially fatal complication
   • Can occur with minimal or no preceding trauma

2. Visible splenomegaly: When the spleen is visibly enlarged (palpable below the costal margin), it indicates significant enlargement

   • Splenomegaly occurs in approximately 50% of IM cases 1
   • Visible enlargement suggests more severe involvement

Emergency Assessment Algorithm

1. Initial Evaluation

• Assess hemodynamic stability (blood pressure, heart rate)
• Evaluate for signs of intraabdominal hemorrhage:
  • Left upper quadrant pain (may be insidious or abrupt) 2
  • Referred left shoulder pain 3
  • Peritoneal signs
  • Signs of hypovolemia (tachycardia, hypotension)

2. Diagnostic Imaging

• Hemodynamically stable patients:

  • Contrast-enhanced CT scan (gold standard for evaluating splenic injuries) 3, 4
  • Complete abdominal ultrasound may be used in stable patients 3
  • Doppler ultrasound to evaluate splenic vascularization 3, 4

• Hemodynamically unstable patients:

  • Bedside E-FAST to rapidly identify intraperitoneal hemorrhage 3
  • Proceed to immediate surgical intervention if positive

3. Management Based on Findings

If No Evidence of Splenic Rupture:

• Admission for observation if splenomegaly is severe
• Discharge with strict precautions if mild-moderate splenomegaly and reliable follow-up:
  • Activity restriction for 4-6 weeks (mild) or 2-4 months (moderate/severe) 4
  • No contact sports or strenuous exercise for at least 8 weeks or while splenomegaly persists 1
  • Clear return precautions for abdominal pain, dizziness, or syncope

If Evidence of Splenic Rupture:

• Hemodynamically stable with contained rupture:

  • Consider non-operative management with close monitoring in ICU setting 2, 5
  • Serial hemoglobin measurements
  • Immediate access to operating room if deterioration occurs

• Hemodynamically unstable or active bleeding:

  • Immediate surgical intervention (splenectomy) 2, 5
  • Blood product resuscitation

Special Considerations

1. Asymptomatic visible splenomegaly: Even without abdominal pain, patients with visible splenomegaly and IM should be evaluated in the ER, as splenic rupture can occur without preceding symptoms 6

2. Delayed rupture risk: Splenic rupture can occur up to 21 days after diagnosis of IM, emphasizing the need for appropriate activity restrictions 2

3. Follow-up imaging: Serial imaging (ultrasound or CT) is recommended to monitor resolution of splenomegaly before resuming normal activities 4

Common Pitfalls to Avoid

1. Dismissing abdominal pain in IM patients: Any abdominal pain in a patient with IM should prompt immediate evaluation for splenic rupture 2

2. Inadequate activity restrictions: Failing to provide clear guidance on activity limitations can lead to preventable splenic rupture

3. Premature return to activities: Allowing return to contact sports before documented resolution of splenomegaly increases rupture risk

4. Missing the diagnosis: Splenic rupture can be the presenting feature of IM without other typical symptoms 6