What is OPSI (Overwhelming Post-Splenectomy Infection) in a child who has undergone a splenectomy?

What is OPSI (Overwhelming Post-Splenectomy Infection)?

OPSI is a fulminant, life-threatening infection that occurs in patients without a functioning spleen, presenting as rapidly progressive sepsis, meningitis, or pneumonia primarily caused by encapsulated bacteria, with mortality rates of 30-70% even with treatment. 1

Clinical Definition and Pathophysiology

OPSI represents a true medical emergency where patients can progress from mild flu-like symptoms to fulminant septic shock within hours, with most deaths occurring within the first 24-48 hours of symptom onset. 1, 2 The condition is caused by the loss of the spleen's critical role in clearing encapsulated bacteria from the bloodstream and mounting rapid immune responses to these pathogens.

Causative Organisms

The most common pathogens responsible for OPSI include:

• Streptococcus pneumoniae accounts for approximately 50% of all OPSI cases 1, 2
• Haemophilus influenzae type B is significant, particularly in children 3
• Neisseria meningitidis is associated with serious infection 3
• Other organisms include Escherichia coli, malaria, babesiosis, and Capnocytophaga canimorsus (from dog bites) 3, 2

Risk Factors and Timeline

Age-Related Risk

Children under 5 years—especially infants—face dramatically higher risk with infection rates exceeding 10%, compared to less than 1% in adults. 3 Neonates have the highest risk, exceeding 30%. 1

Temporal Risk Pattern

• The risk is highest in the first year after splenectomy but remains elevated for more than 10 years and is almost certainly lifelong 1, 2
• While most infections occur within the first two years, up to one-third manifest at least 5 years after splenectomy 3, 2
• Cases have been documented more than 20 years post-splenectomy 3

Clinical Presentation

OPSI typically begins with nonspecific symptoms including fever, malaise, chills, headache, and myalgias that rapidly progress to:

• Fulminant septic shock
• Meningitis
• Pneumonia
• Disseminated intravascular coagulation
• Multi-organ failure

1, 4

Who is at Risk?

Surgical Splenectomy

Patients who have undergone splenectomy for:

• Severe splenic trauma
• Splenic cysts
• Hematological malignancies
• Immune thrombocytopenia

3

Functional Hyposplenism

Patients with functional hyposplenism require identical preventive measures as those with surgical splenectomy. 2 This includes:

• Sickle cell disease (HbSS, HbSC)
• Thalassemia major
• Celiac disease
• Inflammatory bowel disease
• Lymphoproliferative diseases

3, 2

Critical Prevention Strategies

Vaccination Protocol

All asplenic patients must receive vaccination against encapsulated bacteria:

• Pneumococcal vaccines: PCV20 (preferred) or PCV15 followed by PPSV23 at least 8 weeks later, with PPSV23 revaccination every 5 years for life 2
• Meningococcal vaccines: Both MenACWY (2-dose series, revaccinate every 5 years) and MenB (revaccinate every 2-3 years) 2
• Haemophilus influenzae type B: Single dose for previously unvaccinated adults 2
• Annual influenza vaccine for life for all patients over 6 months of age 5, 2

Optimal Vaccination Timing

• For elective splenectomy: Administer vaccines at least 2 weeks before surgery (ideally 4-6 weeks) 5, 2
• For emergency splenectomy: Wait at least 14 days post-operatively before vaccinating, as antibody response is suboptimal before this time 5, 2

Antibiotic Prophylaxis

Lifelong prophylactic antibiotics should be offered to all patients, with highest priority in the first 2 years post-splenectomy. 5, 2 Patients must also have emergency standby antibiotics at home to use immediately at the first sign of fever, malaise, or chills. 5, 1

Patient Education Essentials

Every asplenic patient must understand:

• Their lifelong increased risk of life-threatening infection 2
• The need for immediate medical attention with any fever >101°F (38°C) 2
• They should carry medical alert identification indicating asplenic status 2
• Special precautions for travel to malaria-endemic areas 1
• Immediate antibiotic treatment needed after animal bites, particularly dog bites 2

Common Pitfalls to Avoid

• Failing to vaccinate before elective splenectomy when optimal antibody response can be achieved 2
• Assuming the risk diminishes over time—the risk is lifelong 1
• Not providing emergency standby antibiotics for home use 1
• Inadequate patient education about the severity and rapidity of OPSI progression 2
• Forgetting that functional hyposplenism carries the same risk as surgical splenectomy 2