Introduction:

• Hyposplenism is a condition in which there is decreased splenic function resulting from diseases that impair function of spleen or absence of splenic tissue because of agenesis or atrophy or splenectomy

Etiology:

• Splenic causes
  • Surgical splenectomy
  • Splenic irradiation
  • Sickle cell anemia resulting in autosplenectomy
  • Congenital asplenia
  • Thrombosis of splenic artery or vein
  • Normal infants
• GI and hepatic diseases
  • Celiac disease
  • Dermatitis herpetiformis
  • Inflammatory bowel disease
  • Cirrhosis
• Autoimmune diseases
  • Systemic lupus erythematosus
  • Rheumatoid arthritis
  • Vasculitis
  • Glomerulonephritis
  • Hashimoto disease
• Hematologic and neoplastic disorders
• Sepsis/ infectious diseases

Pathogenesis:

• Disturbed splenic circulation leading to disturbed culling, phagocytic and pitting functions.
• Deficiency of opsonic IgG antibodies, which leads to defective phagocytosis.

Indications for splenectomy: (It should be done for clinical indications rather than specific diagnosis. Clinical benefits must outweigh risk of post-splenectomy complications)

• Haemolyticanemias
• Immune thrombocytopenic purpura
• Sickle cell anemia with splenic sequestration crisis
• Splenic marginal zone lymphoma

Timing of splenectomy:

• Delay until patient is 5 years old

Investigations:

• Peripheral smear: 
  • RBCs- Target cells, acanthocytes, red cell inclusions (Howell Jolly bodies and Pappenheimer bodies), pitted RBCs
  • Increased platelet count
  • Increased WBC count

Complications:

• Over whelming post splenectomy infection (OPSI)
  • Usually caused by encapsulated bacteria such as streptococcus pneumoniae, meningococcus, H. Influenza
  • Risk is higher if immune system is not mature enough to counteract bacterial infection
  • Presentation
    • Rapid progression from nonspecific flu like syndrome to irreversible endotoxic shock
    • Purpura with evidence of DIC
    • Multi organ failure
    • Hypotension
    • Peripheral limb ischemia
    • Diarrhoea and vomiting
  • Overall risk- 0.04 for 100 patient years
• Other complications of splenectomy
  • Immediate complications of any abdominal operation
  • Increased risk of thrombosis (As there is thrombocytosis)- Hence all patients should receive thromboprophylaxis post operatively.
  • Development of subphrenic abscess
  • Injury to pancreas
  • Intestinal obstruction due to adhesions.

Treatment:

• Vaccination
  • Against streptococcus pneumoniae (Pneumovax-23), meningococcus (Quadrimeningo), and H. Influenza B
  • Usually, polyvalent polysaccharide vaccines are used.
  • Should be given 2-3 weeks prior to anticipated splenectomy to optimize antigen recognition and processing and induce more effective immunity.
  • Reimmunization is needed every 5 years.
  • Not useful in children less than 2 years of age
  • If emergency surgery is planned postpone vaccination until at least 2 weeks post-splenectomy, to avoid transient immune suppression which occurs because of general anaesthesia and surgery.
  • Annual influenza vaccine also must be given
• Oral penicillin/ macrolide prophylaxis should be given lifelong (phenoxymethyl penicillin or Penicillin V- <7 years- 125mg- BD, >7 years- 250mg- BD or Penicillin G Potassium sulfate- Pentids- 400mg- BD)
• Any febrile illness must be considered as a medical emergency and must be treated with IV antibiotics (after sending blood and urine cultures). Patients must carry a card stating splenectomised status.
• Patients must be educated about malaria and animal bites. These can be deadly unless properly treated.