Splenectomy and hyposplenism

The spleen is involved in producing protective humoral antibodies, the production and maturation of B and T cells and plasma cells, removal of unwanted particulate matter (eg, bacteria) and also acting as a reservoir for blood cells, especially white cells and platelets.

Splenectomy

Splenectomy may occur in three different ways:

• Planned, where prophylactic measures can be used to prevent later complications.

• Traumatic, due to an accident or during surgery.

• Autosplenectomy, which refers to the physiological loss of spleen function (hyposplenism) - eg, associated with sickle cell anaemia (chronic damage to the spleen results in atrophy), coeliac disease, dermatitis herpetiformis, essential thrombocythaemia and ulcerative colitis.

Indications for splenectomy

• Trauma: 25% of injuries are iatrogenic.

• Spontaneous rupture: this usually occurs in patients with massive splenomegaly (eg, infectious mononucleosis) and is often precipitated by minor trauma.

• Hypersplenism: hereditary spherocytosis or elliptocytosis, immune thrombocytopenia.

• Neoplasia: lymphoma or leukaemic infiltration.

• With other viscera: total gastrectomy, distal pancreatectomy.

• Other indications: splenic cysts, hydatid cysts, splenic abscesses.

Complications of splenectomy

• Thrombocytosis: platelet count usually peaks after 7-10 days. There is no evidence of an increased risk of thromboembolic disease but prophylactic aspirin may be considered for very high platelet counts.

• Overwhelming post-splenectomy infection¹:
  

  • Due to encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis.

  • Occurs post-splenectomy in 4% of patients without prophylaxis.

  • The greatest risk of mortality is in the first two years and is estimated at 50%.

  • Management: immunisation and antibiotic prophylaxis as outlined under 'Management', below.

Hyposplenism

Causes

• Operative splenectomy: for severe splenic trauma, splenic cysts, or as part of a resective procedure for an abdominal tumour.

• Functional hyposplenism: sickle cell anaemia (HbSS) disease and haemoglobin sickle-C (HbSC) disease, thalassaemia major, essential thrombocythaemia, and lymphoproliferative diseases (Hodgkin's lymphoma and non-Hodgkin's lymphoma, chronic lymphocytic leukaemia (CLL)), coeliac disease, inflammatory bowel disease. Often, Howell-Jolly bodies on peripheral blood film give an important clue to diagnosing hyposplenism.

• Bone marrow transplantation: splenic irradiation or chronic graft-versus-host disease.

• Congenital asplenia: associated with cardiac abnormalities and biliary atresia.

Investigations

• Blood film: features of hyposplenism include Howell-Jolly bodies, Pappenheimer bodies, target cells and irregular contracted red blood cells.

• Imaging techniques: ultrasound, CT scanning, and MRI scanning.

• Other investigations, which will depend on the clinical context.

Complications of hyposplenism²

• Individuals with an absent or dysfunctional spleen are at increased risk of severe infection, particularly those caused by encapsulated bacteria. The most common organism associated with severe infection is S. pneumoniae (pneumococcus) but other organisms also appear to be a more common cause of overwhelming infection, including H. influenzae type b (Hib) and N. meningitidis.

• Other infections include Escherichia coli, malaria, babesiosis, and Capnocytophaga canimorsus (associated with dog bites).

• Fulminant, potentially life-threatening infection is a major long-term risk of hyposplenism; yet, such infection is largely preventable.

• Asplenic patients should be strongly advised of the increased risk of severe falciparum malaria, should take all antimalarial precautions/prophylaxis and ideally avoid holidays in malaria-endemic areas.

Management

In summary, the management can be considered to be two-fold:

1. Immunisations

2. Antibiotic prophylaxis

Immunisations²³⁴

Vaccinations against S. pneumoniae, N. meningitidis, H. influenzae type b and influenza virus are strongly recommended.

• Because of the high risk of overwhelming infection, additional vaccination against pneumococcal infection is recommended for all individuals who have or are at high risk of developing splenic dysfunction in the future, including those with coeliac disease and sickle cell disease.

• Given the high risk of secondary bacterial infection, annual influenza vaccine is also recommended. Additional booster doses of pneumococcal polysaccharide vaccine (PPV) are recommended every five years.

• Additional vaccination against meningococcal groups A, C, W, Y and B should be offered to patients with absent or dysfunctional spleens, at appropriate opportunities.

• Hyposplenism in coeliac disease is uncommon in children, and the prevalence correlates with the duration of exposure to gluten. Therefore, patients diagnosed with coeliac disease early in life and well managed are unlikely to require additional doses of these vaccines beyond those given in the routine immunisation schedule. Only those with known splenic dysfunction should receive additional vaccination against meningococcal infection.

• Although additional vaccination against H. influenzae type b (Hib) used to be recommended for asplenic patients, current control of Hib is excellent because of a long-standing successful vaccination programme in children, and the risk of Hib disease is extremely low. Therefore, additional Hib vaccination is no longer recommended.

A practical schedule for vaccinating asplenic patients, depending on the age of diagnosis is shown in Chapter 7 of The Green Book (see references). Additional booster doses of other vaccines should be considered depending on the person's underlying condition. Specialist advice may be required.

If validated assays are available then it is recommended that response to pneumococcal vaccination and timing for repeat doses be checked.

Prophylactic antibiotics

These are recommended in patients at high risk of pneumococcal infections. The antibiotics of choice are oral phenoxymethylpenicillin or macrolides⁴.

Patients developing infection, despite measures, must be given systemic antibiotics and admitted urgently to hospital.

Risk factors for high risk in hyposplenism include:

• Age <16 years or >50 years.

• Poor response to pneumococcal vaccination.

• Previous invasive pneumococcal illness.

• Underlying haematological malignancy resulting in splenectomy (increased risk if immunosuppressed).

As the infection risk is highest in the initial years after splenectomy, all splenectomised patients are recommended to take daily antibiotic prophylaxis for the initial few years. Guidelines vary in their recommendations for duration of daily antibiotic use post-splenectomy. Individuals who are at high risk for infections due to other comorbidities are recommended to take daily lifelong antibiotics¹.

Antibacterial prophylaxis may be discontinued in children over 5 years of age with sickle cell disease who have received pneumococcal immunisation and who do not have a history of severe pneumococcal infection⁵.

Use phenoxymethylpenicillin, amoxicillin, erythromycin orally. Antibiotics may need to be altered due to differing local antibiotic sensitivities - on the advice of the local public health department.

Consider recommending that the patient take a full therapeutic dose of antibiotics if they develop infective symptoms such as pyrexia, malaise, shivering, etc and that they seek medical advice immediately.

Allowing patients to have a reserve supply of antibiotics at home or on holiday may also seem appropriate.

Pneumococcal resistance to penicillins remains low in the UK. Knowledge of local resistance patterns should be used to guide the choice of antibiotic⁴.

A case can be made for the establishment of a disease register of hyposplenic patients and for regular auditing⁴. The British Committee for Standards in Haematology recommends the following⁴:

• Patients should be given written information and carry a card to alert health professionals to the risk of overwhelming infection. Patients should wear an alert bracelet or pendant.

• Patients should be aware of the potential risks of overseas travel, particularly with regard to malaria and unusual infections - eg, those resulting from animal bites.

• Patient records should be clearly labelled to indicate the underlying risk of infection. Vaccination and re-vaccination status should be clearly and adequately documented.