Complications

• chronic sickle pain
  • is defined as an episode of pain of greater than 3-6 months (1)
  • often caused by orthopaedic conditions such as avascular necrosis, vertebral collapse, or chronic arthritis (2)
    
    
• bones and joints
  • vaso occlusive episodes resulting in infarcts are often seen in bones and joints
  • "fish mouthing" (abnormalities of the vertebrae) are characteristic of SCD
  • growth disturbances and osteopenia may occur due to hyperplasia of the bone marrow
  • avascular necrosis of hip and shoulder causes chronic pain (particularly in adults)
  • SCD patients also are at an increased risk of infection and failure of prosthesis
  • osteomyelitis is also more common (may be difficult to differentiate from infarction) (2)
    
    
• impaired nutrition and growth
  • growth impairment becomes evident after 6 months of age and is usually caused by
    • decreased absorption of nutrients and/or
    • an increase in the metabolic rate
    • poor appetite associated with febrile or painful episodes
  • a delay in puberty may be seen - by about 6 months in HbSC patients and by 2-3 years in HbSS patients
  • pituitary and/or primary gonadal deficiencies may be seen in patients who are on long-term transfusion programmes (due to iron overload) (3)
    
    
• neurological conditions
  • epilepsy
    • seizures occur in 10-15% of patients with SCD (10 times the incidence of general population)
    • associated with cerebrovascular disease and silent infarction o chronic headaches
    • common in SCD patients
    • may be secondary to migraine, benign intracranial hypertension, hypertension, sleep apnoea or tension (1)
  • cognitive impairment
    • mild cognitive impairment may be seen in children with silent infarcts (seen on MRI scan) (3)
    • in adults evidence of cognitive abnormalities is thought to be due to covert infarctions (1)
      
      
• chronic lung disease
  • chronic sickle lung disease
    • may be associated with a history of acute chest syndrome or with low level pulmonary damage which occurs during painful episodes (1)
    • divided according to the presence of chest pain, degree of hypoxia, chest X-ray and lung function test findings (1)
  • obstructive sleep apnoea
    • common in SCD and may be caused by tonsillar hypertrophy or other causes of sleep disordered breathing
    • increased painful episodes and increased neurological events can also be associated with overnight hypoxia
  • pulmonary hypertension
    • one third of adults with SCD will develop pulmonary hypertension (2)
    • is thought to be due to chronic haemolysis which releases free haemoglobin, causing a deficiency of nitric oxide. This in turn leads to acute and chronic pulmonary vasoconstriction (1)
    • both chronic sickle lung disease and pulmonary hypertension are predominantly seen in adulthood although it is increasingly being recognised in older children and adolescents (3)
      
      
• chronic leg ulcers
  • relatively uncommon in children, commonly seen during adolescence, prevalence increases with age
  • almost all ulcers are seen in the ankle region (near the malleolous) and are bilateral.
  • can be painless or very painful (3)
  • recurrence is high (1)
  • HbSS genotype is more likely to develop leg ulcers
    
    
• chronic renal disease
  • renal complications are common specially with increasing age
  • renal failure primarily due to SCD is rare in childhood (3)
  • sickle nephropathy
    • presentation may range from painless haematuria, proteinuria and progressive loss of function to end stage renal disease (ESRD)
  • renal medullary carcinoma
    • occurs in patients with sickle cell trait and young patients with sickle cell anaemia (2)
      
      
• priapism
  • very common and 89% of males with sickle cell anaemia will have had at least one episode of priapism by adulthood
  • obstruction of the venous drainage of the penis by vaso cocclusion leads to painful, persistent erection (2)
  • can present as an "acute" attack (which requires hospital admission) or a self limiting "stuttering" episode (1)
    
    
• eye complications
  • proliferative retinopathy
    • accounts for around 73% of sudden visual loss in SCD patients
    • caused by recurrent microvascular occlusion which leads to ischemia and growth of new blood vessels
    • can lead to vitreous haemorrhage and retinal detachment
    • commonly seen in young adults between the ages 15-29 years
  • non proliferative retinopathy (1)
    
    
• gallstones
  • seen in over 50% of children with SCD
  • usually asymptomatic or commonly presents with intermittent abdominal pain (3)

Reference:

• 1. Sickle Cell Society 2008. Standards for the clinical care of adults with sickle cell disease in the UK
• 2. Claster S, Vichinsky EP. Managing sickle cell disease. BMJ. 2003;327(7424):1151-5.
• 3. NHS Sickle Cell and Thalassaemia Screening Programme 2009. Sickle cell and Thalssaemia. Handbook for laboratories