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Haemoglobinopathies 35

grounds. Diagnosis is further confounded by the range of abdominal transfusion programme or undergo a splenectomy. There is no high-
disease seen in this population. Important differentials to consider are quality evidence to support one of these approaches over the other, and
shown in Table 7.2. both are associated with potential complications.
Acute Splenic Sequestration Crisis The particular concern following total splenectomy is infection, so
Acute splenic sequestration is a life-threatening complication of sickle partial splenectomy has been proposed as an alternative to retain some
cell disease. It mainly occurs in children with homozygous sickle cell immune function. A recent case series by Vick et al. showed that sickle
disease (HbSS) who have not undergone autosplenectomy and older cell patients who underwent a partial splenectomy were not subject to
patients with HbSC disease or HbSβ thalassaemia. It affects between 7% increased rates of infection. Nevertheless, a theoretical risk of seques-
and 30% of children with sickle cell anaemia and is less common in other
forms of SCD. It is the second most common cause of death in children
with sickle cell anaemia under the age of 10. Acute hepatic sequestration
is much rarer, but has also been described in this population (Figure 7.1).
In acute splenic sequestration, splenic outflow obstruction leads
to massive sequestration of red cells and platelets in the spleen,
often causing a significant decrease in circulating blood volume.
Patients present with abdominal pain and distention and signs of
haemodynamic compromise. The diagnosis is based on evidence of
acute splenic enlargement accompanied by a rapid decrease in the
haematocrit, usually to half the patient’s “baseline value”, as well as
brisk reticulocytosis with increased nucleated red cells and moderate to
severe thrombocytopaenia.
Acute splenic sequestration is a medical emergency, and treatment
in the form of blood transfusion should be instigated rapidly to restore
circulating volume and replenish red cell mass. Adequate analgesia is
also important.
Patients who recover from a first episode of acute splenic seques-
tration have a 50% chance of having further episodes. Two possible Figure 7.1: Acute liver enlargement should raise suspicions of a hepatic
management strategies can prevent this: children can be enrolled in a sequestration crisis.

Table 7.2: Differential diagnosis of acute abdominal pain in sickle cell disease.
Cause Frequency Characteristic features Investigations
May mimic acute surgical disease with
guarding and distention; often attributed to
Vaso-occlusive painful crises Very common A specific cause is rarely identified
micro-infarcts of mesentery and abdominal
viscera
Gallstone disease
Epigastric pain that comes on gradually
Biliary colic Relatively common over several hours and subsides over a Pigment stones may be visible on a plain
abdominal radiograph
similar period
Persistent right upper quadrant pain with or Ultrasound shows pericholecystic fluid and
Acute cholecystitis Relatively common
without guarding; possible fever thickening of the gallbladder
Right upper quadrant pain with or without Ultrasound shows dilatation of the common
Cholangitis Uncommon
guarding; fever and rigors; jaundice bile duct
Falling haemoglobin, often with a 2 g/dl
Common, occurring in Left upper quadrant pain; acute splenic
Acute splenic sequestration drop below baseline; thrombocyopaenia;
up to 30% of patients enlargement; hypovolaemic shock
erythrocytosis
Liver Disease
Common, affecting Right upper quadrant pain; low-grade Mild to moderate elevation of liver trans-
Acute sickle hepatic crisis approximately 10% of fever; nausea; increasing jaundice; tender aminases, bilirubin level generally less
patients hepatomegaly than 15 mg/dl (257 µmol/l)
Right upper quadrant pain, acute liver Falling haemoglobin; thrombocytopaenia;
Hepatic sequestration Uncommon
enlargement, hypovolaemic shock erythrocytosis
Right upper quadrant or epigastric pain;
Sickle cell intrahepatic cholestasis Rare acute liver enlargement; fever; nausea and Significant hyperbilirubinaemia
vomiting
Increased risk due to Malaise; jaundice; low grade fever; tender Elevated liver transaminases; positive viral
Viral hepatitis
multiple transfusions hepatomegaly serology
Increased risk due to Epigastric pain radiating through to the
Pancreatitis Raised amylase
pigment gallstones back; fever; nausea and vomiting
Less than in general Right iliac fossa pain with or without guard-
Appendicitis
population ing; nausea and vomiting; fever
Sudden onset of abdominal pain and dis-
Ischaemic colitis Rare Raised lactate
tention; can pass bloody stool
Urinary tract infection Common Dysuria, frequency, fever Positive urine dip and culture