Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Sickle-cell disease and vaso-occlusive crisis
Paediatrics and child health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Fever, chest, neurological or sequestration emergency
Fever, hypoxia, respiratory symptoms, new neurological deficit, altered consciousness, rapidly enlarging spleen, extreme pallor, shock or priapism in a child with sickle-cell disease may deteriorate within hours.
Action: Use ABCDE, give analgesia within 30 minutes when pain is present, obtain urgent paediatric-haematology input, culture and give IV antibiotics promptly for suspected infection, and activate acute chest, stroke, sequestration or transfusion pathways according to findings.
Overview
Understand sickling and childhood organ vulnerability, recognise painful crisis and rapidly lethal mimics or complications, deliver analgesia and supportive care in the correct order, and maintain infection prevention and specialist follow-up without undertreating pain.
Ask genotype, baseline haemoglobin, spleen status, previous acute chest syndrome, stroke risk, transfusions, antibodies, intensive-care admissions, renal disease and current specialist plan. Establish pain onset, sites, severity, function, triggers and home medicines, then ask whether this resembles the child's usual episode. Record fever, chest and neurological symptoms, urine, hydration, abdominal swelling, priapism, infection exposure and adherence to prophylaxis without judgement.
Use ABCDE and an age-appropriate early-warning score. Observe work of breathing, oxygen saturation on air and perfusion; examine chest, abdomen, spleen, joints, bones and neurological function. Measure pain with a developmentally suitable tool. A child may have vaso-occlusive pain and another diagnosis simultaneously, so focal peritonism, joint restriction or respiratory change must not be normalised as 'just a crisis'.
Practice
Two practice questions
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Question 1 of 2
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Paediatrics and child healthOriginal SBA
Time-critical pain treatment
A 12-year-old with HbSS presents with severe limb and back pain typical of previous vaso-occlusive episodes. Observations are stable and no complication is apparent. What should happen next?
Sources and review status3 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Give analgesia promptly. NICE recommends treatment within 30 minutes; severe pain receives a strong-opioid bolus using the child's individual plan or local paediatric protocol, with regular paracetamol and an NSAID unless contraindicated. Account for doses already given. Reassess every 30 minutes, repeat opioid when severe pain persists, and move to supervised patient-controlled analgesia when repeated boluses are needed. Co-prescribe laxative and as-needed antiemetic or antipruritic with opioids.
Support normal physiology: keep warm, encourage drinking, treat vomiting and prescribe IV maintenance only when oral intake is inadequate. Excess fluid can worsen acute chest syndrome, so repeated large boluses are inappropriate without shock. Give supplemental oxygen for saturation 95% or below and investigate any fall from baseline. Incentive spirometry or regular supported deep breathing is valuable during chest or upper-abdominal pain where the local paediatric pathway supports it.
Tests are selected by severity rather than ordered reflexively for every familiar mild episode. FBC, reticulocytes and comparison with baseline distinguish haemolysis, aplasia and sequestration; group and save is important if transfusion might be needed. Fever prompts cultures and sepsis investigations without delaying antibiotics. Chest features require radiography, blood gas when severe and early acute-chest discussion. New neurological signs activate an immediate stroke and exchange-transfusion pathway; do not delay for imaging logistics.
At discharge, pain must be controlled on an agreed oral plan, observations stable and serious complications excluded. Confirm medicines, hydration, warming, school support and explicit fever, chest, neurological, splenic and priapism return criteria. Notify the haemoglobinopathy team and arrange timely review after an admission. Explore recurrent-pain effects on sleep, learning, mood and family life; psychology, physiotherapy, school nursing, pain services and social support may all be part of good sickle care.
Key points
Treat an acute painful sickle episode as a medical emergency and listen to the child and family as experts in the child's usual pattern and effective plan.
Use an age-appropriate pain score and give suitable analgesia within 30 minutes of hospital presentation; severe pain needs a strong-opioid bolus under the individual or local protocol.
Reassess pain and sedation every 30 minutes until satisfactory control, then at least every 4 hours; consider patient-controlled analgesia if repeated boluses are needed within 2 hours.
Record temperature, respiratory rate, pulse, blood pressure and oxygen saturation on air; give oxygen when saturation is 95% or below and investigate the cause.
Fever or an unwell child needs prompt cultures and IV antibiotics under the local sickle and sepsis pathway; prophylactic penicillin does not exclude invasive infection.
Do not transfuse an uncomplicated painful episode routinely; acute chest syndrome, stroke, sequestration and severe symptomatic anaemia require early haematology-led simple or exchange transfusion decisions.
Encourage oral fluids to normal requirement when able, use carefully calculated maintenance IV fluid if needed and avoid both dehydration and fluid overload.
Check for focal infection, chest disease, neurological change, splenic enlargement, priapism and a pain pattern that differs from previous crises at every assessment.
Aetiology
01
Autosomal-recessive haemoglobin disorder
Sickle-cell disease results when pathogenic beta-globin variants are inherited from both parents, most commonly HbSS, HbSC or sickle beta-thalassaemia.
02
Sickling triggers
Infection, dehydration, hypoxia, cold exposure, acidosis and physiological stress favour deoxygenation and polymerisation, although many painful episodes have no obvious trigger.
03
Population distribution
The condition is more prevalent in people with African, Caribbean, Middle Eastern and South Asian ancestry but can occur in any population.
Pathophysiology
1
HbS polymerisation
Deoxygenated HbS polymerises, distorting erythrocytes into rigid cells that damage their membranes and have reduced deformability.
2
Vaso-occlusion
Rigid cells, activated endothelium and inflammatory adhesion obstruct the microcirculation, producing ischaemia, infarction and severe nociceptive pain.
3
Chronic haemolysis
Repeated red-cell destruction shortens survival, causing anaemia, reticulocytosis, jaundice and bilirubin gallstones while consuming nitric oxide and promoting vasculopathy.
4
Functional asplenia
Repeated splenic infarction progressively impairs clearance of encapsulated bacteria, creating a lifelong risk of rapidly invasive pneumococcal infection.
5
Cumulative organ injury
Recurrent ischaemia and haemolysis can damage brain, lungs, kidneys, eyes, bones and spleen even between clinically obvious crises.
Clinical features and red flags
Vaso-occlusive pain
Acute severe bone, joint, back, chest or abdominal pain occurs with no better explanation and often resembles previous episodes.
Dactylitis
Painful swelling of hands or feet can be an early vaso-occlusive manifestation in infants and young children.
Acute chest syndrome
Fever or respiratory symptoms with hypoxia and a new radiographic infiltrate define a high-risk pulmonary complication.
Splenic sequestration
Sudden splenic enlargement, pallor, weakness and circulatory compromise reflects rapid trapping of red cells and blood volume.
Aplastic crisis
Abrupt worsening anaemia with an inappropriately low reticulocyte count often follows parvovirus B19 infection.
Neurological emergency
Any new focal deficit, seizure, confusion or severe unusual headache may indicate stroke and needs immediate specialist action.
Red flags requiring action
Temperature 38°C or above, rigors, hypothermia or toxic appearance may represent overwhelming bacterial infection despite prophylactic penicillin.
Chest pain, cough, fever, tachypnoea, increased work of breathing, falling oxygen saturation or a new pulmonary infiltrate suggests acute chest syndrome.
Weakness, facial asymmetry, speech or gait change, seizure, severe headache or altered consciousness is a sickle stroke emergency even if transient.
Investigations
01First-line bedside observations and pain scoreFirst stepFirst line
Why
Grade illness, detect hypoxia or sepsis and measure response to analgesia repeatedly.
Interpretation and limitations
Oxygen saturation 95% or below warrants oxygen and investigation; trends and deviation from the child's baseline matter.
02FBC and reticulocyte count
Why
Compare haemoglobin with baseline and distinguish haemolysis, aplasia and sequestration patterns.
Interpretation and limitations
Low haemoglobin with reticulocytopenia supports aplasia; a brisk reticulocyte response with splenomegaly supports sequestration or haemolysis.
03Blood culture and sepsis bloods
Why
Identify invasive infection in fever, hypothermia or clinical deterioration before antibiotics when feasible.
Interpretation and limitations
Do not delay antimicrobial treatment for difficult sampling; normal early inflammatory markers cannot exclude overwhelming infection.
04Chest radiograph
Why
Detect a new infiltrate when chest pain, fever, cough, tachypnoea or hypoxia suggests acute chest syndrome.
Interpretation and limitations
Early imaging may be normal; repeat assessment and imaging are needed when respiratory features evolve.
Differential diagnosis
01
Osteomyelitis or septic arthritis
Focal persistent pain, fever, swelling, restricted joint movement and inflammatory markers require cultures and imaging because infection can resemble bone infarction.
02
Acute surgical abdomen
Localised guarding, bilious vomiting, peritonism or progressive distension should not be attributed automatically to sickling pain.
03
Aplastic or sequestration crisis
Both cause acute anaemia: reticulocytes are low in aplasia, whereas splenic enlargement and reticulocytosis support sequestration.
04
Trauma or thrombosis
A clear mechanism, unilateral swelling, line history or atypical distribution may indicate fracture, soft-tissue injury or venous thrombosis.
Management
01Painful crisisTreat pain promptly and reassessFirst stepPain is compatible with vaso-occlusion and no immediate organ complication dominates.+
1Use the individual plan, score pain and give severity-appropriate analgesia within 30 minutes.
2Add regular non-opioid analgesia when safe and reassess pain and sedation every 30 minutes.
3Maintain normal hydration and warmth, support breathing and search repeatedly for an evolving complication.
4EscalationEscalate to supervised patient-controlled analgesia if repeated strong-opioid boluses are required within 2 hours.
02Fever or sepsisTreat infection before it declares itselfFever, hypothermia, rigors, focal infection or toxic appearance occurs.+
1Obtain cultures and focused infection samples without delaying treatment.
Complications
01
Acute chest syndrome
Pulmonary infection, infarction or fat embolism causes a new infiltrate with respiratory features and can progress rapidly to hypoxic failure.
02
Stroke and silent cerebral infarction
Large-vessel vasculopathy causes overt stroke while silent infarcts can impair cognition and school progress without a dramatic neurological event.
03
Severe infection
Functional asplenia permits overwhelming pneumococcal and other encapsulated bacterial infection, so fever remains an emergency despite vaccination and antibiotics.
04
Renal and skeletal disease
Hyposthenuria, haematuria, albuminuria, chronic kidney injury, avascular necrosis and osteomyelitis can emerge through childhood and adolescence.
05
Transfusion complications
Alloimmunisation, delayed haemolytic reactions and iron overload complicate repeated transfusion, requiring specialist antigen matching and longitudinal surveillance.
Monitoring and follow-up
Record pain score every 30 minutes until controlled and at least every 4 hours thereafter, with sedation and opioid adverse effects.
Trend oxygen saturation on air, respiratory rate, work of breathing and chest findings because acute chest syndrome can evolve after admission.
Monitor temperature, perfusion, urine output and fluid balance while avoiding routine overhydration.
Compare haemoglobin and reticulocytes with the child's known baseline and recheck when pallor, splenic size or clinical state changes.
Document spleen size in a child at risk of sequestration and teach caregivers the specialist-approved home assessment where provided.
Maintain long-term surveillance for transcranial Doppler eligibility, renal albuminuria, vision, growth, puberty, bones and transfusion complications through the specialist service.
Review school attendance, cognition, sleep, mood, transition readiness and the family's access to an emergency plan and medicines.
Special situations
The family holds clinical data
Their account of usual pain, baseline spleen and effective analgesia may be more useful than a generic pathway alone.
Normal early imaging can mislead
Acute chest changes may lag symptoms, so respiratory deterioration warrants repeated clinical and radiographic assessment.
Reticulocytes separate crises
A low count points toward aplasia, while an appropriate rise accompanies haemolysis or sequestration.
Oxygen is targeted therapy
NICE recommends oxygen at saturation 95% or below; it does not replace investigation of the cause.
Pain care is safety care
Undertreated thoracic pain limits ventilation and may increase pulmonary complication risk as well as suffering.
Common pitfalls
01
Delaying analgesia until investigations or opioid concerns are resolved.
02
Calling atypical abdominal, joint or chest pain an uncomplicated crisis without examination.
03
Reassuring a febrile child because prophylactic penicillin is prescribed.
04
Giving excessive IV fluid in the absence of shock.
05
Transfusing uncomplicated pain without a specialist indication.
06
Missing acute chest syndrome because the first radiograph is normal.
07
Using pethidine or failing to monitor sedation after opioid boluses.
08
Ignoring school, psychological and family effects of recurrent pain.
Long-term prevention includes antibiotic prophylaxis, routine and additional immunisation, education, an emergency plan and specialist consideration of hydroxycarbamide or transfusion programmes.
Pain behaviour and opioid need must be assessed without stigma; repeated presentations do not imply exaggeration or drug-seeking.
Rapid splenic enlargement with pallor, tachycardia, lethargy or hypotension suggests acute splenic sequestration and hypovolaemic anaemia.
Marked pallor and reticulocytopenia after viral symptoms suggests aplastic crisis; haemoglobin can fall profoundly without splenic enlargement.
Priapism lasting 2 hours, severe abdominal pain, bilious vomiting, focal bone tenderness or pain unlike the child's usual crisis needs urgent alternative-complication assessment.
05
Group and save with transfusion history
Why
Prepare compatible antigen-matched blood when severe anaemia or organ complication may require transfusion.
Interpretation and limitations
Alert transfusion laboratory to sickle status and known antibodies because alloimmunisation complicates urgent matching.
06Urgent neuroimaging after pathway activation
Why
Define haemorrhage or infarction in a child with acute neurological dysfunction.
Interpretation and limitations
Imaging helps diagnosis but must not postpone haematology-led transfusion and stroke-network decisions.
2
Give IV broad-spectrum antibiotics immediately under the local sickle and sepsis guideline.
3Assess spleen, chest and perfusion and involve senior paediatrics and haematology early.
4Monitor closely because functional asplenia permits rapid deterioration despite prophylaxis.
03Chest complicationActivate acute chest careRespiratory symptoms, hypoxia or a new infiltrate is present.+
1Give oxygen for saturation 95% or below, obtain radiography and start appropriate antibiotics.
2Provide effective analgesia, supported deep breathing or spirometry and cautious fluids.
3Discuss simple versus exchange transfusion and critical-care transfer early with the specialist team.
04Stroke or sequestrationRestore perfusion and oxygen deliveryA focal neurological deficit or rapidly enlarging spleen with acute anaemia develops.+
1Call paediatric haematology and critical-care support immediately while continuing ABCDE stabilisation.
2Send urgent FBC, reticulocytes, group and save and relevant imaging without delaying the treatment pathway.
3Use specialist-directed simple or exchange transfusion with careful volume and viscosity targets.
Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
Provides rapid first-line control of severe acute vaso-occlusive pain and enables breathing, movement and hydration.
Strong opioid for severe vaso-occlusive pain
Give one age- and weight-appropriate strong-opioid bolus by a suitable route within 30 minutes using the child's individual care plan or locally agreed paediatric sickle protocol; reassess at 30 minutes and repeat if severe pain persists.
Record pre-hospital doses, monitor respiratory rate, sedation and oxygenation, use local maximum and renal or hepatic adjustments, avoid pethidine, and prescribe regular laxative with as-needed antiemetic and antipruritic when opioid therapy continues.
Reduces invasive pneumococcal infection risk in childhood sickle-cell disease alongside the recommended immunisation programme.
Phenoxymethylpenicillin prophylaxis
Give 62.5 mg orally twice daily up to age 1 year, 125 mg twice daily from 1 to under 5 years, and 250 mg twice daily from age 5 years onward, following the specialist plan.
Confirm allergy phenotype and local alternative, reinforce that prophylaxis does not make fever safe, check adherence and supply of liquid formulation, and review duration with the haemoglobinopathy service rather than stopping independently.