Sickle cell disease -refers to a group of disorders arising from defective genes that produce abnormal Hb molecules (HbS). -Defective genes produce abnormal haemoglobin α- or β-chains resulting in HbS. - homozygous sickle cell anaemia/sickle cell disease (HbSS) and heterozygous sickle cell trait (HbAS). -SCAthe erythrocytes are fragile, with a short life span of 17 days, compared with 120 days in a healthy individual. -The erythrocytes have a characteristic crescent, or sickle, shape which blocks up the capillaries.

-This predisposes to clot formation in the capillaries. -Diagnosis is by Hb electrophoresis, and identification of the abnormal sickle-shaped cells on a blood film. -A bone marrow biopsy may also be required. - Treatment outside of pregnancy includes: 1- the administration of 1 mg/day oral folic acid tablets 2- prophylactic penicillin 3- thromboprophylaxis, iron chelation agents 4- exchange blood transfusion.

A sickle cell crisis arises when the sickle cells form clots in the capillaries resulting in deoxygenation, and tissue death as a result of infarction. -The crisis presents acutely with : -severe pain -breathlessness -pallor - fever - joint swelling - pain, - general weakness

-The crisis exacerbated, by : -infection -cold temperature -dehydration - stress - exercise. *Other complications are : 1-chronic anaemia 2- bone marrow suppression 3- thromboembolic disease 4- cardiac failure due to chronic hypoxaemia 5- aplastic anaemia, 6- sudden death

*pre-conception care -the folic acid should be increased to 5 mg/day - iron chelation discontinued 3–6 months prior to conception due to possible teratogenicity -If the woman has pulmonary hypertension, pregnancy is contraindicated due to the 50% maternal mortality risk -In pregnancy the woman's care should be shared between the obstetric and haematology team, with appointments being made for every 2–4 weeks to assess maternal and fetal wellbeing.

- The woman presenting with sickle cell anaemia is at risk of experiencing a sickle cell crisis secondary to: - infection -pre-eclampsia -miscarriage - IUGR -stillbirth

- diagnosis -FBC, -blood group -antibody screen - reticulocyte count - serum ferritin levels - HIV and hepatitis screening (because of history of blood transfusions) -renal and liver function tests. -Folic acid should be increased to 5 mg/day if not done so pre-conceptually, and iron supplements only given if indicated by serum ferritin results. - Antibiotic therapy may need to be continued.

-In the third trimester serial growth scans should be undertaken ( -In labour: - an epidural is recommended for pain relief as opiates should be avoided. - Blood should be taken for FBC, group and save. -Graduated compression stockings are used to reduce the risk of VTE - the woman should be kept warm and hydrated to prevent any sickle cell crisis from occurring.

-Oxygen therapy might be required to maintain adequate oxygenation and improve cardiac function. -Prophylactic antibiotics may be considered to reduce infection. -A prolonged labour should be avoided and active management or caesarean section may be advised depending on the woman's health -Where there is IUGR, continuous fetal monitoring would also be recommended

-During the postnatal period, the midwife should be vigilant in her observations as the woman is at increased risk of sickle cell crisis, thromboembolism and postpartum haemorrhage. -Prophylactic antibiotics and thromboprophylaxis should continue - early mobilization is encouraged. - observations should be undertaken, including respiration rate.

-The woman should be advised about subsequent pregnancies and the risk they carry in increasing the frequency of crises. -It is therefore important that the woman uses appropriate contraception in order to maximize her health as intrauterine contraceptive devices (IUCDs) are relatively contraindicated due to the risk of infection. - Neonatal screening of babies must be undertaken by obtaining a capillary or venous sample of blood at birth. -Those with a positive result require a follow-up appointment and electrophoresis at 6 weeks, including prophylactic antibiotic cover from 3 months of age

-In sickle cell trait (HbAS) the individual is usually asymptomatic. - Although the sickle screening test is positive - the blood appears normal. - In pregnancy the woman may present with mild anaemia and so 5 mg/day folic acid is recommended to improve erythropoiesis.