LABORATORY DIAGNOSIS OF ANAEMIA IN PREGNANT WOMEN ANNETTE MOBIT B.M.L.S (HONS.) LABORATORY SCIENTIST MEDICAL AND HEALTH SERVICES CDC

INTRODUCTION A knowledge of a patient’s symptoms and clinical history can often establish the cause of anaemia. Laboratory tests can help to identify the type of anaemia and monitor patient’s response during treatment. Techniques for measuring haemoglobin and assessing anaemia will also depend on available faculties and resources the Laboratory has in place.

TECHNIQUES FOR DIAGNOSING ANAEMIA IN PREGNANCY Haemoglobin Measurement. Packed cell volume (haematocrit) measurement Red cell indices Blood films Examination Electrophoresis to detect Haemoglobin sickle cells. Reticulocyte count Platelet count

DIAGNOSIS CONT. Platelet count WBC count Stool examination. Urinalysis

Haemoglobin Measurement Anaemia occurs when the conc. of Hb falls below what is normal for a person’s age, gender and environment. Hb values are expressed in grams per litre (g/dl) or grams per decilitre (g/dl). Hb reference range will also depend on the method used, manufacturer’s produces and reference range.

Hb Normal reference ranges Children at birth 13.5-19.5g/dl. Children (2-5) yrs 11.0-14.0g/dl. Children (6-12)yrs 11.5-15.5g/dl. Adult men 13.0-180g/dl. Adult women 12.0-15.0g/dl. Pregnancy women 11.0-13.8g/dl.

Measurement Techniques Haemoglobin can be measured using two techniques. Photometric Techniques. Here the absorbance of Hb in blood sample is measured electronically using filter colorimeter or read out Hb meter. Visual comparative Technique This is use when it is not possible to measure Hb accurately using a photometric technique e.g -Who Haemoglobin colour scale. Sahli’s method (less reliable).

Packed cell volume (PCV) or Haematocrit Measurement Packed cell vol (PCV) is the proportion of whole blood occupied by red cells expressed as a ratio PCV is also used to calculate red cell indices, which are also used to investigate anaemia.

PCV VALUES Pcv values vary according to age, gender and attitude, pcv is measured in litre. Children at birth 0.44-0.54l/l Children (2-5) yrs 0.34-0.40l/l Children (6-12)yrs 0.35-0.45l/l Adult men 0.40-0.54l/l Adult women 0.36-0.46l/l

Measurement of Red cell indices. Red cell indices frequently used to investigate anaemia are: Mean cell haemoglobin conc.(MCHC). This gives the conc of Hb in gll in 1litre of packed red cells. That is calculated from Hb and PCV MCHC = Hb (g/l) Pcv (l/l). Normal Range – 315-360gll (31.5-36.0)gldl.

MCHC, MCV Mean red cell volume (MCV)-This gives the red cell size. It is determined from PCV and electronically obtained RBC count. MCV = PCV L/L = MCV fl. RBC x 1012/L fl= 10-15 /L Mean cell haemoglobin (MCH) –This gives the amount of Hb in an average red cell. It is determined from the Hb and RBC. MCH = Hb g/L = MCH pg RBC x 1012/L pg = 10-12 /L

EXAMINATION OF BLOOD FILMS This include thin blood films from finger pricking or bone marrow smear. Examination using thin blood films is important in the investigation and management of anaemia which produce changes in the appearance of red blood cells and differential white cell count. Analysing thin blood film includes the following:

EXAMINATION OF BLOOD FILMS CONT. Differential white cell count and white cell morphology. Red cell morphology. Platelets. A differential white cell count provides information on the different white cells in the circulating blood, That is Neutrophils Lymphocytes Monocytes Eosinophils Basophils (rarely seen).

Differential WBC reference range for adults. Cells Percentages Neutrophils_______________40-75 % Lymphocytes______________21-40 Monocytes________________ 2-10 Eosinophils________________ 1-6 Basophils_________________ 0.1-1

Children % Cells Percentages Neutrophils_______________20-45 Lymphocytes______________45-70 Monocytes________________ 2-10 Eosinophils________________ 1-6 Basophils_________________ 0.1-1 %

Red Cell Appearance Size and Shapes. Normocytic – Normal red cell measuring about 8Nm in diameter. Microcytic – smaller than normal red cells having diameter less than 6.5Nm seen in iron deficiency anaemia. Macrocytic – Larger than normal red cells with diameter greater than 8Nm seen in Folate, vit B12 def anaemia. Sphecrocytosis – small densely staining spherical red cells with no central pallor seen in haemolytic anaemia’s.

Red Cell Appearance Cont. Anisocytosis – unequal variation in the size of red cells. Seen in many anaemia’s. Pencil cells – Elongated narrow red cells seen in iron deficiency anaemia. Sickle cell – Elliptical cells with pointed ends or cresent shaped or boat shape cells. Seen in sickle cell anaemia. Schistocytes – Irregularly contracted red cell fragments often with projections seen in red cell damage due to burns, drugs, toxins, uraemia, and pre-eclampsia

Red Cell Appearance Cont. Poikilocytosis – significant variation in cell shape seen in many anaemia’s. Reticulocytes (Nucleated Red cells)- Nucleus in red cell seen in sickle cell diseases. Megaloblast – Larger than normal red cells between (10-20) Nm with an immature nucleus with fine lacy chromatin pattern. seen in megaloblastic anaemia (def of folate or B12).

Colour of Red blood cell (Haemoglobinization). Hypochromic – Pale staining red cells with increased area of central pallor. seen in ferrus def anaemia. Polychromasia – Blue –grey staining of immature red cells which are larger than normal red cells. Seen in haemolytic anaemia.

Platelets count This can be requested to investigate mucosal bleeding with a decreased in platelet count usually below 20x109 /L Normal value 150-400x109/L An increased in platelets count can be seen in iron def anaemia associated with active bleeding

White Blood cell count can be used to investigate infections Normal range in pregnancy 4-15x109 /L leukopenia (decrease in WBC) can be seen in -Aplastic anaemia, Folate and vit B12 deficiency (megaloblastic anaemia).

Other non frequent Anaemia investigations Stool Examination. For hook – worm ova. Microscopy for stool wet preparation and fecal occult blood test. Severe hook worm infection may lead to iron deficiency anaemia. Liver function Test Yellowish plasma to detect Bilirubin conc. Urinalysis Blood in urine is an indication of haemolysis.

Summary of red cell indices in common anaemia’s. MCHC MCV MCH. Ref value 31.5-36.0gldl. 80-98fl 27-32pg. Anaemias. Normocytic N N N Normochromic Microcytic Hypochromic e.g Fe def. Macrocytic N e.g Folate Deficiency

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