prevalence and antenatal screening of beta thalassaemia trait in pregnancy by naked eye single tube red cell osmotic fragility test

ABSTRACT

To evaluate the prevalence of Beta Thalassaemia Trait [BTT] detected by Naked Eye Single Tube Red cell Osmotic Fragility Test [NESTROFT]. We also highlight the validity and importance of this test for antenatal screening of BTT to prevent incidence of Beta Thalassaemia major in our community as well as differentiating the BTT, BTT with coexisting iron deficiency anemia and only iron deficiency anemia in pregnancy. Experimental and observational study. This study was conducted at Pathology and Gynae-Obs Out Patient departments of Peoples University of Medical and Health Sciences for Women [PUMHSW] Hospital, Shaheed Benazirabad from February 2013 to February 2014. Total 461 pregnant women with their age ranged between 18 - 42 years including multigravida and primigravida as well as first trimester to second trimester of pregnancy were selected. The family history of thalassaemia and history of cousin marriages were noted. 4ml of anti-coagulated whole blood and 2ml of clotted blood samples were collected from each pregnant women and sent to the pathology department for NESTROFT testing, and later tested for Complete Blood Count [CBC] along with peripheral blood smear stained with Leishman's stained on the 2 to 3 slides as enhanced tool for BTT case finding while estimation of serum Ferritin were done from the clotted blood sample. Screening for BTT was done on Naked Eye Single Tube Red cell Osmotic Fragility Test [NESTROFT] with 0.36% freshly prepared saline. The diagnosis of BTT was confirmed on automated Hemoglobin Electrophoresis at cellulose acetate alkaline pH from the 2ml of clotted blood in NESTROFT positive cases. Out of total 461 pregnant women with their mean age 30 +/- 12, 30 were diagnose with BTT, out of 18 [54.5%] women were married with their cousins, neither the family history of Beta thalassaemia major was present nor husband of any women was carrier of thalassaemia. NESTROFT showed sensitivity, specificity, positive and negative predictive values and efficiency of 84%, 98.6%, 82%, 99% and 93% respectively. The laboratory parameters such as The mean values of hemoglobin g/dl, RBC count millions/cmm, PCV%, MCV fl, MCH pg, MCHC g/dl among these subjects were 11.9 g/dl, 4.5 millions/cmm, 82 fl, 38.7%, 26.9 pg, 33.2 g/dl respectively were showed in cases of BTT and co-existent iron deficiency anemia in pregnancy. Coexistent iron deficiency anemia did not preclude diagnosis of beta thalassaemia major. The prevalence of BTT in pregnant women is 6.5% and NESTROFT is a valuable, cost effective screening test for beta thalassaemia trait in pregnancy with cousin marriage ratio of 54.6%. The significant difference of hematological parameters in BTT alone, BTT coexistence iron deficiency anemia and iron deficiency anemia alone were founded in our study