Screening for haemoglobinopathy--a comparison of two methods in an Irish maternity unit.

Two-pronged retrospective and prospective studies were carried out to compare opportunistic versus systematic screening for carriers of haemoglobinopathy in an Irish maternity unit. Identification was either performed opportunistically on the basis of ethnicity or systematically on the basis of a low mean corpuscular haemoglobin. A comparison was made between the numbers that were tested for haemoglobinopathy and subsequent detection rates. In the prospective study women were identified again on the basis of either ethnicity or a low MCH and all women identified were tested for haemoglobin variants. A comparison was made between the numbers tested and subsequent detection rates. In both studies systematic screening identified similar rates as opportunistic screening. However, opportunistic screening identified a greater absolute number of carriers. Our retrospective study showed a disappointing uptake of testing of those identified, regardless of the method of screening. Better identification of carriers requires that all those identified as at-risk of haemogiobinopathy carriage should be tested, irrespective of the method of screening.