OBJECTIVES. To compare early and late presentations of fetal haemoglobin Bart's disease in the Kowloon West Cluster in Hong Kong, and to find reasons for the re-emergence of late presentations.

DESIGN. Case series with internal comparisons.

SETTING. Two tertiary obstetric units in Hong Kong.

PATIENTS. All cases with confirmed diagnosis of fetal haemoglobin Bart's disease from 1 January 2000 to 31 December 2009.

MAIN OUTCOME MEASURES. Primary outcome: antenatal care in the current pregnancy. Secondary outcomes: clinical presentations, ultrasound features, and pregnancy outcomes.

RESULTS. A total of 59 cases (46 early presentations and 13 late presentations) of fetal haemoglobin Bart's disease were identified during the study period. All the late presentations were identified from year 2003 onwards. Late presentations were significantly associated with non-eligible obstetric patients (69% vs 11%; P<0.001), non-booked status at our antenatal service (62% vs 0%; P<0.001), and unavailability of partner's mean corpuscular volume status (23% vs 0%; P=0.009). Mothers presenting late were more likely to have symptoms or signs (85% vs 0%; P<0.001) and to suffer from gestational hypertensive disorder (54% vs 0%; P<0.001). Ultrasound features of these pregnancies included cardiomegaly (94%), placentomegaly (98%), and hydrops fetalis (77%). All pregnancies presenting early were either legally terminated or miscarried. The perinatal mortality in late presentations was 85%.

CONCLUSION. The re-emergence of late presentations of fetal haemoglobin Bart's disease after 2003 was related to influx of non-eligible obstetric patients without proper antenatal screening and diagnosis of thalassaemia. Maternal low mean corpuscular volume and characteristic prenatal ultrasound features such as cardiomegaly, placentomegaly, and hydrops fetalis are useful for detecting affected pregnancies in this group of patients. Better education of both patients and doctors is necessary to explain the importance of early diagnosis of the disease and the seriousness of complications due to late presentations, so as to reduce undesirable maternal and perinatal outcomes.

Key words: alpha-Thalassemia; Congenital abnormalities; Hemoglobins, abnormal; Hydrops fetalis; Prenatal diagnosis

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