Neural tube defect diagnosis and outcomes at a tertiary South African hospital with intensive case ascertainment.

Background: Neural tube defects (NTDs) are an important category of birth defect, but surveillance remains inadequate in South Africa.

Objectives: To assess the identification of NTDs at a tertiary hospital using a range of prenatal, perinatal and postnatal data sources, and to estimate the impact of prenatal diagnosis and birth prevalence for the referral area.

Methods: Cases of anencephaly, encephalocele and spina bifida (SB) in a 6-year period were retrospectively identified from 5 data sources covering prenatal, perinatal and postnatal care. These were cross-correlated to avoid duplicate entries and to determine the contribution of different data sources. Details of prenatal diagnosis and termination of pregnancy (TOP) were obtained for 10 years, and birth prevalence over 2 years.

Results: During a 6-year period 195 NTDs were identified at a Western Cape Province tertiary hospital. These included 59 (30%) cases of anencephaly, 28 (14%) of encephalocele and 108 (55%) of SB. The majority of NTDs (71%) were detected prenatally, although SB was less commonly diagnosed prenatally than cranial defects (56% v. 88%; p<0.001). Of SB cases ascertained pre- or postnatally, 57% of patients were born alive and 50% discharged alive, but 72% of survivors had not been diagnosed prenatally. Women receiving prenatal diagnosis of any type of NTD before 24 weeks' gestation were nearly always offered TOP, and the majority accepted termination after non-directive counselling. For SB, later prenatal diagnosis was associated with much lower termination rates because the option was less often offered (51% v. 100%; p<0.001), and perhaps less often accepted (57% v. 78%; p=0.06). The estimated NTD birth prevalence for the referral area was 0.76 - 0.80 per 1 000 live births, but perhaps up to 1.18 per 1 000 when considering under-referral of lethal cranial lesions from rural areas.

Conclusions: A substantial number of NTDs can be ascertained from a tertiary hospital environment if multiple data sources are used, even though adding data from the Perinatal Problem Identification Program for outlying health facilities increases detection of lethal defects. Hospital-based surveillance can be considered, especially for SB. Prenatal diagnosis was fairly common and pregnancy termination was often offered and accepted if detected before 24 weeks' gestation. A regional prenatal ultrasound programme, predominantly based in primary care but with ready access to a tertiary centre, can be quite effective, although limited or delayed access to prenatal diagnosis must be addressed.