title: Epidemiology of Omphalocele and Gastroschisis in Glasgow
Creators: name: Rimaz, Shahnaz
Publisher: name: University of Glasgow
Year: 1997
Subjects: subject: Epidemiology.

description: Omphalocele and gastroschisis (O&amp;G) are relatively common congenital anomalies. Omphalocele (or exomphalos) is defined as herniation of some intra-abdominal contents through the umbilical ring in to the cord. This defect has a membrane over it, and may contain abdominal organs. Gastroschisis is defined as a full-thickness defect in the abdominal wall without herniation or a covering membrane. The aetiology of omphalocele and gastroschisis is still in doubt. Epidemiological studies suggest that the cause of these defects might be multifactorial, but hypotheses relating to gastroschisis have focused more on environmental factors. This study reports descriptive and case-control epidemiological findings from an investigation of abdominal wall defects in Greater Glasgow Health Board, Scotland, United Kingdom between the birth years 1980 and 1993. All registered cases (live births, stillbirths and induced abortions following prenatal diagnosis) of O&amp;G, primary and secondary were included. The aims of the study were, firstly, to establish the epidemiology of O&amp;G in Glasgow; secondly, to determine the extent of any association between the prevalence of O&amp;G and a number of the hypothetical risk factors, particularly maternal age, cigarette smoking, and socio-economic status; thirdly, to assess the extent and epidemiological impact of prenatal diagnosis on the prevalence of O&amp;G. During 1980-1993, 73 cases of omphalocele (4.1 per 10,000 births) and 24 cases of gastroschisis (1.3 per 10,000 births) were registered. The pregnancy prevalence of gastroschisis (but not omphalocele) showed a significantly increasing trend over time. The prevalence rate of omphalocele in Glasgow appears to be the highest in the United Kingdom. The male to female ratio was 2.0 for gastroschisis and 0.8 for omphalocele. The risk of gastroschisis was inversely correlated maternal age (chi-square= 8.8; p&lt;0.003). The highest rate was found for maternal age under 20. There was a greatly increased risk for young mothers of isolated gastroschisis (under 20 years) compared to those aged over 20 years; these young mothers were 7.8 times more at risk (95% CI= 3.08 to 19.79). In the case-control study, age remained a significant risk factor in the multivariate analysis. The prevalence of the two malformations showed no significant seasonal variation, nor a strong and consistent association with socio-economic status, as determined by postcode of maternal residence. Both defects were associated with early birth and low birth weight, an effect that was more pronounced for multiple malformed than for isolated cases. Isolated cases of gastroschisis had significantly lower birth weights than isolated cases of omphalocele. There was a significant association of omphalocele with other malformations (p&lt; 0.0001). The most common abnormalities among O&amp;G were musculoskeletal anomalies (26%), genital and urinary abnormalities (15%), neural tube defects (13%), and GI in the upper alimentary tract (13%). Omphalocele was also associated with trisomies 13, 18 and Beckwith-Wiedemann syndrome. The percentage of smokers in isolated cases of gastroschisis was significantly higher than that in associated cases (Fisher's exact test, two tailed = 0.01). In the case-control study, after logistic regression smoking remained a significant risk factor among gastroschisis cases compared to non-malformed controls (RR= 3.8, 95% CI =1.16 to 12.45) and malformed+ non-malformed controls (RR= 2, 95% CI =1.12 to 3.4). The length of survival during first week and first year was significantly longer among infants with gastroschisis than omphalocele (p=0.005 up to first week; p=0.001 up to one year). Perinatal deaths were more frequent among omphalocele cases than gastroschisis (p=0.09). While the proportion of gastroschisis prenatally diagnosed significantly increased fi-om 1980-1986 to 1987-1993 (Fisher's exact test=0.01), the proportion terminated did not. Although the proportion of omphalocele prenatally diagnosed non-significantly increased in that time, the proportion of prenatally diagnosed cases that were terminated showed a non-significant decrease. Although the numbers of cases are small, this study has highlighted several epidemiological features of O&amp;G that could be important aetiologically. A comprehensive public health strategy, including antenatal screening, is probably required to prevent these anomalies.