Congenital abdominal wall defects in the United Kingdom

Editor—Stone et al have a very different view from ours of abdominal wall defects in our regions (former South East Thames and North West Thames).¹ As they acknowledge, the cited rates for abdominal wall defects were derived from sources with different reporting patterns. In particular, the rates quoted for England and Wales were from data from the Office for National Statistics,² which take no account of terminations for abnormalities diagnosed prenatally, whereas the Glasgow and northern England registers have tried to be comprehensive.

More appropriate north-south comparisons could have been achieved from the rates reported by individual regional registers such as those in the former South East Thames and North West Thames regions. These registers obtain data in a similar manner to the northern regional registers, with active data collection from multiple sources and inclusion of terminations and stillbirths. The table shows the data for abdominal wall defects from the South East Thames and North West Thames registers in 1992-6. These data confirm a higher incidence of abdominal wall defects in the south of England than that quoted by Stone et al. Consequently, the gradient hypothesis is not supported when comparable data are used. The apparent excess of exomphalos in Scotland does not distinguish between cases with isolated exomphalos and those with multiple defects or inherited syndromes, which may have completely different causes; it is therefore inappropriate to speculate on possible causal factors for all defects.

What Stone et al’s study does show, however, is the need for fully funded comprehensive regional registers for congenital malformations, which take account of the changes in perinatal practice and the frequent fragmentation of prenatal and postnatal tertiary services. The data derived from the Office for National Statistics are an exhaustive attempt to ascertain incidence on a national level but cannot be seen to be as efficient as data from regional registers.³ Until a national network of comparable registers is achieved, information derived for planning and public health issues will be seriously flawed at best and at worst misleading.

Table.

Incidence of abdominal wall defects according to former South East Thames and North West Thames registers, 1992-6

	South East Thames			North West Thames			Both regions
Abdominal wall defect	No of cases	Incidence		No of cases	Incidence		No of cases	Incidence
Total No of births and terminations*	252 462	—		237 614	—		490 076	—
Exomphalos	63	2.5		108	4.55		171	3.5
Gastroschisis	67	2.8		49	2.06		116	2.37
Abdominal wall defects	130	5.15		157	6.61		287	5.86
Ratio of gastroschisis: exomphalos	1:0.9	—		1:2.2	—		1:1.47	—

Incidence per 10 000 total births ^*Includes live births, still births, and terminations.