Due to the dynamics of testicular descent, the true birth prevalence of cryptorchidism can only be known after the first year of life. Previous epidemiological studies have reported widely varying estimates of birth prevalence,1,15,16
probably reflecting challenges in case ascertainment. However, it is difficult to compare rates due to the inconsistency in methodology and inclusion criteria used both nationally and internationally. Within the north of England, there was no existing structured data capture system for cryptorchidism and hypospadias. However, we constructed such a dataset from the routinely collected HES database.
Cases of true undescended testis and hypospadias were estimated by assuming that only true undescended testis and the clinically significant cases of hypospadias would be operated on. Close examination of the dataset showed that there were minimal missing values and contradicting variables, and so it appeared to be of high quality.
The birth prevalence for cryptorchidism seen in this investigation is higher than the rates previously reported in England and Wales between 1981 and 198315
and is also higher than that in the recent report by Carbone and colleagues in Italy.16
The orchidopexy rate was 1.1 per 1000 male population aged 0–14 years. This is slightly lower than previously published data from Great Britain between 1992 and 1998. Toledano et al
had reported the rate in the northern and Yorkshire region as 1.4 per 1000 male population aged 0–14 years in 1998.17
The rate of surgical corrective procedures for cryptorchidism was therefore decreasing in trend. As suggested by a previous report, as orchidopexy rate is a marker of the actual prevalence of undescended testis,17
this may indicate a real decrease in cryptorchidism. However, it must be acknowledged that the apparent decline in prevalence could be due to a trend towards less intervention in equivocal cases of undescended testes.
The birth prevalence for hypospadias (3.1 per 1000 male live births) was lower than that reported by Ahmed and colleagues.18
The Northern Congenital Anomaly Survey considered a combination of hypospadias and epispadias and also used total births as denominator. Between 1992 and 1997, for both conditions the Northern Congenital Anomaly Survey reported a rate of 0.8 per 1000 live and still births.19
However, the comparability of findings is made difficult due to inconsistencies in the denominator data used. In addition, most of the previous estimates have been based on total births rather than male live births. There are also differences in inclusion criteria across many registries for hypospadias as reported by the European Surveillance of Congenital Anomalies (EUROCAT).20
It is difficult to determine whether or not the milder form of hypospadias was included in the registries and the prevalence estimates.
The trend of corrective procedures for hypospadias appears not to show any temporal change across the entire study period. Assuming that mostly clinically significant forms of hypospadias will have been operated on, and that the indications for surgery have remained unchanged over the study period, there is no evidence of an increase in the birth prevalence of clinically significant cases of hypospadias in the region. It has been previously been reported from earlier studies in different parts of Europe that there were increasing trends for both cryptorchidism and hypospadias. However, it is possible that much of this increase can be explained by improved ascertainment in recent years.1
The aetiology of these conditions remains poorly understood, although a number of previous studies have examined potential aetiological factors. Exposure to environmental endocrine disruptors is the most popular theory; an oestrogenic effect is suggested to be involved as it interferes with the feed‐back mechanism of sex hormones in the pituitary gonadal axis during the fetal period. Mothers may be exposed to endocrine disruptors through inhalation, through the skin, or ingestion via food and water. They may also come into contact with these chemicals in the workplace.21
Low birth weight has also been linked with the occurrence of cryptorchidism and hypospadias.22,23,24,25,26
There is also strong evidence of hereditary or familial factors being involved. The risk of siblings also having hypospadias is about 4.2%.27
In conclusion, the HES data were of high quality for the study period. Data on correctional procedures were used to assess prevalence trends. There did not appear to be any change in the prevalence of hypospadias. There was a possible decline in the prevalence of cryptorchidism which may be due to a real decrease in disease prevalence or a decrease in interventions in equivocal cases during the study period. Further research should include a prospective study to confirm the continuing high quality of the HES data.
What is already known on this topic
- There is controversy as to whether there is an increasing birth prevalence of cryptorchidism and hypospadias.
- Complete datasets of these anomalies are rare because their construction is difficult, with reported trends often hard to interpret due to incomplete ascertainment and varying inclusion criteria.
- Comparison of rates between studies is made difficult by inconsistent choice of denominators.
What this study adds
- Taking correctional procedures into account there did not appear to be a significant change in the prevalence of hypospadias.
- There was an apparent decline in prevalence of cryptorchidism which may be real or may be due to a decrease in interventions.