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Anomaly Data
Regional data: geographical anomaly data based on postcode of pregnancy is provided for the South West Region. All anomalies and births for Dorset and South Wiltshire have been removed as these areas are covered by the WANDA Register (Wessex Clinical Genetics Service). Anomalies and births for one hospital have also been omitted to avoid rate distortion as they did not commence notification until late 2005.
Regional data is available to everyone as rates and percentages (see “South West Region data for public access” below). Regional data is also available as real numbers of cases and totals, to people who have been supplied with a password to access their hospital data (see “South West Region and hospital data for authorised persons” below).
Hospital data: anomaly data based on booking hospital is provided for each of the major 14 reporting hospitals. As this data is hospital based it will include some cases with postcodes outside our boundaries.
Anomaly group data last updated: November 2011.
South West region and hospital anomaly data for the years 2002 – 2010 is included in the tables below.
More information about the data and status of anomalies
South West Region data for public access |
South West Region and hospital data for authorised persons |
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Contact SWCAR to get the password. |
Strategic Health Authority web site
South West Strategic Health Authority
Data and the status of anomalies
Data by Anomaly Groups: total cases
The anomalies have been divided into common groupings in line with classifications used by our neighbouring anomaly register CARIS. Only confirmed or probable anomalies have been included. CASES are counted for a given anomaly group. Where a case has more than one anomaly in a given group it is only counted once. Where a case has anomalies in different anomaly groups within a body system it will be counted in each group but only once in the overall total for the body system and only once in the total for All Cases.
Rates
Rates quoted are the Total Prevalence Rate or Gross Rate per 10,000 registered births (livebirths and stillbirths). Cases ending in live or stillbirth, termination of pregnancy or spontaneous fetal loss are all included in the numerator but only livebirths and stillbirths are included in the denominator.
For the Region, the numbers and rates for Livebirth cases only are also given. The Livebirth Prevalence Rate is the rate of liveborn cases for a particular anomaly per 10,000 Livebirths in the region. Only cases ending in a livebirth are included in the numerator. Only livebirths are included in the denominator.
Allocation of cases/anomalies to Years
The years refer to the date when the pregnancy ended (DEP) or, if this is not known, the date the pregnancy was expected to end (EDD). All numbers and rates for 2005 include pregnancies that ended between 01/01/2005 and 31/12/2005 and pregnancies where the DEP is not known but the EDD was in 2005.
Regional Data
The SWCAR Region shares the boundaries of the new South West Strategic Health Authority created in July 2006. This incorporates the old strategic health authorities: Avon Gloucestershire and Wiltshire; South West Peninsula and Dorset and Somerset.
The Wessex Clinical Genetics Service, WANDA covers Dorset and South Wiltshire which are within the South West Region. SWCAR have removed all anomalies and births from these areas to avoid duplicate reporting. As our regional data is population based any cases with South Wiltshire and Dorset postcodes are not included. This does mean that some cases notified from Yeovil hospital are lost from our regional data.
We have a small number of under-reporting hospitals within our region. In order to avoid distortion of numbers and rates the anomalies and births for these hospitals have been removed from the data. This only affects the regional data.
Data for the region is population-based. Only cases with postcodes in the region or SHA are included. Wherever possible this is the known pregnancy postcode but in some cases we are given an unspecified address and cannot be certain that the mother was at this location in early pregnancy.
We hope to gain anomaly notifications for residents who deliver outside the geographic boundaries from neighbouring anomaly registers. However case ascertainment is unlikely to be complete.
Hospital Data
Hospital data is based on the Booking Hospital rather than the hospital where the pregnancy ended. Thus a pregnancy booked at Hospital A but referred to Hospital B for delivery will appear in the data for Hospital A.
There is a significant transfer of high-risk pregnancies towards tertiary units. For a high risk unit this results in increased birth rates compared to bookings, for referring hospitals this results in lowered birth rates. Anomaly rates based on Booking Hospitals will be affected accordingly.
Tertiary units are likely to have higher anomaly rates due the increased proportion of high risk pregnancy bookings including early referrals from out of area.
Coding of anomalies:
The anomalies have been coded using the World Health Organisation ICD-10 classification of diseases. Wherever possible we use the Paediatric Adaptation of ICD-10 developed by the Royal College of Paediatrics and Child Health in 2002. This allows for more precise coding of the Q-chapter within ICD-10 dedicated to congenital anomalies. For further information use the link below to access the WHO site:
World Health Organisation International Statistical Classification of Diseases (web site)
Status of Anomalies
Reported anomalies are given a status depending on how much detail has been provided and on the reliability of the source. Each anomaly is classed as confirmed, probable or suspected.
Confirmed anomalies
We have details of the test confirming the anomaly or we consider the source to be sufficiently reliable. We confirm some anomalies, such as anencephaly and renal agenesis, antenatally when reported by fetal medicine specialists.
Probable anomalies
We consider these anomalies to be likely but do not have full diagnosis details. Most of these anomalies have been reported by IT departments. We hope to obtain follow up details to confirm anomalies reported in this way.
Suspected anomalies
Anomalies remain suspected when they are reported antenatally but we receive no follow up at birth. Some conditions reported by IT departments or notified with insufficient details will remain suspected until further confirmation is provided.
Notes on particular anomalies:
Hydronephrosis (Dilated renal pelves)
These cases are only confirmed if the condition persists postnatally, verified by renal ultrasound. They are only included in the renal anomaly data if the measurements are 10mm or over at any time. Where the dilatation is mild (5-9mm) the data is collected by SWCAR but reported on separately, see below.
Undescended Testes
Not included in genital anomaly group. Large numbers reported and the register is unable to follow up cases to verify whether the problem persists or resolves.
Hypospadias
This uro-genital anomaly is classified in SWCAR data as a Genital anomaly from 2007 (previously under Urinary)
Exclusion list
SWCAR exclusion list The European Register EUROCAT introduced an extended exclusion list in January 2005. This has now been adopted by SWCAR. Data publication from 2007 excludes any anomaly on the EUROCAT exclusion list.
Anomalies on the exclusion list are NOT added to the database if they occur as isolated anomalies. We do record them on the database as additional background information if the case has additional significant anomalies in line with other UK register practise but we do not count them in data numbers or rates.
This change has had a particular impact on the following anomaly groups and body systems:
Eye/Ear: no longer contains epicanthic folds, hypotelorism, minor ear anomalies
Respiratory no longer includes laryngomalacia, tracheomalacia, laryngeal stridor
Digestive no longer includes pyloric stenosis
Urinary no longer includes hypospadias (now classed as Genital)
Musculoskeletal no longer includes hernias (see below)
Blood, Immune and Lymphatic no longer includes lymphangioma, haemangioma
For our own purposes SWCAR have decided to continue collection of the following anomalies on the EUROCAT exclusion list:
- Inguinal hernia
- Pyloric stnosis
- Mild hydronephrosis 5-9mm
- Vesico-ureteric reflux
- Other branchial cleft malformations
- Café au Lait spots
- Balanced translocations
- Congenital subluxation of hip
The anomaly numbers and rates for these anomalies are provided separately at the bottom of each table but not included in the overall data numbers/rates.
Notes on Anomaly Inclusions
For any given case we list ALL anomalies reported to SWCAR. This means that in a case of Down’s Syndrome we include all the features and additional anomalies notified. This case will then appear in several anomaly groups: chromosomal; eye/ear (epicanthic folds and low set ears) and , in some cases cardiac if a heart anomaly is reported. No case is counted more than once in a given group.
If a condition is known to be secondary to another anomaly we do not include it in the numbers/rates. Examples include: Pulmonary hypoplasia secondary to renal anomalies; PDA in ductus-dependant cardiac cases; PDA or other complication of prematurity.
Termination for Fetal Anomaly
Wherever possible we aim to gain post-mortem verification of antenatally diagnosed anomalies where the pregnancy is terminated. This is not always possible: consent for post-mortem is not always given and problems can arise with service provision. Treating all such cases as confirmed risks over-reporting of anomalies. Holding these cases as suspected risks under-reporting. The working compromise is to confirm anomalies that can be reliably identified antenatally and those reported by fetal medicine or cardiology specialists. In some cases a general anomaly code is allocated where it is clear that an anomaly is present but detailed diagnosis is not possible.
Case Ascertainment
SWCAR receives reports of congenital anomalies from multiple sources: Antenatal clinics, Fetal Medicine units, Maternity units, Neonatal units, Paediatricians, Physiotherapists, hospital inpatient data from IT Departments, Cytogenetics, Clinical Genetics.
Complete ascertainment is difficult to achieve and relies on workable reporting methods, the hard work of reporting clinicians around the region, and responding to changes in hospital systems and staff as effectively as possible. However, there is scope for fluctuations in reporting to lead to minor fluctuations in the data, although every effort is made to minimise this. Follow-up is sought wherever possible and SWCAR strive to establish new reporting sources, especially in the post-neonatal period to overcome under-notification of conditions diagnosed at a later stage.
Validation Procedures
Great care is taken to avoid duplication. Available identifiers for mother and/or baby are carefully checked against the database each time a new source of information is received. Regular duplicate checks are run using unique identifiers such as NHS number, Hospital number or combinations of other identifiers.
One source of duplication arises where an anomaly is reported antenatally but no outcome is reported. The same baby can then be notifed by a postnatal source providing no matenal details . To avoid such duplication we try to follow up unknown outcomes and obtain maternal details on postnatally reported cases. We also run checks for cases with the same date of end of pregnancy with duplicate anomalies.
Birth rates
All birth rates used by SWCAR to calculate Anomaly Rates are available on request.
The birth rates for Regional and SHA data are based on Office for National Statistics (ONS) published rates of livebirths and stillbirths. They are available on the ONS website or from SWCAR. These have been adjusted to remove non-reporting hospitals.
Thus the hospital-based birth rates for non-reporting hospitals have been deducted from the population-based ONS birth rates. This method was chosen as population based birth rates are not available from individual hospitals and use of regional hospital based birth rates leads to distorted SHA birth figures due to transfers to tertiary units.
The birth rates for Hospital data have been obtained from Information Analysts or Midwifery Managers in each unit.
We have not yet established reliable sources in all units for rates of termination, termination for fetal anomaly and spontaneous fetal loss. These will be required for publication of more detailed anomaly rates in the future. Alternative sources are being investigated.
South West Congenital Anomaly Register
Institute of Child Life and Health
Level D, St Michael's Hospital
Southwell Street, Bristol BS2 8EG
Tel: 0117 342 5142
Fax: 0117 342 5154
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