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About CARIS - Maternity and neonatal screening in Wales

The Congenital Anomalies Register and Information Services (CARIS) for Wales was established in 1998 within Public Health Wales, for gathering data on congenital anomalies in all Welsh births. A congenital anomaly is defined as any structural or functional anomaly that has developed inside the uterus. Diagnosis can be during the antenatal period, at birth, infancy, or childhood.

In Wales, a standard antenatal and postnatal screening program is in place for the detection of chromosomal and congenital problems in pregnancies. Specialist care for the confirmation and the diagnosis is offered via fetal medicine units.

  1. A booking for all antenatal women is made through community midwives at around 9-10 weeks of gestation, as per last menstrual period date.
  2. Routine booking of bloods including full blood count, viral infection screening in high-risk mothers with haemoglobinopathies (blood diseases) and sickle cell disease are offered at 11 weeks of pregnancy. In cases where women are carriers of haemoglobinopathies or sickle cell disease have been confirmed, further testing with partners is offered.
  3. Where mothers are 11-14 weeks of gestation or more, a patient can have combined screening with Nuchal Translucency (NT) measurement.
  4. If the patient presents to a midwife later in pregnancy (14 to 18 weeks’ gestation) they will be offered NT screening as part of Quad testing.
  5. NIPT (Non – invasive Pre-natal Testing) is offered for high-risk mothers who have been identified through NT screening and combined test, or through their Quad screening results.
  6. Rhesus negative mothers around 16 weeks of gestation are offered a blood test “cell free fetal DNA (cffDNA) to find out baby’s blood group whether it is negative or positive.
  7. A detailed anomaly scan is performed at 18-20 weeks of gestation.
  8. Glucose tolerance testing (GTT) is provided for previous GDM (Gestational diabetes mellitus) mothers at 16 weeks’ gestation and for the high-risk mothers at 28 weeks.
  9. Growth scans for high-risk pregnancies are performed every 3 weeks from the detection of problem or from 28 weeks onwards.

Antenatal Detection

Information on congenital anomalies detected during the antenatal period is contained in the documents linked to above.

All pregnant women in Wales are offered the same antenatal screening programme which consists of  seven blood tests and two ultrasound scans. The two ultrasound scans offered through the Antenatal Screening Wales programme are the ‘early pregnancy ultrasound scan’ and the ‘fetal anomaly scan’.  These scans are often a pleasurable experience for women as they offer a chance to see their baby moving and developing.  However occasionally these scans will identify a problem with either the mother or the baby.

The early pregnancy ultrasound scan is offered to determine viability, the gestational age and to detect multiple pregnancies. Some fetal anomalies may be detected, but this is not the primary purpose of this scan. The purpose of the fetal anomaly ultrasound scan is to detect significant fetal anomalies that are likely to have an adverse effect on the health of the mother or baby, and for which an effective intervention is available and warranted. Anomalies can also be detected on scans which take place later in pregnancy. The CARIS data  on antenatal ultrasound detection includes cases detected at any of the scans which take place during the pregnancy.

For some conditions, preventive treatment is available during the antenatal period or after delivery to improve the baby’s health. For other conditions, while the condition can be identified by ultrasound scanning , no preventive treatment is available. In such cases, women can then make an informed decision about whether they wish to continue with the pregnancy.

An antenatal anomaly will be notified to CARIS by the ultrasonographer at the time of detection. This has enabled CARIS to estimate the detection rate in certain conditions.   Changes to the Radiology Information System (RadIS) reporting module used by ultrasonographers has made reporting easier and quicker.  Roll out of the updated RadIS II system has been achieved in all hospitals in Wales except one.

CARIS works closely with staff in health boards so that antenatal ultrasound outcomes can be audited and those cases not detected can be reviewed by radiology departments. CARIS also works closely with Antenatal Screening Wales in monitoring detection rates. CARIS data shows that for many conditions there has been continual improvement in the detection of anomalies over the last 17 years. For more easily identified anomalies, such as anencephaly or spina bifida, high levels of detection have been maintained across the whole of this period.

The detection of cardiac anomalies in the antenatal period has improved dramatically from a very low base, so that now Wales has the best detection rates in the UK for cardiac anomalies. This means that now around four to five babies each year are saved that previously would have died before treatment could be given. 

Postnatal Detection

The postnatal checks on baby after delivery include:

A NIPE (Newborn and Infant Physical Examination) takes place within 72 hours of birth and forms part of the wider systemic checks. These tests aim to identify any anomalies of the heart, eyes, ears, palate, hips, and genitalia.

This is usually followed up with another examination, 6 to 8 weeks after delivery at the local GP surgery.

Newborn bloodspot screening

Newborn bloodspot screening detects rare but serious diseases, which respond well to treatments when identified early leading to an improved quality of life.

The screening test is performed between day five and day eight of life and is part of routine postnatal care. The test picks up a few diseases that are recorded by the CARIS team, such as

Phenylketonuria, Homocystinuria or Cystic Fibrosis. More details can be found on the Newborn Bloodspot Screening Wales website.

Newborn hearing screening

One or two babies in every 1,000 are born with a hearing loss that may affect the development of their speech and language. Newborn hearing screening was introduced in Wales in March 2003 and is usually carried out during a baby’s first week of life. CARIS records incidence of babies born with congenital hearing loss. More information is available from the Newborn Hearing Screening Wales website.

CARIS Data

CARIS works closely with antenatal screening Wales, cytogenetic department, fetal medicine units, antenatal radiographers, delivery suites, neonatal and paediatric units for data gathering. There is robust system in place for reporting cases including both electronic and paper notes. When the case is reported to CARIS, it is further validated through Welsh clinical portal and through contacting clinicians if there are any doubts for correct information.

The International Coding for diseases (ICD) version 10 is used for classifying the congenital anomalies. This coding is compatible with other international congenital anomaly registers like EUROCAT and ICSBDR (International Clearing House for Birth Defects Surveillance and Research). CARIS exchanges data with EUROCAT and ICSBDR to aid international comparisons and surveillance

CARIS has data from 1998 onwards. Such an extensive dataset makes it possible to look at long-term trends and enables clinicians to obtain better information on the Welsh population for rare cases, which can help both parents and clinicians.

Page last reviewed: 19th August 2026