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Musculoskeletal System


What is it?

The anterior abdominal wall fails to form normally and abdominal contents can push out through the defect into the amniotic cavity. The defect is usually to the right of the cord insertion at the umbilicus.


Several theories exist about failure of normal embryological development that could give rise to the condition, including failure of fusion of the lateral body folds, abnormal involution of the right umbilical vein or disruption of the right vitelline artery.

Causes and risk factors

The cause of gastroschisis is not understood. It is not usually associated with known genetic defects or other congenital anomalies. Possible links to various environmental pollutants have been suggested, including proximity to landfill sitesand certain pesticides.

It is thought that development of the anomaly may be a consequence of vasoconstrictive episodes in early pregnancy. Gastroschisis can affect any pregnancy but known maternal risk factors include smoking; younger age; low BMI; socially disadvantaged groups; substance misuse; use of aspirin and anti-cold remedies.


Gastroschisis can be easily detected at the 20 week scan. 100%  of cases were detected antenatally (2012-2014).

Management and outcome

Vaginal delivery is possible if all is well, though there can be associated intra uterine growth restriction.  Neonatal surgery is necessary soon after birth to replace the bowel in the abdominal cavity. The majority do well but some babies have long term problems with feeding due to bowel wall atresias or thickening.

Patterns and trends

Within Wales

Recent high rates for Wales and the particular cluster of cases in Bridgend County during 2005 mean that gastroschisis has remained under close monitoring by CARIS (see anomalies of concern).  The prevalence in Wales is one of the highest in the world at 5.3 per 10,000 total births. In 2006 prevalence topped 10 per 10,000 total births but has since fallen and in 2014/16 the rate was 4.1/10,000 total births.

Wales compared to elsewhere

European registers generally report rates of around 2 per 10,000 total births although considerable variation exists between reported rates.  Only Mainz (Germany) reports a higher rate through EUROCAT of 6.26 per 10,000 total births.


2021 Gastroschisis Prevalence












Congenital Diaphragmatic Hernia (CDH)

What is it?

This is an abnormal opening in the diaphragm that allows part of the abdominal contents to move into the chest cavity before birth. The contents can compress the lungs and compromise lung development.

What causes it?

If the diaphragm does not close completely at 6 weeks, some abdominal organs can pass into the chest when they return to the abdomen from the umbilical cord at 10 weeks. The cause for this is unknown but there is a recurrence rate of 2%.

Any risk factors?

There is an association with chromosomal disorders particularly trisomy 21, trisomy 18 and deletion of the short arm of chromosome 12.

What about detection?

CDH is often seen at the anomaly scan. CARIS records that 63% were detected antenatally (including all gestations). The hernia is most common on the left with cardiac displacement from left to right. The stomach may be visible next to the heart and the right lung may look compressed.

What about management and outcome?

Early compression of the lungs between 17 and 24 weeks gestation usually predicts the degree of pulmonary hypoplasia. Delivery is best planned in a specialist unit equipped to provide respiratory support. Surgical repair takes place after stabilisation.

The outlook has improved with advances in neonatal intensive care. CARIS reports that 75% of cases survived to the end of the first year of life.


What is it?

This is when the sutures between the bony plates of the skull fuse prematurely. The normal fusion of most of the sutures occurs when the baby is about 2 years of age. Single or multiple sutures can be involved and it may form part of a syndrome with a recognised pattern of anomalies e.g. Apert syndrome.

What causes it?

No clear cause has been found.

Any risk factors?

A review by the Texas birth defects group identified several risk factors:

  • Increasing maternal and increasing paternal age

  • Male gender for sagittal and lambdoidal craniosynostosis

  • Female gender for coronal craniosynostosis

  • Living in urban areas for coronal and lambdoidal craniosynostosis

  • Maternal smoking

  • Maternal use of nitrosatable drugs (some antibiotics, antihistamines, and aspirin)

  • Many craniosynostosis syndromes have a genetic association.

What about detection?

Craniosynostosis alone is not normally detected on ultrasound.

What is the pattern of craniosynostosis in Wales and the world?

The overall prevalence rate of craniosynostosis in Wales is 6.2 per 10,000 total births. In the years 1998 -2016,  94% were live born (368 births). Of these, 65% were isolated cases, 18.4% were cases with multiple anomalies, 7.5% were part of a syndrome and 6.4% were chromosomal/genetic anomalies.

What about management and outcome?

Usually diagnosed in the first year of life, surgery may be necessary to enable the cranium to develop properly. This is also important to prevent raised intracranial pressure and improve appearance. It is performed at one of the designated specialist centres in England usually between 6 and 12 months.

Limb Reduction Defects

What is it?

Upper and lower limb reduction defects occur when a part of or the entire arm or leg of a fetus fails to form completely during pregnancy. This means the limb is reduced from its normal size or is missing.

What causes it?

These defects can occur as isolated or as part of a syndrome. Isolated defects can be caused by the presence of amniotic bands in utero which can cause transverse defects of the limbs. Vascular compromise due to the drugs misoprostol or  phenytoin or the procedure of chorionic villus sampling can cause defects. Teratogens that affect the morphogenesis of the limb include thalidomide, warfarin, phenytoin and valproic acid.

Syndromic limb defects include  Mobius syndrome and aglossia- adactyly syndrome.

Any risk factors?

Mothers using any of the drugs mentioned above are at increased risk. Chorionic villus sampling before 10 weeks gestation has been reported to be associated with the subsequent development of limb defects (ref below). Smoking may be associated but more research on thi is needed.

What about detection?

Visualising the four limbs is on the agreed checklist of the fetal anomaly scan at 20 weeks. This results in good antenatal detection.

What is the pattern in Wales and the world?

The gross rate of limb reduction defects in Wales is 9.6 per 10,000 live births (1998-2016), about 34 per year.

What is the management and outcome?

Good antenatal detection and discussion can prepare parents for birth and ensure early access to orthopaedic services. Outcome is better in isolated cases


Developmental Dysplasia of the Hip

What is it?

The normal anatomy of the hip does not develop properly with an abnormality in the shape of the head of femur, the shape of the acetabulum or the supporting structures around them. This prevents normal close contact of the hip joint. It can be mild (subluxation) or severe when the hip is dislocated with no contact between the head of femur and the acetabulum.

What causes it?

The cause is unknown but thought to have genetic and environmental influences.

Any risk factors?

If the acetabulum is shallow and the surrounding connective tissue is lax the hip is more likely to dislocate. This may explain the increased frequency in females with sensitivity to the relaxing effects of oestrogen. 

The risks are increased if the baby is large or a breech presentation. Vaginal breech delivery poses a higher risk than delivery by Caesarean section. Reduced liquor, first born babies and multiple pregnancy are other risk factors.

Having a sibling with hip dysplasia increases the risk.

What about detection?

This is not diagnosed antenatally but after delivery those babies who had a breech presentation, talipes or spinal abnormality indicate the need for closer attention.

Manual procedures to detect developmental dislocation of the hip include Ortolani’s and Barlow’s test.

If there are risk factors or problems with the manual checks then an ultrasound can confirm the diagnosis.

What is the pattern in Wales and the world?

The rate in Wales is 7.1 per 10,000births(1998-2016), so there are about 28 babies born each year with this condition. Not all will be diagnosed at birth.

What is the management and outcome?

Early diagnosis is important. The longer the hip is left in an abnormal position, the more the anatomy changes thereby increasing the need for surgical correction of the joint. Conservative measures include the Pavlik hip harness or Von Rosen splint. The chances of these working falls significantly after 7 weeks of age.