Chapter 48 Congenital anomalies, fetal and neonatal surgery, and pain
Introduction
Congenital anomalies are defects/abnormalities present at birth, occuring in approximately 2–3% of babies (Boyd et al 2005, ONS 2010). Congenital abnormality is distinguished as:
Congenital anomalies can affect any part of the body; and can be major, for example a congenital heart defect such as Fallot’s tetralogy, through to minor, such as an extra digit or tongue tie. Minor anomalies are usually only registered if they are associated with other major malformations or syndromes (EUROCAT 2009). The focus of this chapter is the registered anomalies and syndromes; for more minor anomalies, see website.
Registration of anomalies and syndromes
Ever since rubella and thalidomide were discovered as powerful teratogens, various worldwide registries have been set up to facilitate research and surveillance concerning environmental causes of congenital anomalies (Misra et al 2006). These include:
Antenatal anomaly screening
Ultrasound scan screening for fetal anomalies has been fully integrated into antenatal care, but ultrasound scans have their limitations and hold no guarantee that all anomalies may be identified (see Ch. 33); in a small number of cases, babies are born with abnormalities. It is vital that midwives take a detailed medical, family and obstetric history at antenatal booking in order to identify risk factors for specific diseases and facilitate genetic counselling and appropriate investigations.
It is also essential the midwife carries out a thorough initial examination of the newborn at birth because some anomalies need to be investigated and dealt with immediately (see Ch. 41).
Antenatal screening enables greater parental choice as ultrasound scanning can identify:
Midwives should ensure that women get the opportunity to discuss fully the risk factors, possible results, implications, prognosis and management options for any condition with the appropriate health professional prior to further screening to ensure informed consent is given (NICE 2008, UKNSC 2007).
Aetiology
Whilst the cause of many congenital anomalies remains unknown, there are some known factors:
Genetic factors
Each human cell has a total of 46 chromosomes arranged in 23 pairs, one of the pair from each parent (see Ch. 26). Every chromosome carries a unique blueprint of its parent’s characteristics in the form of genes. There are two sex chromosomes (X from the mother and either X or Y from the father); the remainder are called autosomes.
Genes may be dominant or recessive:
The incidence of complex abnormalities is also increased with certain maternal diseases, such as unstable diabetes (Farrell et al 2002) and phenylketonuria.
Teratogenic factors
Examples of well-documented teratogens are:
Central nervous system anomalies
Spina bifida
There are three main types of spina bifida:
Anencephaly
The vault of the skull is absent with almost no development of the exposed brain. The baby has large protruding eyes and wide shoulders, the face presents during labour and polyhydramnios is found in about 50% of cases. Second trimester screening for abnormally elevated maternal serum alpha-fetoprotein and low oestriol concentration, has been cited as highly predictive of lethal defects, particularly anencephaly (Benn et al 2000). This condition is incompatible with life and many parents may opt for termination of pregnancy. Parents who decide to continue with the pregnancy need ongoing support, especially during labour and birth.
Whether or not parents see the baby at birth is a matter for them to decide but it has been recognized that this may assist with the grieving process and helps in understanding the nature of the abnormality; also, in reality, the baby may not look as the parents imagined (see Ch. 70). The baby should be carefully wrapped before showing the infant to the parents and the midwife should establish whether the mother wishes to hold the baby rather than just look. Not all women will initially want to hold the baby but may want to do so later and this should be accommodated. If the baby is born alive, he or she will be nursed in the Special Care Baby Unit. These babies usually do not survive more than a few days.
Microcephaly
Microcephaly is defined as a very small vault to the skull, and may be either:
These babies are usually mentally impaired and there is a high association with other abnormalities.
Abnormalities of the respiratory system
Diaphragmatic hernia
This condition develops as the result of a defect in the formation of the diaphragm, usually on the left side. The bowel and abdominal viscera herniate through the diaphragm and continue to develop in the thoracic cavity. These organs compress the developing lung and can result in pulmonary hypoplasia (Jesudason et al 2000).
This abnormality may be identified by early ultrasound scanning. Prenatal counselling should prepare parents for high mortality and morbidity rates – only approximately 50% of affected babies survive. Open fetal surgery has been carried out for this condition but carries significant risk to both mother and fetus; the development of fetoscopic surgery has improved outcomes and is considered to be the way forward (Nelson et al 2006).
Abnormalities of the alimentary system
Cleft lip and cleft palate
The cause of cleft lip and/or palate remains largely unknown. The majority are believed to have a multifactorial aetiology including genetic and environmental factors. Cleft lip and palate is also associated with other syndromes, including trisomy 13 and 18 and fetal alcohol syndrome (Hodgkinson et al 2005). There is often a family history of such abnormalities, and prenatal genetic counselling should be offered in such cases.
A cleft lip can look disfiguring, but the midwife can reassure parents that these can now be repaired extremely skilfully. Feeding problems frequently occur, often related to the baby being unable to form a seal around the nipple or teat. Breastfeeding is not impossible and should be encouraged and assisted wherever possible, with referral to a lactation specialist (see Ch. 43).
In the past, because of concern about speech function, repair would be undertaken during the neonatal period; it is now recommended that lip repair takes place at 3 months and palate repair at 8 months of age (Hodgkinson 2005).
