1.4 Congenital Anomalies - Definitions

Box 1.1. Selected external major congenital anomalies
  • Anencephaly
  • Cleft lip
  • Cleft palate
  • Cleft palate with cleft lip
  • Craniorachischisis
  • Encephalocele
  • Exomphalos/omphalocele
  • Gastroschisis
  • Hypospadias
  • Iniencephaly
  • Reduction defects of upper and lower limbs
  • Spina bifida
  • Talipes equinovarus/clubfoot

Congenital anomalies comprise a wide range of abnormalities of body structure or function that are present at birth and are of prenatal origin. For efficiency and practicality, the focus is commonly on major structural anomalies. These are defined as structural changes that have significant medical, social or cosmetic consequences for the affected individual, and typically require medical intervention. Examples include cleft lip and spina bifida.

Major structural anomalies are the conditions that account for most of the deaths, morbidity and disability related to congenital anomalies (see Box 1.1). In contrast, minor congenital anomalies, although more prevalent among the population, are structural changes that pose no significant health problem in the neonatal period and tend to have limited social or cosmetic consequences for the affected individual. Examples include single palmar crease and clinodactyly.

Major anomalies are sometimes associated with minor anomalies, which might be objective (e.g. preauricular tags) or more subjective (e.g. low-set ears). Box 1.2 represents selected external minor congenital anomalies frequently captured by different surveillance systems, but only when associated with any of the major anomalies under surveillance. For a more detailed listing of minor anomalies, please refer to Appendix B.

When establishing a new congenital anomalies surveillance programme, the initial anomalies that are included can be limited to structural anomalies that are readily identifiable and easily recognized on physical examination at birth or shortly after birth. The list may vary, depending on the capacity and resources of the health-care system and surveillance programme, but typically includes major external congenital anomalies. Examples include:

  • orofacial clefts,
  • neural tube defects, and
  • limb deficiencies.

In contrast, detecting the vast majority of internal structural anomalies (e.g. congenital heart defects, intestinal malrotation and unilateral kidney agenesis) requires imaging techniques or other specialized procedures that may not be available consistently. In some cases, internal anomalies have external manifestations that allow the observer to suspect a particular diagnosis, as is the case with the urethral obstruction sequence.

Classification by developmental mechanism or clinical presentation can be important in surveillance, because the same congenital anomaly can have different etiologies. Also, the distinction may be important both clinically and in etiological studies. Please refer to Appendix C for more information about the causes of congenital anomalies and their classification according to developmental mechanism and clinical presentation.

Box 1.2. Selected external minor congenital anomalies
  • Absent nails
  • Accessory tragus
  • Anterior anus (ectopic anus)
  • Auricular tag or pit
  • Bifid uvula or cleft uvula
  • Branchial tag or pit
  • Camptodactyly
  • Cup ear
  • Cutis aplasia (if large, this is a major anomaly)
  • Ear lobe crease
  • Ear lobe notch
  • Ear pit or tag
  • Extra nipples (supernumerary nipples)
  • Facial asymmetry
  • Hydrocele
  • Hypoplastic fingernails
  • Hypoplastic toenails
  • Iris coloboma
  • Lop ear
  • Micrognathia
  • Natal teeth
  • Overlapping digits
  • Plagiocephaly
  • Polydactyly type B tag, involves hand and foot
  • Polydactyly type B, of fingers, postaxial
  • Polydactyly type B, of toes, postaxial
  • Preauricular appendage, tag or lobule
  • Redundant neck folds
  • Rocker-bottom feet
  • Single crease, fifth finger
  • Single transverse palmar crease
  • Single umbilical artery
  • Small penis (unless documented as micropenis)
  • Syndactyly involving second and third toes
  • Tongue-tie (ankyloglossia)
  • Umbilical hernia
  • Undescended testicle, bilateral
  • Undescended testicle, unilateral
  • Webbed neck (pterygium colli)