What are Congenital Anomalies?
Congenital anomalies, also called congenital malformations or congenital differences, refer to developmental disturbances and tissue variations that differ from the normally structured state, present from the moment of birth. The cause of these developmental disturbances is not yet fully understood. Possible reasons include the intake of certain medications during pregnancy. However, in some cases, even after discontinuation of such medications, anomalies still occur, suggesting that other factors must be responsible.
Potential Causes of Congenital Anomalies
There are confirmed causes, probable causes, and some instances where the etiology is unclear. Chromosomal disorders, genetic and environmental factors, ethnicity, geography, and socioeconomic status seem to play roles in the development of anomalies, although many cases arise from random events during pregnancy. An anomaly often develops in the first trimester of pregnancy, especially between the 4th and 7th weeks. In some instances, the anomaly may not be apparent at birth but only becomes evident later in childhood. Radiation exposure (such as X-rays) during the first trimester is more frequently associated with developmental disturbances. In some instances, inherited factors play a role, although in most cases no definitive cause can be established for congenital anomalies.
Common Congenital Anomalies and Their Characteristics
Cleft Lip and Palate
Clefts are the most common congenital facial anomalies, caused by incomplete formation of the soft and hard structures of the mouth. The most common forms are cleft lip (commonly called harelip) and cleft palate (commonly called cleft palate), characterized by discontinuity in the tissue structure of the midface. Beyond the cosmetic aspect, clefts cause a range of functional problems related to breathing, speech, hearing, and feeding in infants.
Simple Craniosynostoses (Non-syndromic)
Craniosynostosis is the premature fusion of one or more cranial bones. In infants, the skull consists of bones that have not yet fused and are connected by flexible sutures. Premature fusion interferes with the skull and brain’s normal growth, leading to changes in the head shape and causing functional and developmental issues. There are four general types:
- Scaphocephaly (including frontal and occipital subcategories)
- Plagiocephaly
- Trigonocephaly
- Brachycephaly
Additional categories can be distinguished based on specific characteristics and types of skull deformation.
Syndromic Craniosynostoses (Crouzon, Apert, and Others)
These are rare craniosynostoses (less than 10% of cases) associated with other anomalies that present specific morphological and functional differences. Crouzon syndrome affects approximately 1 in 60,000 births and mainly impacts the skull and facial bones. Apert syndrome (1 in 160,000 births) carries the highest risk for mild to moderate intellectual disabilities compared to other cranioskeletal syndromes. The primary anomaly that characterizes these syndromes is complex syndactyly, especially in Apert syndrome. In some instances, intellectual disabilities are observed in conjunction with these anomalies.
Treacher Collins Syndrome
Treacher Collins syndrome (or Franceschetti-Klein syndrome) includes craniofacial anomalies that affect the ears, eyes, cheekbones, and jawbones.
Pierre Robin Sequence
Pierre Robin sequence is not a syndrome but a sequence of developmental events. It is marked by micrognathia (a very small lower jaw), leading to breathing and feeding issues. The tongue tends to fall backward (glossoptosis), and there is an associated partial cleft of the soft palate. It occurs in approximately 1 in 8,500–14,000 births and may be associated with other syndromes such as Treacher Collins, Stickler, and velocardiofacial syndrome.
Microtia and Anotia
Microtia is the underdevelopment of the ear, while anotia is the complete absence of the ear. The inner ear is usually normally developed. Certain medications (e.g., isotretinoin) during pregnancy have been implicated, as have certain syndromes (e.g., Treacher-Collins or hemifacial microsomia).
Limb Anomalies
When fingers are fused, this is called syndactyly. Simple syndactyly involves only skin and soft tissue and can be classified as complete or incomplete. Complex syndactyly involves bones and may cause significant finger deformation. Polydactyly (extra fingers or toes) can be treated surgically for functional and cosmetic reasons. Thumb aplasia may occur in isolation or with partial or complete absence of the radial bone, making reconstructive surgery critically important for hand function.
Trunk Anomalies (Poland Syndrome)
Poland syndrome is a congenital anomaly affecting the chest wall, usually arising from a random embryonic event around the 6th week of pregnancy. Characteristics include partial or complete absence of the pectoralis major muscle, underdevelopment or absence of the breast and nipple-areola complex, and potentially associated anomalies such as absence of costal cartilages, a lack of subcutaneous tissue or hair in the axilla, and syndactyly of the hand on the same side.
Vascular Anomalies (Hemangiomas and Vascular Malformations)
Hemangiomas are overgrowths of blood vessels within the skin and are common vascular tumors appearing within the first weeks of life, especially on the face. Vascular malformations can be classified into venous, arterial, or combined types. Venous malformations, the most common, result in the abnormal dilation of veins. Arterial malformations, which occur in about 2% of cases, involve underdevelopment of an arterial segment and abnormal connections that can cause compression, thrombosis, or aneurysms. Mixed-type malformations have features of both venous and arterial anomalies.
Congenital Melanocytic Nevi and Giant Nevi
These nevi appear as pigmented skin lesions with defined borders and a relatively uniform color, although variations in shade can occur. They range in size from small (<1.5 cm) and medium (1.5–10 cm) to large (10–20 cm) and giant (>20 cm). Large and giant nevi have an estimated melanoma risk of 5–10%.
Rehabilitation of Congenital Anomalies
Early prenatal screening is vital for at-risk parents to detect congenital anomalies. When anomalies are identified postnatally, surgical treatments can often yield highly satisfactory results. The approach for each case is decided by a multidisciplinary team of specialists led by a plastic surgeon. The role of the plastic surgeon is critical in guiding interventions for complex cases, aiming for an outcome that is both aesthetically and functionally satisfactory. Early intervention improves the quality of life for infants and children and has long-lasting benefits throughout their lives. If you have any concerns, don’t hesitate to visit us and discuss a treatment plan. Remember, regardless of the nature of the problem, a solution is always available and feasible.
References
- Lee KS, Choi YJ, Cho J, Lee H, Lee H, Park SJ, Park JS, Hong YC. (2021). Environmental and Genetic Risk Factors of Congenital Anomalies: An Umbrella Review of Systematic Reviews and Meta-Analyses. Journal of Korean Medical Science, 36(28):e183.
https://doi.org/10.3346/jkms.2021.36.e183 - Abebe S, Gebru G, Amenu D, Mekonnen Z, Dube L. (2021). Risk factors associated with congenital anomalies among newborns in southwestern Ethiopia: A case-control study. PLoS ONE, 16(1):e0245915.
https://doi.org/10.1371/journal.pone.0245915 - Zaganjor I, Sekkarie A, Tsang BL, Williams J, Razzaghi H, Mulinare J, Sniezek JE, Cannon MJ, Rosenthal J, Alverson CJ, Correa A. (2016). Describing the prevalence of neural tube defects worldwide: A systematic literature review. PLOS ONE, 11(4):e0151586.
https://doi.org/10.1371/journal.pone.0151586
