Amelia

Amelia is a congenital anomaly characterized by the complete absence of one or more limbs (see Fig. 36). It can be distinguished from other limb deficiencies, especially terminal transverse deficiencies, and rare conditions such as sirenomelia and limb-body wall spectrum (see Fig. 37 and Table 2). Radiographs are strongly recommended to confirm the condition and characterize the bony anatomy.

Fig. 36. Amelia

Photograph source: CDC–Beijing Medical University collaborative project.

Diagnosis

Prenatal. Amelia can be diagnosed prenatally but can be missed or misdiagnosed. Cases identified or suspected prenatally should be confirmed postnatally before inclusion in a surveillance programme.

Postnatal. Careful examination of the newborn, aided by radiography, confirms the diagnosis of amelia and distinguishes it from other limb reduction defects (e.g. terminal transverse defects) and sirenomelia (very rare).

Clinical and epidemiologic notes

A carefully clinical examination is crucial, with special attention focused on confirming the absence of the proximal segment of the humerus or femur. Radiological examination is essential to firmly characterize the bony anatomy of the region.

Clinical presentation:

Multiple congenital anomalies are the most frequent. Amelia has been reported in association with musculoskeletal defects, intestinal defects, some renal and genital defects, oral clefts, defects of cardiac septa, and anencephaly.
Though infrequently, amelia can be seen in certain syndromes, genetic (e.g., Roberts syndrome) as well as teratogenic (e.g., thalidomide embryopathy).

Clinical tips:

Make sure that all bony segments of the affected limb are absent. If a segment is present, the defect is not amelia.
Look for additional birth defects, not uncommon in cases with amelia.

Checklist for high-quality reporting

Checklist for high-quality reporting
Amelia – Documentation Checklist
Describe in detail (avoid using only the term “amelia”), including: Limb(s) involved. The segment(s) involved for each affected limb – confirm that all segments of the limb are absent. Laterality – right, left, bilateral. Use Fig. 35 to distinguish amelia from other limb deficiencies. Describe procedures to assess further additional malformations and, if one or more is present, describe. Distinguish from transverse terminal defects, sirenomelia and limb-body wall spectrum. Take and report photographs: Very useful; often crucial for review. Take and report radiographs: Crucial for review and classification. Report whether specialty consultation(s) were done and if so, report the results.

Table 2. Distinguishing amelia from other congenital anomalies

Table 2. Distinguishing amelia from other congenital anomalies
Congenital anomaly	Main features
Amelia	Complete absence of one or more limbs.
Transverse terminal defect	Terminal transverse limb deficiencies appear as an “amputation” of an arm, leg, or digit. Some remnant of the limb is present.
Sirenomelia sequence	Complex phenotype, with total or partial fusion of lower limbs, variably associated with sacral defects, anal atresia, malformed genitalia and renal a/dysgenesis.
Limb-body wall complex	Complex phenotype, consisting of a spectrum of anomalies, including limb deficiencies, atypical exencephaly/encephalocele, ventral body wall defects, atypical facial clefts, and at times, amniotic bands.