4.9e Limb Deficiency: Transverse Intercalary (Q71.1, Q72.1, Q72.4)

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Fig. 4.38. Transverse intercalary

Transverse intercalary limb deficiencies are characterized by the absence of proximal or middle segments of a limb with all or part of the distal segment present. Radiographs are strongly recommended to confirm the condition and characterize the bony anatomy.

Relevant ICD-10 codes

Q71.1 Congenital absence of upper arm and forearm with hand present
Phocomelia of upper limb
Q72.1 Congenital absence of thigh and lower leg with foot present
Phocomelia of lower limb
Q72.4 Longitudinal reduction defect of femur
Proximal femoral focal deficiency

Note:
Avoid using the generic Q71, Q72 or Q73 codes for intercalary limb deficiencies. These generic codes include other limb deficiencies.

Diagnosis

Prenatal. Transverse intercalary limb deficiency can be suspected prenatally, but is easily missed or misdiagnosed. Cases identified or suspected prenatally should be confirmed postnatally before inclusion in the surveillance programme. When this is not possible (e.g. termination of pregnancy or unexamined fetal death), the programme should have criteria in place to determine whether to accept or not accept a case based solely on prenatal data.

Postnatal. The newborn examination confirms the diagnosis of intercalary limb deficiency and distinguishes it from other limb deficiencies (such as amelia). A careful clinical examination and documentation, aided by imaging (photos and radiographs), are essential for an accurate and complete diagnosis.

Clinical and epidemiologic notes

Typical intercalary deficiencies present with absence of all limb bones proximal to a normal or malformed hand or foot which attaches directly to the trunk. Atypical intercalary deficiencies present with absence of humerus or femur, or both radius-ulna (tibia-fibula) with normal or malformed hand or foot. Distinguishing intercalary defects from other limb reduction defects is important because these conditions have different causes and disease associations. With careful clinical and radiological examination, the diagnosis of intercalary limb deficiencies is possible.

Note that the English translation for the term “phocomelia” is considered pejorative and should not be used. Translation from Latin to English alludes to the shape of the limb resembling that of a flipper on a seal.

About half of transverse intercalary limb deficiency cases are isolated. Most of the remaining cases have multiple congenital anomalies. A small proportion of cases are syndromic. Syndromes with intercalary limb deficiencies include Roberts syndrome; in its most severe form, thrombocytopenia absent radius (TAR) syndrome can have intercalary limb deficiencies.

A teratogen that can cause intercalary limb deficiencies is thalidomide. Maternal pregestational diabetes has been associated with femoral hypoplasia-unusual facies syndrome (now more commonly called femoral-facial syndrome). This condition is characterized by unilateral or bilateral deficiency of femurs, with variable deficiencies of other long bones.

The prevalence of intercalary limb deficiencies is around 0.45 per 10 000 births.

Inclusions

Related codes

Q87.25 Thrombocytopenia absent radius syndrome
Q86.82 Congenital malformations due to thalidomide

Exclusions

Q71.0 Congenital complete absence of upper limb(s); amelia of upper limb
Q71.2 Congenital absence of both forearm and hand
Q71.3 Congenital absence of hand and finger(s)
Q71.30 Congenital absence of finger(s)
Q72.0 Congenital complete absence of lower limb(s); amelia of lower limb
Q72.2 Congenital absence of both lower leg and foot
Q72.3 Congenital absence of foot and toe(s)
Q72.30 Congenital absence or hypoplasia of toe(s) with remainder of foot intact
Q73.0 Congenital absence of unspecified limb(s)

Checklist for high-quality reporting

Checklist for high-quality reporting
Intercalary Defects – Documentation Checklist
Describe in detail, including: Limbs involved. Note each segment involved for each limb affected – describe what is deficient or absent. Indicate involvement of forearm, arm, leg, thigh. Indicate bones involved. Laterality right, left, bilateral. Avoid using solely a “diagnostic term” (e.g. phocomelia). Document specialty consultations (e.g. genetics, orthopaedics). Use Fig. 4.35 to distinguish transverse intercalary defects from other subtypes of limb deficiencies. Describe procedures to assess further additional malformations; if one or more is present, describe these. Describe procedures to assess syndromes. Distinguish from other limb deficiencies (e.g. transverse terminal deficiencies). Take and report photographs: Very useful; can be crucial for review. Take and report radiographs: Crucial for review and classification, at times even more so than photographs. Report whether specialty consultation(s) done, and if so, report the results.

Suggested data quality indicators

Suggested data quality indicators
Category	Suggested Practices and Quality indicators
Description and documentation	Review sample for documentation of key descriptors: Take and attach radiographs and photographs – essential for review and correct classification. Specify which limbs are involved and laterality. Specify affected segments. Specify affected bones
Coding	Track and minimize cases coded with generic ICD-10 RCPCH codes: Q71, Q72, Q73.
Clinical classification	Syndromes are not frequent in intercalary defects. A high proportion of syndromes suggests misclassification with other limb deficiencies
Prevalence	Prevalence is around 0.45 per 10 000 births. A higher prevalence suggests misclassification with other limb deficiencies.
Key visuals	Distinguishing intercalary defects from transverse terminal defects (side-by-side comparison):