1 Glossary

2 Introduction

2.1 Purpose

The Oxford English Dictionary (http://www.oed.com) defines “bilateral” as “Of, pertaining to, affecting, or arranged upon two sides; disposed on opposite sides of an axis.”

The word “bilateral” appears in more than 500 concepts in the July 2015 release of the International Edition of SNOMED CT; however, the modeling approach is not consistent and editorial policy regarding the inclusion of new content that pertains to bilateral structures is not available.

The purpose of this content project is:

1. To identify all concepts with a status of active that are descendants of 404684003|Clinical finding (finding) and contain the word “bilateral” in the Fully Specified Name or in a synonym.
2. Investigate how these existing “bilateral” concepts should be represented in future releases of SNOMED CT, specifically:
   1. In which hierarchy should these concepts be positioned?
   2. How should the laterality be modeled?
   3. How should the descriptions be constructed?
   4. Recommend clear and consistent editorial guidance for the management of requests for new content that includes the word “bilateral” and that would currently be considered to be in scope for the clinical findings hierarchy.  
      1. What type of request will be considered as acceptable for inclusion as a pre-coordinated concept?
      2. What (if any) type of request may be declined in favour of post-coordination?

2.2 Audience and Stakeholder Domain

The audience for this document includes all standards terminology leaders, implementers and users of SNOMED CT.

A further significant audience is the community of SNOMED CT terminologists that may be requested to implement the recommended specification. This will include stakeholders who need to represent clinical finding and disorder content that affects bilateral anatomic sites.

2.2.1 Input from Stakeholders

There are currently approximately 200 requests in the IHTSDO request portal (SIRS) for new concepts that reference the word “bilateral.”  These requests originate from across a variety of users and National Release Centers. 

Direct input from identified stakeholders will include those parties that are currently working on associated content projects including artf6236 Unilateral and artf223747 finding/disorder with laterality.

Input will be sought from the IHTSDO Consultant Terminologist community and the IHTSDO 2015 Cohort for the Consultant Terminologist Program. 

2.2.2 Degree of Consensus on the Statement of Problem

It has been suggested in the Consultant Terminologist community that Clinical finding and also Procedure concepts that include the word bilateral should become descendants of 243796009|Situation with explicit context (situation). 

Some content that references the word “unilateral” and originated in the clinical finding hierarchy was moved to become a descendant of 444166003|Unilateral clinical finding (situation) back in 2009.  The rational for this move was that unilateral includes negation, where one part of a paired structure is involved and the other part is not.

The impact of a change of this nature for content that uses the term “bilateral” would require further investigation due to the likely consequences specifically on implementers and end users. Furthermore, it may be desirable to revisit the idea that laterality is a characteristic of a situation. 

The future disposition of content that references unilateral is to be considered separately in the content project art6236.  Retirement of this content may be desirable in some instances as the content is classification derived. A clinician would likely prefer to record the site of the disorder or procedure, since use of the word “unilateral” in a clinical record leaves scope for ambiguity.

3 Statement of the Problem or Need

3.1 Summary of Problem or Need, as reported

Artifact artf6188 is located on CollabNet and contains the following information “Representation and retrieval of bilateral disorders.”

Two comments are noted in CollabNet in relation to this artifact. 

1. Bilateral may represent a single entity for example 162301005|Bilateral headache (finding).
   1. It is not possible to suffer from a bilateral and a unilateral headache at the same time.
   2. Bilateral may represent the summation of two entities for example 162359003|Bilateral earache (finding).
      1. This would be the more commonly occurring case where there is a clinical finding or disorder that is affecting both parts of a paired structure.

3.2 Summary of Requested Solution

The content project tracker artifact on CollabNet does not offer a suggested solution, however, there is the comment that the bilateral content that is a subtype of 404684003|Clinical finding (finding) might be moved to become a descendant of 243796009|Situation with explicit context (situation).  It is noted that this comment was added to the CollabNet artifact in 2012 and has not been updated further. Thinking around this proposal may have changed since that time.

3.3 Statement of Problem, as understood

Two hundred seven (207) active concepts are descendants of 404684003|Clinical finding (finding) and include the word “bilateral” in the July 2015 release.  There are also requests for content of this nature to be added.

There is a requirement firstly for published editorial policy to clearly inform requesters about the IHTSDO policy for inclusion of clinical finding and disorder concepts that include a bilateral finding site.  If the approach will be post coordination, then there is a requirement for wide consultation with stakeholders and implementers as any proposed post-coordinated approach must be consistent.  Short cuts to deal with current modeling issues may have an impact on post coordination should this be the final agreed approach, and this potential impact must be taken into consideration.

If pre-coordination of bilateral content is to be the agreed approach, there is a need to agree upon a consistent methodology for the modeling of this content in order to standardise representation and improve retrieval.

3.4 Detailed Analysis of Reported Problem, Including Background

IHTSDO does not currently publish a policy about the inclusion of pre-coordinated content that includes bilateral body structures into the clinical finding hierarchy.  This has resulted in an inconsistent approach to the inclusion of content. Some requests are accepted, some requests are rejected and a large number of requests have effectively been placed on indefinite hold pending a policy.

There are currently 207 concepts that include the word “bilateral,” are active and located as a descendant of the concept 404684003|Clinical finding (finding).  There are some inconsistencies across released content. 

For example, Figure 1 (below) demonstrates the concept 407671000|Bilateral pneumonia (disorder), which is active in the July 2015 release and is fully defined incorporating two separate relationship groups and two separate lateralized anatomic structures.  This concept is a child of 233604007|Pneumonia (disorder) and this is arguably where end users would expect to see the concept. 

Figure 1: Current modeling for 407671000|Bilateral pneumonia (disorder)|. The green rounded rectangles indicate that this model is consistent with the solution proposed in Section 6.

Conversely, in Figure 2 the concept 95820000|Bilateral hearing loss (disorder) has a status of active in the July 2015 release, is primitive and is not subsumed by 473424007|Hearing loss of left ear (disorder) or 473423001|Hearing loss of right ear (disorder).   These three concepts are primitive and have a finding site of 91159003|Structure of auditory system (body structure) inherited from the stated primitive parent 15188001|Hearing loss (disorder).  It is not possible to apply a lateralized finding site to descendants of 15188001|Hearing loss (disorder).  This concept is currently an intermediate primitive.

Figure 2: Current modeling for 95820000|Bilateral hearing loss (disorder)|. The red rounded rectangle indicates that this model is not consistent with the solution proposed in Section 6.

There are also approximately 200 requests with a status of inception/elaboration in SIRS that include the word bilateral in the requested description, with around 50 of these requests for new content for the clinical finding hierarchy. A further review of SIRS requests that reference “left disorder” or “right disorder” elicits a result of more than 900 requests.

An example of a request that is currently on hold and awaiting resolution of this content project is SIRS request ID 185889.  This is a request for a new concept Osteoarthritis of both knees (disorder) and has usage statistics of 11,358.  The requested concept is released in the Kaiser Permanente namespace and forms part of the Top 2500 concepts that are used in their clinical records.

The volume of usage statistics for this request demonstrates that the inclusion of pre coordinated “bilateral” concepts into the clinical findings hierarchy is likely to be well received by end users.

Detailed analysis of this problem has elicited the following issues to be addressed:

1. Should new content that uses the word bilateral be accepted for inclusion into the international edition of SNOMED CT?

                       I.         What would be the criteria for including a new concept?

                                              i.         Should there be different approaches depending on the request type? For example, should a single entity (bilateral headache) be considered acceptable, but a summation of two entities (bilateral earache) be regarded as not acceptable?

                     II.         Is the vast majority of “bilateral” content actually more suited to a post-coordinated approach to implementation?

                   III.         Both the pre and post-coordinated approaches will require editorial guidance. This will ensure that both terminologists and stakeholders are clear about the IHTSDO policy for inclusion of content of this nature. Editorial guidance should incorporate policy for

                                              i.         A consistent approach to modeling.

                                             ii.         A consistent approach to naming in descriptions for example bilateral, both, left and right.

                                           iii.         Inclusion of plural “s” in descriptions.

1. The addition of bilateral content may lead to a large increase in the amount of pre- coordinated concepts in SNOMED CT

                             I.         Depending on modeling approach there may be a requirement for a large number of new anatomy concepts.

                           II.         The number of requests for bilateral concepts may increase once there is a published policy that these will be accepted.  This may also include other domains not in scope for this content project such as the procedure hierarchy.

1. If pre-coordination is the preferred option for new content, which hierarchy should the concepts be represented in?
   1. If the concepts are to be pre-coordinated, then consistency in the representation and modeling of existing and new content will benefit the overall quality of SNOMED CT.

The diagrams shown in Figure 3 through Figure 10 provide further analysis of the problem by illustrating how some example bilateral concepts are currently modeled in SNOMED CT. Inconsistencies in the current modeling approach are apparent, as can be seen by comparing the captions for the different diagrams.

Figure 3: Current modeling for 3560000 |Bilateral recurrent inguinal hernia (disorder)|. The green rounded rectangles indicate that this model is consistent with the solution proposed in Section 6.

Figure 4: Current modeling for 38163003 |Bilateral femoral hernia with gangrene (disorder)|. The red rounded rectangle indicates that this model is not consistent with the solution proposed in Section 6.  The modeling of this concept has a number of issues because it has inherited two Associated morphology attributes into role group 2, which is erroneous and addressed in a separate content project.  In order to rectify the issues with this concept the parent concept 45845003|Femoral hernia with gangrene (disorder) and 79990007|Hernia, with gangrene (disorder) would require review and remodeling.  There are two released anatomic structures that could be used to remodel the concept in Figure 4 442034005|Structure of left femoral canal (body structure) and 441654009|Structure of right femoral canal (body structure).

Figure 5: Current modeling for 20143001 |Bilateral bundle branch block (disorder)|. The green rounded rectangle indicates that this model is consistent with the solution proposed in Section 6.  Also note that this appears to be a duplicate concept to its parent 32758004|Right bundle branch block with left bundle branch block (disorder), and this requires further analysis.

Figure 6: Current modeling for 6481005 |Diplegia (disorder)|. The red rounded rectangle indicates that this model is not consistent with the solution proposed in Section 6. The concept 66019005|Limb structure (body structure) does not currently have lateralised subtypes Left limb structure and Right limb structure in the anatomy hierarchy. Lateralised subtypes of 61685007|Lower limb structure (body structure) and 53120007|Upper limb structure (body structure) are available.

Figure 7: Current modeling for 194290005 | Acute bilateral otitis media (disorder) |. The green rounded rectangles indicate that this model is consistent with the solution proposed in Section 6.

Figure 8: Current modeling for 201858005 |Post-traumatic gonarthrosis, bilateral (disorder)|. The red rounded rectangle indicates that this model is not consistent with the solution proposed in Section 6.  Suggest further investigation of the term gonarthrosis, as this appears to be used synonymously with Osteoarthritis in other concepts.

Figure 9: Current modeling for 204950001 |Bilateral renal dysplasia (disorder)|. The green rounded rectangles indicate that this model is consistent with the solution proposed in Section 6.

Figure 10: Current modeling for 237808008 |Bilateral atrophy of testes (disorder)|. The green rounded rectangles indicate that this model is consistent with the solution proposed in Section 6.  Suggest the FSN should be Bilateral atrophy of testis (disorder) to align with current editorial policy; however, this must take into account policy about acceptable changes to a released fully specified name.

3.5 Subsidiary and Interrelated Problems

For the purpose of this content project, all concepts outside of the clinical finding hierarchy will be out of scope.

There are released concepts that will not be fully defined despite any proposed changes that result from this content project.  For example the clinical finding hierarchy contains a number of classification type concepts such as

384986002|pT2c: Bilateral disease (prostate) (finding)

397127000|pN2: Bilateral regional lymph node metastasis (vulva) (finding)

397374000|pN2 (IVB): Bilateral regional lymph node metastasis (pT1-pT4, pM1) (TNM category and FIGO stage) (vulva) (finding)

Content of this nature will be reviewed as part of the construction phase of this content project but it is very unlikely any changes will be implemented.

This project should align with the proposed outcomes for other content projects:

4 Risks/Benefits

Achieving a workable solution to this content project is desirable because there are currently around 200 requests in SIRS that reference the word bilateral along with the existing released concepts in the clinical finding hierarchy.  This suggests that there is a requirement from end users to see either the inclusion of content of this nature or a workable alternative in action.

End users will benefit from resolution of this content project if a solution that meets their needs is provided. A clear and consistent approach to the management of this content will also ensure that vendors can implement a dependable approach. 

For those involved in translation, the implementation of a consistent approach is likely to reduce anomalies in translated content and may assist with an algorithmic approach to translation.  The development of editorial guidance will ensure that National Release Centers are able to manage their requests more efficiently, especially when deciding whether a request is extension-specific or may be promoted to the International Edition.

By addressing this content and the existing backlog of requests, overall quality and consistency of content will be improved.

Achieving a workable solution for this content project will also benefit the IHTSDO content team, as the disposition of requests that reference “bilateral” will be consistent and more efficient.   The value of the effort involved with the undertaking of this content project is considerable when considering its likely impact.

4.1 Risks of Not Addressing the Problem

End users, vendors, NRC and the IHTSDO content team will remain unclear about IHTSDO policy for the inclusion of this type of content.  This will lead to inconsistent inclusion of content and concept modelling.

The project risk is calculated by utilizing the Project Risk Profile assessment tool as detailed on Page 11 of “A Guide to Stakeholder Engagement” https://csfe.aceworkspace.net/sf/go/doc7359?nav=1

The controversy level is assessed as a score of 2.

In addition to the risks quantified above, not addressing the problem means that “bilateral” concepts will be scattered inconsistently across hierarchies and user queries for “bilateral” concepts will consequently be more difficult to formulate. Furthermore, IHTSDO content modelers will not have a clear understanding of where to put new “bilateral” concepts or indeed if the request can be accepted at all.

4.2 Risks of Addressing the Problem

Depending upon the recommended solution, there may be an increase in the number of concepts required to fully define some of the new content, it very is likely that new body structure concepts will be required.  Where a request for a new “bilateral” clinical finding concept is received, it is arguable that the left variant and right variant should also be added for completeness and also to subsume the “bilateral” clinical finding concept.

Publication of a policy about inclusion of content may lead to a surge in requests for new content, although this risk is hypothetical and not currently supported by any compelling evidence.  

Should the decision be made to recommend post coordination as the approach to laterality, this would need to be supported by comprehensive implementation guidance to ensure a consistent approach for software suppliers and end users.  Sudden changes to guidance may impact on solutions that are already in place for end users.  A robust and widespread consultation process would be needed to minimize this potential impact.

5 Requirements: Criteria for Success and Completion

5.1 Criteria for Success/Completion

Released concepts that include the words bilateral or both and are descendants of 404684003|Clinical finding (finding) and are in scope for this content project (see Section 3.5) will:

1. Be clearly and consistently represented in SNOMED CT
2. Have descriptions that align to an agreed format
3. Have stated IS_A relationships, attributes and values that have been assigned in a consistent manner to ensure that classification results in logical inferred relationships.

Editorial Guidance will be published in order to:

1. Support customers in deciding whether to request a new concept
2. Support modelers in deciding whether a new request is an acceptable addition to SNOMED CT
3. Support modelers in adding new concepts in a consistent manner.

5.2 Strategic and/or Specific Operational Use Cases

This content project aligns with the following aspects of the IHTSDO strategic direction:

Section 1: Make it easier to use SNOMED CT - this will be achieved by improving the consistency of existing content, ensuring that the addition of new content is developed using an approach that has predictable and reproducible results.

Section 4: Strengthen responsiveness and clinical governance of SNOMED CT - this will be achieved by producing guidance to allow the content team to reduce the current backlog of requests for bilateral content in the clinical findings hierarchy whilst publishing guidance that will be of utility for both modelers and requesters.

6 Solution Development

6.1 Initial Design

6.1.1 Outline of Initial Design

Four possible solutions were initially considered.

Option one – Use a single role group with nested expression to represent laterality.

Figure 11: A possible representation using a nested laterality attribute

Option two - Use two role groups, each with a “lateralized” pre-coordinated anatomy concept (one for the structure on the right side of the body and another for the corresponding structure on the left side of the body).

Figure 12: A possible representation using two role groups, each has the same morphology but different lateralized finding sites.

Option three - Model using one role group, with a finding site of a single new concept that refers to a “right and left” structure.

Figure 13: A possible representation using a new concept to represent an "abstract" bilateral structure.

Option four - Model with a single role group where the finding site is a single new concept that is a descendant of 422525002|Structure of bilateral paired structures (body structure).

Figure 14: A possible representation using a new "abstract" anatomy concept to represent a bilateral paired structure.

A further option five has been added after consultation with the IHTSDO content team.  The US extension allows the routine addition of lateralized content using 31156008|Structure of left half of body (body structure) and 85421007|Structure of right half of body (body structure) in role group zero whilst role group one has an un-lateralized body structure. 

This approach is not considered a viable option for the purpose of this content project because it is likely to prove problematic for concepts where more than one role group is used.

Figure 15: A possible representation using “Structure of left half of body” and “Structure of right half of body” in role group zero, along with Associated morphology and un-lateralized Finding site attributes in role group one. 

6.1.2 Significant Design or Implementation Decisions/Compromises

Addressing any inconsistency amongst the modeling and representation of already released concepts may require changes to way the concept is currently modeled, the addition of new concepts to the body structure hierarchy or changes to descriptions.  The impact of this on end users is likely to be minimal when compared with the benefit of improvement of the quality of existing content.

One option for consideration may be to address future new content that incorporates both parts of a paired structure using a post coordinated expression.  A concept can be represented using pre-coordination or as a post-coordinated expression. The two approaches can have the same meaning if the post-coordinated expression is presented by following the concept model.

Throughout this content project reference is made to the option of post coordination for bilateral content.  Pre versus post coordination is likely to provoke further debate for the foreseeable future.  For the purpose of this content project the option of post coordination for expressing laterality is not considered to be a workable solution for many end users. Widespread consultation and implementation guidance would be required taking a considerable period of time. 

One of the strategic goals of IHTSDO is to make SNOMED CT easier to use.  In the context of this content project, pre-coordination of bilateral content would fulfill that strategic goal.  It is clear that end users wish to be able to record the presence of a clinical finding to both parts of a paired structure.  The submission of requests for new bilateral content supports this assumption.  The impact for end users from the inclusion of bilateral content to the clinical finding hierarchy would be immediate.  End users would have a pre-coordinated concept that meets a clinical requirement, improves data aggregation and ensures that data is recorded in a clear and consistently reproducible manner.  This must of course be balanced against the potential for a “combinatorial explosion” which could increase the amount of content in the clinical findings hierarchy exponentially and equally make implementation of SNOMED CT more difficult.   The challenge is to ensure this immediate requirement is met while ensuring that any interim solution that is instigated does not impede future progress and development of SNOMED CT.

6.1.3 Evaluation of Design

All of the proposed solutions have significant disadvantages.

Option 1 is arguably the most straightforward and would not typically require the creation of new anatomy concepts, but it requires support for nested relationships. Release Format 2 (RF2) does not currently support nesting and it is unlikely that such support will be added in the near future.  For this reason, option one was discounted.

Options 2, 3, and 4 all require the creation of new anatomy concepts. For Options 3 and 4, the new concepts would arguably be abstractions rather than physical anatomical entities. For example, concepts such as “Structure of lens of left and right eye (body structure)” or “Bilateral lens of eyes (body structure)” are not “real,” in the sense that an anatomist could point to a single, physical anatomical structure that precisely corresponds to the fully specified concept name (FSN). Furthermore, introducing such “abstract” anatomical concepts could complicate classification. 

The concepts 116007004|Combined site (body structure) and its subtypes and 422525002|Structure of bilateral paired structures (body structure) and its subtypes might be considered candidates for retirement.  The presence of these concepts may be confusing to end users and the concepts do not have any logical association to the single anatomic structure, for example 304913001|Bilateral knee joints (body structure) has a single parent concept 422525002|Structure of bilateral paired structures (body structure) but should also have the parent 49076000|Knee joint structure (body structure). 

Option 2 avoids difficulties with abstract notions, because any new concepts that need to be created would be “real” and simply add laterality to the concept name. Indeed, many body structure concepts currently include the words “right” or “left” in the FSN. Examples are 72345007|Structure of lens of right eye (body structure) and 88258005|Structure of lens of left eye (body structure). For these reasons, Option 2 is preferred with the conventional approach to relationship grouping involving two finding site attributes with different values in two separate relationship groups.

As illustrated in the following diagrams, this approach makes it possible to correct inconsistencies in some of the existing bilateral concepts and to respond to requests for new bilateral content in a consistent manner.

The diagrams in Figure 16 through Figure 18 illustrate proposed modeling changes for some existing SNOMED CT concepts that would be made in accordance with the proposed solution described above. Each of these figures corresponds to a previous figure in Section 3.4.

Figure 16: Proposed modeling changes for 38163003 |Bilateral femoral hernia with gangrene (disorder)|, correcting the portion of the model shown in the rounded red rectangle in Figure 4.

Figure 17: Proposed modeling changes for 6481005 |Diplegia (disorder)|, correcting the portion of the model in the rounded red rectangle in Figure 6.

Figure 18: Proposed changes for 201858005 |Post-traumatic gonarthrosis, bilateral (disorder)|, correcting the portion of the model shown in the red rounded rectangle in Figure 8.  Note this concept requires further review to establish the accuracy of the term Gonarthrosis.

The diagrams in Figure 19 through Figure 21 illustrate how the proposed solution can be applied to some example SIRS requests.

Figure 19: Proposed model for SIRS Request 33152, Bilateral carotid artery atherosclerosis (disorder).

Figure 20: Proposed model for SIRS Request 188525, Osteoarthritis of both ankles (disorder).

Figure 21: Proposed Model for SIRS Request 476734, Bilateral viral conjunctivitis (disorder).

6.1.4 Exceptions and Problems

Proposed solutions should be considered in terms of how they relate to (1) the manner in which laterality is currently represented in SNOMED CT and (2) the anatomy redesign project.  It is not proposed to add a new anatomy concept for any clinical finding that could possibly occur bilaterally, but rather to add this content upon request.  It is also noted that an interim solution may not be useful if the long-term goal is to introduce nesting.

The proliferation of a large amount of content is one factor that requires further consultation, engagement with implementers and consideration.  If laterality is to be accepted into the international edition of SNOMED CT, then for each clinical finding concept that can be lateralised a left, right and bilateral clinical finding variant may be required along with the anatomy concepts in order to provide a finding site for the new content. 

It is also questionable whether this may lead to a proliferation in requests for new subtypes of 413350009|Finding with explicit context (situation). For example 391093004|History of hip fracture (situation) may also result in three further subtype concepts of left, right and bilateral.

6.1.5 Design Strengths

The recommended solution follows the conventional and existing approach to concept modeling, and applying this approach to all content will ensure that any existing inconsistencies that can be resolved are resolved.   Rigor in the logic applied will improve the outputs of queries for end users.

6.1.6 Design Weaknesses

New content will be required for the anatomy hierarchy, some of this may be addressed by the ongoing content project for anatomy redesign; however, new lateralized body structure concepts would be added upon request.

If this proposed outcome is to be adopted as an interim solution with the long-term goal being to introduce nesting, this may result in future large scale changes to the content that has been re-modeled and also retirement of the lateralised content from the anatomy hierarchy.

6.1.7 Design Risks

7 Recommendation

7.1 Detailed Design Final Specification

Subject to the outcome of the Laterality project artf223747 it is proposed:

1. Requests for new content that refers to both parts of a paired structure (bilateral) should be accepted for addition into the International edition of SNOMED CT.  There should be no addition criteria applied in order for the request to be accepted for inclusion.
2. Where a request is suitable for addition to the clinical finding hierarchy, it may be added to this hierarchy with either the semantic tag of clinical finding or disorder. 
3. It is recommended that bilateral clinical finding or disorder content should NOT routinely be added to the hierarchy 243796009|Situation with explicit context (situation).
4. New concepts should be added as a pre-coordinated concept using two finding sites.  The finding site will be a lateralized subtype of an existing concept from the anatomy hierarchy.  The two lateralized finding sites will be added in most cases into two separate role groups.
5. New concepts to be added on request and not in anticipation of a request.
6. Review all existing concepts (see Appendix one) in the clinical finding hierarchy to improve their current modeling and apply the new recommendation for the addition of two finding sites.
7. Proposed change to the Editorial Guidance:

                             I.         Incorporate a section to explain the decision to include bilateral content into the clinical finding hierarchy and how this content will be modeled.

                           II.         The term “bilateral” is preferred for the Fully Specified Name, for example

• Bilateral cataract (disorder)
• Osteoarthritis of bilateral joint of knee (disorder)
• Atherosclerosis of bilateral carotid artery (disorder)

Note: ‘S’ is not used in the Fully Specified Name or any description in order to align with existing editorial policy.  Section 7.2.1 Plurals in the Editorial Guide states “...rules apply to the FSN, and should apply to preferred display names to be used in coding. Exceptions to these rules might be allowed for special synonyms used for navigation, where the broad category is more naturally named using a plural. However, it would be advisable to keep track of these exceptions in a separate subset…”

                        III.         The terms “both” or “left and right” may be added as synonyms, for example

• Left and right cataract
• Osteoarthritis of both knees
• Osteoarthritis left and right knee
• Atherosclerosis of both carotid arteries
• Atherosclerosis of left and right artery

8 Quality Program Criteria

8.1 Quality Metrics

8.1.1 Quality Metric 1

8.1.2 Quality Metric 2

9 Project Resource Estimates

Estimated project size: medium

The implementation of review of existing content could be undertaken over one release. 

9.1 Scope of Construction Phase

The proposed solution is detailed in Section 6 of this document with recommendations detailed in Section 7.  The scope of the initial phase of the this content project will be to review all existing content that references the word bilateral in the clinical finding hierarchy and align the relationship groups and descriptions as set out in the detailed recommendations in Section 7 where possible.  The second phase will be to review all existing requests for new “bilateral” content for the clinical finding hierarchy that currently remains in inception/elaboration status in SIRS.  This content can be added where the request is otherwise acceptable along with the new concept in the anatomy hierarchy where the concept does not already exist.  It is not envisaged that this would need to be undertaken over more than one release if sufficient manpower is available within the content team to make the necessary changes.

To prevent recurrence of the problem the editorial guide must be aligned with the recommendations of Section 7 to ensure that modelers and requesters are supported by documentation.

9.2 Projection of Remaining Overall Project Resource Requirements

9.2.1 Expected Project Resource Requirement Category

This content project in isolation does not require project management and can be implemented by the content team.  However, implementation of this content project alongside the large-scale implementation of pre coordinated lateralised content would be resource intensive and is likely to require project management and a staged approach to implementation.

9.2.2 Expected Project Impact and Benefit

The implementation of this content project will benefit end users by providing the concepts that they wish to use with a single concept ID.  The quality of existing content will also improve.

9.2.3 Indicative Resource Estimates for Construction, Transition and Maintenance

Approximately 207 existing concepts to be reviewed and changes made where necessary.

Existing SIRS requests (approximately 50 requests) are to be reviewed and added to SNOMED CT.  This may result in the requirement for additional anatomy content.

Maintenance is not required assuming that going forward new content follows the recommended approach for term construction and modeling.

Appendix A  

“Bilateral” Concepts in Clinical Finding Hierarchy

2058001    Bilateral loss of labyrinthine reactivity (disorder)

3560000    Bilateral recurrent inguinal hernia (disorder)

3762005    Bilateral recurrent femoral hernia with gangrene (disorder)

5311007    Bilateral hyperactive labyrinth (disorder)

6481005    Diplegia (disorder)

7815009    Bilateral inguinal hernia with gangrene (disorder)

9359003    Bilateral inguinal hernia with gangrene AND obstruction (disorder)

10155006  Bilateral congenital dislocation of hip (disorder)

12073000  Bilateral recurrent femoral hernia without obstruction AND without gangrene (disorder)

13093003  Bilateral traumatic amputation of legs at any level with complication (disorder)

13916005  Bilateral recurrent femoral hernia with gangrene AND obstruction (disorder)

14977000  Multiple AND bilateral precerebral artery thrombosis (disorder)

17604001  Bilateral right-sidedness sequence (disorder)

17650003  Bilateral femoral hernia with obstruction but no gangrene (disorder)

20143001  Bilateral bundle branch block (disorder)

23728006  Partial bilateral paralysis (disorder)

23740006  Bilateral paralysis of tongue (disorder)

24194000  Complete bilateral cleft palate (disorder)

26320009  Bilateral recurrent femoral hernia with obstruction but no gangrene (disorder)

29188005  Complete bilateral paralysis (disorder)

36211009  Bilateral traumatic amputation of feet without complication (disorder)

37943007  Multiple AND bilateral precerebral artery embolism (disorder)

38163003  Bilateral femoral hernia with gangrene (disorder)

42140004  Bilateral recurrent inguinal hernia with gangrene AND obstruction (disorder)

42655007  Complete bilateral paralysis of vocal cords (disorder)

47686007  Incomplete bilateral cleft palate (disorder)

49813000  Bilateral congenital macrostomia (disorder)

52777008  Bilateral small kidney (disorder)

53462005  Bilateral recurrent inguinal hernia with gangrene (disorder)

53927006  Bilateral traumatic amputation of arms at any level without complication (disorder)

62815003  Incomplete bilateral cleft lip (disorder)

66135001  Bilateral inguinal hernia with obstruction but no gangrene (disorder)

67069009  Bilateral femoral hernia without obstruction AND without gangrene (disorder)

67992007  Multiple AND bilateral precerebral artery obstruction (disorder)

68126001  Bilateral femoral hernia with gangrene AND obstruction (disorder)

71682006  Bilateral hypoactive labyrinth (disorder)

72425000  Bilateral left-sidedness sequence (disorder)

73052009  Bilateral recurrent inguinal hernia with obstruction but no gangrene (disorder)

73192008  Multiple AND bilateral precerebral artery stenosis (disorder)

73600009  Bilateral traumatic amputation of legs at any level without complication (disorder)

80446009  Complete bilateral cleft lip (disorder)

84886001  Bilateral traumatic amputation of arms at any level with complication (disorder)

85502002  Bilateral inguinal hernia (disorder)

89824004  Bilateral traumatic amputation of feet with complication (disorder)

92503002  Neurofibromatosis type 2 (disorder)

92505009  Bilateral crossbite (disorder)

95581005  Bilateral hydronephrosis (disorder)

95722004  Bilateral cataracts (disorder)

95820000  Bilateral hearing loss (disorder)

109548000                  Bilateral cleft of primary palate (disorder)

109717005                  Bilateral condylar hyperplasia of mandible (disorder)

109720002                  Bilateral coronoid hyperplasia of mandible (disorder)

109721003                  Bilateral condylar hypoplasia of mandible (disorder)

109724006                  Bilateral coronoid hypoplasia of mandible (disorder)

162344009                  Bilateral deafness (disorder)

181225007                  Bilateral hilar adenopathy syndrome (disorder)

194248004                  Bilateral chronic serous otitis (disorder)

194286008                  Bilateral suppurative otitis media (disorder)

194290005                  Acute bilateral otitis media (disorder)

194373002                  Hyperactive bilateral labyrinthine dysfunction (disorder)

194375009                  Hypoactive bilateral labyrinthine dysfunction (disorder)

194377001                  Labyrinthine bilateral reactive loss (disorder)

194417009                  Conductive hearing loss, bilateral (disorder)

194424005                  Sensorineural hearing loss, bilateral (disorder)

194429000                  Mixed conductive and sensorineural hearing loss, bilateral (disorder)

195183002                  Multiple and bilateral precerebral arterial occlusion (disorder)

195201005                  Multiple and bilateral precerebral artery syndromes (disorder)

195236009                  Occlusion and stenosis of multiple and bilateral cerebral arteries (disorder)

195844002                  Bilateral partial vocal cord paralysis (disorder)

195845001                  Bilateral total vocal cord paralysis (disorder)

196812007                  Bilateral irreducible inguinal hernia (disorder)

196813002                  Bilateral recurrent irreducible inguinal hernia (disorder)

196818006                  Bilateral simple inguinal hernia (disorder)

196819003                  Bilateral recurrent simple inguinal hernia (disorder)

196840002                  Bilateral irreducible femoral hernia (disorder)

196841003                  Bilateral recurrent irreducible femoral hernia (disorder)

201839001                  Primary coxarthrosis, bilateral (disorder)

201840004                  Coxarthrosis resulting from dysplasia, bilateral (disorder)

201841000                  Primary gonarthrosis, bilateral (disorder)

201842007                  Primary arthrosis of first carpometacarpal joints, bilateral (disorder)

201857000                  Post-traumatic coxarthrosis, bilateral (disorder)

201858005                  Post-traumatic gonarthrosis, bilateral (disorder)

201859002                  Post-traumatic arthrosis of first carpometacarpal joints, bilateral (disorder)

204614006                  Bilateral complete cleft palate with cleft lip (disorder)

204615007                  Bilateral incomplete cleft palate with cleft lip (disorder)

204620007                  Cleft hard palate with cleft lip, bilateral (disorder)

204950001                  Bilateral renal dysplasia (disorder)

205052001                  Congenital subluxation of hip, bilateral (disorder)

205057007                  Bilateral dysplastic hip (disorder)

205060000                  Bilateral unstable hip (disorder)

210767003                  Traumatic bilateral amputation of leg with complication (disorder)

231986000                  Acute retinal necrosis (disorder)

233655000                  Asbestos-induced bilateral diffuse pleural thickening (disorder)

233767005                  Stage 1 pulmonary sarcoidosis (disorder)

233768000                  Stage 2 pulmonary sarcoidosis (disorder)

237808008                  Bilateral atrophy of testes (disorder)

238676008                  Lofgrens syndrome (disorder)

253311006                  Bilateral superior vena cava (disorder)

253315002                  Inferior vena cava interruption with bilateral azygos continuation (disorder)

253575005                  Bilateral muscular infundibula (disorder)

253576006                  Bilateral deficient infundibula (disorder)

253817004                  Congenital absent hemidiaphragm - bilateral (disorder)

253845005                  Maldescent of testis, bilateral (disorder)

253897003                  Congenital vesicoureterorenal reflux, bilateral (disorder)

253984004                  Bilateral complete and incomplete cleft lip (disorder)

253989009                  Bilateral incomplete cleft lip and alveolus (disorder)

253990000                  Bilateral complete cleft lip and/or alveolus (disorder)

253994009                  Cleft hard palate, bilateral (disorder)

254000002                  Cleft soft palate, bilateral (disorder)

254027003                  Bilateral craniofacial microsomia (disorder)

263177009                  Bilateral fracture of condylar head and midline fracture of mandible (disorder)

263960005                  Bilateral atria (disorder)

263961009                  Bilateral isomeric atria (disorder)

264508001                  Bilateral hilar adenopathy (disorder)

268228006                  Undescended testes - bilateral (disorder)

268232000                  Bilateral renal hypoplasia (disorder)

275416002                  Congenital bilateral aplasia of vas deferens (disorder)

304068004                  Bilateral cleft lip (disorder)

314419002                  Bilateral diffuse uveal melanocytic proliferation (disorder)

371189003                  Bilateral acheiria (disorder)

371191006                  Bilateral congenital absence of feet (disorder)

371015003                  Congenital absence of both testes (disorder)

41962002  Oligohydramnios sequence (disorder)

396286008                  Bilateral bronchopneumonia (disorder)

400944001                  Bilateral superior oblique palsy (disorder)

407671000                  Bilateral pneumonia (disorder)

396184003                  Isometropic amblyopia (disorder)

427644005                  Bilateral central hearing loss (disorder)

425414000                  Bilateral renal artery stenosis (disorder)

425996009                  Bilateral basal pneumonia (disorder)

425802001                  Bilateral pleural effusion (disorder)

426651005                  Bilateral carotid artery occlusion (disorder)

428130003                  Bilateral traumatic amputation of arms below elbow (disorder)

428777001                  Obstruction of both fallopian tubes (disorder)

430985005                  Bilateral sensory hearing loss (disorder)

433097005                  Bilateral traumatic amputation of upper limbs (disorder)

430977001                  Bilateral neural hearing loss (disorder)

438583008                  Congenital bilateral perisylvian syndrome (disorder)

444325005                  Deep vein thrombosis of bilateral lower extremities (disorder)

444718001                  Bilateral enlargement of atria (disorder)

445543002                  Intracardiac location of anomalous pulmonary venous connections to bilateral isomeric atriums (disorder)

445498009                  Bilateral traumatic amputation of lower limbs (disorder)

448647006                  Bilateral bilobed lungs due to isomerism of left lung (disorder)

448648001                  Bilateral trilobed lungs due to isomerism of right lung (disorder)

448092000                  Vascular ring due to aberrant subclavian artery and bilateral arterial ducts (disorder)

448202002                  Left bronchial isomerism (disorder)

447674005                  Right bronchial isomerism (disorder)

461098000                  Cardiovascular abnormality due to bilateral ductus arteriosus (disorder)

461096001                  Bilateral patent ductus arteriosus (disorder)

461097005                  Bilateral closed ductus arteriosus (disorder)

461094003                  Bilateral ductus arteriosus with patent left ductus arteriosus and closed right ductus arteriosus (disorder)

461093009                  Bilateral ductus arteriosus (disorder)

461095002                  Bilateral ductus arteriosus with closed left ductus arteriosus and patent right ductus arteriosus (disorder)

698769001                  Bilateral posterior lingual occlusion of mandibular teeth (disorder)

218951000119100      Bilateral visual impairment (disorder)

8771000119104          Bilateral moderate to severe visual impairment (disorder)

702319000                  Bilateral cerebral palsy (disorder)

702381007                  Horizontal gaze palsy with progressive scoliosis (disorder)

34201000119101        Distal obstruction of both fallopian tubes (disorder)

7271000119107          Acute bilateral otitis media with effusion (disorder)

10819341000119100  Open bilateral fracture of multiple ribs (disorder)

1085341000119100    Cleft of soft palate and bilateral cleft lip (disorder)

1085331000119100    Cleft palate and bilateral cleft lip (disorder)

8661000119102          Intestinal obstruction due to bilateral recurrent inguinal hernia (disorder)

1083751000119100    Intestinal obstruction due to bilateral femoral hernia (disorder)

8631000119105          Intestinal obstruction due to bilateral inguinal hernia (disorder)

8651000119104          Intestinal obstruction due to bilateral recurrent femoral hernia (disorder)

1084521000119100    Intestinal obstruction due to bilateral recurrent irreducible inguinal hernia (disorder)

127378008                  Bilateral paresis (finding)

34063005  Homonymous hemianopia (finding)

50314001  Partial bilateral paresis (finding)

78119002  Complete bilateral paresis (finding)

134374006                  Hearing test bilateral abnormality (finding)

162301005                  Bilateral headache (finding)

162359003                  Bilateral earache (finding)

163853001                  On examination - plantars-bilateral flexor (finding)

164750000                  Audiogram bilateral abnormality (finding)

246588005                  Bilateral extensor plantar response (finding)

246591005                  Bilateral equivocal plantar response (finding)

246594002                  Bilateral absent plantar response (finding)

251479006                  Bilateral periodic epileptiform discharges (finding)

271717004                  Bilateral flexor plantar response (finding)

297262003                  Bilateral fixed dilatation of pupil (finding)

299739007                  Bilateral upper motor neurone lesion (finding)

345121001                  Heteronymous bilateral visual field defects (finding)

369838003                  T3a: Prostate tumor with extracapsular extension (unilateral or bilateral) (finding)

370007009                  N2: Bilateral metastasis in lymph node(s) > 6 cm in greatest dimension, above supraclavicular fossa (finding)

370010002                  N2c: Metastasis in bilateral or contralateral lymph nodes, none > 6 cm in greatest dimension (finding)

370026001                  N1b: Metastasis in bilateral, midline, or contralateral cervical or mediastinal lymph node(s) (finding)

59695000  Bilateral visual field constriction (finding)

384986002                  pT2c: Bilateral disease (prostate) (finding)

385308001                  pN3: Metastasis in perirectal and inguinal lymph nodes AND/OR bilateral internal iliac AND/OR inguinal lymph nodes (anal canal) (finding)

396634009                  pN2c: Metastasis in bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension (upper aerodigestive tract) (finding)

396638007                  pN2: Bilateral metastasis in lymph node(s), 6 cm or less in greatest dimension, above the supraclavicular fossa (nasopharynx) (finding)

397127000                  pN2: Bilateral regional lymph node metastasis (vulva) (finding)

397150006                  pT4: Tumor invades any of the following: main portal vein or its branches bilaterally, common hepatic artery, or other adjacent structures, such as the colon, stomach, duodenum, or abdominal wall (extrahepatic bile ducts) (finding)

397373006                  pN2 (IVA): Bilateral regional lymph node metastasis (pT1-pT4) (TNM category and FIGO stage) (vulva) (finding)

397374000                  pN2 (IVB): Bilateral regional lymph node metastasis (pT1-pT4, pM1) (TNM category and FIGO stage) (vulva) (finding)

399704006                  pN1b: Metastasis to unilateral, bilateral, or contralateral cervical or superior mediastinal lymph nodes (thyroid) (finding)

417262009                  Bilateral sacral flexion (finding)

417056009                  Bilateral sacral extension (finding)

428948008                  Disability of bilateral lower limbs (finding)

429634002                  Disability of bilateral upper limbs (finding)

442778006                  Bilateral tonsillar swelling (finding)

4831000119102          Bilateral tinnitus (finding)

7731000119103          Bilateral homonymous altitudinal hemianopia (finding)

162839007                  On examination - thyroid swelling -bilateral (finding)