Skip to main content
  1. Right Decisions
  2. GGC - Clinical Guideline Platform
  3. Maternity
  4. Back
  5. Ultrasound
  6. Twin Pregnancy Ultrasound Guideline (330)
Announcements and latest updates

Right Decision Service newsletter: September 2024

Welcome to the Right Decision Service (RDS) newsletter for September 2024.

1.Business case for permanent provision of the Right Decision Service from April 2025 onwards

This business case has now been endorsed by the HIS Board and will shortly be submitted to Scottish Government.

2. Management of RDS support tickets

To balance increasing demand with available capacity and financial resource, the RDS team and Tactuum are now working together to  implement closer management of support tickets. As a key part of this, we want to ensure clear, timely and consistent communication with yourselves as requesters.  

Editors will now start seeing new messages come through in response to support ticket requests which reflect this tightening up and improvement of our processes.

Key points to note are:

2.1 Issues confirmed by the RDS and Tactuum teams as meeting the critical/urgent and high priority criteria will continue to be prioritised and dealt with immediately.

Critical/urgent issues are defined as:

  1. The Service as a whole is not operational for multiple users. OR
  2. Multiple core functions of the Service are not operational for multiple users.

Example – RDS website outage.

Please remember to email ann.wales3@nhs.scot and his.decisionsupport@nhs.scot with any critical/urgent issues in addition to raising a support ticket.

High priority issues are defined as:

  1. A single core function of the Service is not operational for multiple users. OR:
  2. Multiple non-core functions of the Service are not operational for multiple users.

Example – Build to app not working.

2.2 Support requests that are outwith the warranty period of 12 weeks since the software was originally developed will not be automatically addressed by Tactuum. The RDS team will consider these requests for costed development work and will obtain estimate of effort and cost from Tactuum for priority issues.

2.3 Support tickets for technical issues that are not classified as bugs will not be automatically addressed by Tactuum. The definition of a bug is ‘a defect in the software that is at variance with documented user requirements.’  Issues that are not bugs will also be considered for costed development work.

The majority of issues currently in support tickets fall into category 2 or 3 above, or both.

2.4 Non-urgent requests that require a deployment (i.e a new release of RDS) will normally be factored into the next scheduled release (currently end of Nov 2024 and end of Feb 2025) unless by special agreement with the RDS team.

Please note that we plan to move in the new year to a new system whereby requests all come to an RDS support portal in the first instance and are triaged from there to Tactuum when appropriate.

We will be organising a webinar in a few weeks’ time to take you through the details of the current support processes and criteria.

3. Next scheduled deployment.

The next scheduled RDS deployment will take place at the end of November 2024.  We are reviewing all outstanding support tickets and feature requests along with estimates of effort and cost to determine which items will be included in this deployment.

We will update you on this in the next newsletter and in the planned webinar about support ticket processes.

4. Contingency arrangements for RDS

Many thanks to those of you who attended our recent webinar on the contingency arrangements being put in place to prevent future RDS outages as far as possible and minimise impact if they do occur.  Please contact ann.wales3@nhs.scot if you would like a copy of the slides from this session.

5. Transfer of CKP pathways to RDS

The NES clinical knowledge pathway (CKP) publisher is now retired and the majority of pathways supported by this tool have been transferred to the RDS. Examples include:

NHS Lothian musculoskeletal pathways

NHS Fife rehabilitation musculoskeletal pathways

NHS Tayside paediatric pathways

6. Other new RDS toolkits

Include:

Focus on frailty (from HIS Frailty improvement programme)

NHS GGC Money advice and support

If you would like to promote one of your new toolkits through this newsletter, please contact ann.wales3@nhs.scot

To go live imminently:

  • Focus on dementia
  • NHS Lothian infectious diseases toolkit
  • Dumfries and Galloway Adult Support and Protection procedures
  • SIGN guideline – Prevention and remission of type 2 diabetes

 

7. Evaluation projects

We have recently analysed the results of a survey of users of the Scottish Palliative Care Guidelines toolkit.  Key findings from 61 respondents include:

  • Most respondents (64%) are frequent users of the toolkit, using it either daily or weekly. A further 25% use it once or twice per month.
  • 5% of respondents use the toolkit to deliver direct patient care and 82% use it for learning
  • Impact on practice and decision-making was rated as very high, with 80% of respondents rating these at a 4-5 on a 5 point scale.
  • Impact on time saving was also high, with 74% of respondents rating it from 3-5.
  • 74% also reported that the toolkit improved their knowledge and skills, rating these at 4-5 on the Likert scale

Key strengths identified included:

  • The information is useful, succinct, and easy to understand (31%).
  • Coverage is comprehensive (15%)
  • All information is readily accessible in one place and users value the offline access via mobile app (15%)
  • Information is reliable, evidence-based and up to date (13%)

Users highlighted key areas for improvement in terms of navigation and search functionality. The survey was very valuable in enabling us to uncover the specific issues affecting the user experience. Many of these can be addressed through content management approaches. The issues identified with search results echo other user feedback, and we are costing improvements with a view to implementation in the next RDS deployment.

8.RDS High risk prescribing (polypharmacy) decision support embedded in Vision and EMIS primary care E H R systems

This decision support software, sponsored by Scottish Government Effective Prescribing and Therapeutics Division,  is now available for all primary care clinicians across NHS Tayside. Board-wide implementation is also planned for NHS Lothian, and NHS GGC, NHS Ayrshire and Arran and NHS Dumfries and Galloway have initial pilots in progress. The University of Dundee has been commissioned to evaluate impact of this decision support software on prescribing practice.

9. Video tutorials for RDS editors

Ten bite-size (5 mins or less) video tutorials for RDS editors are now available in the “Resources for providers of RDS tools” section of the RDS.  These cover core functionality including Save and preview, content page and media management, password management and much more.

10. Training sessions for new editors (also serve as refresher sessions for existing editors) will take place on the following dates:

  • Wednesday 23rd October 4-5 pm
  • Tuesday 29th October 11 am -12 pm

To book a place, please contact Olivia.graham@nhs.scot, providing your name, organisation, job role, and level of experience with RDS editing (none, a little, moderate, extensive.)

If you have any questions about the content of this newsletter, please contact his.decisionsupport@nhs.scot  

With kind regards

 

Right Decision Service team

Healthcare Improvement Scotland

 

 

 

Twin Pregnancy Ultrasound Guideline (330)

Please report any inaccuracies or issues with this guideline using our online form

Gestational Age, Chorionicity and Amnionicity

Women should be offered a first trimester USS (< 14+0 weeks) to estimate gestational age and determine chorionicity and amnionicity.

Chorionicity and amnionicity should be determined by the number of placental masses, the presence of amniotic membranes and membrane thickness, the lambda or T-sign.

Clear nomenclature should be assigned e.g inferior and superior, or left and right, in a twin or triplet pregnancy to ensure consistency throughout pregnancy.

If a multiple pregnancy presents after 14+0 weeks then determination of chorionicity and amnionicity could also take into account discordant fetal sex if required.

If TAUSS views are poor because of a retroverted uterus or a high BMI, use a transvaginal ultrasound scan to determine chorionicity and amnionicity.

The largest baby should be used to calculate the estimated date of delivery for the pregnancy.

A photographic record should be placed in the patient’s hospital held records documenting the ultrasound appearance of the membrane attachment to the placenta and an electronic / hard drive record stored. Chorionicity must be checked by senior sonographer

If there is still doubt about the chorionicity, the woman should be referred to medical staff for chorionicity assessment without delay.

Following this if there is still doubt, the pregnancy should be managed as monochorionic until proved otherwise.

Screening

Referral should be made for counselling for antenatal screening for combined trisomy (21,18,13) following the diagnosis of a twin pregnancy (fetal medicine at QEUH, Day Care counselling midwife PRM, Screening midwife Clyde). This should ideally be prior to the 11+2 to 14+1 week scan.

The test of choice for twin pregnancies is first trimester combined screening. Every opportunity must be made to maximise the offer of first trimester combined screening. Chance results to be reported are:

  • a term chance of T21 and a term chance of T18/T13
  • a term chance of T21 only
  • a term chance of T18/T13 only

First trimester combined screening will be reported in a dichorionic twin pregnancy as a chance for each fetus whereas in a monochorionic twin pregnancy it will be reported as a chance per pregnancy.

Women who ‘miss’ or have unsuccessful first trimester screening for aneuploidy should be offered second trimester screening for T21. Chance results are reported as a pregnancy related chance that is not fetal specific.

Monochorionic Twins

Fetal ultrasound assessment should be performed every two weeks in uncomplicated monochorionic twins from 16+0 weeks onwards until delivery.

Scans at 16 and 20 weeks (detailed anomaly scan) should be performed by a medical sonographer. The detailed fetal anomaly scan should include extended cardiac views (5 standard views).

At every ultrasound, the following should be assessed and recorded:

  • liquor volume (LV) should be assessed in each sac and deepest vertical pool (DVP)
  • Umbilical artery pulsatility index (UAPI)*
  • Fetal bladders should be assessed.
  • Middle Cerebral Artery Peak Systolic Velocity (MCA PSV)

*See Umbilical Artery Pulsatility Index Chart

Increase the frequency of diagnostic monitoring for TTTS in the woman’s 2nd and 3rd trimester to at least weekly if there are concerns about differences between the babies’ amniotic fluid level (a difference in DVP depth of 4cm or more). Include Doppler assessment of the umbilical artery flow for each baby.

Refer for medical scan if LV DVP>8 cm or <2cm before 20 weeks or LV DVP >10cm or <2cm after 20 weeks. If abnormality confirmed discussion with fetal medicine at QEUH is indicated.

Staging of Twin-to-twin transfusion syndrome (TTTS)

Stage Description

I

II

III

IV

V

Poly/oligohydramnios with bladder of the donor still visible

Bladder of the donor no longer visible

Presence of either absent or reverse end-diastolic velocity of the umbilical artery, reverse flow in either twin

Hydrops in either twin

Demise of one or both twins prior to surgery

From 16+0 weeks fetal biometry (HC, AC and FL) should be assessed and abdominal circumference (AC) and Estimated fetal weight (EFW) recorded for each twin. The discordance in EFW should be calculated and documented in monochorionic twins at each visit:

([EFW larger fetus − EFW smaller fetus] ÷ EFW larger fetus) × 100

Increase diagnostic monitoring in the 2nd and 3rd trimesters to at least weekly, and include Doppler assessment of the umbilical artery flow for each baby, if there is an EFW discordance of 20% or more and/or the EFW of any of the babies is below the 10th centile for gestational age.

Refer women with a monochorionic twin pregnancy to a tertiary level fetal medicine centre if there is an EFW discordance of 25% or more and the EFW of either of the babies is below the 10th centile for gestational age because this is a clinically important indicator of selective fetal growth restriction.

Selective intrauterine growth restriction (growth discordance of >20%). Approximately 10-15 % of MCDA twins

Stage Description

I

II

III

Growth discordance but positive diastolic velocities in both fetal umbilical arteries.

Growth discordance with absent or reversed end-diastolic velocities (AREDV) in one or both fetuses.

Growth discordance with cyclical umbilical artery diastolic waveforms (positive followed by absent then reversed end-diastolic flow in a cyclical pattern over several minutes [intermittent AREDV; iAREDV]).

Offer weekly USS monitoring for TAPS from 16 weeks of pregnancy using middle cerebral artery peak systolic velocity (MCA-PSV) to women who pregnancies are complicated by:

  • feto-fetal transfusion syndrome that has been treated by fetoscopic laser therapy or
  • selective fetal growth restriction (defined by an EFW discordance of 25% or more and an EFW of any of the babies below the 10th centile for gestational age)

Aim for delivery between 36+0 and 36+6 for uncomplicated MCDA twins after which point continuing the pregnancy increases the risk of fetal death

For monochorionic monoamniotic twins birth should be planned between 32+0 and 33+6

Dichorionic Twins

Fetal anomaly scan can be performed by sonographer if there are no other obstetric reasons for a medical FAS.

Growth USS should be performed every 4 weeks from 24 weeks onwards. Estimated fetal weight, umbilical artery PI and deepest vertical pool of liquor should be measured at each visit.

Fetal weight discordance should be calculated for dichorionic twins:

([EFW larger fetus − EFW smaller fetus] ÷ EFW larger fetus) × 100

Increase monitoring in 2nd and 3rd trimesters to at least weekly, and include Doppler assessment of the umbilical artery flow for each baby if there is EFW discordance of 20% or more and/or the EFW of any of the babies is below the 10th centile for gestational age.

Refer women with a dichorionic twin pregnancy to a tertiary level fetal medicine centre if there is an EFW discordance of 25% or more and the EFW of any of the babies is below the 10th centile for gestational age because this is a clinically important indicator of selective fetal growth restriction.

Aim for delivery between 37+0 and 37+6 for uncomplicated DCDA twins as after this point continuing the pregnancy increases the risk of fetal death.

Appendix: Umbilical Artery Pulsatility Index (UAPI) Reference Chart

> 95th percentile is abnormal

Appendix: MONOCHORIONIC DIAMNIOTIC TWINS – antenatal appointments

(File in notes)

Monochorionic diamniotic twins - antenatal appointments - pdf

Appendix: DICHORIONIC DIAMNIOTIC TWINS –antenatal appointments

(File in notes)

Dichorionic diamniotic twins - antenatal appointments - pdf

Editorial Information

Last reviewed: 24/10/2023

Next review date: 31/10/2028

Author(s): Victoria Watson ST7 PRM, Donna Bean, Lead Sonographer Obstetrics and Gynaecology.

Version: 3

Approved By: Maternity Clinical Governance Group

Document Id: 330

References
  1. NICE [NG137. Twin and triplet pregnancy. 2019.
  2. Khalil A. ISUOG Practice Guidelines: role of ultrasound in twin pregnancy. Ultrasound in Obstetrics and Gynaecology. ISUOG. November 2015.
  3. NHS Fetal Anomaly Screening Programme (FASP). Public Health England. September 2019.