Guidance

20-week screening scan pathway requirements

Updated 19 December 2024

Applies to England

This document provides an overview of the 20-week screening scan by describing what should happen at each stage of the pathway. It should be read alongside other guidance for the NHS fetal anomaly screening programme (FASP), including:

• screening standards
• programme handbook

Please also read the general information relevant to all the NHS screening programme pathways.

20-week screening scan

The NHS offers an ultrasound scan to all women pregnant with singleton and twin pregnancies. This 20-week screening scan is performed between 18⁺⁰ and 20⁺⁶ weeks to screen for 11 physical conditions. The screening pathway must be completed by 23⁺⁰ weeks.

The purpose of the 20-week screening scan is to identify specified conditions that:

• benefit from treatment before or after birth
• need treatment in a specialist setting after birth to improve health outcomes
• could mean the baby may die shortly after birth
• may lead to a discussion about the options of continuing or terminating the pregnancy

A confirmatory ultrasound scan and/or prenatal diagnosis (PND) will be offered if a physical condition is identified or suspected.

The time allocation for appointments for a singleton pregnancy is a minimum of 30 minutes and for a twin pregnancy is a minimum of 45 minutes.

Trans men who are pregnant should be offered the same antenatal and newborn screening tests as other pregnant individuals.

Find out more about the scan in the programme overview.

End-to-end pathway

The pathway for the 20-week screening scan consists of the following elements.

The dotted boxes and numbered labels show how the different parts of the pathway map to the generic headings used below.

An accessible text-only version of this pathway is also available.

1. Before screening test

These requirements relate to making sure that screening is offered to the correct people.

Providers must have systems in place to:

• maintain accurate records of eligible population
• make sure women receive verbal and digital information (see Screening tests for you and your baby (STFYAYB)) about the 20-week screening scan during first contact or booking visit with the midwife; this must be recorded
• make sure women who are unable to access the digital version of STFYAYB are given a physical copy
• make sure women are signposted to or given STFYAYB translations or STFYAYB easy guides as appropriate
• make sure all eligible women are offered the 20-week screening scan
• maintain clear and accurate records of the woman’s decision in line with local guidelines
• provide a weekly failsafe process to track all women from offer of screening to the end of the screening pathway and have a recorded outcome
• make sure there is effective communication between maternity and ultrasound services, for example when interpreting services are needed
• encourage all healthcare professionals who offer the 20-week screening scan to complete the 20-week screening scan e-learning resource every 24 months

Refer to the 20-week screening scan section of FASP handbook for additional details.

2. Screening test

These requirements relate to the processes of carrying out the screening test.

Coverage

Providers must have systems in place to return data for the:

• coverage standard FASP-S02: fetal anomaly ultrasound (KPI FA2)

Carrying out the screening test

Providers must have systems in place to:

• make sure that the ultrasound practitioner checks the woman’s understanding of the 20-week screening scan and records the woman’s decision clearly and accurately in line with local guidelines
• make sure that the screening scan appointment incorporates:
  • pre-scan discussion
  • the ultrasound examination
  • post-scan information giving
  • recording scan results and actions appropriately
• perform the scan in accordance with the FASP handbook guidance covering the 20-week screening scan
• make sure an interpreter is available as required
• report 20-week screening scan findings to the woman on the day of the scan
• advise women whose baby is developing as expected that their baby will be followed up at the newborn and infant physical examination; the 20-week screening scan pathway ends for this group
• complete a single repeat screening scan by 23⁺⁰ weeks if the initial 20-week screening scan cannot be completed
• record screening episode as incomplete if the 20-week screening scan was incomplete
• make sure there are weekly failsafe systems in place to track women who do not attend appointments
• make sure any ultrasound practitioner performing the NHS FASP screening or diagnostic ultrasound scans holds, as a minimum, the qualifications outlined in the FASP handbook
• make sure ultrasound practitioners are aware of:
  • Royal College of Radiologists (RCR) and Society and College of Radiographers (SCoR) standards for the provision of an ultrasound service
  • British Medical Ultrasound Society (BMUS) guidelines for the safe use of diagnostic ultrasound equipment
• encourage ultrasound practitioners who undertake the 20-week screening scan to complete the:
  • 20-week screening scan e-learning every 24 months
  • fetal cardiac e-learning every 24 months (this is mandatory for ultrasound practitioners who are new to the 20-week screening scan)
• return data for the test standard FASP-S04: fetal anomaly ultrasound

Refer to the 20-week screening scan section of the FASP handbook for additional details.

Screening outcome and referral

Providers must have systems in place to:

• refer the woman locally or to a tertiary centre if there are unexpected findings at scan or a diagnosis linked to the 11 physical conditions, as clinically appropriate
• make sure local and tertiary referrals are recorded

3. After screening test (diagnosis)

These requirements relate to the process of following-up women with screen positive results to get a confirmed result.

Diagnosis or suspected diagnosis occurs at the time of the 20-week screening scan.

Providers must have systems in place to:

• offer, perform or refer for PND as indicated
• make sure, for women who accept PND, a sample is received by the laboratory
• provide a failsafe process to make sure genomic laboratories know which samples to expect and follow up any missing samples with maternity services in a timely manner
• provide a weekly failsafe process to make sure each PND sample taken has a reported outcome
• report 20-week screening scan results to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS) if there are unexpected findings
• refer women to appropriate services and support organisations as per local guidelines
• return data for referral standard FASP-S08: time to intervention

4. After screening test (intervention)

These requirements relate to the process of following-up people with a confirmed diagnosis and maximising the overall benefits from screening in terms of the final outcome to the person being screened.

Intervention and treatment

Providers must have systems in place to:

• support women who choose to continue their pregnancy
• support and refer women who choose to terminate their pregnancy
• report PND test results to NCARDRS
• record pregnancy outcome
• return data for the diagnosis/intervention standard FASP-S09: diagnostic tests

Pathway outcome

Providers must have systems in place to:

• follow up baby at birth and offer NIPE as appropriate
• report pregnancy outcome to NCARDRS