Anomaly scan or TIFFA scan checks your baby’s development around 18 to 22 weeks. Learn what it examines, its limitations, and what happens after a finding.
The anomaly scan is one of the more detailed ultrasound examinations performed during pregnancy. It is usually carried out in the second trimester, when the baby has developed enough for many important anatomical structures to be examined in detail. It is also commonly called the 20-week scan, anatomy scan, or TIFFA scan, although the exact terminology and scope can vary between centres.
The scan looks closely at the baby's anatomy, including structures of the brain, face, spine, heart, abdomen, kidneys and limbs. The placenta, amniotic fluid and aspects of fetal growth are also assessed.
For many parents, however, the biggest question is not simply “What does the scan check?” It is:
“If the report is normal, does that mean everything is definitely normal?”
Not quite. Anomaly scanning is an important screening examination, but it cannot detect every congenital condition. The quality of the examination can also be affected by factors such as fetal position and the ability to obtain the required views.
This guide explains what happens during the scan, what doctors look for, what the examination can and cannot tell you, and what may happen if an unexpected finding is seen.
TIFFA is commonly used in India to refer to a Targeted Imaging for Fetal Anomalies examination.
In everyday conversations, the terms TIFFA scan, anomaly scan, detailed scan, anatomy scan and 20-week scan are sometimes used interchangeably. The exact protocol can differ depending on the indication, gestational age, clinical history and the expertise of the person performing the examination.
The important point for parents is that this is not simply another routine pregnancy ultrasound.
The purpose is to take a systematic look at fetal anatomy and identify structural findings that may require further assessment.
The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) describes the routine mid-trimester ultrasound as an examination performed mainly for fetal anatomical evaluation. In experienced hands, many clinically important structural abnormalities can be detected.
The anomaly scan is generally performed during the middle part of the second trimester.
A commonly used window is approximately 18 to 22 weeks, although some professional patient information resources describe the mid-trimester examination more broadly, depending on the structure being assessed and local practice.
The timing matters because the fetus has reached a stage where many anatomical structures can be examined in greater detail than earlier in pregnancy.
Your doctor may recommend a particular appointment window based on:
If a specific scan has been recommended for a particular clinical reason, the timing may not be identical to the routine schedule.
By the second trimester, the baby has developed recognisable structures that can be examined systematically.
The scan is intended to identify structural abnormalities, assess fetal anatomy and document important aspects of the pregnancy. ISUOG's routine mid-trimester guideline includes assessment of the fetal head and brain, face, chest and heart, abdomen, skeletal structures, placenta and umbilical cord.
Finding a significant abnormality before birth can give the healthcare team more time to:
A scan therefore isn't only about producing an image of the baby. It can be an important part of planning appropriate care.
The exact examination protocol can vary, but a detailed mid-trimester assessment typically looks at several major areas of fetal anatomy.
The head is assessed for its overall size, shape and structural appearance.
The brain is examined in specific ultrasound planes to assess structures that should be visible at this stage of pregnancy. These include the cerebral hemispheres, ventricles, midline structures, cerebellum and other parts of the posterior fossa.
The skull is also examined for its shape and integrity.
The fetal brain examination requires careful technique. The position of the baby can sometimes make obtaining the necessary views difficult.
If an unusual finding is suspected, a more detailed fetal brain assessment may be recommended.
The fetal face can be examined for features that are visible during the examination.
Depending on the protocol and technical conditions, assessment may include:
Some facial abnormalities can be detected during the mid-trimester examination, but ultrasound does not identify every facial or developmental condition.
The position of the fetus can again make certain views difficult to obtain.
The spine is examined using different ultrasound views.
The purpose is to look for major structural abnormalities and to assess the general continuity and appearance of the spine.
ISUOG notes that the fetal spine examination is an important part of the mid-trimester assessment, but satisfactory imaging requires expertise and can be influenced significantly by fetal position.
This is one reason why a scan may occasionally need additional imaging even when there is no confirmed problem.
The heart receives particular attention during the anomaly scan.
The basic fetal cardiac assessment includes views that allow the examiner to evaluate the heart's position, four chambers and major outflow structures. The ISUOG mid-trimester guideline includes assessment of the four-chamber view and the major arterial outflow tracts, among other cardiac views.
However, a routine anomaly scan and a fetal echocardiogram are not the same examination.
A fetal echocardiogram is a more specialised assessment of the fetal heart and may be recommended when there is a specific indication or increased risk.
This distinction is important because parents sometimes assume that a normal four-chamber view means every possible heart condition has been ruled out. It does not.
The abdominal examination looks at the position and appearance of structures that should be identifiable at this stage.
The stomach, bowel, abdominal wall and umbilical cord insertion are among the structures included in the basic anatomical survey.
The examiner may also assess whether the abdominal organs appear to be in their expected locations and whether there are obvious structural concerns.
Both kidneys are assessed, together with the urinary bladder.
The examiner looks at their presence, position and appearance. The urinary bladder can also be observed during the examination.
These observations are part of the broader assessment of fetal abdominal anatomy.
The limbs are examined for their presence, general development and positioning.
Depending on what can be visualised, the examination includes assessment of the arms, hands, legs and feet and the relationship of the major joints.
As with other anatomical structures, not every skeletal or developmental condition can be excluded simply because the limbs appear normal on ultrasound.
The scan isn't limited to the baby's organs.
Other important observations can include:
The placenta is located and its relationship to the cervix is assessed.
Placental position can be particularly relevant when it is low in the uterus or when there are other obstetric considerations.
The amount of fluid surrounding the baby is assessed as part of the overall pregnancy evaluation.
Measurements of the fetus are taken to assess growth and help determine whether the baby's size is appropriate for the gestational age.
The cord and its insertion may also be assessed according to the examination protocol and technical feasibility.
No.
This is one of the most important limitations parents should understand.
The anomaly scan is designed to detect many structural abnormalities, but no ultrasound examination can identify every possible birth defect or medical condition.
Some abnormalities are easier to see than others. Some may be too subtle to identify during a routine scan. Others may become apparent only later in pregnancy, while certain genetic, biochemical, developmental or functional conditions cannot be diagnosed through a structural ultrasound alone.
The NHS similarly explains that the 20-week screening scan cannot find all conditions.
ISUOG's guidance states that most clinically important structural anomalies can be detected in expert hands, but this should not be interpreted as a guarantee that every abnormality will be identified.
That distinction is worth keeping in mind when reading a scan report.
This distinction can be confusing.
An anomaly scan is primarily a screening examination for structural abnormalities.
Screening asks:
“Does the examination show anything that needs closer assessment?”
Diagnosis asks a different question:
“What exactly is the condition, and is it confirmed?”
An ultrasound finding that looks unusual does not automatically mean that a particular diagnosis has been confirmed.
Depending on the finding, the next step could involve:
The appropriate next step depends entirely on what was seen and the clinical circumstances.
This happens fairly often and does not necessarily mean something is wrong.
A baby may be facing in a direction that makes it difficult to obtain a particular view. The spine, face, heart or other structures may not be positioned ideally for imaging.
In these situations, the examiner may:
The NHS specifically notes that the 20-week scan may take longer when the baby's position makes clear images difficult to obtain, and another appointment may be offered when necessary.
A request to repeat part of the scan therefore does not automatically mean an abnormality has been found.
Sometimes the images simply weren't good enough to complete the examination.
Hearing that a scan has shown an “abnormality” can be frightening. It is important to understand that the word may refer to a finding that needs clarification rather than a confirmed diagnosis.
The next step depends on the nature of the finding.
Your doctor may recommend a more detailed examination to answer questions such as:
ISUOG guidance recommends more detailed examination or referral to an expert centre when an anomaly is suspected.
For certain suspected brain abnormalities, for example, specialist ultrasound, genetic testing or fetal MRI may be considered depending on the circumstances.
The important thing is that one unexpected ultrasound finding should be interpreted in context, rather than treated as a final diagnosis on its own.
There isn't one standard pathway for every abnormal scan.
A specialist will usually first determine exactly what has been seen and whether the finding can be confirmed with better imaging.
Depending on the situation, further evaluation may include:
A specialist may perform a more targeted examination of the area in question.
If the concern involves the heart, a dedicated fetal cardiac examination may be recommended.
Where an anatomical finding raises the possibility of a chromosomal or genetic condition, genetic counselling can help parents understand available testing and what the results could mean.
Depending on the findings and pregnancy history, diagnostic or screening tests may be discussed.
MRI is not required for every pregnancy or every ultrasound finding. In selected cases, particularly certain suspected brain abnormalities, it may provide additional information.
The choice depends on the specific clinical question.
The underlying purpose remains the assessment of fetal anatomy, but a high-risk pregnancy may require additional or more targeted evaluation.
A pregnancy may be considered higher risk for many different reasons, including:
In these situations, the doctor may recommend additional examinations rather than relying on a single routine scan.
The important point is that the appropriate investigation depends on the reason the pregnancy is considered high risk.
An IVF pregnancy does not mean that the anatomy scan becomes unnecessary.
The pregnancy still requires appropriate fetal anatomical assessment.
Depending on the individual circumstances, the doctor may also consider other forms of prenatal screening, genetic counselling or additional monitoring.
The choice of testing should be based on the pregnancy history, maternal and fetal findings and any other relevant risk factors rather than simply on the fact that conception occurred through IVF.
Twin pregnancies require additional attention because there are two or more fetuses to assess.
The scan may need to document the anatomy of each baby separately and take into account the type of twin pregnancy and placental arrangement.
The examination can also be technically more demanding because of the position of the babies and the limited space available for imaging.
A twin pregnancy therefore deserves an assessment tailored to the individual pregnancy rather than simply treating it as a single-baby scan performed twice.
The duration isn't identical for every pregnancy.
A routine examination may be completed within a reasonable appointment period, but a detailed fetal assessment can take longer when:
The NHS notes that a 20-week scan commonly takes around 30 minutes, although it can take longer when adequate images are difficult to obtain.
Preparation instructions can vary between centres and according to the type of examination being performed.
Follow the instructions provided by your scan centre rather than relying on advice from another pregnancy appointment or an online article.
If you have previous scan reports, screening results, genetic test reports or relevant medical records, taking them with you can be useful, particularly when the examination has been recommended because of a previous finding.
Once the examination is complete, don't hesitate to ask questions if something in the report is unclear.
Useful questions include:
If the report mentions a finding that you don't understand, ask your doctor to explain what it means in the context of your pregnancy.
No test can provide that guarantee.
A normal anomaly scan means that no significant structural abnormality was identified within the scope and quality of that examination.
That is reassuring, but it is not the same as confirming that every possible genetic, developmental, functional or medical condition is absent.
Some conditions are simply not visible on routine ultrasound. Others may develop or become detectable later.
This is why pregnancy care continues after the 20-week scan even when the report is completely normal.
If you are looking for an anomaly scan or fetal medicine consultation in Trichy, the most useful approach is to consider the examination as part of the wider pregnancy-care pathway.
This becomes particularly important when there is:
Trichy Fetal Medicine and Fertility Centre provides fetal medicine services including anomaly scans, fetal echocardiography, fetal neurosonography, growth scans with Doppler, genetic counselling and other specialist fetal assessments, according to the centre information provided for this project.
The centre is located at 73C/9, Annamalai Nagar Main Road, Tiruchirappalli, Tamil Nadu 620018.
This article is intended for general educational purposes and should not be used to diagnose or treat a medical condition. Pregnancy care and the need for additional investigations vary from person to person. If an ultrasound report contains an unexpected finding, discuss it with your obstetrician or fetal medicine specialist rather than trying to interpret the result independently.
Medical review: Dr. Malathi G. Prasad, MD, FRCOG (UK), Diploma in Fetal Medicine, FMF (Barcelona), subject to final clinical review before publication.
For appointments, the anomaly scan page has the details, and our fetal medicine specialists can advise whether it fits your situation.
This guide is for general information and does not replace a consultation with a fetal medicine specialist.
In line with the PCPNDT Act, we do not perform or support sex determination.
Anomaly Scan
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