Disease prevention/screening

Screening is a form of secondary prevention, meaning we intend to detect the disease early on. There are a couple of conditions that need to be screened for to ensure proper management is set in place early on.

We will discuss screening of the following:

ANTENATAL SCREENING

We screen for a few things in antenatal care, this includes genetic abnormalities, NTDs, gestational diabetes.

Genetic abnormalities

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Aneuploidy screening

• Down’s syndrome (trisomy 21)
• Edward’s syndrome (trisomy 18)
• Patau’s syndrome (trisomy 13)

1. First-trimester screening (combined test)- this is done at 11-14 weeks. It has 2 components:
1. Ultrasound - measuring nuchel translucency. Fluid accumulates in the neck and nuchel thickness >6mm.
2. Maternal blood test - there are 2 tests that are done:
1. Beta-hCG - increases.
2. Pregnancy-associated plasma protein-A (PAPPA) - decreases.
2. Second-trimester screening (triple/quadruple test)

Triple test - only involves maternal blood testing.

Performed at 14 - 20 weeks.

1. Beta-hCG - increases.
2. Alpha-fetoprotein (AFP) - decreases.
3. Serum oestriol - decreases.

Quadruple test - triple test + inhibin-A.

Performed at 14 - 20 weeks.

4. Beta-hCG - increases.
5. Alpha-fetoprotein (AFP) - decreases.
6. Serum oestriol - decreases.
7. Inhibin-A - increases.

Gestational diabetes

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Gestational diabetes screening:

NICE recommends that all women with at least 1 risk factor be tested for gestational diabetes using a 2 hour 75g oral glucose tolerance test (OGTT). It is done in the first trimester or second trimester. If the screening is normal, then it is recommended to redo it at 24-28 weeks.

The risk factors include:

• BMI >30
• Previous macrosomic baby >4.5kg
• Previous pregnancy with GD
• Family history of diabetes (1º relative)
• Black, Afro-Caribbean and South Asian ethnicity

Neural tube defects

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NTD screening

• Spina bifida
• Anencephaly

It also has 2 components:

1. Maternal serum alpha-fetoprotein - done at 15-22 weeks. It is considered abnormal if it is 2.5x the median. If they screen positive they get an ultrasound.
2. Ultrasound - to look if there are multiple gestations or to assess fetal anatomy for NTDs and other defects with an elevated MS-AFP such as omphalocoele, gastroschisis, cystic hygroma.

Some other conditions which all pregnant women should be offered screening for, according to the National Screening Committee:

• Anaemia
• Bacteriuria
• Blood group, Rhesus status, anti-red cell antibodies
• Hepatitis B
• HIV
• Pre-eclampsia risk factors
• Syphillis

They may also be offered screening for certain things depending on their history:

• Placenta previa
• Sickle cell
• Thalassemia
• Tay-Sachs disease

ABDOMINAL AORTIC ANEURYSM SCREENING

Screening for AAA entails a single abdominal USS for males aged 65 years old (men are at 5x more risk compared to women).

The outcome of this scan will determine further screening options:

BREAST CANCER SCREENING

Women aged 50-70 are offered a mammogram every 3 years. After 70 years old they will be encouraged to make their own appointments

Referral for breast cancer is done using the 2 week suspected cancer pathway if:

1. 30 years old+ with an unexplained lump
2. 50 years old+ with unilateral nipple discharge, retraction or any other changes that are noticeable. ]

2ww referral may also be done in individuals with skin changes suggestive of breast cancer or 30y/o+ with an axillary lump.

CERVICAL CANCER SCREENING

Cervical cancer screening used to involve a pap smear that was assessed for dyskaryosis/dysplasia (synonymous terms) and the evidence of CIN (cervical intraepithelial neoplasia). The management was solely based on the degree of dysplasia, however, modern screening has allowed further risk-stratified management.

The new NHS system is an HPV first system in which we test samples for high-risk strains of HPV (hrHPV). If it is HPV-positive, only then do we perform cytological examinations.

It has been associated with 70% reduction in cervical cancer mortality

Before we look at the criteria of the screening programme, we need to recap the hrHPV strains as well as the grading of cervical cancer:

• High risk strains include:
• HPV-16
• HPV-18
• HPV-31
• HPV-33
• HPV-45

• Grading for HPV is as such:
• CIN I - mild dysplasia. 1/3rd of thickness of epithelium covered in atypical cells.
• CIN II - moderate dysplasia. 2/3rds of thickness of epithelium is covered in atypical cells.
• CIN III - severe dysplasia. Full thickness of epithelium covered in epithelium. It is considered CIS at this stage and is still pre-malignant as it hasn’t Invaded through the basement membrane. The peak incidence of CIS is 25-29 years old.

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Treatment of CIN

• Large loop excision of transformation zone (LLETZ) - most common treatment for CIN.
• Cryotherapy

COLORECTAL CANCER SCREENING

Screening for CRC has reduced mortality rate by 16%.

Within the NHS, a Faecal Immunochemical Test (FIT) is offered to patients aged 60 - 74 years every 2 years. It is used to identify the amount of haemoglobin (blood) in a a stool sample, however, it differs as it can differentiate human haemoglobin from ingested animal haemoglobin.

Any patient with an abnormal result is offered a colonoscopy.

At the colonoscopy, approximately 10% will have cancer, 40% will be found to have polyps, and 50% will be normal.

DEPRESSION SCREENING

2 simple questions can be used for depression screening:

1. During the last month, have you often been bothered by feeling down, depressed or hopeless?
2. During the last month, have you often been bothered by having little interest or pleasure in doing things?

If the answer to either of the above is yes, a more in-depth assessment should be performed using the Hospital Anxiety and Depression scale (HAD scale), and the Patient Health Questionnaire-9, this will be discussed further in the CCC for depression.

DIABETIC EYE SCREENING

Diabetic eye screening is used to assess for any signs of proliferative diabetic retinopathy.

Everyone with diabetes over 12 years old will get an invite. Initially, the invite should be every year but this can change depending on the results.

With diabetic retinopathy screening, the eyes are inspected followed by testing visual acuity, the fundus is then assessed with fundus photography.

An M1 may indicate maculopathy too.

NEONATAL BLOOD SPOT SCREENING

The neonatal blood spot screening, previously known as Guthrie test or commonly known as the heel-prick test, is a screening test done at 5-9 days after birth, assessing for a range of congenital conditions such as:

PROSTATE CANCER SCREENING

Prostate cancer is not a part of the national screening programme, but there is an informed choice programme where healthy men >50 may opt to get their PSA levels tested, and if it is raised, the GP may suggest further testing.

PSA testing is unreliable and has a poor sensitivity and specificity. MRI and biopsy is better to identify prostate cancer.

TUBERCULOSIS SCREENING

The Mantoux test is the main test for screening for latent TB. IGRA has also been re-introduced in recent years.

Mantoux test involves injecting 0.1ml of 1:1,000 purified protein derivative (PPD) and the result is interpreted 2-3 days later.

Results are as follows:

There may be false negatives due to: