3.10.3 Diagnostic Techniques to Include Screening Tests

• Used in a group of people/population.  
• To detect/early detection of certain diseases/disorders.
• Detect diseases/disorders where there are no signs/symptoms. 
• Identify apparently healthy people who may be at increased risk of a disease/condition.

These tests are carried out on pregnant women.

• Amniocentesis
• Chorionic Villus Sampling (CVS)
• Blood Tests

How

• an antiseptic solution is used to clean the abdomen 
• area where needle is inserted into abdomen is numbed with anaesthetic 
• needle inserted through abdomen into amniotic sac/uterus 
• positioned with the aid of an ultrasound scan 
• amniotic fluid extracted 
• at 15/20 weeks into the pregnancy 
• Sent Away For analysis

What is the test looking for:
It is looking for conditions that the foetus could have when it is born such as:

• Down's syndrome
• Spina bifida
• Sickle cell anaemia

Name:
Chorionic Villus Sampling

Procedure (Transabdominal): 

• The tummy is cleaned with antiseptic 
• A needle is inserted through the tummy and abdomen wall
• The needle is guided towards the womb using the image on the ultrasound scan 
• Attachefd to the needle is a syringe, which is used to extract a small sample of chorionic villi, after which the needle is removed

Procedure (Transcervical):

• The vagina and cervix will be cleaned with antiseptic
• A tube is inserted through the vagina and cervix, and is guided toward the chorionic villi using the ultrasound scan
• Gentle suction is used to remove a small sample of chorionic villi
• The tube is removed 

What is the test looking for:
After the test has been carried out the sample is sent to the lab where the number of chromosomes are counted, and the structure of the chromosomes can be checked for any abnormalities. If CVS is being carried out to test for a specific genetic disorder, the cells in the sample can also be tested for this.

• A torniquet (tight band) is placed around the area above the elbow.
• This causes the veins to swell and fill.
• A needle attached to a syringe is inserted into the swollen vein.
• A sample or samples of blood are drawn into phials/little bottle.
• Needle is removed.
• Pressure is applied.
• A small plaster is applied.

It is looking for 

• Spina Bifida 
• Down's syndrome
• Sickle cell anaemia 

The following tests are carried out on infants and children:

• PKU
• Dental Examination
• Eye Tests
• Hearing Tests
• Hip Dislocation

• Phenylalanine/amino acid 
• Heel *****/Guthrie test 
• Blood sample is taken from baby’s heel 
• Blood is collected (on a piece of filter paper) and sent to a laboratory for analysis 
• Where levels of phenylalanine amino acid will be measured
• If levels are unusually high 
• A second blood sample will be taken to confirm diagnosis 
• Test carried out during first week of baby’s life 
• Baby must be on full milk feeds for 3 days before testing

• The dentist will discuss the procedure with the parents before the examination.
• Dentists like to see children once their first tooth appears, this will help the child get used to seeing the dentist.
• The dentist will ask the parents about dental history (they may also check their database) and the childs diet.
• The dentist will then start the examination by lying the child on the dental chair. All teeth must be examined as should any exposed and accessible surfaces for dental caries. All teeth should be counted.
• A bright operatory light should be used, to ensure thge dentist can see, they should also use a mirror and explorer.
• Compressed air can be used to dry teeth and remove debris in order to allow for a better visual examniation. A small flashlight is used.
• A number of colour changes can be seen with dental caries. A dentist must examine these areas carefully and determine whether these areas are alse cavitated.

Pupil Relex Test:

• Shining a light into each of the baby's eyes from a distance of 10cm to check the relex of the pupils to light.
  NR=The pupils automatically inn resopnse to the light.
  PR=The pupils do not, which indicates a problem with their pupils reflex response.

Red Reflex Test:

• Using an instrument called an ophthalmoscope, which magnifies images and has a light on one end.
  NR=When the light is shone into the eye a red reflection shoould be seen as it is reflected back.
  PR=If a white reflection is seen it could indicate a condition such as cataracts, in this case the baby will be refered to a specialist.

Attention To Visual Objects:

• To check if the newborn baby pays attention to visual objects. A midwife or doctor will try to catch the babys attention with an interesting object and see if the baby's eyes will follow it if they move it.
  NR=The infants eyes follow the object
  PR=The infant fails to follow the object with their eyes, the test is often repeated as the infant may be distracted.

Snellen Chart:

• Once the child can recognise or match letters, their vision will be tested using a chart that have rows of letters and numbers of decreasing decreasing sizes. The child will be asked to asked to read out or match the lettters they can see from a specific distance. These charts are called Snellen or LogMAR charts.

How The Tests Are Performed:

• It will be done by an optician.
• The child will be asked to remove any glasses/contact lenses that they are wearing if applicable.
• They will sit 20 feet away from the eye chart and will keep both eyes open.
• The child will then cover one eye with the palm of their hand/piece of paper/small paddle while they read the letters/numbers/pictures off of the chart.
• If not sure then guess.
• They may also be asked to read off of a card 14 inches away from their face. This will test their near vision.

What Is Being Looked For:
The visual acuiity test is part of a eye examination to see if there is a change ion vision or a problem with vision.

Results:
Visual acuity is expressed as a fraction.

• The top number refers to the distance you stand from the chart. This usually 20 feet.
• The bottom number indicates the distance at which a person with normal eyesight could read the same line you correctly read.
• Even if you miss one or two letters on the smallest line you can read, you are still considered to have vision equal to the line.
  

NR:
A negative result means that the person doesn't have a visual defect. They will still need to come in for regular check-ups.

PR:
Abnormal results may be a sign that you need glasses or contacts. Or it may mean that you have an eye condition that needs further evaluation.

Ishihara Test:
Looking at images that are made up of dots in two different colours. If a child is colour vision is normal, they will be able to recognise a letter or number within the images.

How is This Test Performed:
It uses plates made up of multi-coloured dots. Some of the dots will be a different colour and depict a number. The child will be asked to look at the plate and say if they see a number. A note will be taken of numbers they have difficulty identifying of identify incorrectly. Different ishihara plate tests can be used to detect different types of colour vision deficiency. The most common test is to detect for a red-green defiency.

Results:
The child may have a colour defiency if they have difficulty completing the Ishihara plate test. A child who can't tell the difference between two colours won't be able to see the number, which means that they have a colour vision problem. Colour blindness is more common in males.

Arrangement Test:The arrangment test is where you arrange coloured objects in order of their different hues. A mistake in this test could indicate a colour vision defiency. There is no cure for colour blindness. The child may be given tinted coloured lenses. This will help them to distinguish colours more easily.

Automated Otoacoustic Emissions (AOAE) test:
Works on the principle that a healthy cochlea (inner ear) will produce a faint echo when stimulated with sound.

How is the Test Performed:

• A small ear-piece, containing a speaker and a microphone, is placed in the baby's ear.
• A clicking sound is played and if the cochlea is functioning properly the ear-piece will pick up the echo.
• This is recorded on a computer and analysed telling the scrreener if the baby needs to be referred for a further screening test. If the test records strong responses from the baby's ear then they will not need any further tests.
• Sometimes, the results from an AOAE test are not clear. In such cases, the test will be repeated or an AABR test can be used.

Automated Auditory Brain Stem Response (AABR) test:Sensors are placed on your child's head and neck to check the response of their nerves to sounds played through headphones.

Automated Auditory Brain Stem Response (AABR) test: Sensors are placed on your child's head and neck to check the response of their nerves to sounds played through headphones.

How is the test performed:

• The AABR screening test works by recording brain activity in response to sounds. Sound travels through the outer earas vibrations. When it reaches the cochlea it is converted into an electrical signal. This travels along the nerve of hearing to the brain where it is processed into recognisable sounds.
• The AABR test does this by playing a series of clicking sounds through headphones that cover the baby's ears. Three small sensors are placed on the baby's head and connected to the computer equipment. If the hearing system is working normally then the computer will report strong responses. If there is no strong response then the computer will report that a referral should be made.

It is common for babies to have second screening hearing tests, but this does not mean that there is something wrong with their hearing loss. It may be because  the baby was unsettled during the first test due to background noise or they may have had a temporary blockage in their ear.

NR:
The baby's ear is working normally, reaction sounds (echoes) should be produced in a produced in a part of the ear known as the cochlea. 

PR:
Babies who do not show strong responses to the two screening tests will referred on a full diagnostic assessment of the hearing. This will be done at your local audiology department or sometimes offered at home. 
The diagnostic assessement will include tympanomenty and Auditory Brainstem Response (ABR) testing. 

Other Audio Tests Can Be Carried Out:
Play audiometry tests= sounds of different volumes and frequencies are played to the child and they carry out a simple task when they hear them.

A number of difference hearing tests may be used to check for hearing problems in older babies and young children. 

How is the Test Performed:
The Ortolani test or Ortolani maneuver is part of the physical examination for developmental dysplasia of the hip, along with the Barlow manuever.

Ortolani Test: The examiner's hands are placed over the child's knees with his/her thumbs on the medical thigh and the fingers placing a gentle upward stress on the lateral thigh and greater trochanter area. With sllow abduction, a dislocated and reducible hip will reduce with a descibed palpable "clunk."

The Barlow Manuever: This is done by guiding the hips into mild adduction and applying a slight forward pressure with the thumb. If the hip is unstable, the femoral head will slip over the posterior rim of the acetabulum, again producing a palpable sensation or subluxation or dislocation. 

• Blood Pressure
• Eye Tests
• Smear Tests
• Mammography
• Physcial Examination for Testicular Cancer

• using a sphygmomanometer – digital electronic (blood pressure) monitor
• cuff placed around upper arm 
• pressure exerted as cuff inflates-tightens 
• stops pulse- restricts arterial blood flow 
• systolic reading – pressure of heart beat recorded 
• deflation-loosening of cuff 
• takes diastolic reading – pressure between beats. 

Test for Glucoma

• Surface of eye numbed with eye drops 
• fine sheet of paper with dye is touched to side of the eye/ placed onto the transparent layer of tissue 
• slit lamp place in front of eye 
• chin and forehead is supported to keep head steady 
• lamp/blue light is moved towards the eye until tip of tonometer just touches the cornea 
• optometrist/optical assistant records the pressure reading on the instrument

The woman lies down on a couch 
• Undressed from waist down 
• A speculum 
• Inserted into vagina 
• Holds the walls of the vagina open 
• Cervix is visible  
• A small soft brush/spatula 
• Sample of cells taken from surface of cervix 
• Sample sent to the laboratory for analysis 

• Uses x-rays/ionising radiation 
• Taken of each breast one at a time/separately 
• Breast placed on X-ray machine and gently/firmly compressed with a clear plate 
• Two x-rays are taken of each breast at different angles/one from above and one from side 
• X-ray results/mammogram viewed as images/examined by radiologist/radiographer 
• Results sent to patient/discussed with patient 

• Self examination by the client at home finds a lump 
• The GP may hold a small light or torch against the lump in the testicle to see whether light passes through it.
• Cancerous lumps tend to be solid, which means that light is unable to pass through them.