7.3 Neonatal Blood Spot Screening, Hearing Screening & Infection Prevention

Neonatal Blood Spot Screening, Hearing Screening & Infection Prevention

Public health screening and infection prevention during early neonatal life are paramount to reducing infant mortality and long-term neurodevelopmental morbidity. In the United Kingdom, robust population screening programmes established by the UK National Screening Committee (UK NSC) provide universal screening for rare metabolic and endocrine disorders, as well as congenital hearing impairment. Simultaneously, midwives guide parents in fundamental postnatal hygiene, evidence-based umbilical cord care, and safe sleeping practices. Mastery of sampling technique, diagnostic rationales, early infection identification, and sudden unexpected death prevention is essential for the registered midwife.

---

The UK Newborn Blood Spot (NBS) Screening Programme

The Newborn Blood Spot (NBS) screening test (historically known as the Guthrie test) is a population-level screening programme offered universally to all infants in the United Kingdom. It aims to identify presymptomatic babies affected by rare but serious conditions, allowing life-saving dietary, medical, or enzyme interventions to commence before irreversible clinical damage, profound intellectual disability, or death occurs.

┌─────────────────────────────────────────────────────────────────────────────────┐
│                     UK NEWBORN BLOOD SPOT (NBS) TIMELINE                        │
└─────────────────────────────────────────────────────────────────────────────────┘
 Day 0                      Day 5                      Day 8           Day 28
 ┌──────────────────┐       ┌──────────────────┐       ┌───────────┐   ┌───────────────┐
 │  Date of Birth   │       │ Mandatory Test   │       │ Latest    │   │ Preterm Repeat│
 ├──────────────────┤       ├──────────────────┤       ├───────────┤   ├───────────────┤
 │• Day of birth is │  ───► │• Ideal day for   │  ───► │   Valid   │──►│• Born before  │
 │  strictly Day 0  │       │  NBS sampling    │       │  Sampling │   │  32 weeks: CHT│
 │• Antenatal info  │       │• Enteral feeding │       │  Window   │   │  repeat test  │
 │  re-confirmed    │       │  established     │       │           │   │  at 28 days   │
 └──────────────────┘       └──────────────────┘       └───────────┘   └───────────────┘

Timing & Methodological Rationale

• Mandatory Timing Window: The blood spot sample must be taken on Day 5 of life (the day of birth is counted as Day 0; for example, a baby born on a Tuesday has Day 5 on the following Sunday). Exceptionally, testing can be performed between Day 5 and Day 8.
• Rationale for Day 5: Testing cannot be performed prior to Day 5 because:
  1. The neonate must have established regular enteral feeding (breast milk or infant formula) containing protein and lactose for at least 48 to 72 hours to allow toxic dietary metabolites (such as phenylalanine or leucine) to accumulate to detectable diagnostic thresholds.
  2. Endogenous thyroid stimulating hormone (TSH) surges physiologically within the first 24 to 48 hours following birth; sampling before Day 5 produces a high rate of false-positive results for congenital hypothyroidism.
• Preterm Infants (Born before 32 Weeks, i.e. ≤31+6): Because of hypothalamic-pituitary-thyroid axis immaturity, preterm infants require a routine initial blood spot on Day 5, followed by a mandatory repeat blood spot for Congenital Hypothyroidism (CHT) at 28 days of age (or on discharge home, whichever is sooner).
• Blood Transfusions: Blood transfusion introduces donor adult red blood cells and donor enzymes, invalidating sickle cell and metabolic screening. Therefore, if a neonate requires an urgent blood transfusion, a pre-transfusion blood spot card must be collected immediately, regardless of day of life; a repeat sample for the remaining conditions is collected on Day 5.

The Ten Conditions Screened in England

The blood spot card in England screens for ten conditions: hereditary tyrosinaemia type 1 (HT1) was added in October 2025, and an in-service evaluation of screening for spinal muscular atrophy (SMA) began in parts of England in October 2026. Other UK nations' programmes are similar but can differ:

---

Blood Spot Sampling Technique & Sample Integrity

Meticulous sampling technique is vital. Suboptimal sampling causes specimen rejection at the laboratory, requiring traumatic re-bleeds and delaying critical diagnostic timelines.

Preparation & Pain Management

• Informed Consent: Confirm documented parental consent. Verify infant demographics, NHS number, date of birth, and date of sampling.
• Non-Pharmacological Pain Relief: Midwives should actively promote comfort strategies during the heel prick: facilitate maternal skin-to-skin contact or encourage active breastfeeding before and during the procedure. Alternatively, administer 0.2 to 0.5 mL of oral 24% sucrose solution onto the anterior tongue 2 minutes prior to skin puncture.

┌─────────────────────────────────────────────────────────────────────────────────┐
│                     HEEL PRICK ANATOMICAL SAFETY ZONES                          │
└─────────────────────────────────────────────────────────────────────────────────┘
                               ┌─────────────────┐
                               │   TOES / BALL   │
                               │    (DO NOT USE) │
                               └────────┬────────┘
                                        │
                                        │
                       ┌────────────────┴────────────────┐
                       ▼                                 ▼
              ┌─────────────────┐               ┌─────────────────┐
              │  MEDIAL BORDER  │               │ LATERAL BORDER  │
              │   SAFE ZONE     │               │   SAFE ZONE     │
              │ (Plantar aspect)│               │ (Plantar aspect)│
              └────────┬────────┘               └────────┬────────┘
                       │                                 │
                       └────────────────┬────────────────┘
                                        │
                               ┌────────┴────────┐
                               │  CENTRAL PLANTAR│
                               │   & POSTERIOR   │
                               │  (CALCANEUS)    │
                               │   STRICT DANGER │
                               └─────────────────┘

Step-by-Step Procedure & Safety Zones

1. Warm the Heel: Ensure the infant's foot is warm to touch (warmth enhances peripheral capillary blood flow, avoiding excessive squeezing). If cold, wrap the foot in a warm, moist flannel or encourage skin-to-skin warming.
2. Identify Safe Anatomical Puncture Site:
   • The Safe Zones: The puncture must be performed on the medial or lateral plantar border of the heel.

   • Warning

   • Prohibited Danger Zones: Never puncture the central plantar area of the foot or the posterior curvature of the heel. Puncturing the central plantar area risks damaging the medial plantar nerve and posterior tibial artery; puncturing the posterior heel risks penetrating the calcaneus bone, predisposing the infant to calcaneal osteomyelitis or chronic aseptic periostitis.
3. Skin Cleansing: If skin is soiled, cleanse with mild soap and warm water, then dry thoroughly. Alcohol wipes should not be used routinely; if an alcohol wipe is used, the skin must be allowed to air-dry completely for at least 30 seconds, as residual alcohol causes chemical haemolysis, invalidating laboratory mass spectrometry.
4. Automated Incision Device: Use a single-use, sterile, automated spring-loaded heel incision device calibrated to a depth of ≤1.0 mm for preterm infants and ≤2.0 mm for term infants. Manual lancets and surgical needles are strictly contraindicated.
5. Wipe Away the First Drop: Trigger the automated device. Wipe away the very first drop of blood using a sterile dry gauze swab. The initial drop contains excess intracellular and interstitial tissue fluid that hemodilutes the specimen.
6. Filling the Filter Paper Circles:
   • Allow a second, large, hanging drop of blood to form naturally under gentle, intermittent pressure. Do not squeeze, massage, or "milk" the heel aggressively, as this causes tissue bruising, acute pain, and interstitial fluid contamination.
   • Bring the circular pre-printed area of the filter paper card lightly into contact with the blood drop, allowing capillary action to draw the blood into the card in a single application.
   • Ensure the blood soaks completely through the filter paper, evenly saturating both the front and reverse sides of all required circles.
   • No Layering: Never apply multiple drops to the same circle; layering creates uneven chromatographic density and causes specimen rejection.
7. Drying & Despatch: Allow the card to air-dry horizontally for at least 4 hours at ambient room temperature on an open, non-absorbent drying rack, away from direct sunlight, radiators, or heat sources. Do not enclose in plastic bags until completely dry. Despatch the card to the regional newborn screening laboratory within 24 hours.

Newborn Hearing Screening Programme (NHSP)

Permanent childhood hearing impairment occurs in approximately 1 to 2 per 1,000 live births. In the absence of universal screening, congenital sensorineural deafness is rarely diagnosed before 2 to 3 years of age, severely arresting expressive speech, language acquisition, and cognitive development. The Newborn Hearing Screening Programme (NHSP) ensures that all infants are offered screening within the first 4 to 5 weeks of life (and completed before 3 months of age).

┌─────────────────────────────────────────────────────────────────────────────────┐
│                     UK NHSP SCREENING TECHNOLOGY PROTOCOL                       │
└─────────────────────────────────────────────────────────────────────────────────┘
                                         │
         ┌───────────────────────────────┴───────────────────────────────┐
         ▼                                                               ▼
┌───────────────────────────────────┐           ┌───────────────────────────────────┐
│  STANDARD WELL-BABY SCREENING     │           │  SPECIAL CARE / NICU >48 HOURS    │
├───────────────────────────────────┤           ├───────────────────────────────────┤
│• First-line: AOAE 1               │           │• High risk of auditory neuropathy │
│• If no clear response: AOAE 2     │           │• Direct combined protocol:        │
│• If still no clear response: AABR │           │  AOAE + AABR both mandatory       │
│• If AABR no response: Audiology   │           │• Direct audiology referral if     │
│  referral within 4 weeks          │           │  either test shows no response    │
└───────────────────────────────────┘           └───────────────────────────────────┘

Screening Technologies: AOAE vs AABR

1. Automated Otoacoustic Emission (AOAE):
   • Mechanism: A soft miniature probe containing a sensitive speaker and microphone is inserted gently into the external auditory meatus. The speaker emits low-intensity clicking sounds. In a normal cochlea, healthy outer hair cells respond to acoustic energy by contracting and vibrating, which generates an acoustic reflection or echo (otoacoustic emission). This tiny sound wave travels back through the middle ear ossicles and is captured by the probe microphone.
   • Clinical Strengths: Non-invasive, rapid (takes 2–3 minutes), and highly sensitive to cochlear function.
   • Limitations: Debris, vernix, or amniotic fluid in the ear canal, as well as infant movement or ambient background noise, frequently cause a false-positive "no clear response".
2. Automated Auditory Brainstem Response (AABR):
   • Mechanism: Three surface disposable electrodes are placed on the infant (forehead, nape of neck, and shoulder). Soft disposable earphones deliver sound stimuli. The electrodes record electrophysiological brainstem waveforms, assessing the integrity of the acoustic pathway from the cochlea along the eighth cranial nerve (vestibulocochlear nerve) through to the brainstem auditory nuclei.
   • Specific Indications:
     • Used as a second-tier screen for well babies who do not achieve a clear bilateral response on two AOAE attempts.
     • Mandatory primary screen for all infants admitted to a neonatal intensive care or special care unit (NICU/SCBU) for >48 hours. Preterm and sick infants carry a substantially elevated risk of auditory neuropathy spectrum disorder (ANSD), where outer hair cells function normally (yielding a misleadingly normal AOAE) but neural signal conduction along the auditory nerve is damaged.

Audiological Referral Pathway

Infants who do not display a clear response in one or both ears following AABR screening must be referred directly to a paediatric audiology service for comprehensive diagnostic electrophysiological evaluation within 4 weeks (or by 44 weeks post-menstrual age for preterm infants).

---

Umbilical Cord Care, Hygiene & Infection Prevention

The devitalised umbilical cord stump represents an anatomical conduit into the neonatal venous circulation, predisposing the newborn to invasive bacterial infection if hygiene is compromised.

Natural Separation & Wharton's Jelly Mummification

The umbilical cord contains two umbilical arteries and one umbilical vein surrounded by Wharton's jelly. After cord clamping, drying of Wharton's jelly occurs via evaporation. The vessels contract, blood flow ceases, and the tissue undergoes aseptic dry gangrene (mummification). The cord stump darkens, dries, turns brittle black, and spontaneously detaches between day 5 and day 15 of life.

Evidence-Based Cord Care Protocols

Under NICE Guideline NG194 (Postnatal Care) and WHO standards:

• Clean, Dry Cord Care: Routine application of topical antiseptics (chlorhexidine, surgical spirit, alcohol, antibiotic ointments, or talcum powders) is not recommended in healthy term infants in high-resource settings. Antiseptics delay natural separation by destroying non-pathogenic commensal bacteria necessary for enzymatic tissue sloughing.
• Hygiene & Nappy Positioning: Midwives must instruct parents to wash their hands thoroughly before and after handling the cord. The cord should be kept clean and dry, exposed to air by folding the top edge of the nappy downward below the cord stump. If the cord is contaminated with urine or stool, it should be cleansed gently with plain water and dried thoroughly with a clean cloth.

┌─────────────────────────────────────────────────────────────────────────────────┐
│                     CLINICAL SPECTRUM OF OMPHALITIS                             │
└─────────────────────────────────────────────────────────────────────────────────┘
 Normal Separation                 Mild Infection                    Severe Omphalitis
 ┌──────────────────┐       ┌──────────────────┐       ┌──────────────────┐
 │ Clean & Dry      │       │ Localized        │       │ Life-Threatening │
 ├──────────────────┤       ├──────────────────┤       ├──────────────────┤
 │• Dry, hard stump │       │• Slight discharge│       │• Erythema >5 mm  │
 │• No surrounding  │  ───► │• Moist base      │  ───► │• Purulent fluid  │
 │  erythema        │       │• Minimal redness │       │• Oedema & warmth │
 │• Separation 5–15d│       │  <5 mm           │       │• Systemic sepsis │
 └──────────────────┘       └──────────────────┘       └──────────────────┘

Recognition & Escalation of Omphalitis

Omphalitis is an acute, life-threatening bacterial infection of the umbilical stump and surrounding anterior abdominal wall tissues, commonly caused by Staphylococcus aureus, Streptococcus pyogenes, or Gram-negative enteric bacilli (Escherichia coli).

• Clinical Presentation: Periumbilical erythema (redness) extending >5 mm beyond the cord base into the surrounding abdominal wall skin, marked local oedema, warmth, tenderness on palpation, and foul-smelling purulent umbilical discharge.
• Systemic Signs of Sepsis: Temperature instability (pyrexia ≥38.0°C or hypothermia <36.0°C), lethargy, poor feeding, weak cry, tachypnoea, abdominal distension, and prolonged capillary refill time (>3 seconds).

---

Safe Sleeping Guidance & Sudden Infant Death Syndrome (SIDS) Reduction

Sudden Infant Death Syndrome (SIDS) describes the sudden, unexpected, and unexplained death of an apparently healthy infant under one year of age, occurring almost exclusively during sleep. In the UK, evidence-based public health interventions spearheaded by The Lullaby Trust and codified in NICE Guideline NG194 have reduced SIDS mortality by over 80% since 1991. Midwives are clinically responsible for providing clear, non-judgmental safe sleeping education to all expectant and new parents.

The Core Safe Sleeping Principles

1. "Back to Sleep" (Supine Sleep Positioning):
   • Place the baby on their back (supine) for every single sleep—both night and day.
   • Placing an infant prone (on the tummy) or in a side-lying position dramatically increases SIDS risk. Prone sleeping impairs spontaneous arousal responses, increases carbon dioxide rebreathing, and precipitates thermal overheating.
   • Anatomical safety: In the supine position, the trachea lies superior/anterior to the oesophagus; if the infant regurgitates milk, fluids pool safely in the posterior pharynx and are swallowed down the oesophagus rather than aspirated into the larynx.
2. "Feet to Foot" Positioning:
   • The infant is placed with their feet touching the bottom edge of the cot or Moses basket.
   • This prevents the infant from wriggling down under the bedcovers during sleep.
   • Bedclothes (lightweight sheets or cellular blankets) must be tucked in firmly around the mattress sides and foot, reaching no higher than the infant's armpits/chest, keeping the head completely uncovered.
3. Clear Cot Sleeping Environment:
   • The infant must sleep on a firm, completely flat, waterproof mattress that fits the cot snugly without lateral gaps.
   • The cot must be completely clear: NO pillows, NO duvets or quilts, NO sheepskins, NO cot bumper pads, NO sleep positioners or wedges, and NO soft toys. Soft, loose bedding creates fatal suffocation, strangulation, and carbon dioxide entrapment hazards.
4. Thermal Environment & Room Temperature:
   • Maintain room temperature between 16°C and 20°C (61°F to 68°F).
   • Overheating is an established independent trigger for SIDS. Remove hats and outdoor clothing as soon as the infant is indoors.
5. Room-Sharing for the First Six Months:
   • The baby must sleep in their own separate cot or Moses basket in the same room as the parents for all sleeps (day and night) for the first six months of life. Room-sharing halves the risk of SIDS.

Co-Sleeping Risks & Absolute Contraindications

While recognizing that many parents share a bed with their baby (intentionally or unintentionally), midwives must provide clear, objective counselling regarding high-risk scenarios.