Oxford Handbook of Midwifery (131 page)

• Urine amino acids
  
• Urine organic acids
  
• Plasma amino acids
  
• Blood and CSF lactate
  
• Beutler test for galactosaemia
  
• Plasma carnitine.
  

• Specific enzyme assays on blood or skin fibroblasts, e.g. lysosomal enzyme studies
  
• DNA mutation analysis
  
• Special metabolite studies, e.g. long-chain fatty acids, bile acid analysis.
  ¹
  

  Screening
  

  Routine neonatal screening is offered for five disorders:
  

Collecting the sample

Parents will receive an information leaflet, and have the reasons for the test explained to them, in the third trimester of the pregnancy. The reasons should also be discussed with them again just before the proce- dure is carried out.

The health professional responsible for the baby will usually take the sample on day 6 of milk feeding, and will also record the event in the maternity notes.

Gather equipment

The procedure

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• Lance the heel on the planter surface beyond the lateral and medial limits of the calcaneus. Avoid the posterior curvature of the heel.
  
• Allow the blood to fill the circle by natural flow.
  
• Apply the drop to one side of the card.
  
• Fill all the circles completely. Avoid layering the blood and ensure that the blood permeates through to the back of the card.
  
• Wipe the foot and apply gentle pressure and the plaster if required.
  
• Comfort the baby.
  
• Complete the records and inform the parents how and when they will receive the results.
  
• Send the card within 12h of the sample being taken.
  ²
  

  Phenylketonuria
  

• The incidence in Britain is 1:10 000 births.
  
• 0 If it is not treated it leads to permanent brain damage.
  
• It is treated with a diet restricting phenylalanine.
  
• The baby is born with a normal blood phenylalanine level.
  
• There is a block in the normal metabolic pathway, preventing conversion of unused phenylalanine into tyrosine.
  
• The baby quickly shows a marked rise in blood phenylalanine when given feeds containing protein.
  

  Screening
  

  2 It takes a few days for levels of blood phenylalanine to accumulate, therefore the screening test is usually done after 6 days of milk feeding or at least 48h of intravenous feed containing protein.
  

  

  Guthrie’s test
  

  Introduced by Dr Robert Guthrie, this test was originally based on inhibi- tion of bacterial growth. It is now carried out using a fluorometric assay to test for PKU. A 6.25mm diameter disc is punched out of a dried blood spot on a blood-screening card. Water is added and the sample is then left to dry. Reagents are added to cause the phenylalanine to fluoresce and the fluorescence is measured. Any rise in serum phenylalanine above a given standard stands out on the chart. This will be followed up with further tests on the original sample before confirmation of the diagnosis with the parents.
  ³
  ,
  4
  

  Congenital hypothyroidism
  

• The incidence in Britain is 1:3500 births.
  
• It is due to an absent or small thyroid gland and reduced/absent thyroxine production.
  
• TSH levels will be increased.
  
• 0 If it is not treated, the individual will have a decreased IQ.
  
• Treatment is a regular daily dose of thyroxine to replace the missing hormone.
  ⁴
  ,
  5
  
• The baby may
  
  • Have prolonged jaundice, beyond 10 days
    
  • Be lethargic
    
  • Be feeding poorly
    
  • Be constipated
    

    METABOLIC DISORDERS AND THE NEONATAL BLOOD SPOT TEST
    

    617
    

    • Have an odd appearance with a large tongue
      
    • Have a hoarse cry.
      

    Screening
    

    The test involves punching a small hole out of the blood-screening card. A radioactive marker is added to the blood spot, the sample is left overnight and the TSH is measured the next day.
    

    Cystic fibrosis
    

Screening

Sickle cell disorders and thalassaemia major

and making the baby more prone to serious infections.

All parents in these situations will be carriers and are usually offered genetic counselling. CLIMB—Children Living With Inherited Metabolic Diseases—is a support group for parents and health professionals.
^4,7

Medium-chain acyl CoA dehydrogenase deficiency (MCADD)

• Children with MCADD cannot break down the fat quickly enough to provide energy.
  
• This leads to a hold-up in the breakdown of medium-chain fats, due to the lack of the correct enzyme.
  

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  • The banked-up medium-chain fats form toxic substances, which lead to life-threatening symptoms or death.
    
    • MCADD has no apparent symptoms at birth.
      
    • The most acute presentations occur within the first 2 years of life.
      
    • It is not possible to predict which children will develop symptoms.
      
    • Symptoms occur if the child is not feeding well or is ill with an infection.
      
    • The child becomes:
      
      • Drowsy, and may vomit
        
      • Hypoglycaemic
        

• • • • Comatose, due to low blood sugar and also the build up of the toxins.
        
    • Most children with this condition will be well as long as they eat regularly. The main problem occurs when the child has additional viral illnesses with a sore throat, vomiting, and diarrhoea, which makes them reluctant to eat or drink.
      
    • The body also requires increased energy to cope with the infection, so children with MCADD need to eat more often during such infections.
      

      Management of MCADD
      

    • The main focus for treatment is to prevent a ‘metabolic crisis’.
      
    • Closely monitor the child to determine ‘safe’ time periods between meals.
      
    • Follow a strict feeding schedule.
      
    • If the child becomes unwell, drowsy or vomits, give glucose supplements and refer to a doctor.
      
    • There is no cure for MCADD, but with early detection and monitoring
      the child can lead a normal life, and the ‘safe’ time between meals
      

      increases with age.
      ⁴
      ,
      8
      

      1. Wraith JE (1999). Inborn errors of metabolism in the neonate. In: Rennie JM, Roberton NRC (eds)
         Textbook of Neonatology
         , 3rd edn. London: Churchill Livingstone, pp. 986–1002.
         
      2. UK Newborn Screening Programme Centre (2004).
         Proposed standards and Policies for newborn blood spot screening
         —
         an integrated consultation
         . London: DH.
         
      3. National Society for Phenylketonuria.
         Phenylketonuria
         . London: NSPKU. Available at: M www.
         nspku.org.uk (accessed 14.4.10).
         
      4. General information. Available at: M
         www.newbornscreening.bloodspot.nhs.uk (accessed 14.4.10).
         
      5. UCL Institute of Child Health.
         Congenital Hypothyroidism
         . London: UCL. Available at: M www.
         ich.ucl.ac.uk/factsheets (accessed 14.4.10).
         
      6. Cystic Fibrosis Trust.
         Cystic Fibrosis
         . Kent: Cystic Fibrosis Trust. Available at: M www.cftrust.org.
         uk (accessed 14.4.10).
         
      7. Sickle Cell Society.
         Sickle Cell Disease
         . London: Sickle Cell Society. Available at: M www.sickle-
         cellsociety.org (accessed 14.4.10).
         
      8. National Information Centre for Metabolic Diseases.
         MCADD
         . Crewe: National Information Centre for Metabolic Diseases. Available at: M
         www.climb.org.uk (accessed 14.4.10).
         

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      Developmental dysplasia of the hip (DDH)
      

      In its severest form, developmental dysplasia of the hip is one of the most common congenital malformations.
      ¹
      Neonatal screening programmes, based on clinical screening examinations, have been established for more than 40 years but their effectiveness remains controversial. The longer- term outcomes of developmental hip dysplasia with its contribution to premature degenerative hip disorders in adult life, and the benefits and harms of newborn screening are not clearly understood. High quality studies of the adult outcomes of developmental hip dysplasia and the childhood origins of early degenerative hip disease are needed, as are ran- domized trials to assess the effectiveness and safety of neonatal screening and early treatment.
      ²
      

      It is becoming more common for midwives with appropriate training to be responsible for screening the hips as part of the holistic assessment of the newborn. Approximately 1.5 per 1000 babies is born with a dislocatable or subluxable hip. This used to be called congenital dislocation of the hips but the terminology has changed to reflect its potentially progressive nature.
      

      If the condition remains untreated the hip will function well initially but ultimately lead to problems with walking and premature degenerative disease of the hip.
      

      Risk factors
      

    • Breech presentation
      

      •
      Family history of hip dysplasia
      

    • Increased birthweight
      
    • Females more at risk than males
      
    • First baby more at risk than subsequent babies.
      

      Diagnosis
      

      The diagnosis is made in the first instance by physical examination and then confirmed by ultrasound scan. Two methods are used.
      

    • Ortolani’s manoeuvre detects a dislocatable but reducible hip.
      
    • Barlow’s manoeuvre is a provocation test for an unstable hip.
      

      Carrying out the examination
      

    • Consent is obtained from the parents before the test is carried out and then performed in their presence.
      
    • Ortolani’s—the baby must be relaxed and on a firm surface.
      
    • The hip is flexed to 90* and then gently abducted (an outward movement away from the body).
      
    • The examiner’s finger on the outer part of the hip can detect the ‘clunk’ as the head of the femur slides into the hip socket.
      
    • This differs from the benign click of soft tissues snapping over bony prominences during the manoeuvre.
      
    • Barlow’s—the hip is flexed to 90* and then the leg adducted (an inward movement towards the body) and the leg gently pushed backwards.
      

    DEVELOPMENTAL DYSPLASIA OF THE HIP (DDH)
    

    621
    

Should either test be positive the result should be sensitively explained to the parents and arrangements made to confirm the diagnosis by ultrasound scan. Following diagnosis the most common treatment is for the baby to wear a Pavlik’s harness or hip spica cast which gently keeps the hips in abduction until the hip capsule tightens and the hips are kept in place by the normal action of the ligaments.

Recommended reading

Stricker SJ, Barone SR (2001). Tips about hips in children.
International Pediatrics
16
, 196–206.

1. Dezateux C, Rosendhal K (2007). Developmental dysplasia of the hip.
   Lancet
   369
   , 1541–52.
   
2. Sewell MD, Rosendhal K, Eastwood DM (2009). Developmental dysplasia of the hip.
   British Medical Journal
   339
   , b4454.
   

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   Birth injuries
   

   Birth injuries are most commonly caused by trauma or mechanical dif- ficulty at delivery. Head injuries are most common, followed by injury to limbs, internal organs, and the skin.
   

   Head injury
   

   • Cephalhaematoma and caput succedaneum
     are common birth injuries (b see Examination of the newborn: monitoring progress, p. 578).
     
   • Hypoxia
     is the most common cause of cerebral injury following birth. This may result in intracranial haemorrhage or oedema. Occasionally cerebral trauma may result in cerebral palsy; this is often linked to pregnancy complications such as pre-eclampsia.
     
   • Tentorial tears:
     these are due to the fetal skull being exposed to excessive, rapid, or abnormal moulding, which exerts pressure and stress on the cranium. If this pressure is stretched to its limit, the underlying soft tissues of the brain are vulnerable to tearing (the tentorium cerebelli and the falx cerebri). The source of the bleeding is usually from rupture of the great cerebral vein.
     
   • Fractured skull
     : serious fracture to the skull is extremely rare. Where a woman may have a severely immobilized sacrococcygeal joint and coccyx, this can cause abnormal compression to the fetal head, which may result in a small depressed fracture of one of the frontal bones. Unusual or excessive moulding may produce a fine linear fracture of the cranial bone. Neither of these injuries requires treatment.
     
   • Facial paralysis:
     this injury is usually caused by trauma at delivery.
     

     Damage to a branch of the seventh cranial nerve occurs when pressure
     is applied on the facial nerve as the head emerges at delivery. The
     

     affected side shows no movement when the baby cries, the eye is permanently open, and the mouth droops. This may affect the baby’s feeding ability if severe. Invariably full recovery occurs within hours or up to several days. Care of the affected eye is important to prevent corneal damage.
     

     Other injuries
     

   • Dislocations and fractures:
     the humerus or clavicle may be fractured in a difficult shoulder dystocia. Occasionally, the femur may be fractured, and in a mismanaged breech delivery the fetal hip may be dislocated.
     
   • Sternomastoid haematoma
     : this may occur following traction to expedite delivery of the head or shoulders. Swelling occurs to the sternomastoid muscle due to blood oozing from a torn blood vessel. Shortening of the muscle results in the head twisting to one side, this is commonly known as torticollis or wry neck. This condition takes several weeks to subside and rarely causes permanent damage.
     
   • Klumpke’s palsy:
     this is caused by traction on the arm when delivering the shoulders, resulting in damage to the lower brachial plexus. Paralysis to the hand and wrist drop occurs and sometimes a fracture is also apparent. Physiotherapy is the main treatment and recovery is usually slow.
     
   • Erb’s palsy:
     this is caused by excessive traction on the neck during a breech or cephalic presentation, resulting in damage to the upper
     

BIRTH INJURIES

623

brachial plexus. The arm hangs loosely from the shoulder with the palm of the hand turned backwards in the ‘waiter’s tip’ position. Physiotherapy is the main treatment, again this may be slow but the condition does usually resolve completely.