Medical and Surgical Interventions before birth

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Medical and Surgical Interventions before birth

• Dr Margaret Ramsay
• Senior Lecturer, Fetomaternal Medicine,
• University of Nottingham

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Red cell alloimmunisation

• Rhesus disease used to be a major cause of
  perinatal mortality
• Mortality has decreased 100-fold in the last 30
  years
• Other red cell antibodies are less common, but
  can also cause haemolysis during fetal life

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Pathophysiology of red cell alloimmunisation

• Fetal red cells entering maternal circulation
  stimulate antibody production
• Transplacental passage of IgG
• Fetal haemolysis, leading to progressive anaemia
  and sometimes hydrops
• Unconjugated hyperbilirubinaemia causes problems
  after birth

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Antibodies known to cause fetal and neonatal
haemolytic disease

• Anti D
• Anti c
• Anti E
• Anti Kell
• Anti Fy

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Prevention of red cell alloimmunisation

• Avoiding unmatched blood transfusions
• Anti-D prophylaxis to pregnant women after events
  known to be associated with feto-maternal
  haemorrhage
• Anti-D administration to all Rh-D negative women
  in the 3rd trimester
• to cover silent fetomaternal haemorrhages
• programme not established yet in Nottingham

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Detection of the fetus at risk of haemolytic
disease

• Red cell antibody screen at booking and 28 weeks
• In a woman with antibodies, identify genotype of
  the father of the child
• At least 2-weekly antibody titres
• Fetal genotyping is possible by amniocentesis or
  chorionic villus sampling ( in maternal blood)
  - Bristol Lab

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Maternal antibody titres

• With anti-D, fetal haemolysis is unlikely if the
  maternal titres are lt 5iu/L
• Rapidly rising titres suggest active antibody
  production
• Cannot directly correlate maternal titres with
  chance of fetal haemolysis
• Very difficult to relate titres of other
  antibodies with chance of haemolysis

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Surveillance of fetus at risk of haemolysis

• NON - INVASIVE
• Ultrasound to look for hydrops
• Middle cerebral artery peak systolic velocity
  measurements

• INVASIVE
• Amniocentesis for delta OD 450
• Fetal blood sampling for measurement of Hb

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Fetal Hydrops

• Late sign of anaemia, since represents heart
  failure in utero
• Placenta thick due to extramedullary
  haematopoeisis
• Effusions in chest and around heart, ascites,
  subcutaneous oedema

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Problems with invasive tests

• Amniocentesis for delta OD450 is indirect measure
  of jaundice, which does not always correlate with
  fetal Hb. Plot on Lilley chart
• Further feto-maternal haemorrhage and hence
  worsening of the maternal sensitisation.
• Risks of membrane rupture, chorioamnionitis,
  preterm delivery

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Measuring Middle cerebral artery peak systolic
velocity

• Identify transverse section through fetal skull
  base
• Colour flow Doppler to identify the circle of
  Willis
• Put Doppler gate over middle cerebral artery in
  proximal third of its course

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Middle cerebral artery peak systolic velocity
(MCA-PSV)

• Avoid excessive pressure on fetal skull
• Need fetus in quiescent state
• Angle correct so that true velocities measured
• Compare with chart of normal MCA-PSV measurements
  for gestation
• If values above 1.5 MOM, significant chance of
  anaemia

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Performance of MCA-PSV

• BJOG 2002 109, 746. Zimmermann et al
• Not useful after 35 weeks
• Sensitivity to detect moderate-severe anaemia (Hb
  below 0.65 MOM) 88
• Specificity 87
• PPV 53
• NPV 98

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Management of the anaemic fetus in utero

• Aim not to do fetal blood sampling just to
  confirm normal fetal Hb
• Perform blood sampling when have transfusion
  ready to give
• fresh, irradiated, CMV-negative, highly packed
  red cells (Rh negative, cross-matched against
  maternal blood)

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Intrauterine transfusion (IUT)

• Directly into fetal circulation is best
• ultrasound guided needle placement in the
  intrahepatic portion of the umbilical vein
• free loop of cord needling more hazardous
• At early gestation, put red cells into the
  peritoneal cavity
• Follow-up scans and titres
• Repeat IUT every 2-3 weeks

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Immunoglobulin treatment

• Intravenous infusions of immune globulins (Iv Ig)
  have been used to reduce maternal antibody titres
• This helps temporise when severe alloimmunisation
  at early gestations, before it is possible to
  support the fetus with an IUT

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Planning delivery of baby who has haemolytic
disease

• Rarely give IUT gt 33 weeks
• Deliver when next IUT due
• Liase with NNU team
• Not at weekend / public holiday!
• Steroids before delivery
• X match blood ready for baby
• Have phototherapy on standby

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Anterior abdominal wall defects

• Usually detected mid-trimester at time of
  detailed ultrasound scan (20 weeks)
• Raised serum alphafetoprotein (SAFP) may be first
  pointer (15-16 weeks)
• Gastroschisis
• Omphalocoele

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Anterior abdominal wall defects

• Gastroschisis
• usually isolated
• no covering sac
• defect to the right of cord insertion

• Omphalocoele
• may be part of a wider syndrome, including
  chromosomal abnormalities (eg Trisomy
  18)
• covering sac
• at cord insertion

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Defect to right of umbilicus
Umbilical ring
GASTROSCHISIS
No membrane cover
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Covered with membrane
EXAMPHOLOS MINOR-Defect lt 5 cms diam.
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Antenatal risks with gastroschisis

• Poor somatic growth
• Torsion of bowel loops or obstruction at site of
  abdominal wall defect
• Sometimes bowel atresia
• Acute dilatation of bowel loops
• Bowel perforation
• Late intrauterine death

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Surveillance of fetus with gastroschisis

• Serial measurements of fetal head and abdominal
  circumference (NB beware if internal bowel loop
  dilatation)
• Umbilical artery Doppler measurements
• Liquor, fetal biophysical parameters
• Serial bowel loop dimensions, evidence of
  peristalsis (both internal and external to defect)

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Omphalocoele

• Careful assessment that no other anomalies
• Can have considerable distortion, making heart
  anatomy difficult to see
• Offer karyotyping by amniocentesis / placental
  biopsy
• Follow somatic growth (NB macrosomia may point to
  Beckwith-Weidemann Syndrome)

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Covered with membrane
Defect gt 5 cms. Diam.
EXAMPHOLOS MAJOR
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Macroglossia
Beckwith-Wiederman syndrome ( exampholos-macroglo
ssia-gigantism) (EMG)
Watch for hypoglycaemia- Associated with
exampholos and not gastroschisis
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Involvement of paediatric team before birth

• Always a good idea to prepare parents for what
  will happen after birth
• Meet surgical team and NNU staff
• Show round NNU
• Discuss mode of delivery (vaginal delivery
  preferable)
• Discuss surgery and its risks

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Surgical issues for anterior abdominal wall
defects

• Risks of anaesthetic, especially if premature
• May not be possible to obtain a primary closure.
  Discuss use of a silo.
• Possibility of damage to bowel and need for
  resection
• Nutritional support with TPN
• Delayed bowel function
• Short bowel syndrome

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Management after birth of a baby with
gastroschisis / omphalocoele

• Paediatrician present at delivery
• Deliver baby onto sterile sheet
• Cut cord
• Put baby into sterile body bag to keep bowel
  loops moist and clean
• Allow parental bonding time
• Transfer to NNU to prepare for surgery

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Ruptured sac
RUPTURED EXAMPHOLOS AND NOT GASTROSCHSIS
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Gastroschisis wrapped in kitchen film
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