interventional ultrasound an overview dr.r.udayakumar

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INTERVENTIONAL ULTRASOUND

• AN
• OVERVIEW
• DR.R.UDAYAKUMAR
• CHENNAI, INDIA.

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ULTRASOUND GUIDANCE

• TRICKS AND TIPS
• GENESIS SCANS ULTRASOUND TRAINING CENTER

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PROCEDURES

• AMNIOCENTESIS-diagnostic / therapeutic
• C V S
• CORDOCENTESIS-sampling / transfusion
• BIOPSY- fetal skin / liver
• SHUNTS-vesicoamniotic / thoracoamniotic
• FETOSCOPY -usg guided
• FETAL GENE Rx- stem cell transplants

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PRINCIPLES

• AMNIOCENTESIS
• C V S
• CORDOCENTESIS
• BASICS ARE THE SAME

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PLANE OF BEAM - tips

• Varies with different transducers
• Unusual to be in precise middle of Tz.
• Identify the sweet spot
• 22g and above needles bend ( get rigid 22)
• Use PHANTOM to practise ( Jar of GEL)
• Optimize machine setting

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FREE HAND TECHNIQUE

• PERPENDICULAR OFFSET ( 90º ) needle too far
  away
• PARALLEL or SIDE ON only
  needle tip is visualized
• END ON APPROACH ( 45º)
  variable angle / probe can be rocked

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targetSEEN - targetNEEDLED

• SONOENHANCED needles ( ??)
• STERILE ZONE -double glove, shroud
• LOCAL ANAESTHETIC (amnio??) initial marker for
  needle path
• ANTIBIOTICS ( for high risk cases)
• COLOUR DOPPLER
• DETAILED INFORMED CONSENT

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TECHNIQUE

• Proper planning
• Good equipment
• Operator skill
• CONTINUOUS NEEDLE VISUALISATION IS A MUST.

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TECHNIQUE

• Single main operator ( assistant)
• Two operators ( sonologist operator)
• ONE CEREBELLUM IS BETTER THAN TWO FOR
  CO-ORDINATION.

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ARTEFACTS

• NEAR FIELD BACKSCATTER REVERBERATION( ? Anterior
  Placenta)
• RING DOWN (Comet tail)- Needle Tip
• REFRACTION MIRROR IMAGE (Wrong location)
• BEAM THICKNESS- Needle position.

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Coelocentesis

• Between 6 -12 weeks
• Advantage of early Prenatal diagnosis(lt 10w)
• 95 success rate bet 7 - 10weeks
• Low rate of contamination by maternal cells.

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Coelocentesis

• Early amnio and CVS not performed before 10weeks
• Less traumatic to embryo placenta
• Fetal loss 0r lt that in early amnio.

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Coelocentesis

• Biochem. different from early Amniotic fluid and
  maternal serum.
• Study materno-fetal exchange when FBS cannot be
  obtained.
• Prenatal diagnosis of chromosomal and genetic
  disorders.

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Coelocentesis-Procedure

• EVS Needle guide 20g needle
• Through Anterior ut.wall
• Needle ? ?el to amniotic membrane.
• Needle afaap from YS and Amn.membrane

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Coelocentesis-Procedure

• Low pressure aspiration.
• Continuous monitoring of needle.
• Yellow coloured and more viscous than Amniotic
  fluid (always clear)

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Coelocentesis

• 5 to 6 ml volume by 9weeks
• 1 to 2.5ml required for diagnostic purpose.
• 90 of cells are viable (before 7weeks)
• Cells mostly of haemotopoietic origin.

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Coelocentesis (vs) Placental DNA

• Complete concordance in results for
• (1) Diagnosis of single gene disorders
  
  (sickle cell)
• (2) PCR with Y centromeric primers for Sex
  prediction ( 100)

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Coelocentesis

• Easy to learn, new invasive approach to prenatal
  diagnosis.
• Using FISH probes it appears Karyotyping is
  possible at 6weeks gestation.
• Further work is necessary to improve culture
  success later in gestation

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Umbilical cord catheterization

• Fetal blood exchange transfusions
• lt 5mins procedure
• Catheter in vein for 30 - 210 mins

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Umbilical cord catheterization

• No haematomas within Whartons jelly
• No chorioamnionitis.
• Nutrient supplementation / Gene therapy/
  treatment of fetal pain and infection.

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Tracheal Ligation in CDH

• Purposeful occlusion of the fetal airway results
  in lung growth avoiding pulmonary hypoplasia,
  which is the main complication in fetuses with
  CDH.
• The hernia is then repaired after birth

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Tracheal ligation - exclusion criteria

• Unwilling patient
• Presence of major congenital anomalies
• Abnormal karyotype
• Ruptured membranes
• Chorioamnionitis
• Diagnosis made after 25 weeks gestation

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EXIT- ex utero intrapartum treatment
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What is an Amniopatch?

• ONE unit of maternal blood.
• Blood Bank obtains platelets and cryoprecipitate
  (cryo) in 2 days
• USG guided injection of these into amniotic
  cavity takes only a few minutes.

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Amniopatch

• Platelets activate the clotting mechanism and the
  cryo acts like a cement to hold the platelets in
  place.
• It can take 2 weeks for the membrane to reattach.