← All decks
Radiology
Fetal Shunts
Built from Obstetric Imaging
What’s inside
12 sections · 90 slides
Overview
- Scope of this presentation
What a fetal shunt is
A drain placed before birth, and the thinking behind it
- Definition and purpose of a fetal shunt
- How the shunt is put in
- The two established fetal shunts
- Other reported uses of fetal shunts
- Where a fetal shunt may be placed
Lower urinary tract obstruction
Why a blocked fetal bladder threatens the kidneys and the lungs
- Fetal lower urinary tract obstruction
- Consequences of a blocked bladder outlet
- Oligohydramnios and pulmonary hypoplasia
- Cascade from bladder outlet obstruction
- Aims of vesicoamniotic shunt placement
- Dilated collecting system inside a kidney
Recognising the obstructed fetal bladder
The ultrasound picture that starts the whole conversation
- Confirming the diagnosis before any shunt
- The keyhole sign
- Distended fetal bladder before and after shunting
- Three-dimensional view of the distended bladder
- Other causes and the value of fetal sex
The shunt itself and how it is placed
Hardware, entry site and the steps around the procedure
- Double-pigtail shunt design
- Double-pigtail catheter shape
- Harrison and Rocket shunts compared
- Trade-offs in shunt selection
- Trocar and cannula set
- Vesicoamniotic shunt placement in utero
- Choosing the entry point on the fetus
- Confirming the shunt is working
- Amnioinfusion before shunt placement
- Risk of amnion-chorion separation
- Antibiotics and tocolysis around the procedure
Counselling and informed consent
What families must understand before a shunt is offered
- Counselling after a diagnosis of LUTO
- Limits of what a shunt can achieve
- Alternative fetal procedures for LUTO
- Multidisciplinary consultation
Assessing kidney function before shunting
Sampling fetal urine to see whether the kidneys are worth saving
- Rationale for fetal urinalysis
- Normal fetal urine chemistry
- Urine chemistry in a damaged kidney
- Serial vesicocentesis
- Work-up before a vesicoamniotic shunt
- Urinary analyte thresholds
- Accuracy of the analyte cut-offs
- Cases presenting before 20 weeks
- Other tests of fetal kidney function
Who is offered a vesicoamniotic shunt
Indications, hard stops and the genuinely contested cases
- Indications for vesicoamniotic shunt placement
- Absolute contraindications
- Relative contraindications
- LUTO presentations not offered a shunt
- LUTO with preserved amniotic fluid volume
- Shunting despite an unfavourable urine profile
Outcomes after vesicoamniotic shunting
What the trial, the series and the survivors actually show
- Quality of the outcome evidence
- The PLUTO trial
- 16 vs 15
- Interpreting the PLUTO findings
- Comparison with the untreated natural course
- Short-term procedural complications
- Shunt misplacement, migration and occlusion
- Fetal and maternal injury
- Long-term renal outcomes in survivors
- Other long-term problems in survivors
Fluid in the fetal chest
Hydrothorax, macrocystic CPAM and the thoracoamniotic shunt
- Primary fetal hydrothorax
- Signs of fetal compromise from an effusion
- Prognosis without intervention
- One hemithorax filled and the heart pushed across
- How a thoracoamniotic shunt is expected to help
- Evaluation before thoracoamniotic shunting
- Counselling for fetal hydrothorax
- Role of thoracocentesis before shunting
- Genetic testing alongside chest drainage
- Deciding when to move from taps to a shunt
- Large pleural effusion treated by shunt
- Shunting for congenital pulmonary airway malformation
- Thoracoamniotic shunt technique
- Chest wall vessels cannot be mapped
- Indications for thoracoamniotic shunt placement
- Contraindications and the state of consensus
Outcomes after thoracoamniotic shunting
Complications, the case series and what they can and cannot show
- Short-term complications
- Shunt migration and obstruction
- Reported serious complications
- Quality of the thoracic evidence
- Determinants of outcome
- Systematic review of primary fetal hydrothorax
- Shunting outcomes for CPAM
Summary
The points to carry away
- Key points on fetal shunts
- Key points on vesicoamniotic shunting
- Key points on thoracoamniotic shunting
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition