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The first 25 slides, exactly as they appear. The full deck has 76 content slides.
Radiology
Oligohydramnios
Built from Obstetric Imaging
What’s inside
6 sections · 76 slides
Overview
- What this deck covers
- The fluid the baby floats in
- Why low fluid is taken seriously
Measuring the fluid
Normal volume, the two ultrasound yardsticks, and the numbers that define low fluid
- How fluid volume changes through pregnancy
- Amniotic fluid index: four pockets added up
- Single deepest pocket: one measurement only
- How the scan is actually performed
- The numbers that define oligohydramnios
- AFI ≤ 5 cm
- Which yardstick describes low fluid better?
- What the pooled trials showed
- A more recent randomised trial
- AFI against SDP, side by side
- Severe oligohydramnios at 21 weeks
Why low fluid harms the fetus
Where the fluid comes from, why the lungs depend on it, and how outcome turns on timing
- Where amniotic fluid comes from early on
- Where it comes from later, and how it leaves
- The loop that keeps the fluid topped up
- The lungs are the organ most at risk
- Second trimester against third trimester
- The cohort behind those numbers
- Borderline fluid: the grey zone
- 25%
What causes it
Leaking out, not being made, or shifted to a twin: maternal, fetal and placental causes
- How to think about the causes
- Three levels at which urine output fails
- Prerenal causes: a starved, not damaged, kidney
- How placental insufficiency dries up the fluid
- Reversed end-diastolic flow with low fluid
- Drugs that reduce fetal urine
- Renal causes: the kidney itself is at fault
- Postrenal causes: urine cannot get out
- The blockages that cause it
- Ruptured membranes, the commonest cause
- Ruptured membranes in a twin pregnancy
- When the fluid moves to the other twin
- Unequal fluid in a twin pregnancy
- The full list of associated conditions
- Conditions Associated With Oligohydramnios
- Conditions Associated With Oligohydramnios (continued)
- Conditions Associated With Oligohydramnios (continued)
Finding it and working out why
Clinical clues, membrane tests, the targeted renal survey, and when MRI adds something
- How it usually comes to light
- Classic signs
- Confirming that the membranes have ruptured
- When those tests are equivocal
- Rescan the anatomy, even if it was normal before
- The renal agenesis trap
- Multicystic dysplastic kidney on ultrasound
- Polycystic kidney disease on ultrasound
- Spotting a blocked urinary tract
- What to assess once obstruction is suspected
- Bladder size localises the blockage
- The keyhole sign
- Distended bladder with obstructed outflow
- Dilated left renal collecting system
- Reading the obstructed kidney
- What too little fluid does to the fetal body
- When to add Doppler
- When ultrasound is not enough: MRI
Managing a pregnancy with low fluid
Cause plus gestational age drive every decision, from shunting to delivery timing
- The two questions that drive management
- From scan to plan
- When the condition is lethal
- Draining a blocked bladder: the vesicoamniotic shunt
- Watching an unexplained second-trimester case
- Managing low fluid caused by ruptured membranes
- What to watch for while waiting
- When the leaking stops: resealing
- Isolated low fluid at term
- During labour
- What the referring clinician needs to know
- Key points
- Key points, continued
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition