In a pregnant patient (≥20 weeks gestation), does the direction and degree of tilt affect prevention of aortic compression, and what tilt angle is recommended?

Yes, Direction Matters: Use LEFT Lateral Tilt at 15-30° or Manual LEFT Uterine Displacement

In pregnant patients ≥20 weeks gestation, the direction of tilt absolutely matters—you must use LEFT lateral tilt at 15-30° on a firm surface, or preferably manual LEFT uterine displacement, to effectively relieve aortocaval compression. 1

Why LEFT Lateral Tilt?

The anatomical position of the aorta and inferior vena cava dictates that displacement must be to the LEFT:

• The gravid uterus compresses both the inferior vena cava (IVC) and aorta when the patient is supine
• These vessels lie to the RIGHT of midline, so displacing the uterus to the LEFT moves it off these critical structures
• Manual displacement technique: Place your hand below the uterus on the maternal RIGHT side and push upward and to the LEFT using an "up, off and over" method 1

The Optimal Angle: 15-30° LEFT Lateral Tilt

Research demonstrates clear differences in effectiveness based on angle:

• 15° tilt is insufficient: MRI studies show that 15° left lateral tilt does NOT significantly increase IVC volume compared to supine position 2
• 30° tilt is effective: A 30° left lateral tilt significantly increases IVC volume (mean 10.7 mL vs 5.2 mL supine, p<0.001) and cardiac output increases by approximately 5% at ≥15° tilt 3, 4
• The 15-30° range recommended in guidelines 1 represents a practical compromise—30° is more effective but 15° may be more feasible while still allowing adequate chest compressions during resuscitation

What About RIGHT Lateral Tilt?

Right lateral tilt is NOT recommended. While one MRI study found that 30° right lateral tilt achieved optimal IVC volume in 23% of patients (vs 70% with left tilt), this variability is unpredictable and left tilt remains the standard 3. The guidelines make no mention of right lateral positioning as an acceptable alternative 1.

Preferred Method: Manual LEFT Uterine Displacement

Manual uterine displacement is the preferred technique over tilting 1 because:

• Keeps the patient supine, allowing optimal chest compressions during cardiac arrest
• More effective than inadequate tilt angles
• Can be performed immediately without equipment
• Maintains spinal alignment in trauma cases

Critical pitfall: Do NOT use soft surfaces (pillows, blankets, beds) for tilting—these compromise chest compression effectiveness and should never be used 1. Only use firm wedges, tilting tables, or spinal boards.

Clinical Algorithm

For pregnant patients ≥20 weeks (uterus palpable at or above umbilicus):

1. First choice: Manual LEFT uterine displacement (hand on maternal right, push up and left)
2. Alternative: 15-30° LEFT lateral tilt on FIRM surface only (tilting table, solid wedge with spinal board)
3. Never: Right lateral tilt, soft surfaces, or angles <15°

In cardiac arrest specifically: Manual displacement is superior because it maintains supine positioning for effective chest compressions while relieving compression 1, 5. Meta-analyses show that 27-30° tilt reduces correct compression depth by 19% and correct hand position by 9% 5.

In trauma cases: Protect the spine with a spinal board before applying any tilt; if unavailable, use manual displacement 1.