How to Perform Left Uterine Displacement

Left uterine displacement is performed by placing one or both hands on the right side of the pregnant abdomen and pushing the uterus toward the patient’s left, lifting it off the large blood vessels that run along the spine. The technique takes only seconds but can meaningfully restore blood flow to both the mother and the fetus whenever a pregnant person beyond roughly 20 weeks of gestation is lying on her back. It comes up most often during cesarean deliveries, maternal cardiac arrest, and trauma resuscitation, and the specifics of hand placement and body mechanics matter more than you might expect.

Why the Uterus Needs to Be Moved

In late pregnancy the uterus grows heavy enough to press the inferior vena cava and, to a lesser degree, the abdominal aorta against the lumbar spine when the mother lies flat. Angiographic studies in the 1960s first confirmed this directly: the aorta was pushed to one side and became less densely opacified at the level of the third through fifth lumbar vertebrae, and during uterine contractions or when blood pressure was already low, a common iliac artery could be transiently occluded altogether.¹ The vena cava, which carries blood back to the heart from the lower body, is softer-walled and even easier to flatten. MRI studies have shown that in the supine position, vena cava height shrinks and flow through it drops, while blood reroutes through the spinal venous plexus as a backup pathway.²

The downstream effects are measurable. Cardiac output can fall by nearly 3 liters per minute in women who develop supine hypotensive syndrome, compared with about 1 liter per minute in those who tolerate supine positioning better, and mean arterial pressure drops by roughly 11 mmHg versus 2.5 mmHg in women without the syndrome.³ Most pregnant women compensate by reflexively increasing vascular resistance, but fewer than one in five cannot compensate adequately and develop frank hypotension, dizziness, or nausea.⁴ Even women who feel fine lying flat show reduced blood flow to the uterus: an MRI study found that the supine position caused roughly a 24 percent reduction in total internal iliac arterial blood flow to the uterus and about a 6 percent reduction in oxygen transfer across the placenta compared with lying on the left side.⁵ That oxygen gap is the reason left uterine displacement exists: you are mechanically removing the weight of the uterus from the vessels so blood can flow freely again.

One-Handed and Two-Handed Techniques

There are two commonly taught hand placements, and both can be performed from either side of the patient. The choice often depends on what else is happening at the bedside, how many hands you have free, and whether the patient is awake or undergoing resuscitation.

In the one-handed method you stand on the patient’s left side, reach across to the right side of the uterus, cup it from below with your fingers, and push it to the left while lifting slightly upward. The goal is to shift the entire mass of the uterus off the midline. Some clinicians prefer to stand on the patient’s right side and push the uterus away from themselves, which can feel more natural if you are right-handed or if the left side of the bed is occupied. Guidelines note that manual left uterine displacement involves placing a hand below the uterus on the maternal right and pushing it slightly upward and to the left, and that this can be done with one hand or two hands, from either side of the patient.⁶

The two-handed method is essentially the same motion performed with both hands cupping the uterus from the right and lower border, providing a broader area of contact and a firmer displacement. It is easier to sustain for longer periods because you can distribute the effort across both arms, though it obviously requires both hands to be free. In practice during CPR, one rescuer typically performs chest compressions while a second person stands at the patient’s side and holds the uterus displaced. During a cesarean section, the displacement is often achieved by a wedge under the right hip rather than by manual effort, though manual technique is sometimes used if a wedge is unavailable or impractical.

How Much Tilt or Displacement Is Enough

This is where the evidence gets more interesting than the textbook answer suggests. For decades the standard teaching has been a 15-degree left lateral tilt, typically achieved by placing a wedge or rolled blanket under the patient’s right hip. But MRI studies have questioned whether 15 degrees actually does the job. One study of pregnant women at term found that 15 degrees of lateral tilt did not significantly relieve inferior vena cava compression, while 30 degrees of tilt partially did.⁷ Another MRI study comparing left-sided and right-sided tilts found that mean vena cava volume was significantly greater at 30 degrees of left tilt than at either 15 or 30 degrees of right tilt.⁸

These imaging findings raise a practical problem: 30 degrees of lateral tilt is a steep angle for a patient on an operating table or a CPR surface, and it makes other interventions harder. Manual left uterine displacement avoids this dilemma because the patient stays flat (or nearly flat) while the rescuer’s hands do the work of moving the uterus off the vessels. The trade-off is that manual displacement requires a dedicated person to maintain it continuously, whereas a wedge is passive.

A prospective study during cesarean sections under spinal anesthesia looked at cardiac output before and after removing lateral uterine displacement and found no significant change, which the authors interpreted as suggesting that the hemodynamic impact of displacement may be smaller than traditionally assumed in the controlled surgical setting where fluids and vasopressors are already being used.⁹ This does not mean displacement is unnecessary; it means that in a well-managed surgical context with other hemodynamic supports in place, the incremental benefit of displacement alone may be harder to measure. In emergency settings without vasopressors running, the effect of aortocaval decompression is more consequential.

Left Uterine Displacement During Cardiac Arrest

Maternal cardiac arrest is the scenario where correct LUD technique matters most urgently. Current resuscitation guidelines call for the patient to remain supine with manual displacement of the uterus rather than tilting her onto her side, because chest compressions are much more effective when the patient is flat. A manikin study comparing supine-with-manual-displacement against lateral tilt using a firm wedge found that the effectiveness of chest compressions was similar in both positions.¹⁰ But a crossover study using both mannequins and swine models found that supine positioning allowed correct hand placement and adequate compression depth far more reliably than left lateral tilt. Rescuers rated compressions in the supine position as significantly easier, with difficulty scores roughly half those reported in the tilted position.¹¹

The practical upshot is straightforward: keep the patient flat, start high-quality chest compressions, and have someone manually displace the uterus at the same time. Tilting may be an option if manual displacement is impossible (for example, with only one rescuer), but it comes at a measurable cost to compression quality. If the rescuer performing displacement stands on the patient’s left side and pushes the uterus from the right, they stay out of the way of the person doing compressions. If they stand on the right side, they need to coordinate positioning so their arms do not interfere with the compressor’s rhythm.

There is also a practical note about rescuer fatigue during tilt-based approaches: a study on lateral tilt during CPR found that performing chest compressions from the right side of a left-laterally tilted patient was associated with greater fatigue and body instability compared with compressions from the left side.¹² Manual displacement sidesteps this issue entirely because the patient stays flat and the compressor works in a normal ergonomic position.

Trauma and Spinal Precautions

In the injured pregnant patient, the same aortocaval compression physiology applies, but there is an added constraint: the spine may need to be immobilized. Canadian trauma guidelines recommend that after mid-pregnancy, the gravid uterus should be moved off the inferior vena cava to increase venous return and cardiac output, and that this can be achieved by manual displacement or left lateral tilt. They specifically note that care should be taken to secure the spinal cord when using left lateral tilt.¹³ Manual displacement is often the better choice in trauma because the patient can remain on a backboard in a neutral spine position. If tilt is used instead, the entire backboard must be tilted as a unit so the spine stays aligned, which requires additional equipment or personnel.

It is worth remembering that supine hypotensive syndrome can start earlier than many people expect. While the classic teaching focuses on the third trimester, case reports and reviews describe symptoms appearing as early as the fifth month of pregnancy, and the size of the uterus, the exact position of the fetus, and individual anatomy all influence how much compression occurs.⁴ In a trauma bay, err on the side of displacing or tilting if there is any doubt about gestational age.

Cesarean Delivery Under Spinal Anesthesia

During planned cesarean sections, left uterine displacement is used prophylactically to prevent the blood pressure drop that commonly follows spinal anesthesia. Spinal anesthesia itself causes vasodilation, and adding aortocaval compression on top of that can produce significant hypotension. One randomized trial compared a prophylactic bolus of phenylephrine against a 15-degree left lateral tilt using an obstetric wedge. Hypotension occurred in about 65 percent of the phenylephrine group and about 54 percent of the tilt group, but this difference was not statistically significant. Neither method alone was sufficient to reliably prevent hypotension, and the authors suggested that combination strategies or more aggressive therapy may be needed.¹⁴

In practice, most anesthesia teams use a combination approach: a phenylephrine or norepinephrine infusion running alongside physical displacement of the uterus, plus a fluid co-load given at the time of the spinal injection. The displacement itself might be achieved by a wedge under the hip, a manually tilted operating table, or a team member’s hands pushing the uterus to the left. The method matters less than ensuring it actually happens consistently, because the hemodynamic support from vasopressors masks but does not eliminate the underlying venous obstruction.

Adjustments for Obesity and Other Special Circumstances

In patients with a high body mass index, the pannus (the abdominal fat apron) adds weight on top of the already heavy uterus, increasing the compression on underlying vessels. Some clinicians combine left uterine displacement with a reverse Trendelenburg position, tilting the entire table so the patient’s head is higher than her feet. One published case placed a morbidly obese patient at a 30-degree reverse Trendelenburg angle with concurrent left uterine displacement to manage both the respiratory and hemodynamic challenges of her body habitus during delivery.¹⁵ The trial comparing phenylephrine with lateral tilt also noted that patients with a BMI over 30 had a higher incidence of hypotension after spinal anesthesia regardless of which prophylactic strategy was used.¹⁴

In these patients, manual displacement may require more force and is harder to sustain. A two-handed technique, or having the person performing displacement brace themselves against the bed rail for leverage, can help. The key point is that heavier patients need more, not less, attention to aortocaval decompression, because the added weight makes compression worse and the hemodynamic reserve to cope with it may be narrower.

Why Training Matters More Than You Would Think

Despite being a standard-of-care intervention during maternal cardiac arrest, left uterine displacement is performed far less consistently than other resuscitation steps. A simulation study involving 18 teams of internal medicine residents found that while all teams correctly dosed epinephrine and 72 percent defibrillated appropriately, only 44 percent displaced the uterus during CPR.¹⁶ Fewer than half. This is a technique that requires no equipment, no medications, and no specialized training beyond knowing to do it and where to put your hands. The bottleneck is not skill; it is recall under pressure.

The gap probably reflects how rarely maternal cardiac arrest occurs compared with other emergencies. Clinicians practice defibrillation, airway management, and drug administration routinely but may encounter a pregnant arrest only once in a career. Simulation training appears to help close that gap: teams that go through maternal arrest scenarios are more likely to remember LUD in subsequent resuscitations. The low baseline performance in simulation studies suggests that periodic rehearsal, even brief tabletop walkthroughs, could have an outsized effect on whether this simple maneuver gets done when it counts.

How the Science of Aortocaval Compression Evolved

Anecdotal mentions of problems with pregnant women lying flat date back to the 17th century, but formal scientific recognition came much later. In the 1950s, researchers in Britain and Texas published the first measurements of supine hypotension in pregnant women. Frank Holmes, working in Edinburgh, recommended lateral tilt. In 1964, Scott and colleagues produced the first radiological evidence of vena cava compression in late pregnancy. Within a few years, the Edinburgh group demonstrated that frank supine hypotension occurred in fewer than 20 percent of pregnant women, with the rest compensating by increasing vascular resistance. Then in 1968, Bieniarz’s group in Montevideo showed angiographically that the aorta, not just the vena cava, was compressed. By 1972, Crawford and colleagues in Birmingham argued that lateral tilt should be used routinely in all cases for fetal welfare, not just for the minority who became overtly symptomatic.¹⁷

That shift in thinking, from treating only symptomatic women to applying displacement or tilt universally, is what makes the modern approach what it is. The recognition that even asymptomatic supine positioning reduces fetal oxygenation by a measurable margin changed the standard of care from reactive to preventive. MRI studies confirming reduced placental oxygen transfer in healthy pregnancies have reinforced that logic in recent years.⁵ The technique itself has not changed much since Holmes first suggested tilting the patient. What has changed is our understanding that the problem is universal in degree, even though it is symptomatic in only a minority, and that solutions need to be applied routinely rather than on a case-by-case basis.

Left Tilt Versus Right Tilt

Left lateral positioning is standard because the vena cava runs slightly to the right of the spine, making it more vulnerable to compression from a uterus that typically dextrorotates (twists to the right) in late pregnancy. But the question of whether right-sided tilt could work has been studied. MRI comparisons found that the greatest vena cava volume was achieved with 30 degrees of left tilt in about 70 percent of subjects, but roughly 23 percent actually had their greatest vena cava volume at 30 degrees of right tilt.⁸ Individual anatomy varies enough that for roughly one in four women, left tilt may not be the optimal direction. In clinical practice, though, you cannot do an MRI to check before choosing a side, so left displacement remains the default because it works for the majority. If a patient’s blood pressure does not improve with left displacement, trying the other side is a reasonable next step rather than assuming the technique has failed.

1
American Journal of Obstetrics and Gynecology. Aortocaval compression by the uterus in late human pregnancy: II. An arteriographic study
2
NMR in Biomedicine. The effect of maternal position on venous return for pregnant women during MRI
3
PubMed. Hemodynamic changes and baroreflex gain in the supine hypotensive syndrome
4
PubMed. Supine hypotensive syndrome
5
The Journal of Physiology. The effects of maternal position, in late gestation pregnancy, on placental blood flow and oxygenation: an MRI study
6
PubMed Central. Effect of maternal positioning during cardiopulmonary resuscitation: a systematic review and meta-analyses
7
Anesthesiology. Effect of Lateral Tilt Angle on the Volume of the Abdominal Aorta and Inferior Vena Cava in Pregnant and Nonpregnant Women Determined by Magnetic Resonance Imaging
8
PubMed. Effect of Right-Lateral Versus Left-Lateral Tilt Position on Compression of the Inferior Vena Cava in Pregnant Women Determined by Magnetic Resonance Imaging
9
PubMed Central. Impact of maternal lateral tilt on cardiac output during caesarean section under spinal anaesthesia: a prospective observational study
10
Anaesthesia. Efficacy of cardiopulmonary resuscitation in the supine position with manual displacement of the uterus vs lateral tilt using a firm wedge: a manikin study
11
PubMed. Coronary perfusion pressure and compression quality in maternal cardiopulmonary resuscitation in supine and left-lateral tilt positions
12
Emergency Medicine International. Left‐Side Versus Right‐Side Lateral Tilt During Maternal CPR: Effects on Compression Quality and Rescuer Fatigue
13
PubMed. Guidelines for the Management of a Pregnant Trauma Patient
14
PubMed Central. A Randomized Evaluation of Prophylactic Phenylephrine and Left Uterine Displacement for the Reduction of Hypotension After Spinal Anesthesia in Cesarean Delivery
15
Bariatric Times. General Anesthesia for Vaginal Delivery of Twins in an Anticoagulated Obese Woman
16
Resuscitation Plus. Cardiac arrest in the pregnant patient – Using simulation to improve internal medicine resident competency
17
International Congress Series. Researches on supine hypotension in pregnancy