To place a patient in Sims’ position, you help them lie on their side and then roll them slightly forward toward a face-down orientation, so they end up halfway between a side-lying and prone position. The upper leg is sharply flexed at the hip and knee, while the lower leg stays mostly straight. This position is commonly used for rectal examinations, enemas, colonoscopy preparation, and certain procedures during labor.
Step-by-Step Placement
Start with the patient lying on their back. Explain what you’re about to do and why, then close any curtains or doors to maintain privacy. Have the patient roll onto their left side (left-lateral Sims’ is the standard preference for most procedures, though right-side placement is used in certain situations). Once on their side, guide them to roll slightly forward so their chest is angled toward the mattress. The final posture should be roughly halfway between lying on the side and lying face down.
Position the arms next. The lower arm (the one closest to the bed) goes behind the patient’s back or slightly behind the trunk, keeping it out of the way so the patient’s weight doesn’t rest directly on it. The upper arm is flexed at the shoulder and elbow, resting comfortably in front of the body, often on a pillow.
Now adjust the legs. The lower leg stays extended or only slightly bent at the knee. The upper leg is the key landmark of Sims’ position: flex it sharply at both the hip and knee to 90 degrees or more, and bring it forward so it rests on the mattress in front of the lower leg. This acute flexion of the upper leg is what tilts the pelvis forward and separates the buttocks, giving clear access to the rectal and perineal area.
Place a pillow under the patient’s head for comfort. A second pillow under the flexed upper knee helps maintain alignment and reduces strain on the hip. Drape a sheet over the patient so only the area needed for the procedure is exposed.
How Sims’ Differs From a Standard Side-Lying Position
In a regular lateral (side-lying) position, the patient’s body stays stacked more or less vertically, with the top leg flexed just enough for stability. Sims’ position takes this further by rolling the patient partly onto their front. The upper hip and knee flex more acutely than in lateral positioning, and the lower arm moves behind the body rather than staying in front. This forward tilt is what makes the position useful: it naturally opens the rectal area and allows gravity to help with procedures like enema administration.
The distinction matters because a standard side-lying position does not provide the same anatomical access. If a patient is simply lying on their side with both legs moderately bent, you won’t get the buttock separation that Sims’ position creates.
Why Left-Side Sims’ Is Preferred
For rectal procedures and colonoscopy, left-lateral Sims’ is the recommended default. This follows the anatomy of the large intestine: the sigmoid colon and rectum curve in a way that makes left-side positioning allow smoother and more comfortable insertion of instruments or fluids. When a specialized procedure table isn’t available, clinical guidelines recommend placing the patient in the left lateral Sims’ position with the hips near the edge of the table or bed.
Right-side Sims’ is used in specific clinical situations, such as certain pregnancy-related positioning or when a patient has injuries or conditions that prevent left-side placement.
Common Uses for Sims’ Position
The position is used most often for rectal examinations, suppository insertion, enemas, and as a starting position for colonoscopy when a specialized table isn’t available. The forward pelvic tilt separates the buttocks and makes identifying anatomical landmarks (like the sacral hiatus, used for certain spinal injections) much easier.
During labor, a modified Sims’ position serves a completely different purpose. When a baby is in an occiput posterior position (face-up instead of the ideal face-down), placing the mother in a semi-prone position on the side opposite the baby’s occiput for 15 to 30 minutes per hour can encourage the baby to rotate into a better position. Studies have found this technique increases spontaneous rotation to the anterior position, raises vaginal delivery rates, and reduces the duration of active labor and postdelivery lower back pain. The forward tilt of the mother’s pelvis changes how gravity acts on the baby and encourages the gradual turn.
Comfort and Safety Considerations
Pillows are your main tool for making this position sustainable. Without support under the upper knee, the weight of the flexed leg pulls on the hip and lower back, which becomes painful quickly. A thin pillow or folded towel under the patient’s waist can also prevent the spine from sagging if the mattress is soft.
Check that the lower arm isn’t trapped under the patient’s body weight. It should rest behind the trunk, not be pinned beneath it. For patients who are unconscious or sedated, this is especially important because they can’t shift to relieve pressure on their own.
Patients with hip replacements, severe arthritis, or limited hip flexion may not be able to achieve the full 90-degree upper leg flex. In these cases, bring the knee forward as far as the patient can comfortably tolerate. Some access is still achieved even with less dramatic flexion. For patients with respiratory issues, keep in mind that the semi-prone orientation can put some pressure on the chest, so monitor breathing and adjust as needed.