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The Water Immersion Technique for Colonoscopy Insertion

The basic concept with water immersion is that water, instead of air, is used to distend the colon enough during insertion to visualize the way forward. During progression of the scope, air pockets that are encountered are also suctioned. Keeping the lumen minimally distended with water appears to reduce angulations in the colon and facilitate advancement with less looping of the instrument in the sigmoid (Figures 1 A-D).

Fig. 1 A: with the patient in the left lateral postion, the sigmoid loop has a more or less pronounced curved bending.

Fig. 1 B: the suction of the air from the sigmoid reduces the width of the sigmoid loop and facilitates the passage of the scope.

Fig. 1 C: the insufflation of air widens the radius of the sigmoid loop, displacing the segment of the viscus toward the right abdominal quadrant (blue arrows); the intubation is therefore more difficult and painful for the patient.

Fig. 1 D: the water infusion through the irrigation port (300-500 cc), makes the sigmoid “collapse” toward the left abdomen thanks to the gravity, facilitating the straightening of the sigmoid and. The intubation is therefore easier. 

Technical steps of the procedure

1. Water immersion is very difficult if the colon is not prepared well for the examination. Residue can be suctioned while infusing more water, which helps to clean the colon, but if there is too much residue, it is very difficult to see clearly enough to insert the colonoscope properly. (Fig. 2 A-B). 

Fig. 2  A-B : The sigmoid colon is distended by water irrigation during colonoscopy. The procedure requires an optimal bowel cleansing (A), otherwise visibility is compromised and the progression becomes difficult or impossible. 

2. As for standard colonoscopy, the water immersion technique starts with the patient in the left lateral postion (Fig. 3), so that the progressive irrigation of water eases down the sigmoid by gravity on the left abdominal quadrant. Instead of syringes, the use of water flushing pumps allow to better adjust the quantity of water needed according to the morphology of the sigmoid and does not delay the maneuvers of scope progression.

Fig. 3: the water immersion colonoscopy starts with the patient in the left lateral position. 

3. While the air insufflated in the recto-sigmoid tends to escape towards the right colon enhancing the tilts of the recto-sigmoid and sigmoido-descending angles, the effect of water is to make the sigmoid heavier so as to make it lay down in the left abdominal cavity ( Fig. 4 A). If at the same time residual air is suctioned away and further water is irrigated (Fig. 4 B), the sigmoid loops are progressively flattened, facilitating the progression of the scope toward the descending colon (Fig. 4 C). 

Fig. 4 A-C: with the patient in the left lateral position, once the colonoscope is introduced in the rectum water irrigation is started through the use of water-jet pump (A). The water gently pushes the sigmoid toward the left abdominal cavity (B). The final outcome is a global shortening of the sigmoid loop and an more comfortable advancement toward the descending colon (C).

4. If the sigmoid loop is particularly curvy, with coil-spring appearance (Fig. 5) the instillation of water instead of air prevents exacerbation of the curvature during progression of the scope.

Fig. 5: the water immersion colonoscopy is particularly effective in case of a very  tortuous sigmoid, when the insufflation of air would exacerbate angulations hampering the progression of the colonoscope.

In this way it is often possible to prevent the formation of an alpha loop, with easier straightening of the sigmoid and negotiation of the progression toward the descending colon (Fig. 6 A-D)

Fig. 6 A-D: in case of a very tortuous sigmoid, the irrigation of water instead of air insufflation prevents the widening of the sigmoid loop and the risk of an alpha loop formation. Instead, it facilitates the torque maneuver to directly straighten the sigmoid (cork-screw twist technique ) and progression toward the descending colon.

5. Once the colonoscope reaches the descending colon (Fig. 6 D), the patient can be rotated in supine position (Fig. 7), in order to facilitate passing of the flexure because it corresponds to a clockwise twist of the colonoscope. If needed, excess water can be removed before engaging the splenic flexure.

Fig. 7 : when the colonoscope reaches the descending colon, the patient can be rotated in supine position.

Usefullness of the Thechnique

Although those endoscopist who routinely perform the “immersion” colonoscopy adopt the technique to explore the entire colon, in clinical practice and also in our experience, its use can be limited to the passing of the sigmoid colon when this is particularly angled or poorly distensible.

The water immersion colonoscopy can be regarded as a true ancillary maneuver in those cases where it is technically demanding to pass a tortuous segment, most of the times an elongated sigmoid, especially with diverticula. 

With the patient in his/her left lateral position, if the insufflation does not provide an adequate distension of the lumen of the sigmoid, the air tends to escape towards the right colon. The instillation/perfusion of water under these circumstances represents an effective alternative to achieve the proper visualization of the sigmoid lumen.

In those cases of a particularly redundant sigmoid loop, when previous attempts at intubation have failed (and especially if a “variable stiffness” scope is not available) , the water immersion colonoscopy is particularly advantageous. 

Water immersion colonoscopy, when adopted in selected cases and correctly carried out, results less distressful for the patients. Usually, once the colonoscope has gained a straight position next to the splenic flexure, the furthjer progression to the cecum is relatively easy in most cases.  


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Collapse-subemergence method: simple colonscopic technique combining water infusion with complete air removal from the rectosigmoid colon

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