A Novel Technique of Gastro Intestinal Anastomosis

INTRODUCTION

Although inverting the mucosa is a surgical discipline that every young resident is taught by his mentor, no specific technique has been described in literature for inverting the mucosa unlike other aspects of intestinal anastomosis like the type of suture bites, suture materials, etc. We present a novel technique of inverting the mucosa by the handsewn technique which causes minimal damage to the tissues. The aim of the present study was to describe a new technique of intestinal anastomosis.

TECHNIQUE

Our technique involved pushing the prolapsing mucosa with one jaw of the forceps using the length of the forceps instead of only the tip and holding the seromuscular layer using the other jaw of the forceps with the wrist being in a supinated position. Then as the suture is tightened, use a pronation of the hand movement to approximate the bowel walls using a torque (circumferential force) [Video 1].

DISCUSSION

There have not been many studies which emphasise the mechanical tissue properties of the gastrointestinal tract and the stress and strain properties of the intestinal wall when subjected to forces in various directions. Our study attempts to bring the focus back on this aspect of tissue handling and also to compare a new technique which incorporates all principles of standard handsewn intestinal anastomosis in addition to the above-mentioned facets and compare it with the default technique.

A handsewn intestinal anastomosis is an important skill for an abdominal surgeon. Although staplers have become ubiquitous in the operation theatre, there are certain instances where handsewn intestinal anastomosis is preferred. For instance, if the mesentery is thickened and short and the bowel is not mobile enough to safely bring into the wound for the proper angulation of the staplers; or if the anastomosis is in the proximal duodenum, where again the angulation can be an issue; or if the bowel wall is oedematous and it’s safer to do a handsewn anastomosis; or in resource-constrained settings where staplers are not available or if it is too costly for the patient to afford.

There are some underlying principles of a handsewn intestinal anastomosis. Some authors advocate that the full-thickness/serosubmucosal sutures seem to provide low rates of anastomotic leak, although the evidence supporting this is weak (Level 2b).^[1] A prolapsing mucosa during anastomosis was considered to be a risk factor in anastomotic leakage by many surgeons. To this effect there have been studies attempting to determine whether inverting the mucosa or everting the mucosa technique was better in preventing anastomotic leakage. Many studies showed that the everting technique produced more adhesions but less stenosis.^[2,3] However, one randomised control trial (RCT) condemned the use of the everting technique in colorectal anastomosis, citing a higher incidence of anastomotic failure.^[4]

A single layer, inverting the mucosa method, seems preferable in that the serosa-to-serosa approximation ensured peritoneal sealing, which would prevent adhesions.^[5] Connel recommended penetrating the submucosa and the mucosa as well in order to ensure that the submucosa is also included since the submucosa might be thin although strong, and it is the submucosal layer which affords the maximum strength to the anastomosis.^[6]

It can be appreciated that the submucosa layer is thin^[7], and it is possible to miss this layer if full-thickness bites are not taken [Figure 1]. Sero-muscular sutures are too fragile to reliably tie knots with necessary loads.^[8] Sutures that don’t stitch on to the submucosa are unreliable.^[8]

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Figure 1:

Hematoxylin and Eosin (H&E) stain 40x magnification. Bracket is highlighting the thinness of submucosa compared to the intestinal wall and how it can be missed in seromuscular bites.

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An argument against the more commonly used Lembert suture to augment the anastomosis is the observation by Fan Feng et al. in their study of handsewn esophagogastric anastomosis that the double layer could reduce the inner diameter, leading to anastomotic stricture.^[9]

While performing a handsewn intestinal anastomosis with full-thickness bites, the posterior walls of the intestines are first sutured, followed by the anterior wall. The mucosa of the posterior wall usually gets inverted along with the bites without any extra manoeuvres required. However, while performing the anterior wall of the anastomosis, the mucosa usually prolapses out of the lumen.

There are two commonly followed methods to invert the mucosa. The first method involves the mucosa being grasped by the forceps and pushed inside the lumen with the tightening of the suture to approximate the wall. The second method involves holding the seromuscular layer and pulling it over the mucosa with the tightening of the suture to approximate the wall. Sometimes both these methods are used simultaneously.

However, both these two methods are associated with concerns as far as tissue damage is concerned. The first method involves concentration of pressure at the tip of the forceps with the potential to tear the mucosa, especially if it is oedematous. The second method utilises tangential force to the curvature of the bowel, and this has the potential to strip the seromuscular layer from the submucosa. This method also concentrates all the pressure onto the tip of the force, thereby increasing the chances of damaging the serosa.

Studies have shown the strain pattern on the layers of the bowel wall was different when the force was applied along the long axis of the bowel as compared to the transverse direction along the curvature of the bowel.^[10] The mechanical properties of the intestine in axial and transversal directions are different.^[8] In the study of Egorov, the tensile strength of the intestinal wall was tested using tensiometers.^[8] In the study, it clearly showed a differential breaking point of the different layers of the intestine when the intestinal wall is subjected to linear stress in one axis. The serosa and muscular layers first show disintegration on linear stress, followed by the submucosa and, finally, the mucosa. The disintegration of the mucosa and submucosa was least for a given force when the force was applied along the curvature of the bowel as compared to the axial direction. A study relating to the geometric configuration and zero-stress state of the gastrointestinal tract found that when the intestinal walls were cut into rings and when the rings were subsequently opened up by cutting radially, the rings always formed sectors instead of completely unravelling to form a line.^[11] This shows that the zero-stress state of the bowel wall is a curved structure instead of a linear structure. Hence, it stands to reason that tangential force during suture tying causes more damage compared with circumferential force.

In an animal model experiment, Li et al. observed that reciprocal sliding friction and tangential force on the small intestine surface would tend to tear the serosa layer and induce the muscularis and mucosa trauma. The damage to the rabbit’s small intestine extended gradually from outside to inside: serosa layer tearing and falling, muscularis bleeding, longitudinal muscularis, and circular muscularis division, and mucosal bleeding and necrosis.^[12] Hence, this study also shows the damage to the intestinal walls by a tangential force.

Our technique uses the entire length of the dissecting forceps to hold the mucosa and seromuscular layer instead of using only the TIP of the forceps. We believe this reduces the concentration of pressure on the tissue. This technique also involves imparting a circumferential force to the intestinal wall instead of a tangential force to approximate the anterior wall during intestinal anastomosis. We believe this reduces the shear strain on the tissue.

Our study brings the focus back onto the technical details of the handsewn anastomosis with special emphasis on a novel technique that can minimise the injury to the tissue and also provide an aesthetically pleasing inversion of the mucosa during a handsewn anastomosis. This technique is easy to learn and reproducible. We would like to name this technique as the Merta Technique of Inverting the Mucosa.

CONCLUSION

This technique of gastrointestinal anastomosis imparts minimal damage to the tissues as compared to the default technique. This technique is easy to learn and reproducible. We would like to name it the Merta technique.