Leaking Anastomosis

John Hartley

Powerpoint File

Anastomotic leak is the most devastating surgical complication following major colon and rectal resection. The varying degrees of sepsis which result from anastomotic failure confer not only major morbidity but also a significant risk of mortality. Historical data show an increase in mortality in excess of three fold in patients suffering leaks, and a duration of hospital stay for those who survive which is increased by the same order of magnitude. There are problems in definition which make comparisons between series difficult. Some authors make distinction between clinical and radiological leaks, whilst other reports will, perhaps appropriately, include all cases of pelvic sepsis following colorectal anastomosis whether or not a leak can be demonstrated.

Fortunately, whilst no surgeon operates without leaks, steps can be taken to minimise their occurrence. Most post-operative problems have their genesis in the operating theatre. Therefore, attention to surgical technique is vital in order to ensure that bowel ends are well vascularised and tension free, whilst excellence in anastomotic technique, whether stapled or sutured, is vital. In addition, patient related factors which predispose to anastomotic failure are well defined and include anaemia, steroid usage, poor nutritional status, previous radiotherapy and ongoing sepsis. All of these factors must play a role in decision making regarding timing of resection in elective cases, whether or not to restore continuity, and the use temporary faecal diversion in order to protect the "high risk" anastomosis. The lower the height of the colorectal anastomosis the greater the risk of leakage, with clinical leak rates in the region of 10% being commonly reported following low anterior resection. However colonic anastomoses are by no means immune from failure with leak rates of up to 12% following right hemicolectomy being reported in some series. The use of a defunctioning proximal stoma appears unlikely to prevent anastomotic leak but is of value in mitigating against the consequences of that leak. Thus the incidence of peritonitis, requirement for re-operation, and 30 day mortality following low anterior resection are all reduced by the use of temporary faecal diversion. However, there is controversy over whether faecal diversion should be used routinely or selectively following low pelvic anastomosis. The risks of clinical anastomotic leak must be balanced against the hazards of ostomy formation and closure which are often not factored in to decision making.

The early diagnosis and timely management of anastomotic leak relies upon clinical observation and appropriate imaging. Clinical signs may be non-specific even at an advanced stage. Patients are commonly misdiagnosed as having a cardiac or primary respiratory event. Non-specific deterioration at the appropriate time post resection should be taken to indicate anastomotic leak until proven otherwise. Clinical examination may be adequate to make the diagnosis but should, almost without exception, be confirmed by plane radiographs, water soluble contrast studies, and or CT scan with oral i.v and rectal contrast. Which of the latter modalities to utilise depends upon the abdominal findings, local facilities, and type of resection performed.

Patients with anastomotic leak can usually be considered as one of three broad categories 1) clinical signs of faecal peritonitis 2) the "septic" patient with an intra-abdominal abscess but no gross abdominal signs, and 3) the "non-acute" patient presenting with an enterocutaneous or colocutaneous fistula. The former group require a rapid confirmation of diagnosis where practical with simultaneous resuscitation prior to re-laparotomy. The procedure undertaken at exploration will depend upon the condition of the patient, the laparotomy findings and the position and state of the anastomosis. The safest option is usually disconnection of the anastomosis and exterioriation of proximal and, if possible, distal ends. There is, however, a place for peritoneal lavage, drainage, and proximal faecal diversion especially when dealing with the low pelvic anastomosis. Such an approach may permit the anastomosis to be salvaged in the long term, whereas disconnection will often result in a permanent stoma. The second group of patients will commonly be managed by drainage of abscess by percutaneous or perhaps transrectal route, with systemic antibiotics, and consideration for nutritional support. Re-laparotomy is usually reserved for those patients who deteriorate despite the above measures. The final group of patients presenting with an enterocutaneous or colocutaneous fistula require initial correction of electrolyte imbalances and nutritional status along with treatment and drainage of sepsis. Such measures aim to restore the patient to a state in which the fistula will either close spontaneously, or where operative closure is likely to be successful. A proximal stoma may be required as part of this treatment in order to control sepsis and fistula output. Decision making in such situations may be complex. Those patients in whom a fistula does not close on such a regimen will thereafter require contrast studies in order to delineate anatomy prior to eventual definitive procedure.

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References

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