With intra-abdominal infection being one of the most common reasons for surgical consultation, understanding the evaluation and management of these processes becomes paramount in the day- to-day practice of the surgeon. The very broad nature of who is affected coupled with the interplay of patient comorbidities and their medications make dealing with intra-abdominal infections a challenge. As with most complex problems in medicine, it is often useful to break them down into simpler and smaller parts. One useful way to categorize intra-abdominal infections is to divide them into those originating from previous abdominal trauma or operations and those presenting in a “virgin” abdomen.
The latter group most commonly includes those patients presenting with specific organ-based infectious processes such as appendicitis, cholecystitis, or diverticulitis. These individual diseases are covered extensively in other chapters and are discussed only superficially in this chapter. The former are those patients who have sustained intra-abdominal trauma or have undergone previous abdominal interventions and are not recovering in the usual expected course. It is this group that taxes diagnostic and clinical skills and may require the most complex medical decision making.
Several factors should come into play once suspicion for an intra-abdominal infection is entertained. These include resuscitation, antibiotic usage, and source control itself. Patients who present with either a suspected or diagnosed intra-abdominal infection should have some form of volume resuscitation. Even without hypotension, there are several reasons why these patients might be volume depleted. These include nausea and vomiting, fluid sequestration within the abdominal cavity or lumen of the bowel, and poor oral intake. As the process progresses, the patient may develop tachypnea, which results in an evaporative fluid loss. By this time, one can often elicit orthostatic hypotension in most patients.
Fluid resuscitation should begin with the administration of isotonic crystalloid and in general be guided by evidence of end organ perfusion (adequate mental status, urine output, correction of acidosis). There is no utility-using colloid such as albumin or hetastarch in these circumstances, and some data suggest a worse outcome. Should the patient present with hypotension or evidence of poor perfusion, a more aggressive approach to volume resuscitation should be employed. Our recommendation is to follow the current surviving sepsis guidelines, which include fluid challenges, monitoring/assessment of filling pressures, and the potential use of pressors and steroids.