I. INTRODUCTION

A. Postoperative gastrointestinal (GI) complications occur most commonly following abdominal and pelvic operations. However, GI complications may occur after any type of operation and may be associated with significant morbidity and mortality. Complications range from benign and self-limiting, such as postoperative nausea and vomiting, to severe and life threatening, such as GI bleeding and abdominal compartment syndrome. In this chapter, we will review the causes, risk factors, diagnostic workup, and treatment options for patients with postoperative GI complications that may be encountered in the postanesthetic care unit. Postoperative nausea and vomiting is discussed separately in Chapter 15. We will not discuss postoperative GI complications that occur more remotely postoperatively, such as bowel obstruction due to adhesions, incisional hernias, and enterocutaneous fistulas.

II. GI BLEEDING

A. Significant postoperative GI bleeding is an uncommon but potentially serious complication of surgery. Causes of postoperative GI bleeding may be divided into three broad categories:

1. Bleeding secondary to the operation or complications of the operation

2. Bleeding resulting from surgical stress or complications of the operation exacerbating the bleeding risk of a preexisting source

3. Bleeding unrelated to the operation and occurring incidentally in the postoperative period.

B. In the immediate postoperative period, the most common etiology of bleeding is as a direct result of the operation or complications of the operation.

C. Most episodes of postoperative GI bleeding are self-limited. Minor postoperative bleeding occurs frequently and often without clinical recognition. However, significant GI bleeding, defined as overt bleeding associated with hemodynamic disturbances, demands immediate attention. The initial evaluation of a patient with GI bleeding should focus on hemodynamic stability and resuscitation in parallel with diagnostic evaluation for the cause of bleeding. The initial goals should be to determine the severity of bleeding, triage patients to the appropriate setting, initiate resuscitation, and determine the source of bleeding.

D. The initial assessment includes history, physical exam, surgical and postoperative course review, laboratory data, and vital signs for hemodynamic stability, keeping in mind that tachycardia and hypotension may not manifest until a significant amount of the patient’s blood volume has been lost. The amount of blood lost and the rate of ongoing blood loss should be estimated to establish the degree of resuscitative measures. At least two large-bore peripheral intravenous (IVs) should be placed. Management of hemorrhage is detailed in Chapter 21 and may be referred to for further details.

E. GI bleeding is often divided into upper and lower GI bleeding. Upper GI bleeding (UGIB), defined as occurring proximal to the ligament of Treitz, may present with hematemesis or melena. Intubation may be required to protect the airway in cases of high-volume UGIB. Esophagogastroduodenoscopy (EGD) to identify the source of bleeding may be required depending on the preceding operation. Better outcomes are associated with patients who are well resuscitated prior to endoscopic evaluation. If the antecedent surgery involved the upper GI tract, return to the operating room for evaluation may be required, depending on the rate of ongoing bleeding.

F. Acute lower GI bleeding occurs distal to the ligament of Treitz and may present with hematochezia or melena. Urgent colonoscopy is the examination of choice after an UGIB source has been excluded. Treatment depends on the source of bleeding, and often patients with exsanguinating lower GI bleeding will require immediate re-operation.

G. The most common sources of bleeding in postoperative patients include bleeding from intestinal anastomosis, ischemic colitis, and preexisting lesions such as ulcers and diverticuli.

III. STRESS-RELATED MUCOSAL DISEASE

A. Most episodes of GI bleeding in critically ill patients are caused by gastric ulcerations from stress-related mucosal injury. Risk factors for stress-related mucosal ulcerations include prolonged mechanical ventilation, coagulopathy, perioperative hypotension, sepsis, spinal cord injuries, severe burns, shock, hepatic failure, renal failure, polytrauma, organ transplantation, and history of GI bleed or ulcers.

B. Prophylaxis against stress ulceration should be initiated in critically ill patients who are at high risk for GI bleeding. According to guideline recommendations from the American Society of Health Systems Pharmacists, stress ulcer prophylaxis should be administered to patients with any of the following characteristics: coagulopathy (platelet levels below 50,000, INR >1.5, prothrombin time (PTT) over 2 times the upper limit of normal), mechanical ventilation >48 hours, history of GI bleeding, traumatic brain or spinal cord injury, or burns. Additionally, stress ulcer prophylaxis should also be administered to critically ill patients with two or more of the following minor criteria: sepsis, intensive care unit (ICU) stay over 1 week, occult GI bleeding over 6 days, and steroids (equivalent of 250 mg of IV hydrocortisone or greater).