Introduction

Major abdominal surgeries, which include gastrointestinal, esophagogastric, hepatobiliary and pancreatic, and colorectal procedures, may present serious postoperative complications. It is important to differentiate these events from the expected postoperative changes in order to detect complications such as bleeding, occlusion, evisceration, and sepsis, and to reduce morbidity and mortality. Various methods have been used to evaluate the postoperative period. These methods are based on clinical, laboratory, and imaging variables.

The Sepsis Related Organ Failure Assessment (SOFA) score and the quick Sequential Organ Failure Assessment (qSOFA) score are commonly used prognostic scales based on clinical variables. While sensitive, they lack specificity. Among laboratory variables, acute phase reactants such as C-reactive protein have recently become more relevant^1,2. The imaging tests more commonly used are ultrasound and computed tomography (CT) scan. Ultrasound is a cost-effective and bedside tool, but it lacks specificity and is operator dependent. The sensitivity and specificity of CT scan are higher to detect complications3.

The aim of this study was to determine the usefulness of CT for the early diagnosis of major abdominal surgery complications.

Material and methods

We conducted a retrospective, observational and descriptive study using data obtained from the medical records of patients undergoing major abdominal surgery between March 2022 and May 2023. The identity of the patients was protected.

Inclusion criteria: elective and emergency major abdominal surgery, either open or through laparoscopy, due to inflammatory causes or neoplasms.

Major abdominal surgery was defined as any gastrointestinal resection with anastomosis or ostomy, esophagogastric surgery, hepatobiliary and pancreatic resections and colorectal resections. All the procedures mentioned above are included in one of the levels 5-7-8-9-10 of Asociación Argentina de Cirugía fee schedule⁴.

Postoperative patient management included intravenous fluid therapy using continuous infusion pump, antiemetic and gastroprotective medications (metoclopramide and omeprazole), analgesia with diclofenac 75 mg every 12 hours for all patients with creatinine levels ≥ 1.2 g/dL. Opioids were indicated as soon as the anesthesiologist removed the epidural catheter placed in the operating room.

The urinary catheter was removed if diuresis was > 50 mL/h at 24 hours postoperatively, and nutrition was initiated according to the ERAS® protocol^5,6.

In the postoperative period, re-operations and their causes were analyzed according to the Clavien-Dindo classification⁷ and distributed as follows: accidental injury, anastomotic fistula, postoperative ileus, subphrenic collection, hemorrhage, and evisceration.

Patients were divided into two groups: one with a favorable postoperative course without symptoms and the other with symptoms suggesting a postoperative complication. In this second group, patients were divided into two subgroups: those who did not undergo CT (T0) and those who did so. Among the patients who underwent CT, those with images suggestive of complications were classified as T+ and those without such images were classified as T-. The CT scans were categorized based on whether they were performed within 48 hours after the operation, between 48 hours and 7 days, or after 7 days. The re-operations and their indications were also analyzed. A descriptive analysis was performed to compare positive findings (T+) with re-operations across all groups. The decision-making process is described in the flowchart in Figure 1.

FIGURE 1 Flow diagram of the decision-making process for patients after major abdominal surgery Abbreviations: S+: with symptoms; S-: without symptoms; T0: Without CT; T+: with abnormal CT findings; T-: without abnormal CT findings 

S+ was defined in the presence of any of the following: tachycardia (heart rate > 100/min), qSOFA (respiratory rate ≥ 22 breaths/min, altered mental status, systolic blood pressure ≤ 100 mm Hg), fever (axillary temperature > 38°C), postoperative paralytic ileus (absence of bowel sounds or bowel motility 96 hours after surgery or greater)⁸, pain (reported by the patient with ≥ 6 points on the verbal numeric scale despite receiving the prescribed analgesia), changes in color, odor, or amount of drain output, or evisceration.

T+ was defined as any of the following⁹:

T- was defined as¹⁰:

All CT scans were performed using a high- resolution Toshiba Aquilion 64 CT scanner. Intravenous contrast agent was used in the absence of kidney failure.

Results

We analyzed the medical records of 154 patients; mean age was 61.3 ± 12.6years and 83 (54%) were men. Fifty-four patients (35%) had symptoms suggestive of complications and 27 of them were re- operated.

Six patients with symptoms, who did not undergo CT scanning (T0), were re-operated due to clinical parameters such as tachycardia, fever, prolonged ileus, or changes in drain output. All of them had positive findings, including hemoperitoneum, evisceration, anastomotic fistula, inadvertent injury, or collection with anastomotic fistula.

The 7 patients with symptoms and suggestive tomographic findings (T+) underwent re-operation. All of them had different findings that supported the surgical management, such as evisceration, hemorrhage, anastomotic fistula, inadvertent lesion, or subphrenic collections.

Of the 41 symptomatic cases without suspicious tomographic findings (T-), 14 were re- operated because their symptoms persisted. In all cases, the surgical findings supported the chosen course of action: anastomotic fistulas, intra-abdominal collections, ureteral injuries, or other types of injuries. The remaining 27 patients did not require re-operation because their clinical condition resolved.

Of the total series of patients who underwent major abdominal surgery, 27 patients (17.5%) had complications requiring general anesthesia or had organ failure (Clavien-Dindo grades 3b and 4). None of the patients were treated with local anesthesia. Mortality rate was 2% (n = 3).

Of the 48 CT scans performed, 12 were conducted within 48 hours after the operation, 25 between 48 hours and 7 days, and 11 after 7 days.

In S+ patients, CT confirmed that 7 patients had true positive results, 27 had true negative results, 14 had false negative results and there were no false positive results.

Most complications occurred between 48 hours and postoperative day 7.

Please refer to tables in the Supplementary Material for further details (Table 1, 2, 3 and 4).

Discussion

The ideal time to perform a post-operative CT scan is still an open question. Some authors suggest early scanning to avoid late re-operations, because of the limited value of physical examination, particularly in patients on mechanical ventilation under the effect of muscle relaxants¹¹. Other authors use a cut-off point of 72 hours¹².

The absence of abnormal findings on computed tomography does not rule out the possibility of a postoperative complication¹³. Tachycardia and a positive qSOFA score were the most useful tools for detecting complications. In the 2018 Annual Report of Surgery, tachycardia was the most commonly observed sign and proved to be a relevant predictor of complications¹⁴.

In our study, imaging provided 13% of the information necessary to make the decision to re- operate, which was lower than the 50% reported by the guidelines of the French Society of Anesthesia^15,16. It should be noted that in this study, the CT scan was requested after clinical and ultrasound findings with a high suspicion of complication. The 3 deaths occurred in T- patients who underwent late re-operation (after postoperative day 7). These data are consistent with the aforementioned guideline, which states that the identification of a postoperative complication and the decision to immediately perform a new laparotomy reduce multiple organ failure by 60% and improve survival.

Our study has two limitations: the retrospective nature of the sample and the fact that C-reactive protein¹⁷ was not measured to detect complications due to limited availability for 24-hour testing. In the PRECious trial PREdiction of Complications, CT was indicated only when CRP levels exceeded a certain value¹⁸.

To the best of our knowledge, this is an original work in Argentina. We did not find similar reports in the bibliography.

The decision to re-operate a patient after major abdominal surgery should be made by consensus among the treating physicians. This decision should be based on the evaluation of all available data. No single imaging score or method is sufficient to confirm a complication. Clinical parameters remain of utmost importance.

Based on the presented results, we can conclude that a postoperative CT scan with positive findings after major abdominal surgery supports the decision to re-operate. Nevertheless, the absence of this finding does not exclude this possibility.