Perforated peptic ulcers (PPU) are relatively rare, and difficult to diagnose. Classically, there is a three-stage process described for the presentation of a PPU . The abrupt onset of abdominal pain is the initial symptom, occurring within 2 h of perforation. The pain persisted, and may become generalized after a short time, with pain originating in the epigastrium. After 2 to 12 h, the pain becomes more severe and significant during palpation of the hypogastrium. Twelve hours after perforation, the patient may exhibit a fever, signs of hypovolemia, and abdominal distention without abdominal pain. Making the diagnosis of PPU as quickly as possible is important. In a patient with an appropriate history, if there is free air on a standing chest radiography or in the left lateral abdominal decubitus view, or on a CT scan, no additional testing is required before treatment . Prognosis is related to the timing of treatment. The prognosis is better if treatment is provided within 6 h of perforation, and a delay in treatment beyond 12 h increases both morbidity and mortality . According to Boey, preoperative shock, concurrent medical comorbidities, and perforations that are present for more than 48 h before treatment were associated with a higher mortality . In our retrospective study, three patients died of uncontrolled septic peritonitis. Two of them have end stage renal disease under regular hemodialysis for more than 5 years. Although diagnose of PPU was made within 3 days postoperatively, they died within a month after emergency surgery due to uncontrolled infection.
Three patients (23%) in the perforated ulcer group had a history of peptic ulcer, compared to only one patient in the control group (4%, p < 0.05). Peptic ulcer disease used to be one of major causes contributing PPU ,and most cases of peptic ulcer disease are associated with Helicobacter pylori infection or use of non-steroidal anti-inflammatory drugs (NSAIDs) and steroid [6, 12]. NSAIDs inhibit the production of prostaglandins in the stomach, which play a critical role in the gastric mucosal defenses against acid- and pepsin-induced injury . Each patient in our study underwent elective spine surgery after at least 6 weeks of conservative treatment, including NSAIDs and rehabilitation. Only one patient received steroids before the surgery due to underlying diseases. Smoking is another important risk factor that predisposes development of PPU . However, we did not detect any significant difference. This could be due to small sample in our study.
The intraoperative blood loss of the spine surgery was significantly different between the two groups (855.4 ± 701.3 ml in the ulcer group versus 333.1 ± 170.3 ml in the control group, p < 0.05). Stress ulcer is induced by hypoperfusion of the mucosa in the upper gastrointestinal tract, and reduced gastric blood flow, mucosal ischemia and reperfusion injury are putative underlying mechanism . Greater intraoperative blood loss plus postoperative close wound drainage caused relative hemodynamic instability during anesthesia and in perioperative period in patients in the perforated ulcer group. This resulted in tissue hypoperfusion and reperfusion injury, similar to that of gastrointestinal mucosa injury.
Elevated serum amylase is a frequent concomitant of PPU. There might be significant correlation between increase in amylase and some of the other factors associated with ulcer perforation . The rise is probably a result of increased gastrointestinal leakage into the peritoneal cavity and subsequent lymphatic absorption . In the present study, mean amylase level of the perforated ulcer group was above three times of upper normal limit. Patients in the perforated ulcer group showed significant elevated serum amylase level after elective spine surgeries, especially in the three who died of severe sepsis and uncontrolled peritonitis during their hospital stay (mean serum amylase level in those three patients: 1253.3 U/L) According to the study of Frank A ., the increase of mortality rate seemed to be related to high serum amylase level in the findings of 1000 cases with PPU. Large amounts of gastrointestinal leakage and large perforations cause higher elevated amylase in patients. To avoid delay diagnosis, clinicians should keep alert to determine the patients, who are highly suspected of perforation and with abnormally high serum amylase level, even if free subphrenic air could not be demonstrated.
In this retrospective study, 13 out of the 24,026 patients that underwent elective spine surgeries; thus, the incidence was 0.054%. Some authors have reported cases of small bowel perforations following lumbar laminectomy or discectomy [18, 19]. The authors considered that ventral hollow organ perforation is a rather rare complication of lumbar decompression surgery, andthe incidence of ventral hollow organ perforationis lower after laminectomy than discectomy. According to a study of 30,000 lumbar discectomies, the ventral hollow organ perforation rate was 0.016% .
Postoperative abdominal distension, poor appetite, nausea or vomiting, constipation, and bowel hypoactivity are not uncommon for patients after elective spine surgery due to the prolonged absence of oral intake, anesthesia, and postoperative bed rest. It is difficult to distinguish between normal postoperative gastritis, and early symptoms of PPU, especially in elderly and ill patients . Feng et al.  presented a-13-patients series, those were diagnosed with acute pancreatitis after scoliosis surgery. The low body mass index, low intraoperative mean arterial pressure and long segment of fusion were independent risk factors. A careful examination of a patients’ medical history, as well physical examination, can assist in evaluating acute abdominal pain after elective spine surgery. Clinicians should consider the presence of PPU if abdominal pain is of abrupt onset, progressively worsening, and located in the epigastrium, and is associated with abdominal rigidity and absent bowel sounds , especially in patients with elevated serum amylase level, a history of a peptic ulcer and NSAID use. Due to high mortality rate in the present study (23%), early diagnosis and emergent surgical treatment are necessary to avoid further complication. Each suspected patient should undergo standing chest posterior-anterior radiography, or a left lateral abdominal decubitus view, or even abdominal CT to check for signs of pneumoperitoneum, free air, and a double-wall sign, and to rule out other conditions in the differential diagnosis, including cholecystitis, appendicitis, acute pancreatitis, diverticulitis, bowel obstruction, and aortic aneurysm .
There are several limitations of this study. This was a retrospective and single-center study. As it is a rather rare complication with a low incidence after elective spine surgery, only a small number of cases were included. Training for the evaluation and management of acute abdominal pain is not common in our orthopedic department. Diagnosis and surgical intervention might have been delayed in the opinion of the general surgeons, and some cases were lost because of a missed diagnosis.