Scholars only studied the risk factors of SBO after gastrectomy previously and did not study the effects of different factors on the recurrence of postoperative SBO. A randomized study studied the influence of the choice of incision mode during gastrectomy on postoperative complications, and the results showed that transverse incision may be more beneficial than middle and upper incision to reduce postoperative wound pain and the incidence of postoperative pneumonia and postoperative intestinal obstruction [10]. Another study identified previous abdominal surgery, open gastrectomy, non-Billroth-1 reconstruction, etc., are risk factors related to adhesive small bowel obstruction (ASBO) after gastrectomy, and based on these factors, a nomogram can be generated to predict the probability of ASBO [11]. Unlike previous studies, this study is the first to focus on the risk factors for recurrence of SBO after gastrectomy, using identified independent risk factors to create a nomogram to predict the probability of recurrence of SBO after gastric cancer surgery. In clinical work, we often encounter patients who are admitted to the hospital due to recurrent SBO after gastrectomy, some patients can be relieved with conservative treatment, and others need to be treated with surgery. However, patients still have a high probability of recurrent SBO after discharge, which brings huge psychological pressure and life burden to patients. Therefore, we believe that preventing the recurrence of SBO to avoid multiple hospitalizations is of great importance to both doctors and patients.

Few clinical studies have explored the effect of age and WBC count on recurrent SBO after surgery. Only a quicker peritoneal regeneration in the immature rat has been experimentally described [12]. A higher frequency of postoperative SBO after abdominal surgery in early life was reported, especially in the neonatal period [13]. In addition, gastrointestinal tract mobility decreases with age, which may have an impact on the recurrence of postoperative SBO [14]. Likewise, experimental studies have investigated the mechanism of leukocytes for postoperative SBO. Researchers proved that iNOS expressed in leukocytes plays a major role in mediating smooth muscle dysfunction and postoperative SBO [15]. Another experiment found that leukocyte-derived interleukin (IL)-10 could induce neutrophil extravasation into the postsurgical bowel wall, which increased the occurrence of postoperative SBO [16]. We included age and WBC count as risk factors in our study because they reflect the underlying physical condition of patients, and our findings showed that younger age and higher WBC count increased the risk of postoperative recurrent SBO.

The tumor size which was reflected by the tumor’s largest diameter was the first independent risk factor. In this study, there was a significant difference in tumor size between the two groups (p = 0.024). The study has proved that the larger the tumor size, the higher the risk of postoperative recurrent SBO in patients. Recently, Lv et al. [17] conducted a large retrospective cohort study of patients’ data in the Surveillance, Epidemiology, and End Results and Medicare claims-linked databases (SEER-M database), and they reported that tumor size was significantly associated with SBO according to the results of multivariate analysis. In addition, there was a study of complications after gastrectomy [18], and the results showed that tumor size was an independent prognostic factor for grade I complications after gastrectomy (p = 0.031). Therefore, we thought that tumor size may be related to postoperative recurrent SBO, which was confirmed in our study.

Postoperative metastases, such as peritoneal metastasis and ovarian metastasis, in patients with GC can significantly increase the risk of developing postoperative recurrent SBO. Metastases can increase pressure on the intestines, leading to intestinal strictures or direct blockage of the intestine, resulting in SBO. A study consisting of 61 patients who underwent surgical treatment following GC metastasis has reported malignant intestinal obstruction as the most common complication in these patients [19]. A Japanese study [20] identified lymph node metastasis and peritoneal dissemination as significant risk factors associated with obstructive tumors, indicating that tumor metastasis can influence the development of SBO. Other studies [21,22,23] have found that tumor metastasis from other sites to the gastrointestinal tract leads to SBO, such as large cell carcinoma of the lung, breast cancer, and renal cell carcinoma, which indirectly proves the correlation between postoperative metastasis of GC and SBO. The specific mechanism of metastasis leading to SBO requires us to conduct in-depth research in the future.

Finally, the results of multivariate regression analysis showed that OR = 1.057 (95% CI 1.031–1.085) for the interval from gastrectomy to first SBO, although the OR value was small, which may be due to the large difference in sample size between the two groups and the mutual influence of multiple factors when analyzed together [24]. A significant difference at p < 0.001 indicated that this variable was a risk factor for postoperative recurrent SBO, so it was included in our nomogram. One study [25] found no significant effect of elapsed time from the latest operation on adhesive postoperative SBO. However, some studies [26, 27] have shown that the risk of recurrence of SBO increases with time and the number of hospital admissions. Moreover, studies by Colonna et al. [28] have proved that the recurrence rate of SBO varies with time interval and the number of previous ileus occurrences, and the longer the time interval or with the increase in the number of ileus recurrence, the risk of recurrent SBO also increases. We hypothesized that the reason is that the longer the time, the worse the physical condition of the patients, and the more likely to suffer from malignant complications such as postoperative tumor metastasis, so the more likely to have multiple episodes of SBO. Currently, there are few studies on this variable, and more and more prospective studies should be conducted to examine this topic in the future.

We can explain the nomogram by the following steps: First, determine the value of the variable on the corresponding axis; second, draw a vertical line to the total points axis to determine the points; third, add the points of each variable; and finally, draw a line from the total point axis to determine the postoperative recurrent SBO probabilities at the lower line of the nomogram. For example, the age of patients with GC was 60 years old (17 points), the WBC count was 8 × 109/L (27.5 points), the tumor size was 4 cm (12 points), no postoperative metastasis (0 points), and the interval from gastrectomy to first SBO was 20 months (11 points). Therefore, a total score of 67.5 corresponds to a recurrence probability of postoperative SBO of about 23%.

To the best of our knowledge, this study is the first to develop a nomogram to predict postoperative recurrent SBO. This novel nomogram may serve as a crucial early warning signal to identify patients at a higher risk of developing recurrent SBO after gastrectomy. Unfortunately, there is no way to completely prevent SBO currently. However, doctors should use any means possible to reduce the risk of recurrent SBO. We can use starch-free gloves during surgical procedures [29], irrigate the abdominal cavity with saline below 37 °C [30], preserve the omentum [6], and intraoperative application of preventive materials such as the antiadhesive agent [31], icodextrin 4% solution (Adept) [32], and hyaluronic acid/carboxymethylcellulose (Seprafilm) [33, 34] may reduce the recurrence rate of SBO in GC patients undergoing gastrectomy. Of course, we can also use conservative treatment methods, such as a manual physiotherapy called the Clear Passage Approach (CPA) [35], advising patients to have a liquid diet and increase exercise.

However, the study also has some limitations that should be acknowledged. First, the retrospective nature of the study and the limited sample size may have undermined the findings, and some uncontrolled confounders might also arise. In addition, further external validation in a multicenter setting is required to determine whether this nomogram could be widely used in other populations. Finally, there was no reliable independent cohort for validating the predictive efficiency of the nomogram. Despite these limitations, the study still has certain research value and provides valuable insights and references for future research on the risk assessment of postoperative recurrent SBO in patients with GC.