Mean Platelet Volume/Platelet Count Ratio: A New Diagnostic Parameter for Necrosis in Adhesive Small Bowel Obstruction—A Retrospective Cohort Study

Despite developments in surgical techniques and instruments, abdominal adhesions are still one of the most common causes of intestinal obstruction.^1–3 Small bowel obstruction (SBO) is associated with serious adverse events, such as bowel ischemia and necrosis. Small bowel obstruction is treated with conservative management with nasogastric tube suction or surgically.^4,5 Recognizing indications for nonoperative treatment, the length of nonoperative treatment, and appropriately timing surgery are all factors that may significantly affect disease course.³ Deciding whether to operate on a patient with SBO or to manage the patient conservatively is difficult. Commonly, the decision to operate is given only after conservative management has failed or peritonitis has been detected. A major challenge in SBO management is to detect ischemia as early as possible to avoid necrosis and resection.³

Mean platelet volume (MPV) is a platelet volume index and was found to be elevated in patients with inflammatory disorders.^6,7 Recent studies have revealed that the MPV/platelet count (PC) ratio is also associated with predicting the outcomes of patients with various diseases, such as ischemic cardiovascular diseases and malignant tumors, and patients in intensive care units (ICUs).^6,8–10

The objective of the current study was to evaluate the value of the MPV/PC ratio for predicting the need for surgery and intestinal necrosis in patients with postoperative adhesive SBO.

Patients and Methods

A total of 129 patients who were admitted to the general surgery department of Dicle University Hospital between November 2010 and March 2014 with postoperative adhesive SBO were included in the study. Demographic data and clinical and laboratory findings of the patients were reviewed retrospectively. This study was approved by the local ethics committee of Dicle University.

The patients were divided into 2 groups: patients in whom conservative treatment was successful [conservative group (CG); n = 43] and in whom conservative treatment had failed [surgery group (SG); n = 86]. The surgery group was further divided into 2 subgroups, according to the presence (BN+; n = 19) or absence (BN–; n = 67) of bowel necrosis, as determined intraoperatively and verified with histopathologic examination.

Small bowel obstruction was diagnosed on the basis of standard clinical signs (such as abdominal pain and distension, nausea or vomiting, and no passage of gas and/or stools) and radiologic findings. Patients with SBO who had a history of abdominal surgery were included in the study. Exclusion criteria were early postoperative obstruction, obstruction with neoplasia, obstruction with inflammatory bowel disease, incarcerated hernia, and colon obstruction.

Initially, each patient was managed conservatively with nasogastric tube suction and administration of diatrizoate meglumine and diatrizoate sodium solution via nasogastric tube. After each patient received diatrizoate meglumine and diatrizoate sodium solution, radiologic imaging was performed at 24-hour intervals. If diatrizoate meglumine and diatrizoate sodium solution was detected in the cecum, or if passage of gas and stools was observed, the nasogastric tube was clamped and removed, oral nutrition was resumed, and the conservative treatment was considered successful. If diatrizoate meglumine and diatrizoate sodium solution was absent from the cecum at the 48th hour or if peritonitis was detected, conservative treatment was considered to have failed and the patient underwent laparotomy.

The open surgical procedure consisted of gut adhesiolysis or adhesiolysis and bowel resection. An ostomy was established or an anastomosis was created depending on the specific bowel conditions. In each case, the presence or absence of bowel necrosis was noted.

Statistical Analysis

Statistical analysis was performed using statistical software (SPSS version 18; SPSS Inc, Chicago, Illinois). Data were expressed as mean ± SD. We used the χ² test for categorical variables, and the Mann-Whitney U test for continuous variables. We considered a P value of less than 0.05 significant.

Results

The mean age of the patients was 49.22 ± 21.65 years, and 87 patients (67.4%) were male. The conservative group consisted of 43 patients (33.3%), while 86 patients (66.7%) underwent surgery. The mean age was 53.53 ± 20.87 years in the CG and 47.07 ± 21.84 years in the SG (P = 0.110). Comorbid disease was present in 11 patients (25.6%) in the CG compared with 27 patients (31.4%) in the SG (P = 0.495). The most common comorbid disease was diabetes mellitus (n = 5, 11.6%) in the CG and hypertension (n = 10, 11.6%) in the SG (P = 0.581).

In the surgery group, the average MPV/PC ratio was higher than in the CG (P = 0.027). Conversely, PC was lower in the SG (P = 0.037). Twenty-six patients (89.7%) in the SG developed systemic inflammatory response syndrome (SIRS) compared with only 3 patients (10.3%) in the CG (P = 0.003). Morbidity rates, mean hospital stay time, and the need for ICU admission were higher in the SG (P = 0.007, P < 0.001, and P < 0.001, respectively). Data for the CG and the SG are summarized in Table 1.

Table 1 Data of the CG and SG groups

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Of the 86 patients who underwent surgery, bowel necrosis was detected in 19 patients (BN+ group, 22.1%). There were 20 female patients (29.8%) in the BN– group and 10 female patients (52.6%) in the BN+ group (P = 0.025). The most common comorbid disease was diabetes mellitus (n = 5, 7.46%) in the BN– group and hypertension (n = 6, 31.7%) in the BN+ group (P = 0.075). The most common previous operation was colectomy (n = 15, 22.3%) in the BN– group, and gynecologic operations (n = 5, 26.3%) were most common in the BN+ group (P = 0.174). In the BN+ group, MPV and the MPV/PC ratio were significantly higher than in the BN– group (P = 0.049 and P = 0.038, respectively). Data for patients of the BN+ and BN– groups are summarized in Table 2.

Table 2 Data of the BN– and BN+ groups

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The cutoff value with the highest sensitivity and specificity for MPV/PC ratio was 0.02855 (sensitivity 68%, specificity 65%) for predicting bowel necrosis in patients with adhesive SBO.

Discussion

Postoperative adhesion formation is the most common complication of abdominal and pelvic surgery. Unlike other postoperative complications, such as wound infection or anastomotic leakage, the consequences of adhesion formation comprise a lifelong risk for various clinical entities.^11–16 Ten Broek et al¹⁷ reported that the incidence of adhesive small bowel obstruction was 2.4%.

It is very important to diagnose bowel strangulation in adhesive small bowel obstruction patients in order to avoid bowel necrosis and associated complications. Therefore, strangulation predictors have been evaluated in a number of human studies.^18–24

Mean platelet volume is a marker of the size and activation of platelets. Large platelets possess higher metabolic and enzymatic activity and show higher thrombogenic potential.²⁵ A direct association has been demonstrated between increased MPV and acute thrombotic events, such as acute myocardial infarction, unstable angina, and stroke.^26–28 Aliosmanoglu et al²⁹ reported that MPV was significantly higher in patients with portal venous thrombosis. Gul et al³⁰ reported that MPV was associated with sudden hearing loss due to ischemia. Similarly, our results demonstrated that the mean MPV was higher in patients who developed bowel necrosis; but we didn't find any significant difference between the conservative group and the surgery group.

However, recent studies have revealed an association between the MPV/PC ratio and the outcomes of patients with various ischemic diseases. Azab et al⁸ reported that the MPV/PC ratio was superior to the MPV alone in predicting long-term mortality after non-STE myocardial infarction. Sezgi et al¹⁰ reported that increasing MPV and decreasing platelet count may alert intensivists to the worse course of the disease in ICU patients. In accordance with these data, in our study, the MPV/PC ratio was greater in patients who developed bowel necrosis. Also, MPV/PC ratio was higher in surgery group than conservative group.

Tsumura et al²³ reported that the presence of SIRS was independently predictive of strangulation in acute small bowel obstruction. Miyauchi et al²⁴ reported that the large number of patients with strangulation obstruction exhibited SIRS before the operation, and the manifestation of SIRS correlated well with the length of the necrosis in the strangulated small bowel. Similarly, in the present study, the presence of SIRS was more common, and the mean heart rate was higher in SG patients. However, there was no statistically significant difference between the BN+ and BN– groups in terms of the presence of SIRS or mean heart rate.

In a study by Cosse et al,⁵ the mean age of the surgical management group was significantly higher than that of the conservative management group. In another study, Markogiannakis et al³¹ revealed that there was no significant difference between the mean ages of the ischemia and nonischemia groups or the mean ages of the necrosis and non-necrosis groups. In our study, neither the CG or the SG, nor the BN+ and BN– groups were statistically significantly different in terms of mean age.

Both Cosse et al⁵ and Markogiannakis et al³¹ reported that patient sex distributions were not statistically different between groups, but Lo et al¹⁸ observed an association between female sex and rate of strangulation in their series of 430 patients. In our study, patient sex distributions were not statistically different between the CG and the SG, but the proportion of female patients was higher in the BN+ group than in the BN– group.

Laparotomy was performed in 66.6% of our patients. This percentage seems to be higher than the rates reported in the literature, which range from 24% to 57%.^{19–21,32,33} The operative treatment rates of SBO were likely high in the present study as it was conducted in a tertiary care hospital, and most of the patient population consists of patients who did not improve in previous hospitals. In the present study, patient bowel necrosis rates were as high as 14.7%, in accordance with the literature (range, 11%–29%).^18,22,32

Although previously time from arrival to operation was determined to be significantly shorter in the necrosis group,³¹ no significant difference was identified between the BN+ and BN– groups in our study. In the same study, postoperative complication rates, ICU admission rates, and mortality rates were reported to be higher in the necrosis group, while there were no significant differences in terms of ICU duration of stay or hospital stay time.³¹ In our study, mean hospital stay time, need for ICU admission, and postoperative morbidity rates were higher in the SG. However, there were no statistically significant differences between the BN+ and BN- groups in terms of hospital stay, ICU admission and duration of ICU stay, or postoperative morbidity and mortality.

Conclusion

Mean platelet volume/platelet count ratio is associated with the failure of the conservative management and the presence of bowel necrosis in patients with adhesive small bowel obstruction. Further studies are needed to determine the importance of MPV/PC in adhesive SBO.

Limitations

The limitations of this study include the retrospective, single-center study format and the small size of the study group. For example, we think that the ratio of patients who need surgery would be lower if we include all patients who were admitted to the hospital, but because we are a tertiary referral hospital, the need for surgery is relatively higher. So, prospective, multicentric studies should be performed in order to evaluate the predictive value of MPV/PC ratio in adhesive SBO.