Predictive value of Serum C-Reactive protein and serum lactate in intestinal obstruction with suspected strangulation

A Mohamad Safwan; K P.C Muhammed Irfan; Rajeev Chellapan; MH Firoz Khan; KN Vijayan

doi:10.4103/ksj.ksj_37_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 28 | Issue : 2 | Page : 143-148

Predictive value of Serum C-Reactive protein and serum lactate in intestinal obstruction with suspected strangulation

A Mohamad Safwan¹, K P.C Muhammed Irfan², Rajeev Chellapan³, MH Firoz Khan¹, KN Vijayan¹
¹ Department of General and Minimal Access Surgery, Kerala Institute of Medical Sciences, Thiruvananthapuram, Kerala, India
² Department of General Surgery, Government Medical College Manjeri, Malappuram, Kerala, India
³ Department of General Surgery, General Hospital, Thalasserry, Kerala, India

Date of Submission	11-Nov-2022
Date of Decision	03-Dec-2022
Date of Acceptance	22-Dec-2022
Date of Web Publication	30-Jan-2023

Correspondence Address:
Dr. A Mohamad Safwan
Kerala Institute of Medical Sciences, Thiruvananthapuram, Kerala
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ksj.ksj_37_22

Abstract

Background: Intestinal obstruction is one of the common clinical problems encountered in surgical practice, and the dreadful complication of intestinal obstruction is strangulation, which requires an emergency surgery for management. The main objective of our study was to evaluate patients with clinical suspicious intestinal obstruction and to find out the significant levels of serum C-reactive protein (CRP) and serum lactate in the early detections of strangulation preoperatively. Materials and Methods: A total of 30 patients who aged between 15 and 80 years were included in the study after excluding the patients of comorbid medical illness and patients with findings other than obstruction or strangulation. The serum values of CRP and lactate were measured pre-operatively and compared between obstruction with strangulation and obstruction without strangulation. Receiver operating characteristic (ROC) curve was drawn, and cut-off values for the diagnosis of strangulation were calculated along the calculation of sensitivity, specificity, positive predictive values (PPVs) and negative predictive values (NPVs). Results: Fifteen patients of strangulated bowel obstruction had significantly higher values of serum CRP and lactate when compared with 15 patients of simple bowel obstruction (99 vs. 38.3 mg/L and 35 vs. 9.9 mg/dl, respectively, P < 0.05). Using ROC analysis, the area under the curve of serum CRP and lactate was found to be 0.809 and 0.947, respectively for bowel strangulation. The serum CRP test has the sensitivity of 80.0%, specificity of 66.7%, PPV of 70.6% and NPV of 76.9% to detect the obstruction with strangulation when using a cut-off value of 49 mg/L. The serum lactate test has the sensitivity of 86.7%, specificity of 73.3%, PPV of 76.5% and NPV of 84.6% to detect the obstruction with strangulation when using a cut-off value of 19 mg/dl. Conclusion: The serum CRP and lactate are useful and reasonable diagnostic markers for predicting strangulation in cases of acute intestinal obstruction in an emergency setting.

Keywords: C-reactive protein, intestinal obstruction, lactate, strangulation

How to cite this article:
Safwan A M, Muhammed Irfan K P, Chellapan R, Firoz Khan M H, Vijayan K N. Predictive value of Serum C-Reactive protein and serum lactate in intestinal obstruction with suspected strangulation. Kerala Surg J 2022;28:143-8

How to cite this URL:
Safwan A M, Muhammed Irfan K P, Chellapan R, Firoz Khan M H, Vijayan K N. Predictive value of Serum C-Reactive protein and serum lactate in intestinal obstruction with suspected strangulation. Kerala Surg J [serial online] 2022 [cited 2023 Mar 25];28:143-8. Available from: http://www.keralasurgj.com/text.asp?2022/28/2/143/368594

Introduction

Intestinal obstruction is one of the common clinical problems encountered in surgical practice. One of the dreadful complications of intestinal obstruction is strangulation, which requires an emergency surgery for management.^[1] Time plays an important role with an earlier detection of ischaemia favouring the increased patient's survival.

The diagnosis of strangulation is primarily by clinical history and examination.^[1] Biomarkers, such as values of serum tumour necrosis factor alpha, C-reactive protein (CRP), interleukin-6, D-lactate, D-dimer, alpha-glutathione S-transferase, intestinal binding protein (I-FABP), creatine kinase B, isoenzymes of lactate dehydrogenase, procalcitonin, alkaline liver phosphatase and urinary phosphatase, have been studied^{[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18],[19]} in cases of intestinal obstruction.

C-reactive protein is an acute-phase reactant which found in the blood, the levels of which rise in response to inflammation. It is belongs to the pentraxin family of proteins and synthesised by the liver in response to factors secreted by adipocytes.^[19] The rise of CRP is rapid with a half-life of 19 h, and there is no diurnal variation compared to other acute-phase reactants. A high serum CRP level occurs with inflammation, infection, tissue trauma and tissue necrosis, malignancies and autoimmune disorders.^[19]

Lactic acid is the normal end point of the anaerobic breakdown of glucose in the tissues. Lactic acid exists in two optical isomeric forms, namely, L-lactate and D-lactate. D-lactate is not produced in mammalian tissue, but it is detected in blood when the enteral bacterial flora abnormally proliferates resulting from the mucosal injury following ischaemia.^[8],[9],[10]

The aim of this prospective, observational study was to evaluate the role of CRP and lactate in combination as markers of bowel strangulation. Hence, we start necessary measures to control morbidity and mortality caused by bowel gangrene, following obstruction in the general surgery department of a tertiary hospital.

Materials and Methods

The aim of this study was to compare the diagnostic accuracy of serum CRP and serum lactate in patients with intestinal obstruction associated with strangulation and those without strangulation. We evaluated the levels of serum CRP and serum lactate in the strangulated bowel obstruction compared with no strangulation.

It was a prospective, observational, comparative study from November 2018 to May 2020 on all the patients above 15 years admitted to the emergency and general surgery departments with a clinical suspicion of intestinal obstruction and operated in the emergency operation theatre with diagnosis of acute intestinal obstruction due to hernia, band, adhesion, volvulus, intussusceptions, stricture, gall stones and malignant obstruction were included.

The sample size estimation was done from the reference study. The expected mean (standard deviation [SD]) value of lactate in obstruction group was 54 (30), that was 15 in each group, and the expected mean (SD) value of lactate in non-obstruction group was 27 (18).^[20] By using 95% confidence interval and 80% power, the sample size estimated for the present study was 30, that was 15 in each group. Patients with the potential causes of lactic acidosis such as diabetic ketoacidosis, shock, chronic kidney diseases, any cardiac ailment, coagulopathy, hepatic failure, connective tissue disorder, rheumatoid arthritis and acute rheumatic fever, patients on antiretroviral drugs, especially stavudine which causes lactic acidosis, patients on oral contraceptive pills, patients with myocardial infarctions and pneumococcal pneumonia and patients <15 years were excluded from the study.

The blood sample was collected before surgery and sent to the laboratory for finding out the level of serum CRP and serum lactate level. During surgery, various intra-operative findings causing acute intestinal obstruction led to formation of two groups, i.e., simple bowel obstruction and strangulated bowel obstruction. Data collection was based on these groups which were group (A) of patients with strangulated bowel obstruction and other group (B) with simple bowel obstruction. Following emergency laparotomy, the values of serum CRP and lactate level were compared among both groups.

Data collected were tabulated in MS Excel and analysed using SPSS version 16.0. (Statistical Product and Service Solutions). Categorical variables were represented using the frequencies and percentages. The continuous variables will be reported using the mean and SD association between categorical variables which were analysed using Chi-square test. Receiver operating characteristic (ROC) curve was used to find out the cut-off values for serum CRP level and serum lactate level. P < 0.05 was considered statistically significant.

Results

Thirty patients were selected based on the intra-operative diagnosis and divided into two groups – each group of 15 patients, Group A of patients with strangulated bowel obstruction and Group B with simple bowel obstruction. The sociodemographic characteristics were not statistically different in the two groups [Table 1].

Table 1: Sociodemographic characteristics (n=30)

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On comparing the laboratory markers, it was observed that Group A (strangulated bowel obstruction), 66.7% of patients, had an increased serum CRP level, 100% of patients had an increased lactate level and 73.3% of patients had an increased total leucocyte count. In Group B (simple bowel obstruction), 33.3% of patients had an increased serum CRP level, 3% of patients had an increased lactate level and 60.0% of patients had an increased total leucocyte count [Table 2].

Table 2: C-reactive protein, lactate and total leucocyte count values of the study population summarised as median interquartile range or mean standard deviation as per the normality of the data (n=30)

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The median and interquartile range (IQR) of the serum CRP level in Group A (strangulated bowel obstruction) were 99 and 76–22, respectively. Whereas, the median and IQR of the serum CRP level in Group B (simple bowel obstruction) were 38.3 and 4–66, respectively. Both groups were comparable and statistically significant (P = 0.004). The median and IQR of the serum lactate level in Group A (strangulated bowel obstruction) were 99 and 4–66, respectively. Whereas, the median and IQR of the serum lactate level count in Group B (simple bowel obstruction) were 9.9 and 8.7–19.3, respectively. Both groups were comparable and statistically significant with P < 0.001. The mean and SD of the total leucocyte count in Group A (strangulated bowel obstruction) were 15200 and 5173, respectively. Whereas, the mean and SD of the total leucocyte count in Group B (simple bowel obstruction) were 10800 and 3587, respectively. Both groups were comparable and statistically significant with P = 0.011 [Table 3].

Table 3: C-reactive protein, lactate and total leucocyte count values of the study population summarised as median interquartile range or mean standard deviation as per the normality of the data (n=30)

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The cut-off levels of CRP, lactate concentration and total leucocyte count (TLC) at which the Youden index exhibited a maximum value were 49 mg/L, 19 mg/dl and 13,600/cu. mm, respectively. Using the ROC analysis, the area under the curve (95% confidence interval) for the serum CRP, serum lactate and total leucocyte count was found to be 0.809 (0.639–0.978), 0.947 (0.876–1.000) and 0.744 (0.560–0.928), respectively, for predicting the bowel strangulation among the intestinal obstruction. For predicting strangulation, using a cut-off value of 49 mg/L for CRP, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 80%, 66.7%, 70.6% and 76.9%, respectively. Using a cut-off value of 19 mg/dl for lactate, the sensitivity, specificity, PPV and NPV were 86.7%, 73.3%, 76.5% and 84.6%, respectively. Using a cut-off value of 13600/cu. mm for the total leucocytes count, the sensitivity, specificity, PPV and NPV were 60.0%, 80.0%, 75.0% and 66.7%, respectively [Table 4] and [Figure 1], [Figure 2], [Figure 3].

Table 4: Receiver operating characteristic curve for predicting strangulation among the intestinal obstruction cases using C-reactive protein, lactate and total leucocyte count values (n=30)

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Figure 1: ROC curve for predicting strangulation among the intestinal obstruction cases using the CRP cut-off values. ROC: Receiver operating characteristic, CRP: C-reactive protein

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Figure 2: ROC curve for predicting strangulation among the intestinal obstruction cases using the lactate cut-off values. ROC: Receiver operating characteristic

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Figure 3: ROC curve for predicting strangulation among the intestinal obstruction cases using the TLC cut-off values. ROC: Receiver operating characteristic, TLC: Total leucocyte count

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Among 15 patients who had strangulated bowel obstruction, 6 (40%) had gangrenous bowel obstruction. The cut-off levels of CRP, lactate concentration and TLC at which the Youden index exhibited a maximum value were 99 mg/L, 35 mg/dl and 16,300/cu. mm, respectively [Table 5] and [Figure 4].

Table 5: Receiver operating characteristic curve for predicting gangrene among the strangulated intestinal obstruction cases using C-reactive protein, lactate and total leucocyte count values (n=15)

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Figure 4: ROC curve for predicting gangrene among the strangulated intestinal obstruction cases using the CRP cut-off values. ROC: Receiver operating characteristic, CRP: C-reactive protein

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Using the ROC analysis for predicting gangrene among the strangulated intestinal obstruction, the area under the curve (95% confidence interval) for the serum CRP, serum lactate and total leucocyte count was found to be 0.898 (0.742–1.000), 0.944 (0.837–1.000) and 0.981 (0.930–1.000), respectively, for predicting the bowel strangulation among the intestinal obstruction [Figure 4], [Figure 5], [Figure 6].

Figure 5: ROC curve for predicting gangrene among the strangulated intestinal obstruction cases using the lactate cut-off values. ROC: Receiver operating characteristic

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Figure 6: ROC curve for predicting gangrene among the strangulated intestinal obstruction cases using the TLC cut-off values. ROC: Receiver operating characteristic, TLC: Total leucocyte count

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For predicting gangrene among the strangulated intestinal obstruction, using a cut-off value of 99 mg/L for CRP, the sensitivity, specificity, PPV and NPV were 83.3%, 77.8%, 71.4% and 87.5%, respectively, Using a cut-off value of 35 mg/dl for lactate, the sensitivity, specificity, PPV and NPV were 83.3%, 77.8%, 71.4% and 87.5%, respectively, Using a cut-off value of 16300/cu. mm for the total leucocytes count, the sensitivity, specificity, PPV and NPV were 83.3%, 88.9%, 83.3% and 88.9%, respectively.

Discussion

We found that the serum CRP and serum lactate were significantly raised in the strangulated bowel obstruction compared with the simple bowel obstruction. Our study has also shown that for predicting gangrene among the strangulated intestinal obstruction, the serum CRP and serum lactate level were having a cut-off value of 99 mg/dL and 35 mg/L, respectively.

Although TLC is a non-specific marker for predicting strangulation among patients with intestinal obstruction, we could find from our study that TLC was significantly raised in the strangulated bowel obstruction compared with the simple bowel obstruction. Moreover, for predicting gangrene among the strangulated intestinal obstruction, TLC had a cut-off value of 16,300/mm. cu.

We also found that the strangulated bowel obstruction was more common among the age group of 15–50 years than the age group of 51–80 years. Moreover, the simple bowel obstruction was more common among the age group of 51–80 years than the age group of 15–50 years. The strangulated bowel obstruction was more common among females than males, and the simple bowel obstruction was more common among males than females. With regard to operative findings or study, the most common causes for the strangulated bowel obstruction from our study are inguinal hernia, incisional hernia and umbilical hernia, followed by adhesion and band. Internal hernia and malignancy were the least common causes of strangulation in our study. The most common cause of the simple bowel obstruction from our study is adhesion followed by malignancy, band and inguinal hernia. 66% of patients with strangulated bowel obstruction were found to have a raised serum CRP level compared to simple bowel obstruction.

One hundred per cent of patients with strangulated bowel obstruction were found to have a raised serum lactate level compared to simple bowel obstruction. Seventy-three per cent of patients with strangulated bowel obstruction were found to have a raised TLC compared to simple bowel obstruction. Our study showed that 40% of patients with strangulated bowel obstruction had gangrenous bowel.

Hassan et al.^[21] also had a similar observation that the serum values of CRP and lactate were significantly higher in patients with strangulated bowel obstruction compared to simple bowel obstruction. The value of TLC was also higher in the strangulated bowel obstruction. Pal et al.^[20] observed that the serum values of CRP and lactate were significantly higher in patients with strangulated bowel obstruction compared to simple bowel obstruction. The value of TLC was also higher in the strangulated bowel obstruction. Thakur et al.^[22] also had an observation that 60% of patients with strangulated bowel obstruction were having an increased serum CRP level and 73% of patients with simple bowel obstruction were having a normal CRP level. Nandyala et al.^[23] also observed a significantly higher TLC and higher serum lactate level in patient with strangulated bowel obstruction. van der Voort et al.^[24] studied 49 patients with chronic gastrointestinal ischaemia and observed a similar and significant raise of L-lactate in ischaemia compared to non-ischaemia group. Lin et al.^[25] observed that the elevated serum CRP was associated with bowel gangrene.

The main strength of our study lies in the fact that it is a prospective study with applicability in an emergency setting in a developing country, where the availability of computed tomography and other costly biomarkers is beyond the reach of poor patients. Furthermore, the patients in our study included those with both small and large bowel obstruction. We also found the incidence of gangrenous bowel among patients with strangulated bowel obstruction and cut-off value of predicting gangrenous strangulation.

The limitations of our study are the study participants were less in number, the duration of the study was short and the patients of paediatric age group were not a part of this study. The radiological findings, post-operative outcome, length of hospital stay and follow-up were not assessed by markers with regard to the diagnosis of strangulation.

Nevertheless, this study does add to the current literature regarding the need of decision-making policy for the management of acute intestinal obstruction incorporating the role of biochemical markers for predicting the ischaemia/strangulation/gangrene status at the time of presentation.

Conclusion

The serum CRP and lactate are useful and reasonable diagnostic markers for predicting strangulation in cases of acute intestinal obstruction in an emergency setting.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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