Bowel obstruction complicated by ischemia: analysis of CT findings

Neutrophil to lymphocyte ratio predicts bowel ischemia in non-strangulated adhesive small bowel occlusions: a retrospective analysis from an acute care surgical service

BACKGROUND

Adhesive small bowel obstruction (ASBO) is a leading cause of hospitalization in emergency surgery. The occurrence of bowel ischemia significantly increases the morbidity and mortality rates associated with this condition. Current clinical, biochemical and radiological parameters have poor predictive value for bowel ischemia. This study is designed to ascertain predictive elements for the progression to bowel ischemia in patients diagnosed with non-strangulated ASBO who are initially managed through conservative therapeutic approaches.

METHODS

The study was based on the previously collected medical records of 128 patients admitted to the Department of Acute Care Surgery of Padua General Hospital, from August 2020 to April 2023, with a diagnosis of non-strangulated adhesive small bowel obstruction, who were then operated for failure of conservative treatment. The presence or absence of bowel ischemia was used to distinguish the two populations. Clinical, biochemical and radiological data were used to verify whether there is a correlation with the detection of bowel ischemia.

RESULTS

We found that a Neutrophil-Lymphocyte ratio (NLR) > 6.8 (OR 2.9; 95% CI 1.41-6.21), the presence of mesenteric haziness (OR 2.56; 95% CI 1.11-5.88), decreased wall enhancement (OR 4.3; 95% CI 3.34-10.9) and free abdominal fluid (OR 2.64; 95% CI 1.08-6.16) were significantly associated with bowel ischemia at univariate analysis. At the multivariate logistic regression analysis, only NLR > 6.8 (OR 5.9; 95% CI 2.2-18.6) remained independent predictive factor for small bowel ischemia in non-strangulated adhesive small bowel obstruction, with 78% sensitivity and 65% specificity.

CONCLUSIONS

NLR is a straightforward and reproducible parameter to predict bowel ischemia in cases of non-strangulated adhesive small bowel obstruction. Employing NLR during reevaluation of patients with this condition, who were initially treated conservatively, can help the acute care surgeons in the early prediction of bowel ischemia onset.

Prediction of bowel necrosis by reduced bowel wall enhancement in closed-loop small bowel obstruction: Quantitative methods

PURPOSE

To assess diagnostic performance and reproducibility of reduced bowel wall enhancement evaluated by quantitative methods using CT to identify bowel necrosis among closed-loop small bowel obstruction (CL-SBO) patients.

METHODS

This retrospective single-center study included patients who diagnosed with CL-SBO caused by adhesion or internal hernia during January 2016 and May 2022. Patients were divided into necrotic group (n = 41) and non-necrotic group (n = 67) according to surgical exploration and postoperative pathology. Two doctors independently measured the attenuation of bowel wall and consensus was reached through panel discussion with a third gastrointestinal radiologist. Reduced bowel wall enhancement was assessed by four quantitative methods. Univariate analyses were used to evaluate the association between each method and bowel necrosis, and kappa/intraclass correlation coefficient values were used to assess interobserver agreement. Diagnostic performance parameters were calculated for each method.

RESULTS

Reduced bowel wall enhancement in arterial phase (OR 8.98, P < 0.0001), reduced bowel wall enhancement in portal phase (OR 16.84, P < 0.001), adjusted reduced bowel wall enhancement in arterial phase (OR 29.48, P < 0.001), adjusted reduced bowel wall enhancement in portal phase (OR 145.69, P < 0.001) were significantly associated with bowel necrosis. Adjusted reduced bowel wall enhancement in portal phase had the best diagnostic performance (AUC: 0.92; Youden index: 0.84; specificity: 94.03 %) and interobserver agreement (kappa value of 0.59-0.73) to predict bowel necrosis.

CONCLUSION

When assessing reduced bowel enhancement to predict bowel necrosis among CL-SBO patients, using unenhanced CT images and proximal dilated loop as standard references in portal phase is the most accurate quantitative method among those tested.

Iodine density mapping for the diagnosis of acute bowel ischemia using fast kV-switching dual-energy CT

PURPOSE

To evaluate the diagnostic capabilities of a supplementary color ramped iodine density map compared to virtual monoenergetic images (VMIs) at 74 keV in the diagnosis of acute bowel ischemia (ABI).

METHODS

Data for this study were prospectively gathered and retrospectively evaluated. Patients referred to the Department of Diagnostic Radiology between October 2020 and August 2022 on the suspicion of ABI and underwent surgery < 12 h following fast kV-switching venous phase abdominal dual-energy CT (DECT) were consecutively included. Images were evaluated by two board-certified radiologists and two radiology residents. First round included only 74 keV VMIs resembling conventional 120 kVp images, and the second round included a supplementary iodine density map. Readers were asked to register presence of ABI as well as their confidence in their diagnosis based on a 5-point Likert scale. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each observer with the surgical findings as the gold-standard. McNemar's and Wilcoxon signed-rank test were used to compare registrations and diagnostic confidence across assessment rounds.

RESULTS

A total of 29 patients resulting in 31 DECT scans were included. Fourteen cases of ischemic/necrotic bowel were reported following surgery. Sensitivity and NPV were decreased with the use of supplementary iodine map images compared to 120 kVp-like images without supplementary iodine map images for three of four observers (round 1 range: 71.4-92.9% and 78.0-94.8%; round 2 range: 57.1-78.6% and 70.1-83.3%, respectively), while specificity and PPV were increased for three of four observers (round 1 range: 64.7-94.1% and 67.4-93.1%; round 2 range: 88.2-94.1% and 73.8-91.1%, respectively). However, no significant difference in ABI diagnosis or diagnostic confidence was found (p-value range: 0.07-1.00 and 0.23-0.58, respectively).

CONCLUSION

No significant difference for the diagnosis of ABI was found using supplementary iodine mapping. Our study may suggest a trend of increased specificity and decreased sensitivity, hence, the use of supplementary iodine mapping should be carefully considered.

The value of MSCT in evaluating the passability of bezoar by conservative treatment for bezoars-induced small bowel obstruction

PURPOSE

To explore the multi-slice spiral computed tomography (MSCT) imaging characteristics of patients with bezoars-induced small bowel obstruction (BI-SBO) to evaluate the risk of conservative treatment.

MATERIALS AND METHODS

This retrospective study included 72 patients with BI-SBO who underwent whole-abdominal MSCT scan within 1 day before treatment. The patients were classified as the non-pass group and pass group depending on whether bezoar can pass after conservative treatment. The CT images were observed and measured by two radiologists. Statistical analysis was performed by using Student's t test, Pearson's chi-squared test, Fisher's exact test, Logistic linear regression, and receiver operating characteristic curve (ROC).

RESULTS

The study population consisted of 72 patients with a mean age of 52.2 ± 16.2 years (32 men and 40 women with an age range of 13-81 years). There were statistical differences between the two groups in the bezoar appearance, maximum HU of bezoar, thickness of intestinal wall, mesenteric haziness, mesenteric fluid, and peritoneal fluid (P = 0.002, 0.024, 0.017, 0.006, 0.021, and 0.030). The appearance of bezoar and mesenteric haziness is independent risk factors affecting whether bezoar can be passed by the conservative treatment. Sensitivity (41.7%) was decreased, NPV (76.3%) was not significantly changed, specificity (93.8%) and PPV (76.9%) were improved when both parameters were met to assess failure of conservative treatment.

CONCLUSION

The observation of important signs by MSCT and its reconstruction technology is of great clinical value in evaluating the passability of bezoar by conservative treatment, and which can provide radiographic basis for clinical treatment selection.

Understanding CT imaging findings based on the underlying pathophysiology in patients with small bowel ischemia

Because acute small bowel ischemia has a high mortality rate, it requires rapid intervention to avoid unfavorable outcomes. Computed tomography (CT) examination is important for the diagnosis of bowel ischemia. Acute small bowel ischemia can be the result of small bowel obstruction or mesenteric ischemia, including mesenteric arterial occlusion, mesenteric venous thrombosis, and non-occlusive mesenteric ischemia. The clinical significance of each CT finding is unique and depends on the underlying pathophysiology. This review describes the definition and mechanism(s) of bowel ischemia, reviews CT findings suggesting bowel ischemia, details factors involved in the development of small bowel ischemia, and presents CT findings with respect to the different factors based on the underlying pathophysiology. Such knowledge is needed for accurate treatment decisions.

Obstrucción intestinal por adherencias: un lienzo en blanco en el que el cirujano elige los colores

Introducción. La obstrucción intestinal es una patología de alta prevalencia. Su abordaje diagnóstico y terapéutico ha evolucionado acorde con el avance del conocimiento e implementación de la tecnología. El impacto de sus complicaciones obliga a redoblar esfuerzos en pro de lograr una mayor efectividad. Se hizo una aproximación reflexiva al problema, mediante una identificación de los puntos controversiales de interés para el cirujano general. Métodos. Se realizó una búsqueda sistemática de la literatura en varias bases de datos, utilizando dos ecuaciones de búsqueda que emplearon términos seleccionados a partir de los tesauros “Medical Subject Heading” (MeSH) y “Descriptores en Ciencias de la Salud” (DeCS). Resultados. Se recolectaron 43 artículos y a partir de ellos se construyó el texto de revisión. La identificación pronta de los posibles candidatos a cirugía, mediante un esquema diagnóstico y terapéutico, se constituye en una prioridad en el manejo de estos pacientes. De igual manera, se efectúan consideraciones en la toma de decisiones con respecto a la vía quirúrgica, así como recomendaciones técnicas operatorias producto de la experiencia y lo reportado en la literatura. Existen factores propios del cirujano, del contexto y del paciente, que inciden en la resolución del problema. Conclusión. La obstrucción intestinal y sus implicaciones clínicas obligan a una reevaluación constante de su estado del arte y avances en el manejo, tendiente a una búsqueda de oportunidades para impactar favorablemente en su curso clínico. Hay estrategias por implementar, inclusive el manejo laparoscópico en casos seleccionados.

Neutrophil-lymphocyte ratio and platelet-lymphocyte ratio use in detecting bowel ischaemia in adhesional small bowel obstruction

BACKGROUND

Bowel ischaemia significantly increases morbidity and mortality from adhesional small bowel obstruction. Current biomarkers and clinical parameters have poor predictive value for ischaemia. Our study investigated whether neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) could be used to predict bowel ischaemia in adhesional small bowel obstruction.

METHODS

This single-centre retrospective study collected clinical, biochemical and radiological data from patients with adhesional small bowel obstruction between 2017 and 2020 who underwent operative management. The presence or absence of bowel ischaemia/infarction was used to distinguish two populations. Biochemical markers on admission and immediately prior to operation were collected to give platelet-lymphocyte ratio (PLR₀ and PLR_PRE-OP , respectively) and neutrophil-lymphocyte ratio (NLR₀ and NLR_PRE-OP , respectively). SAS 9.4 (SAS Institute Inc., Cary, NC) software was used for data analysis with Mann-Whitney U testing for continuous variables and Pearson Chi-square test for categorical variables. Sensitivity and specificity for PLR and NLR were calculated by means of receiver operating characteristic (ROC) curve analysis.

RESULTS

Twenty-seven patients had intra-operative bowel ischaemia whilst the remaining 73 had no evidence of bowel ischaemia. Both median PLR_PRE-OP and NLR_PRE-OP were significantly higher in patients with bowel ischaemia compared to those without (PLR_PRE-OP 272 [IQR 224-433] and 231 [IQR 146-295] respectively, P = 0.027; NLR_PRE-OP 12.5 [IQR 8.6-21.3] v. 5.5 [IQR 3.5-10.2] respectively, P ≤ 0.001). Area under the receiver operator characteristic curve (AUC) was 0.762 for NLR_PRE-OP , with a sensitivity of 85.1% and specificity of 63% for NLR 7.4.

CONCLUSION

Raised NLR is predictive of bowel ischaemia in patients with adhesional small bowel obstruction.

Imaging Signs for Determining Surgery Timing of Acute Intestinal Obstruction

We aimed to analyze the computed tomography (CT) imaging signs of bowel wall ischemia in patients with acute intestinal obstruction and construct an imaging prediction model to guide clinical treatment. The CT imaging signs of patients with acute intestinal obstruction diagnosed in our center in recent 6 years were collected for retrospective analysis. The etiology of intestinal obstruction and incidence rate of bowel wall ischemia were recorded, and the specific CT findings of bowel wall ischemia, including mesenteric edema, bowel wall thickening, and fish tooth sign, were analyzed. Among the 302 patients selected, 130 surgically treated patients were eligible for analysis. Bowel wall ischemia in acute intestinal obstruction showed an incidence rate of 14.90%, and the incidence rates of bowel wall ischemia in intra-abdominal hernia, intussusception, incarcerated external abdominal hernia, and volvulus were about 92.30%, 50%, 35.71%, 33.33%, and 12.59%, respectively. The incidence rate of bowel wall ischemia in simple adhesive intestinal obstruction was about 12.59%, and that in malignancy-induced intestinal obstruction was about 6.56%. Univariate analysis revealed 5 factors with statistical significance, including bowel wall thickening, mesenteric edema, bowel wall pneumatosis, ascites, and fish tooth sign. Multivariate logistic regression analysis indicated that fish tooth sign, bowel wall thickening, and mesenteric edema were able to predict bowel wall ischemia, and the corresponding partial regression coefficients were 2.164, 1.129, and 1.173, odds ratios (ORs) were 8.707, 3.093, and 3.232, sensitivity was 0.356, 0.400, and 0.844, and specificity was 0.859, 0.835, and 0.529, respectively. Imaging signs of bowel wall thickening, mesenteric edema, and fish tooth sign are valuable in predicting bowel wall ischemia, among which bowel wall thickening and mesenteric edema have relatively high specificity and fish tooth sign has a relatively high sensitivity. Furthermore, a fish tooth sign has the most favorable predictive value for bowel wall ischemia in acute intestinal obstruction, followed by bowel wall thickening and mesenteric edema.

Prediction and management of strangulated bowel obstruction: a multi-dimensional model analysis

BACKGROUND

Distinguishing strangulated bowel obstruction (StBO) from simple bowel obstruction (SiBO) still poses a challenge for emergency surgeons. We aimed to construct a predictive model that could distinctly discriminate StBO from SiBO based on the degree of bowel ischemia.

METHODS

The patients diagnosed with intestinal obstruction were enrolled and divided into SiBO group and StBO group. Binary logistic regression was applied to identify independent risk factors, and then predictive models based on radiological and multi-dimensional models were constructed. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) were calculated to assess the accuracy of the predicted models. Via stratification analysis, we validated the multi-dimensional model in the prediction of transmural necrosis both in the training set and validation set.

RESULTS

Of the 281 patients with SBO, 45 (16.0%) were found to have StBO, while 236(84.0%) with SiBO. The AUC of the radiological model was 0.706 (95%CI, 0.617-0.795). In the multivariate analysis, seven risk factors including pain duration ≤ 3 days (OR = 3.775), rebound tenderness (OR = 5.201), low-to-absent bowel sounds (OR = 5.006), low levels of potassium (OR = 3.696) and sodium (OR = 3.753), high levels of BUN (OR = 4.349), high radiological score (OR = 11.264) were identified. The AUC of the multi-dimensional model was 0.857(95%CI, 0.793-0.920). In the stratification analysis, the proportion of patients with transmural necrosis was significantly greater in the high-risk group (24%) than in the medium-risk group (3%). No transmural necrosis was found in the low-risk group. The AUC of the validation set was 0.910 (95%CI, 0.843-0.976). None of patients in the low-risk and medium-risk score group suffered with StBO. However, all patients with bowel ischemia (12%) and necrosis (24%) were resorted into high-risk score group.

CONCLUSION

The novel multi-dimensional model offers a useful tool for predicting StBO. Clinical management could be performed according to the multivariate score.

Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process

The objective of this article is to assess the computed tomography (CT) findings of small bowel obstruction (SBO) complicated by ischemia. SBO is a frequent clinical entity characterized by high morbidity and mortality. The radiologic aim is not just to diagnose the obstruction itself but to rule out the presence of complications related to SBO. This is crucial for differentiating which patients can be safely treated non-operatively from the ones who may need an urgent surgical approach. The main complication of SBO is intestinal ischemia. In the emergency setting, CT imaging is the modality of choice for SBO because of its ability to assess the bowel wall, the supporting mesentery and peritoneal cavity all in one. On the other hand, the radiologist who documents an intestinal ischemia should think about SBO as possible cause. In this case, the main finding which helps the radiologist in the identification of SBO is the presence of multiple and packed valvulae conniventes in the dilated bowel wall and the "transition zone" that indicates the passage between compressed and decompressed small bowel, otherwise the localization of the obstruction cause. Once the site of obstruction has been recognized, the other issue is to assess the cause of obstruction, considering that the most common cause of SBO remains "unidentified" and related to intra-abdominal adhesions. After that, the following most important point is to rule out the presence of an ischemic bowel and mesenteric changes associated to SBO. CT signs of bowel ischemia include reduced or increased bowel wall enhancement, mesenteric edema or engorgement, fluid or free air in the peritoneal cavity. This condition usually leads to an urgent laparotomy and, in some cases, to a surgical resection.

Pneumatosis intestinalis and portal venous gas in mechanical small bowel obstruction: Is it worrisome?

PURPOSE

The purpose of this study was to evaluate the clinical significance of pneumatosis intestinalis (PI) and portal venous gas (PVG) in patients with mechanical small bowel obstruction (SBO), using surgical findings or clinical follow-up as standard of reference.

MATERIALS AND METHODS

Fourteen patients with mechanical SBO associated with PI and PVG were retrospectively included. There were 7 men and 7 women with a mean age of 59±19 (SD) (range: 25-93 years). CT examinations were reviewed by two radiologists to confirm the diagnosis of mechanical SBO and make a description of PI. Interobserver agreement was calculated. The reference standard was intraoperative appearance of the bowel wall (10/14; 71%) or the recovery of a normal bowel function in patients who were managed conservatively (4/14; 29%).

RESULTS

Among the 10 patients who underwent surgery, a normal appearance of the bowel in association with PI on CT was found intraoperatively in 8/10 (80%) patients and a reversible ischemia in the remaining 2/10 (20%) patients. The four patients who were managed conservatively recovered normal bowel function. Two patients died within two weeks following SBO.

CONCLUSION

PI and PVG are not specific signs of bowel necrosis in mechanical SBO.

When is the right time to take an emergency surgery decision in Mechanical Intestinal Obstruction?

BACKGROUND

/Objective: Ischemia is a leading cause of morbidity in Mechanical Intestinal Obstruction (MIO) in which the timing of decisions of whether to proceed to surgical or conservative treatment is critical in emergency departments (ED). While advanced technological options are available, patients may be negatively affected by the application of contrast agents or radiation. The use of ultrasound is limited because of the air in the intestines does not allow a good field of vision. While biomarkers can be considered as a good alternative option at this point. In the present study we examine the effect of hemogram and blood gas parameters on early surgical decision-making in MIO patients.

METHOD

Involved in this observational prospective study were 264 patients diagnosed with MIO who presented to the Department of Emergency Medicine, Ataturk Research and Training Hospital, Katip Celebi University between February 2018 and February 2019. Contrast-enhanced tomography (CECT) and laboratory results of the patients were recorded. Pathology reports of the patients who underwent surgery were collected. Laboratory data were analyzed by comparing CECT and pathology reports.

RESULTS

In a ROC analysis of the laboratory values of the patients who were diagnosed with ileus, the sensitivity was calculated as 80% and the specificity was 57.7 in values above WBC>10.75 (10⁹/L), 96.6%, and the specificity was 31.1% in N/L > 2.9. For intestinal ischemia, the cut-off values were WBC> 12.6 and N/L > 3.2, Lactate >2.8 mmol/L and B.E < -3.6 mmol/L.

CONCLUSION

Diagnoses of ileus are based on the results examinations and imaging methods. More data are needed to support decisions on the timing of surgery in ED. WBC, N/L, Lactate and Base Excess indicate an ischemic segment. When the parameters are evaluated together, they strongly support early surgical decision-making regarding the treatment of intestinal ischemia.

Vascular assessment in small bowel obstruction: can CT predict requirement for surgical intervention?

PURPOSE

Small bowel obstruction (SBO) is a common cause of emergency presentations for abdominal pain and can be complicated by mesenteric ischemia. Computed tomography is currently central to diagnosis and management planning. Currently accepted signs identify secondary effects of the root physiological insult, which is vascular obstruction. We hypothesized that with advancements in CT technology and reconstruction algorithms, we can now more closely interrogate the mesenteric vasculature for obstruction and more accurately predict the need for surgical intervention.

METHODS

We retrospectively audited the charts of all patients presenting with a clinical diagnosis of SBO at a single institution in a 12-month period. Two blinded consultant radiologists were then asked to analyze 3D MIP reconstruction CT scans for vascular obstruction in addition to any currently accepted signs of ischemia. Comparison between vascular cutoff and accepted current signs in the need for surgical intervention and the presence of any signs of ischemia in theater were recorded.

RESULTS

Vascular cutoff had a comparable, with a trend towards superiority, sensitivity and specificity and inter-observer agreement to currently accepted signs of ischemia. The absence of a cut off sign has an excellent negative predictive value for ischemia with only 2 (3.7%) patients demonstrating ischemia at surgery where the vascular cutoff sign was not seen to be present.

CONCLUSION

Interrogating vascular obstruction using 3D MIP reconstructions in small bowel obstruction may be a more sensitive and specific sign for prediction of surgical intervention, possibly occurring earlier in the obstruction pathway.

Multi-slice spiral CT evaluation of chronic radiation colitis and rectitis

The aim of the present study was to retrospectively analyse the multi-slice spiral CT (MSCT) findings of radiation colitis and rectitis (RC&R). A total of 23 cases of RC&R detected by helical CT were included. The CT findings and clinical and endoscopy data of the patients were reviewed. The primary tumours included cancers of the cervix (n=17), rectum (n=4), ovaries (n=1) and bladder (n=1). The total dose of radiation per patient was 46-60 Gy (mean, 49.7 Gy) delivered over 5 weeks. The CT manifestations included different degrees of increased thickness of the intestinal wall (n=20, 87.0%), with a maximum thickness of 16.6 mm. On enhanced CT, the target sign was observed (n=16, 69.9%), with an obviously enhanced mucosa and/or serosa and the following changes observed: Oedema and increased density of the mesentery (n=15, 65.2%); increased density of the subcutaneous fat, and blurred and oedematous pelvic wall muscles (n=4, 17.4%), with the obturator internus and levator ani muscles being most commonly affected; narrowed intestinal lumen (n=3, 13.0%); and a small amount of ascitic fluid (n=2, 8.7%) located in the paracolic sulci and bladder or Douglas pouch. The 23 patients underwent colonoscopy and were diagnosed with RC&R. The major manifestations included telangiectasia and mucosal hyperaemia (n=21, 91.3%). MSCT of chronic RC&R (CRC&R) was associated with certain characteristic findings, which, combined with a medical history of radiotherapy and the clinical manifestations, may prove to be of value in the diagnosis of CRC&R.