Centrifugation of peritoneal fluid improves visual assessment of strangulating lesions in equine colic.

Overview

• This study investigates how centrifugation of peritoneal fluid from horses with colic can improve the visual identification of strangulating intestinal lesions.
• It evaluates whether a standardized color grading scale, applied before and after centrifugation, can better predict the presence of these serious surgical conditions.

Background and Objective

• Strangulating intestinal lesions in horses cause restricted blood flow leading to ischemia, requiring urgent surgical intervention to prevent fatal outcomes.
• Peritoneal fluid analysis is a diagnostic tool in colic cases; however, accurate visual assessment of the fluid’s color can be difficult.
• The study aims to develop and test a simple color grading scale for peritoneal fluid that can predict strangulating lesions more accurately, especially after the fluid has been centrifuged to enhance clarity.

Methods

• Clinical samples of peritoneal fluid were collected from 231 horses and ponies presenting with colic.
• Immediately after collection, fluid was visually assessed and assigned a numerical color score from 1 to 10 using the color scale developed by the researchers.
• Visual assessment included assigning broad color grades (yellow, orange, red) and noting fluid transparency.
• The fluid samples were then centrifuged at 4440g for 3 minutes, and the visual assessments were repeated to see if clarity improved detection accuracy.
• Data on the location and type of intestinal lesion, surgical intervention needs, and patient outcomes were collected to correlate with fluid assessment results.
• Statistical analyses including logistic regression and receiver operating characteristic (ROC) curves were conducted to evaluate the predictive value of the visual assessments for identifying strangulating lesions.

Results

• Of the 231 equids, 58 (25.1%) had confirmed strangulating lesions.
• Before centrifugation:
  • The area under the ROC curve (AUC) values were:
    • 0.85 for the 1–10 color scale
    • 0.82 for the broad color grades (yellow, orange, red)
    • 0.74 for transparency
• After centrifugation:
  • The AUC values improved slightly to:
    • 0.87 for the detailed color scale
    • 0.84 for color grades
    • 0.55 for transparency, which decreased significantly
  • This indicates better discrimination between strangulating and non-strangulating lesions based on color but worse performance based on transparency after centrifugation.

Conclusions

• Visual scoring of peritoneal fluid color using a standardized scale is a useful tool to identify strangulating intestinal lesions in horses with colic.
• Centrifugation improves the clarity of samples and slightly enhances the diagnostic accuracy of color assessment, making it easier to distinguish pathological changes likely related to ischemia.
• The decrease in the usefulness of transparency after centrifugation suggests that color grading is a more reliable parameter than fluid transparency for assessing injury severity.
• Despite the usefulness, variability in color perception among different observers and lack of blinding to case details may have influenced results, indicating the need for standardized training or objective color measurement methods.
• The limited number of strangulating cases suggests further larger studies are needed to validate these findings fully.
• Overall, visual examination of centrifuged peritoneal fluid is a practical, quick, and informative bedside test to help prioritize cases needing urgent surgical intervention.