Early postoperative recurrence after Crohn’s disease surgery can complicate recovery and increase the need for further monitoring. A retrospective analysis published in Insights into Imaging assessed whether hyperechoic mesenteric fat on preoperative intestinal ultrasound could help identify patients at higher risk during the first year after intestinal resection. The work focused on patients who had Crohn’s disease, underwent intestinal resection with anastomosis and received ultrasound assessment within three months before surgery. Follow-up relied on endoscopy or imaging after surgery. Among the ultrasound features assessed, hyperechoic mesenteric fat showed the strongest association with early postoperative recurrence and performed better than bowel wall thickness or abscess and fistula findings.
Preoperative Ultrasound Assessment
The cohort included 124 patients with Crohn’s disease who underwent intestinal resection between March 2015 and March 2021. Patients did not enter the final group when they had enterostomy, insufficient clinical data or ultrasound images that did not allow adequate assessment of the mesentery. Follow-up took place after surgery, with recurrence status assessed at one year.
Early postoperative recurrence meant disease returning at the surgical connection or close to it within the first year. Endoscopy had priority when both endoscopic and imaging findings were available. Imaging features of active Crohn’s disease also supported recurrence assessment when endoscopy was not the diagnostic route.
Almost half of the patients developed early postoperative recurrence. Several clinical characteristics differed between the recurrence and non-recurrence groups. These included smoking history, raised inflammatory markers before surgery and postoperative immunosuppressive therapy. Other baseline factors, such as age, body mass index, disease behaviour, previous intestinal resection and some medication categories, did not differ significantly between the two groups.
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Experienced radiologists performed intestinal ultrasound using the same equipment. The examination assessed affected bowel segments and surrounding mesenteric features before surgery.
Mesenteric Fat as an Imaging Marker
Hyperechoic mesenteric fat refers to homogeneous bright changes around the bowel wall on ultrasound. This appearance differs from the mixed, striated pattern seen in normal mesentery. In Crohn’s disease, the sign is considered to reflect inflammatory mesenteric fat, a recognised feature associated with hypertrophy and chronic inflammation.
The ultrasound review also assessed bowel wall thickness, bowel wall stratification, colour Doppler signal, enlarged mesenteric lymph nodes, abscesses and fistulas. Radiologists reviewed the images without access to clinical data or postoperative outcomes. Agreement between observers was good to excellent for most ultrasound features, including hyperechoic mesenteric fat.
Preoperative hyperechoic mesenteric fat was much more common among patients who developed early postoperative recurrence than among those who did not. Bowel wall thickness and abscess or fistula findings also differed between the groups, but the separation was weaker. Other assessed ultrasound parameters did not show significant differences.
Among the ultrasound variables tested, hyperechoic mesenteric fat had the best ability to distinguish patients who later developed early recurrence. Its predictive performance exceeded that of bowel wall thickness and abscess or fistula. The difference was notable because bowel wall changes and penetrating complications are already familiar ultrasound features in Crohn’s disease assessment.
Stronger Signal After Adjustment
Statistical testing first identified several candidate predictors of early postoperative recurrence. These included raised inflammatory markers before surgery, colonic disease location, postoperative immunosuppressive therapy, bowel wall thickness, abscess or fistula and hyperechoic mesenteric fat. After adjustment in a multivariable model, hyperechoic mesenteric fat remained the only independent predictor.
The strength of the association was substantial. Patients with hyperechoic mesenteric fat had a markedly higher likelihood of early recurrence than those without the sign. Bowel wall thickness and abscess or fistula no longer remained independently associated with recurrence after the broader set of variables entered the model.
The result reinforces the clinical relevance of mesenteric fat in Crohn’s disease. Inflammatory mesenteric fat is linked to immune and endocrine activity, transmural inflammation and complex disease behaviour. It may also affect mucosal drug delivery. Conventional ileocolic resection preserves mesentery along the mesenteric border, and residual inflamed fat and vessels may contribute to ongoing inflammation after surgery.
Several limitations affect interpretation. The cohort came from a single centre, and the sample size was limited. Surgical techniques, surgeon experience and treatment approaches varied across the inclusion period. Follow-up intervals were not standardised, so the first positive assessment may not precisely indicate when recurrence began.
Preoperative intestinal ultrasound detection of hyperechoic mesenteric fat offers a practical, non-invasive way to support recurrence risk assessment in Crohn’s disease surgery. The marker performed better than other ultrasound parameters assessed and remained independently associated with early postoperative recurrence after adjustment. Its use may help radiologists and clinical teams identify patients who require closer follow-up during the first postoperative year, while the limitations underline the need for validation in larger prospective cohorts.
Source: Insights into Imaging
Image Credit: iStock
