Rectum

ImportancePerforming a bowel anastomosis is a critical step in colorectal resection. Assessing the risk of anastomotic leakage remains challenging, even for experienced surgeons.ObjectiveTo evaluate the use of indocyanine green (ICG) fluorescence imaging in assessing perfusion at the anastomotic site before and after anastomosis and determine whether it helps reduce anastomotic leakages.Design, setting, and participantsICG-COLORAL is a prospective, randomized, multicenter study conducted from September 1, 2018, to December 31, 2023. Participants were recruited during preoperative outpatient clinic visits by clinicians not involved in the study, as well as by researchers. Participants were elective patients scheduled for laparoscopic resections, excluding low anterior resections, with planned primary anastomosis in 5 Finnish public hospitals experienced in laparoscopic colorectal surgery.InterventionThe intervention group received 5 mg of ICG intravenously before and after anastomosis formation. The fluorescence signal was assessed with a near-infrared-capable camera. The control group did not receive ICG fluorescence imaging.Main outcome and measureThe primary outcome measure was the anastomotic leak rate as detected by computed tomography.ResultsAmong 1136 patients in the intention-to-treat population, 526 (46.3%) were female and 610 (53.7%) male; they had a mean (SD) age of 70 (11) years, body mass index of 28 (5), and age-adjusted Charlson Comorbidity Index of 5 (3). Overall, the anastomotic leak rate was 5.8% (33/567) in the ICG fluorescence imaging group vs 7.9% (45/569) in the control group (odds ratio [OR], 0.73; 95% CI, 0.48-1.13; P = .16). For right-sided operations, the anastomotic leak rate with ICG fluorescence imaging was 5.9% (16/273) vs 6.7% (20/298) in the control group (OR, 0.87; 95% CI, 0.46-1.65). For left-sided operations, the anastomotic leak rate was 5.2% (14/267) with ICG fluorescence imaging vs 9.5% (23/243) without (OR, 0.55; 95% CI, 0.29-1.05). No patients reported adverse events related to ICG.Conclusions and relevanceThis study found that routine use of ICG fluorescence imaging does not significantly reduce the overall anastomotic leak rate in laparoscopic colorectal surgery if low anterior resections are excluded but may be beneficial in left-sided operations.Trial registrationClinicalTrials.gov Identifier: NCT03602677.

The gut microbiota plays an important role in human health and disease. Stool, rectal swab and rectal mucosal tissue samples have been used in individual studies to survey the microbial community but the consequences of using these different sample types are not completely understood. In this study, we report differences in stool, rectal swab and rectal mucosal tissue microbial communities with shotgun metagenome sequencing of 1397 stool, swab and mucosal tissue samples from 240 participants. The taxonomic composition of stool and swab samples was distinct, but less different to each other than mucosal tissue samples. Functional profile differences between stool and swab samples are smaller, but mucosal tissue samples remained distinct from the other two types. When the taxonomic and functional profiles were used for inference in association with host phenotypes of age, sex, body mass index (BMI), antibiotics or non-steroidal anti-inflammatory drugs (NSAIDs) use, hypothesis testing using either stool or rectal swab gave broadly significantly correlated results, but inference performed on mucosal tissue samples gave results that were generally less consistent with either stool or swab. Our study represents an important resource for determination of how inference can change for taxa and pathways depending on the choice of where to sample within the human gut.

PurposeChanges in fraction size of external beam radiation therapy exert nonlinear effects on subsequent toxicity. Commonly described by the linear-quadratic model, fraction size sensitivity of normal tissues is expressed by the α/β ratio. We sought to study individual α/β ratios for different late rectal effects after prostate external beam radiation therapy.Methods and materialsThe CHHiP trial (ISRCTN97182923) randomized men with nonmetastatic prostate cancer 1:1:1 to 74 Gy/37 fractions (Fr), 60 Gy/20 Fr, or 57 Gy/19 Fr. Patients in the study had full dosimetric data and zero baseline toxicity. Toxicity scales were amalgamated to 6 bowel endpoints: bleeding, diarrhea, pain, proctitis, sphincter control, and stricture. Lyman-Kutcher-Burman models with or without equivalent dose in 2 Gy/Fr correction were log-likelihood fitted by endpoint, estimating α/β ratios. The α/β ratio estimate sensitivity was assessed using sequential inclusion of dose modifying factors (DMFs): age, diabetes, hypertension, inflammatory bowel or diverticular disease (IBD/diverticular), and hemorrhoids. 95% confidence intervals (CIs) were bootstrapped. Likelihood ratio testing of 632 estimator log-likelihoods compared the models.ResultsLate rectal α/β ratio estimates (without DMF) ranged from bleeding (G1 + α/β = 1.6 Gy; 95% CI, 0.9-2.5 Gy) to sphincter control (G1 + α/β = 3.1 Gy; 95% CI, 1.4-9.1 Gy). Bowel pain modelled poorly (α/β, 3.6 Gy; 95% CI, 0.0-840 Gy). Inclusion of IBD/diverticular disease as a DMF significantly improved fits for stool frequency G2+ (P = .00041) and proctitis G1+ (P = .00046). However, the α/β ratios were similar in these no-DMF versus DMF models for both stool frequency G2+ (α/β 2.7 Gy vs 2.5 Gy) and proctitis G1+ (α/β 2.7 Gy vs 2.6 Gy). Frequency-weighted averaging of endpoint α/β ratios produced: G1 + α/β ratio = 2.4 Gy; G2 + α/β ratio = 2.3 Gy.ConclusionsWe estimated α/β ratios for several common late adverse effects of rectal radiation therapy. When comparing dose-fractionation schedules, we suggest using late a rectal α/β ratio ≤ 3 Gy.

Lay summaryEndometriosis is a chronic condition where tissue resembling the uterine lining grows elsewhere in the pelvis, often causing pain, infertility, and inflammation. For decades, textbooks and research papers have described the rectovaginal septum (RVS), the thin layer between the vagina and rectum, as a common site of deep endometriosis. Yet this belief has never been conclusively proven. In our study of 161 patients, combining advanced ultrasound, meticulous keyhole surgery, and tissue analysis, we found no evidence of endometriosis within the RVS. Instead, all lesions were located in surrounding structures, including the uterosacral ligaments, the rectouterine pouch, or the bowel. These findings challenge a long-standing anatomical misconception and call for the retirement of outdated terminology. Clarifying where endometriosis truly occurs is critical for improving diagnosis, surgery, and communication in women's health. Our study overturns decades of dogma by showing that 'rectovaginal septum endometriosis' may be a myth.