BACKGROUND The natural history of rectal intussusception (RI) is poorly understood. We hypothesized that decline in pelvic floor integrity and function leads to increasing RI grades. METHODS Retrospective analysis of a registry of patients with defecatory disorders with high-resolution anorectal manometry and MR defecography. Association of risk factors on increasing RI grades was assessed using logistic regression. RESULTS Analysis included a total of 238 women; 90 had no RI, 43 Oxford 1-2, 49 Oxford 3, and 56 Oxford 4-5. Age (p:0.017), vaginal delivery (p: 0.008), and prior pelvic surgery (p: 0.032) were associated with increased Oxford grades. Obstructive defecation symptoms and dyssynergic defecation were observed at relatively high rates across groups. Increased RI grades was associated with less anal relaxation at simulated defecation yet, higher rates of normal balloon expulsion (p<0.05), linked to diminished anal sphincter. Indeed, increased RI grades was associated with worsening fecal incontinence severity, attributed to higher rates of anal hypotension.Levator ani laxity, defined by increased levator hiatus length and its excessive descent at straining, was associated with increasing RI grades, independent of age, history of vaginal delivery, and pelvic surgeries and could independently predict increased RI grades. Concurrent anterior and posterior compartments, and visceral prolapse were associated with higher Oxford grades. CONCLUSION Our data suggests that decline in pelvic floor integrity with abnormal levator ani laxity is associated with increased RI grades; a process that is independent of age, history of vaginal deliveries and/or pelvic surgeries, and perhaps related to dyssynergic defecation.

中文翻译：

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直肠套叠的程度增加：盆底完整性下降的作用以及与排便失调的关联。

背景人们对直肠套叠（RI）的自然病程知之甚少。我们假设盆底完整性和功能下降会导致 RI 等级升高。方法 通过高分辨率肛门直肠测压和磁共振排粪造影对排便障碍患者的登记进行回顾性分析。使用逻辑回归评估风险因素与 RI 等级增加的关联。结果 分析总共包括 238 名女性；90 没有 RI，43 牛津 1-2，49 牛津 3，56 牛津 4-5。年龄（p：0.017）、阴道分娩（p：0.008）和既往骨盆手术（p：0.032）与牛津成绩的提高相关。各组中观察到的阻塞性排便症状和排便失调症状的发生率相对较高。RI 等级增加与模拟排便时肛门松弛程度降低相关，但正常球囊排出率较高 (p<0.05)，与肛门括约肌减弱相关。事实上，RI 等级的增加与大便失禁严重程度的恶化相关，这是由于肛门低血压的发生率较高。提肛肌松弛（定义为提肌裂孔长度增加及其在用力时过度下降）与 RI 等级的增加相关，与年龄、病史无关阴道分娩和盆腔手术的结果，并且可以独立预测 RI 等级的增加。并发的前室和后室以及内脏脱垂与较高的牛津等级相关。结论 我们的数据表明，盆底完整性下降伴提肛肌异常松弛与 RI 等级升高相关；这一过程与年龄、阴道分娩史和/或盆腔手术无关，并且可能与排便失调有关。