Defecation mechanisms after anterior resection with J-pouch-anal and side-to-end anastomosis in dogs

Exploring the pathophysiology of LARS after low anterior resection for rectal cancer with high-resolution colon manometry

BACKGROUND

A total mesorectal excision for rectal cancer-although nerve- and sphincter-sparing-can give rise to significant bowel symptoms, commonly referred to as low anterior resection syndrome (LARS). The exact pathophysiology of this syndrome still remains largely unknown, and the impact of radical surgery on colonic motility has only been scarcely investigated.

METHODS

High-resolution colon manometry was performed in patients, 12-24 months after restoration of transit. Patients were divided into two groups: patients with major LARS and no/minor LARS, according to the LARS-score. Colonic motor patterns were compared, and the relationship of these patterns with the LARS-scores was investigated.

KEY RESULTS

Data were analyzed in 18 patients (9 no/minor LARS, 9 major LARS). Cyclic short antegrade motor patterns did occur more in patients with major LARS (total: p = 0.022; post-bisacodyl: p = 0.004) and were strongly correlated to LARS-scores after administering bisacodyl (p < 0.001). High amplitude propagating contractions (HAPC's) that started in the proximal colon and ended in the mid-section of the colon occurred significantly less in patients with major LARS compared with patients with no/minor LARS (p = 0.015).

CONCLUSIONS AND INFERENCES

The occurrence of more cyclic short antegrade motor patterns and less HAPC's (from the proximal to the mid-colon) is more prevalent in patients with major LARS. These findings help to understand the differences in pathophysiology in patients developing major versus no/minor bowel complaints after TME for rectal cancer.

Functional results after treatment for rectal cancer

Introduction With improving survival of rectal cancer, functional outcome has become increasingly important. Following sphincter-preserving resection many patients suffer from severe bowel dysfunction with an impact on quality of life (QoL) – referred to as low anterior resection syndrome (LARS).

Study objective To provide an overview of the current knowledge of LARS regarding symptomatology, occurrence, risk factors, pathophysiology, evaluation instruments and treatment options.

Results LARS is characterized by urgency, frequent bowel movements, emptying difficulties and incontinence, and occurs in up to 50-75% of patients on a long-term basis. Known risk factors are low anastomosis, use of radiotherapy, direct nerve injury and straight anastomosis. The pathophysiology seems to be multifactorial, with elements of anatomical, sensory and motility dysfunction. Use of validated instruments for evaluation of LARS is essential. Currently, there is a lack of evidence for treatment of LARS. Yet, transanal irrigation and sacral nerve stimulation are promising.

Conclusion LARS is a common problem following sphincter-preserving resection. All patients should be informed about the risk of LARS before surgery, and routinely be screened for LARS postoperatively. Patients with severe LARS should be offered treatment in order to improve QoL. Future focus should be on the possibilities of non-resectional treatment in order to prevent LARS.

Anterior resection syndrome

Up to 80% of patients with rectal cancer undergo sphincter-preserving surgery. It is widely accepted that up to 90% of such patients will subsequently have a change in bowel habit, ranging from increased bowel frequency to faecal incontinence or evacuatory dysfunction. This wide spectrum of symptoms after resection and reconstruction of the rectum has been termed anterior resection syndrome. Currently, no precise definition or causal mechanisms have been established. This disordered bowel function has a substantial negative effect on quality of life. Previous reviews have mainly focused on different colonic reconstructive configurations and their comparative effects on daily function and quality of life. The present Review explores the potential mechanisms underlying disturbed functions, as well as current, novel, and future treatment options.

Low anterior resection: alternative anastomotic techniques

Low anterior resection (LAR), with its numerous technical modifications, is one of the most commonly performed operations for rectal cancer. In the past, patients with locally advanced distal rectal cancer were most frequently treated by abdominoperineal resection and permanent colostomy. However, over the past two decades and with improved understanding of tumor biology and refinement in technique, use of LAR to treat rectal cancer has increased substantially. Yet, despite the significant increase in LAR and sphincter preservation, patients in many areas of the country have little access to these techniques and continue to commonly be treated with abdominoperineal resection. This article examines the surgeon's unique and critical role in the pretreatment evaluation and decisions leading to choice of surgical therapy for locally invasive distal rectal cancer. In particular, the authors focus on technical aspects to preserve the anal sphincter, and review methods to optimize functional outcomes in the setting of low pelvic anastomosis.

Compliance and capacity of the normal human rectum--physical considerations and measurement pitfalls

The assessment of parameters which adequately represent rectal and neorectal compliance is complex. Biological properties of the rectum during distension and relaxation show significant departures from in vitro physical compliance measurements; as much dependent upon the viscoelastic charateristics of hollow organ deformation as upon the technique of compliance calculation. This review discusses the pressure/volume characteristics of importance in the rectum during distension from a bioengineering perspective and outlines the disparities of such measurements in living biological systems. Techniques and pitfalls of newer methods to assess rectal wall stiffness (impedance planimetry and barostat measurement) are discussed.