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

Low anterior resection syndrome (LARS): cause and effect and reconstructive considerations

Between 25 and 80% of patients undergoing a low or very low anterior resection will suffer postoperatively, from a constellation of symptoms including fecal urgency, frequent bowel movements, bowel fragmentation and incontinence, collectively referred to as the low anterior resection syndrome (LARS). The etiology of LARS is multifactorial with the potential of sphincter injury during anastomosis construction, alterations in anorectal physiology, the development of a pudendal neuropathy, and a lumbar plexopathy with exacerbation of symptoms if there is associated anastomotic sepsis or the use of adjuvant and neoadjuavnt therapies. The symptoms of LARS may be obviated in part by the construction of a neorectal reservoir which may take the form of a colonic J-pouch, a transverse coloplasty, or a side-to-end anastomosis. This review outlines the factors contributing to LARS symptomatology along with the short- and medium-term functional results of comparative trials with the different types of neorectal reconstructions.

Temporary sacral nerve stimulation alters rectal sensory function: a physiological study

BACKGROUND

The indications for sacral nerve stimulation are increasing, but the mechanism remains poorly understood.

OBJECTIVE

This study aimed to examine the effect of sacral nerve stimulation on rectal compliance and rectal sensory function.

DESIGN

This was a prospective study.

SETTINGS

This study took place at a university teaching hospital.

PATIENTS

Twenty-three consecutive consenting patients (22 female; median age, 49 y) undergoing temporary sacral nerve stimulation for fecal incontinence were prospectively studied. Clinical response was assessed by the use of bowel diaries and Wexner scores.

MAIN OUTCOME MEASURES

Anal manometry, rectal compliance, volume and pressure thresholds to rectal distension (barostat), and rectal Doppler mucosal blood flow were measured before and at the end of stimulation.

RESULTS

Sixteen patients (70%) had a favorable clinical response. Median anal squeeze pressures increased with stimulation from 40 (range, 6-156) cmH2O to 64 (range, 16-243) cmH2O. Median rectal compliance did not significantly change with stimulation (prestimulation: 11.5 (range, 7.9-21.8) mL/mmHg, poststimulation: 12.4 (range, 6.2-22) mL/mmHg, P = .941). Rectal wall pressures associated with urge (baseline: 15.4 (range, 11-26.7) mmHg, poststimulation: 19 (range, 11.1-42.7) mmHg, P = .054) and maximal tolerated thresholds (baseline: 21.6 (8.5-31.9) mmHg, poststimulation: 27.1 (14.3-43.3) mmHg, P = .023) significantly increased after stimulation. Rectal Doppler mucosal blood flow did not significantly change with stimulation (baseline: 125.8 (69.9-346.8), poststimulation: 112.4 (50.2-404.1), P = .735). Changes in anal resting pressure and rectal wall pressures with stimulation were evident only in responders; however, changes in anal squeeze pressures were evident in both responders and nonresponders.

LIMITATIONS

The study reports results following short-term stimulation in a small but homogenous group of patients. A larger long-term study will follow.

CONCLUSION

Temporary sacral nerve stimulation does not change rectal compliance, but is associated with significant changes to the pressure thresholds of rectal distension. This, together with the observation that outcome is not related to sphincter integrity, supports the hypothesis of an afferent-mediated mechanism of action.

Functional outcome following restorative rectal cancer surgery

The trend towards preoperative adjuvant and neoadjuvant therapies in selected patients with rectal cancer has led to increases in sphincter preservation with a limited understanding of the factors governing unsatisfactory functional outcomes. Data would suggest the need for a more selective use of standard radiotherapeutic fields in low- to intermediate-risk cases where there appears to be limited survival or locoregional recurrence benefit and where there is under-reported toxicity. This article discusses the complex factors which impact on functional outcome following open rectal cancer surgery particularly when it is accompanied by adjuvant therapy.