Denervation of the neorectum as a potential cause of defecatory disorder following low anterior resection for rectal cancer

Postoperative defecatory function of an ileal pouch-anal anastomosis after a restorative proctocolectomy for ulcerative colitis: evaluation using fecoflowmetry

An ileal pouch is usually reconstructed as an alternative to a neorectum after a total proctocolectomy for ulcerative colitis (UC). However, the real defecatory function of an ileal pouch is uncertain. This study was designed to analyze the functional and clinical outcomes after a proctocolectomy and ileal pouch-anal anastomosis (IPAA) for UC using fecoflowmetry (FFM). Sixteen patients who underwent IPAA for UC between 1990 and 2005 were studied. They were evaluated by FFM, together with Kelly's clinical score (KCS), and anorectal manometric assessments were also performed. FFM showed that the fecoflow pattern (FFP) of 14 patients (87%) was the block type and of 2 patients (13%) was the segmental type. The clinical score and tolerance volume showed no improvement 1 year or more after IPAA. However, the value of the maximum fecal stream flow rate (Fmax) improved with time. FFM shows that the defecatory function improved after IPAA, and it may therefore contribute to a good long-term outcome after the surgery.

Damage to anal sphincter/levator ani muscles caused by operative procedure in anal sphincter-preserving operation for rectal cancer

BACKGROUND

Details of postoperative damage to anal sphincter tonus following sphincter-preserving operation for rectal cancer remain unclear.

METHODS

Postoperative anal tonus was measured using 3-dimensional (3D) vector manometry in 56 patients. Anal length with pressure from any direction was defined as total length (TL). Length with circular pressure (LCP), which is only measurable using 3D manometry, was also evaluated.

RESULTS

In operations associated with low anastomosis, both TL and LCP at rest were significantly shortened when compared with control (high interior resection [HAR]). In particular, degraded LCP at rest was obvious. Anal lengths in squeezing state were preserved except in cases with intersphincteric resection (ISR). Postoperative incontinence score inversely correlated with functional anal length at rest.

CONCLUSIONS

Although the sphincter muscles are mechanically preserved, function of the internal sphincter and subsequent defecatory function can be degraded in cases with operative procedures including surgical maneuvers at the pelvic floor.

Should we preserve the inferior mesenteric artery during sigmoid colectomy?

Ligation of the inferior mesenteric artery (IMA) during sigmoid colectomy may cause sympathetic denervation of the rectal stump. The purpose of our study was to investigate the functional results after sigmoid resection following ligation or preservation of the IMA. We prospectively analysed 44 patients (21 female and 23 male, mean age 60.6 +/- 11.79 years) with sigmoid tumour. Sigmoid colectomy with preservation of the IMA was performed in 21 patients, and ligation of the IMA with sigmoidectomy was carried out in 23 patients. Bowel function follow-up was performed by use of questionnaires: standardized functional questionnaire, constipation-specific, and incontinence scales before, 6 and 12 months after surgery. The quality of life was measured by means of the Fecal Incontinence Quality of Life (FIQL) scale. After sigmoid colectomy with division of the IMA, patients presented with a higher rate of fecal incontinence and increased stool frequency compared with patients after sigmoid resection with preservation of the IMA. Deterioration of FIQL was also observed in patients with ligated IMA. Preservation of the IMA during sigmoid colectomy in selected patients lowers the frequency of postoperative impaired anorectal function.

Correlation between colonic motility and defecatory disorders after anterior resection of the rectum in canine models

The objective of this study was to describe the correlation between changes in colonic motility and defecatory disorders in four experimental canine models, with an emphasis on denervation. Therefore, we constructed a model by dividing 20 healthy mongrel dogs into four groups, i.e. control, denervation, transection and anterior resection of the rectum (AR) (denervation plus transection), and focused on the correlation between colonic motility and defecatory disorders by counting the colonic migrating motor complexes (CMMCs) and colonic non-migrating motor complexes (CNMCs). Gastrointestinal and colonic contractile activities were continuously recorded on a computer with strain gauge force transducers. The dogs' feces were checked daily, and their consistency was recorded as normal, semisolid, or watery. Compared with the control group, the transection group showed elongation of the propagation time (P < 0.05), and the mean motility index of colonic contractile activity at C4 and C5 in the denervation group was greater than that in the control group (P < 0.05). The AR group showed three features of colonic motility: (i) elongation of the mean CMMC cycle (P < 0.05); (ii) shortening of the propagation time (P < 0.05); and (iii) increment of the number of CNMCs. Concerning fecal consistency, the AR group only showed watery diarrhoea. In conclusion, we revealed the existence of a correlation between defecatory disorders and changes in colonic motility. Increased knowledge among colorectal surgeons of the changes in colonic motility that occur following colorectal surgery is very important and could lead to the curtailment of defecatory disorders among patients.

Level of arterial ligation in rectal cancer surgery: low tie preferred over high tie. A review

Consensus does not exist on the level of arterial ligation in rectal cancer surgery. From oncologic considerations, many surgeons apply high tie arterial ligation (level of inferior mesenteric artery). Other strategies include ligation at the level of the superior rectal artery, just caudally to the origin of the left colic artery (low tie), and ligation at a level without any intraoperative definition of the inferior mesenteric or superior rectal arteries. Publications concerning the level of ligation in rectal cancer surgery were systematically reviewed. Twenty-three articles that evaluated oncologic outcome (n = 14), anastomotic circulation (n = 5), autonomous innervation (n = 5), and tension on the anastomosis/anastomotic leakage (n = 2) matched our selection criteria and were systematically reviewed. There is insufficient evidence to support high tie as the technique of choice. Furthermore, high tie has been proven to decrease perfusion and innervation of the proximal limb. It is concluded that neither the high tie strategy nor the low tie strategy is evidence based and that low tie is anatomically less invasive with respect to circulation and autonomous innervation of the proximal limb of anastomosis. As a consequence, in rectal cancer surgery low tie should be the preferred method.

Risk factors for faecal incontinence after rectal cancer treatment

BACKGROUND

Low anterior resection (LAR) may result in faecal incontinence. This study aimed to identify risk factors for long-term faecal incontinence after total mesorectal excision (TME) with or without preoperative radiotherapy (PRT).

METHODS

Between 1996 and 1999, patients with operable rectal cancer were randomized to TME with or without PRT. Eligible patients who underwent LAR were studied retrospectively at 2 years (399 patients) and 5 years (339) after TME.

RESULTS

At 5 years after surgery faecal incontinence was reported by 61.5 per cent of patients who had PRT and 38.8 per cent of those who did not (P < 0.001). Excessive blood loss and height of the tumour were associated with long-term faecal incontinence, but only in patients treated with PRT.

CONCLUSION

Faecal incontinence is likely to occur after PRT and TME, especially when the perineum is irradiated.

Prospective Evaluation of the Defecatory Functional Results in Patients Following Aorto-Aortic Reconstruction Surgery for an Abdominal Aortic Aneurysm

PURPOSE

Anterior rectal resections have been associated with postoperative bowel function abnormalities, a condition defined as anterior resection syndrome. Autonomic denervation could be one of the possible mechanisms underlying this complication. Damage to the preaortic tissue containing autonomic nervous plexus during abdominal aortic reconstruction surgery may affect the anorectal defecation function.

METHODS

The anorectal function was prospectively studied in 22 patients undergoing abdominal aortic reconstruction surgery. The patients were examined preoperatively and 6 months postoperatively by symptom-specific questionnaires.

RESULTS

Postoperatively, the patients showed no significant impairment of the anorectal functions in both constipation- and fecal incontinence-specific questionnaires. Self-estimation of the defecatory function was slightly lower compared with preoperative scores.

CONCLUSION

An injury to the intermesenteric, inferior mesenteric, and superior hypogastric plexuses does not significantly influence the defecatory functions in patients following abdominal reconstruction surgery for an abdominal aortic aneurysm.

Pelvic floor: anatomy and function

The pelvic floor is a dome-shaped striated muscular sheet that encloses the bladder, uterus, and rectum, and, together with the anal sphincters, has an important role in regulating storage and evacuation of urine and stool. This article reviews the anatomy, nerve supply, pharmacology, and functions of the anal sphincters and the pelvic floor. The internal and external anal sphincters are primarily responsible for maintaining faecal continence at rest and when continence is threatened, respectively. Defecation is a somato-visceral reflex regulated by dual nerve supply (i.e. somatic and autonomic) to the anorectum. The net effects of sympathetic and cholinergic stimulation are to increase and reduce anal resting pressure, respectively. Faecal incontinence and functional defecatory disorders may result from structural changes and/or functional disturbances in the mechanisms of faecal continence and defecation.