Colon lengthening slows transit: is this the mechanism underlying redundant colon or slow transit constipation?

Comparing the short-term clinical outcomes and therapeutic effects of different colectomies in patients with refractory slow-transit constipation in eastern countries: a network meta-analysis

Surgical treatment has been widely used in patients with refractory slow transit constipation (RSTC). The aim of this network meta-analysis (NMA) was to compare the effects of different colectomies on short-term postoperative complications and quality of life in patients with RSTC. Electronic literature searches were performed in the PubMed, Web of Science, EMBASE, WANFANG DATA, and Cochrane Central Register of controlled trials databases and were searched up to December 2022. Selected to compare the short-term clinical outcomes and quality of life of the treatment of RSTC. A random-effects Bayesian NMA was conducted to assess and rank the effectiveness of different surgical modalities. This study included a total of six non-randomized controlled trials involving 336 subjects. It was found that subtotal colectomy with cecorectal anastomosis (CRA) demonstrated superior effectiveness in several aspects, including reduced hospital stay (MD 0.06; 95% CI [0.02, 1.96]), shorter operative time (MD 4.75; 95% CI [0.28, 14.07]), lower constipation index (MD 0.61; 95% CI [0.04, 1.71]), improved quality of life (MD 4.42; 95% CI [0.48, 4.42]). Additionally, in terms of short-term clinical outcomes, subtotal colectomy with ileosigmoidal anastomosis (SC-ISA) procedure ranked the highest in reducing small bowel obstruction (OR 0.24; 95% CI [0.02, 0.49]), alleviating abdominal pain (OR 0.53; 95% CI [0.05, 1.14]), minimizing abdominal distension (OR 0.33; 95% CI [0.02, 0.65]), and reducing incision infection rates (OR 0.17; 95% CI [0.01, 0.33]). Furthermore, SC-ISA ranked as the best approach in terms of patient satisfaction (OR 0.66; 95% CI [0.02, 1.46]). Based on our research findings, we recommend that CRA be considered as the preferred treatment approach for patients diagnosed with RSTC.

Can Infant Dyschezia Be a Suspect of Rectosigmoid Redundancy?

Infant dyschezia is a functional gastrointestinal disorder that occurs in children less than nine months of age. This disorder causes much anxiety among parents who consult different physicians when suspecting major intestinal problems. The aim of this study is to verify whether infant dyschezia involves an anatomic abnormality (redundancy) of the colon. In this retrospective study (48 months) we analyzed all the children younger than 9 months who came to our attention through the suspicion of gastrointestinal abnormality (Hirschsprung’s disease, anorectal malformations, colonic disorders or constipation). They all had a complete medical history, clinical examination and diagnostic tests, such as blood samples, suction rectal biopsy, a study of stool characteristics and, finally, a contrast enema. In cases with infant dyschezia, different colonic sizes and rectosigmoid length were measured, which created a ratio with the diameter of the second lumbar vertebra. These values were compared with those reported in the literature as normal for the age of one year. Of the 24 patients evaluated (mean age 4 months), 9 were excluded for different diagnoses (aganglionic megacolon, hypothyroidism, constipation). The comparison of the ratios obtained in the remaining 15 cases showed a significantly higher rectosigmoid length (redundancy) in children with dyschezia, 18.47 vs. 9.75 (p < 0.001). The rectosigmoid redundancy, a congenital anomaly already reported as a cause of refractory constipation, may be present in children with infant dyschezia.

Understanding the physiology of human defaecation and disorders of continence and evacuation

The act of defaecation, although a ubiquitous human experience, requires the coordinated actions of the anorectum and colon, pelvic floor musculature, and the enteric, peripheral and central nervous systems. Defaecation is best appreciated through the description of four phases, which are, temporally and physiologically, reasonably discrete. However, given the complexity of this process, it is unsurprising that disorders of defaecation are both common and problematic; almost everyone will experience constipation at some time in their life and many will develop faecal incontinence. A detailed understanding of the normal physiology of defaecation and continence is critical to inform management of disorders of defaecation. During the past decade, there have been major advances in the investigative tools used to assess colonic and anorectal function. This Review details the current understanding of defaecation and continence. This includes an overview of the relevant anatomy and physiology, a description of the four phases of defaecation, and factors influencing defaecation (demographics, stool frequency/consistency, psychobehavioural factors, posture, circadian rhythm, dietary intake and medications). A summary of the known pathophysiology of defaecation disorders including constipation, faecal incontinence and irritable bowel syndrome is also included, as well as considerations for further research in this field.

慢传输型便秘外科治疗进展

近年来, 慢性便秘呈缓慢上升趋势, 慢传输型便秘(slow transit constipation, STC)是慢性便秘最常见的一种类型, 外科治疗是STC治疗的重要手段. 由于目前对于STC的发病原因及发病机制尚未完全明确, 及术前缺乏精确定位病变结肠的检查方法, 导致治疗STC手术方法的多样性. 近三十年来, 随着医学技术的不断进步, STC的外科治疗不断发展, 手术方法不断创新; 手术方法经历了从简单到复杂再到个体化选择, 从单一手术方法到多种手术方法选择, 从经腹开放手术到腹腔镜微创手术. 本文从STC的术式产生和发展过程来阐述STC外科治疗疗效和进展.

Irritable bowel syndrome evaluation using computed tomography colonography

AIM

To evaluate the morphology of the colon in patients with irritable bowel syndrome (IBS) by using computed tomography colonography (CTC).

METHODS

Twelve patients with diarrhea type IBS (IBS-D), 13 patients with constipation type IBS (IBS-C), 12 patients with functional constipation (FC) and 14 control patients underwent colonoscopy following CTC. The lengths of the rectosigmoid colon, transverse colon and the total colon were measured. The diameters of the rectum, sigmoid colon, descending colon, transverse colon, and ascending colon were measured.

RESULTS

The mean length of the total colon was 156.5 cm in group C, 158.9 cm in group IBS-D, 172.0 cm in group IBS-C, and 188.8 cm in group FC. The total colon in group FC was significantly longer than that in group C (P < 0.05). The mean length of the rectosigmoid colon was 56.2 cm, 55.9 cm, 63.6cm, and 77.4 cm (NS). The mean length of the transverse colon was 49.9 cm, 43.1 cm, 57.0 cm, and 55.0 cm. The transverse colon in group IBS-D was significantly shorter than that in group IBS-C (P < 0.01) and that in group FC (P = 0.02). The mean diameter of the sigmoid colon was 4.0 cm, 3.3 cm, 4.2 cm, and 4.3 cm (NS). The mean diameter of the descending colon was 3.6 cm, 3.1 cm, 3.8 cm, and 4.3 cm. The descending colon diameter in group IBS-D was significantly less than that in group IBS-C (P = 0.03) and that in group FC (P < 0.001). The descending colon diameter in group FC was significantly greater than that in group C (P = 0.04). The mean diameter of the transverse colon was 4.4 cm, 3.3 cm, 4.2 cm, and 5.0 cm (NS).

CONCLUSION

CT colonography might contribute the clarification of subtypes of IBS.

Colonic migrating motor complexes, high amplitude propagating contractions, neural reflexes and the importance of neuronal and mucosal serotonin

The colonic migrating motor complex (CMMC) is a critical neurally mediated rhythmic propulsive contraction observed in the large intestine of many mammals. It seems to be equivalent to the high amplitude propagating contractions (HAPCs) in humans. This review focuses on the probable neural mechanisms involved in producing the CMMC or HAPC, their likely dependence on mucosal and neuronal serotonin and pacemaker insterstitial cells of Cajal networks and how intrinsic neural reflexes affect them. Discussed is the possibility that myenteric 5-hydroxytryptamine (5-HT) neurons are not only involved in tonic inhibition of the colon, but are also involved in generating the CMMC and modulation of the entire enteric nervous system, including coupling motility to secretion and blood flow. Mucosal 5-HT appears to be important for the initiation and effective propagation of CMMCs, although this mechanism is a longstanding controversy since the 1950s, which we will address. We argue that the slow apparent propagation of the CMMC/HAPC down the colon is unlikely to result from a slowly conducting wave front of neural activity, but more likely because of an interaction between ascending excitatory and descending (serotonergic) inhibitory neural pathways interacting both within the myenteric plexus and at the level of the muscle. That is, CMMC/HAPC propagation appears to be similar to esophageal peristalsis. The suppression of inhibitory (neuronal nitric oxide synthase) motor neurons and mucosal 5-HT release by an upregulation of prostaglandins has important implications in a number of gastrointestinal disorders, especially slow transit constipation.

Insights from a novel model of slow-transit constipation generated by partial outlet obstruction in the murine large intestine

The mechanisms underlying slow-transit constipation (STC) are unclear. In 50% of patients with STC, some form of outlet obstruction has been reported; also an elongated colon has been linked to patients with STC. Our aims were 1) to develop a murine model of STC induced by partial outlet obstruction and 2) to determine whether this leads to colonic elongation and, consequently, activation of the inhibitory "occult reflex," which may contribute to STC in humans. Using a purse-string suture, we physically reduced the maximal anal sphincter opening in C57BL/6 mice. After 4 days, the mice were euthanized (acutely obstructed), the suture was removed (relieved), or the suture was removed and replaced repeatedly (chronically obstructed, over 24-31 days). In partially obstructed mice, we observed increased cyclooxygenase (COX)-2 levels in muscularis and mucosa, an elongated impacted large bowel, slowed transit, nonpropagating colonic migrating motor complexes (CMMCs), a lack of mucosal reflexes, a depolarized circular muscle with slow-wave activity due to a lack of spontaneous inhibitory junction potentials, muscle hypertrophy, and CMMCs in mucosa-free preparations. Elongation of the empty obstructed colon produced a pronounced occult reflex. Removal of the obstruction or addition of a COX-2 antagonist (in vitro and in vivo) restored membrane potential, spontaneous inhibitory junction potentials, CMMC propagation, and mucosal reflexes. We conclude that partial outlet obstruction increases COX-2 leading to a hyperexcitable colon. This hyperexcitability is largely due to suppression of only descending inhibitory nerve pathways by prostaglandins. The upregulation of motility is suppressed by the occult reflex activated by colonic elongation.

Hyperhomocysteinemia decreases intestinal motility leading to constipation

Elevated levels of plasma homocysteine (Hcy) called hyperhomocysteinemia (HHcy) have been implicated in inflammation and remodeling in intestinal vasculature, and HHcy is also known to aggravate the pathogenesis of inflammatory bowel disease (IBD). Interestingly, colon is the pivotal site that regulates Hcy levels in the plasma. We hypothesize that HHcy decreases intestinal motility through matrix metalloproteinase-9 (MMP-9)-induced intestinal remodeling leading to constipation. To verify this hypothesis, we used C57BL/6J or wild-type (WT), cystathionine β-synthase (CBS(+/-)), MMP-9(-/-), and MMP-9(-/-) + Hcy mice. Intestinal motility was assessed by barium meal studies and daily feces output. Plasma Hcy levels were measured by HPLC. Expression of ICAM-1, inducible nitric oxide synthase, MMP-9, and tissue inhibitors of MMPs was studied by Western blot and immunohistochemistry. Reactive oxygen species (ROS) including super oxide were measured by the Invitrogen molecular probe method. Tissue nitric oxide levels were assessed by a commercially available kit. Plasma Hcy levels in the treated MMP-9 group mice were comparable to CBS(+/-) mice. Barium meal studies suggest that intestinal motility is significantly decreased in CBS(+/-) mice compared with other groups. Fecal output-to-body weight ratio was significantly reduced in CBS(+/-) mice compared with other groups. There was significant upregulation of MMP-9, iNOS, and ICAM-1 expression in the colon from CBS(+/-) mice compared with WT mice. Levels of ROS, superoxide, and inducible nitric oxide were elevated in the CBS(+/-) mice compared with other groups. Results suggest that HHcy decreases intestinal motility due to MMP-9-induced intestinal remodeling leading to constipation.

How common is colonic elongation in children with slow-transit constipation or anorectal retention?

PURPOSE

Colonic elongation is reported as a possible cause for slow colonic transit, as it is observed in patients with slow-transit constipation (STC). This study aimed to determine the frequency of colonic elongation in children with STC or anorectal retention using radioimaging. We hypothesized that transverse colon elongation may occur in patients with STC, whereas sigmoid colon elongates in patients with anorectal retention.

METHODS

Nuclear transit scintigraphy performed for chronic constipation (1999-2011) was analyzed qualitatively for elongated transverse colon or sigmoid colon. Three major colonic transit patterns were identified: slow transit in the proximal colon (STC), normal proximal colonic transit with anorectal retention (NT-AR), and rapid proximal transit ± anorectal retention (RT). χ(2) Test was used for statistical analysis (P < .05 significant).

RESULTS

From 1999 to 2011, 626 children had nuclear transit scintigraphy. Transverse colon elongation occurred more frequently in STC (73/322, or 23%) compared with NT-AR (9/127, or 7%) and RT (5/177, or 3%; P < .0001). Sigmoid colon elongation was equally common in NT-AR (8/127, or 6%) compared with RT (10/177, or 6%) and STC (14/322, or 4%; P < .9).

CONCLUSION

Transverse colon elongation is more common in STC (23%), whereas sigmoid colon elongation is not more common in anorectal retention. Colonic elongation may be the cause or the result of the underlying slow colonic transit.

Characterization of motor patterns in isolated human colon: are there differences in patients with slow-transit constipation?

The patterns of motor activity that exist in isolated full-length human colon have not been described. Our aim was to characterize the spontaneous motor patterns in isolated human colon and determine whether these patterns are different in whole colons obtained from patients with slow-transit constipation (STC). The entire colon (excluding the anus), was removed from patients with confirmed STC and mounted longitudinally in an organ bath ∼120 cm in length, containing oxygenated Krebs' solution at 36°C. Changes in circular muscle tension were recorded from multiple sites simultaneously along the length of colon, by use of isometric force transducers. Recordings from isolated colons from non-STC patients revealed cyclical colonic motor complexes (CMCs) in 11 of 17 colons, with a mean interval and half-duration of contractions of 4.0 ± 0.6 min and 51.5 ± 15 s, respectively. In the remaining six colons, spontaneous irregular phasic contractions occurred without CMCs. Interestingly, in STC patients robust CMCs were still recorded, although their CMC pacemaker frequencies were slower. Intraluminal balloon distension of the ascending or descending colon evoked an ascending excitatory reflex contraction, or evoked CMC, in 8 of 30 trials from non-STC (control) colons, but not from colons obtained from STC patients. In many control segments of descending colon, spontaneous CMCs consisted of simultaneous ascending excitatory and descending inhibitory phases. In summary, CMCs can be recorded from isolated human colon, in vitro, but their intrinsic pacemaker frequency is considerably faster in vitro compared with previous human recordings of CMCs in vivo. The observation that CMCs occur in whole colons removed from STC patients suggests that the intrinsic pacemaker mechanisms underlying their generation and propagation are preserved in vitro, despite impaired transit along these same regions in vivo.