Idiopathic Slow Transit Constipation: Pathophysiology, Diagnosis, and Management

Abstract

Slow transit constipation (STC) has an estimated prevalence of 2-4% of the general population, and although it is the least prevalent of the chronic constipation phenotypes, it more commonly causes refractory symptoms and is associated with significant psychosocial stress, poor quality of life, and high healthcare costs. This review provides an overview of the pathophysiology, diagnosis, and management options in STC. STC occurs due to colonic dysmotility and is thought to be a neuromuscular disorder of the colon. Several pathophysiologic features have been observed in STC, including reduced contractions on manometry, delayed emptying on transit studies, reduced numbers of interstitial cells of Cajal on histology, and reduced amounts of excitatory neurotransmitters within myenteric plexuses. The underlying aetiology is uncertain, but autoimmune and hormonal mechanisms have been hypothesised. Diagnosing STC may be challenging, and there is substantial overlap with the other clinical constipation phenotypes. Prior to making a diagnosis of STC, other primary constipation phenotypes and secondary causes of constipation need to be ruled out. An assessment of colonic transit time is required for the diagnosis and can be performed by a number of different methods. There are several different management options for constipation, including lifestyle, dietary, pharmacologic, interventional, and surgical. The effectiveness of the available therapies in STC differs from that of the other constipation phenotypes, and prokinetics often make up the mainstay for those who fail standard laxatives. There are few available management options for patients with medically refractory STC, but patients may respond well to surgical intervention. STC is a common condition associated with a significant burden of disease. It can present a clinical challenge, but a structured approach to the diagnosis and management can be of great value to the clinician. There are many therapeutic options available, with some having more benefits than others.

Keywords: colon; constipation; diagnosis; dysmotility; enteric nervous system; management; manometry; pathophysiology; prokinetcs; slow transit constipation.

Figure 1

Diagnostic algorithm for slow transit constipation. † Simple laxatives should be trialled, and further investigations only performed in those who do not respond. †† If anorectal function testing is not available, it may be reasonable to proceed with colonic transit studies if suspicion of DD is not high based on clinical assessment, but testing should be pursued if there is persisting difficulty with management.

Figure 2

Management algorithm for slow transit constipation. † If there is no improvement with these therapies, then they should not be emphasised and discontinuation should be considered due to minimal benefit in STC. †† If there is no response to prucalopride, the other 5-HT4 agonists may be trialled, but may be similarly ineffective. The use of prokinetic agents of other classes may have more benefit in this circumstance. * Limited evidence in STC to guide management but may be beneficial in some patients. ** Assure that DD has been excluded and STC confirmed.