Management of constipation: A narrative review of evolving strategies and methodological challenges

Table 4 History and assessment in patients with constipation

Diagnostic tool	Technique	Utility	Limitations
History and physical examination (including DRE)	Detailed bowel history, which includes frequency, stool form (Bristol chart), straining, sensation of blockage, and incomplete evacuation. Review of fluid, dietary intake, and activity. History of medication use. History of comorbidities (thyroid disease, diabetes, neurologic disorders. Digital rectal examination-Assess the anal tone, voluntary squeeze, pelvic floor relaxation during simulated defecation, and for the presence of stool, hemorrhoids, rectocele[8]	Used to identify secondary causes. DRE can strongly indicate dyssynergic defecation by detecting paradoxical anal sphincter contraction and inadequate pelvic floor contraction[34]. Identifies fecal retention or impaction, anorectal fissures, strictures, masses, or pain-avoidant behavior	It is a highly subjective tool. Dependent on the clinician’s expertise. DRE has low sensitivity for subtle pelvic floor lesions[26]. Cannot diagnose slow-transit constipation. Cannot identify structural lesions higher in the colon
Laboratory evaluation	Blood tests like CBC, TSH, serum calcium, glucose, electrolytes, serum creatinine, etc.[25,34]	Used to identify endocrine or metabolic causes of constipation[8]. It also helps to rule out systemic disease mimicking constipation	Cannot identify the type of constipation (e.g., slow transit vs pelvic floor dysfunction)[27]
Colonoscopy and sigmoidoscopy	Endoscopic evaluation of colonic mucosa with the ability to biopsy[32]	Very useful tool in the presence of alarm symptoms like bleeding per rectum, anemia, weight loss, age > 50 with new onset symptoms, and family history of colorectal cancer[31]. Used to detect neoplasia (polyps, colorectal cancer), strictures, IBD, and solitary rectal ulcer syndrome[31]	Cannot diagnose functional constipation. Normal in most cases of chronic idiopathic constipation[26]. Invasive procedure. Requires patient preparation
Radiographic imaging	Plain abdominal X-ray (KUB)-simple supine radiograph[34]	Detects colonic dilation, megacolon, fecal loading or obstruction[31]	Correlates poorly with the severity of symptoms. Adds limited diagnostic value[26]. Cannot differentiate motility disorders
	CT abdomen/CT colonography-Imaging with contrast (IV or oral) or air insufflation for colonography[8]	Used to identify mechanical obstruction, tumors, volvulus, and strictures[8]. Helpful in identifying complications of constipation, stercoral colitis, and perforation	Radiation exposure. Cannot be used to diagnose functional constipation[26]. Cannot give information about motility
Colonic transit studies	Radiopaque marker test[35]. Patient ingests capsules containing makers. Abdominal X-rays are taken on day 3 and day 5. Distribution pattern is analyzed for segmental or global delay	Gold standard for diagnosing slow transit constipation[8]. Helps to distinguish between normal transit, colonic inertia (severe delay) and segmental delay (often left colon). Helps to distinguish slow transit constipation from pelvic floor dyssynergia	Requires multiple visits over days. Radiation exposure. Does not assess pelvic floor coordination directly. Interpretation requires experience[26]
	Scintigraphic colonic transit studies[35]. Patient eats a radiolabeled meal, and serial gamma camera images track transit through the GI tract	Provides more detailed regional motility mapping. Measures gastric, small bowel, and colonic transit	Costly and limited availability. Radiation exposure
	Wireless motility capsule (smart pill). Patient swallows a capsule that records pH, temperature, and pressure of the tract as it moves. Data are transmitted to the external receiver	Measures segmental transit times-gastric emptying time, small bowel transit, colonic transit. Useful in suspected cases of generalized dysmotility. Can distinguish between global motility disorders and isolated constipation	Expensive. Should not be used if there are strictures or obstructions. Limited availability. Cannot assess pelvic floor mechanics
Anorectal function studies	Anorectal manometry[36]. A high-resolution catheter is inserted into the rectum, which measures resting and squeeze pressures, recto anal inhibitory reflex, rectal compliance, and simulated defecation dynamics	Primary diagnostic tool for dyssynergic dysfunction[38]. Helps to detect paradoxical anal sphincter contraction, inadequate propulsive forces, and sensory deficits. Helps in tailoring biofeedback therapy	Cannot identify structural abnormalities like rectocele, prolapse, etc. Not standardized[38]. Cannot measure transit. Requires experienced and trained personnel
	Balloon expulsion test. Balloon filled with water in rectum and patient attempts to expel it in less than 1-2 minutes	A simple screening test for outlet obstruction. Highly specific when abnormal	Not sensitive. Normal result doesn’t exclude dyssynergia[40]. Does not distinguish the exact type of pelvic floor disorder
	Defecography[40]. Contrast paste is inserted into the rectum, and patient tries to defecate under fluoroscopy	It can be used to visualize structural abnormalities, such as rectocele, internal intussusception, external prolapse, megarectum, and perineal descent	Radiation exposure. Does not evaluate physiology. Very uncomfortable procedure
	MRI defecography. Gel is inserted into rectum and pelvic MRI is performed during rest, squeeze, and defecation phases	It has better soft tissue resolution. Helps in detecting pelvic floor dyssynergia, multi-compartment organ prolapses, and rectocele[41]. No radiation exposure	Expensive. Limited availability. Difficult for patients to defecate in an MRI environment
Endoanal ultrasound	A high-frequency probe is inserted into anal canal[42]	Can identify sphincter defects. Helpful in identifying postpartum sphincter injury or suspected trauma	Not useful for most cases of constipation. Provides very little functional information
Rectal biopsy	Suction or full-thickness biopsy to identify ganglion cells	Definitive diagnostic tool for Hirschsprung disease[43]. Can also identify chronic intestinal pseudo-obstruction with neuropathic or myopathic features	Invasive. Not usually indicated in adults unless there is severe and unexplained megacolon
Psychosocial and behavioral assessment	Evaluate for anxiety, depression, eating disorders, trauma, and abuse history[44]	Can be useful to identify behavioral contributors to constipation[44]. Important tool of assessment in IBS-C and functional GI disorders	It is a very subjective tool. Cannot diagnose primary motility disorders. Requires patient cooperation

CBC: Complete blood count; CT: Computed tomography; DRE: Digital rectal examination; GI: Gastrointestinal; IBD: Inflammatory bowel disease; IBS-C: Irritable bowel syndrome with constipation; KUB: Kidneys, ureters, and bladder (plain abdominal radiograph); MRI: Magnetic resonance imaging; TSH: Thyroid-stimulating hormone.