Obesity is significantly associated with increased odds of defecation disorders, such as fecal incontinence (FI) to liquid stools, fecal urgency, and vaginal digitation in addition to anal resting pressures, according to a study in the American Journal of Gastroenterology.

The single-center, cross-sectional study assessed the role of obesity in consecutive patients referred for evaluation of symptoms of FI and/or chronic constipation between February 2017 and September 2021.

Adult patients aged 18 to 80 years with complete data on symptoms and history, including body mass index (BMI), and a minimum diagnostic dataset of findings from high-resolution anorectal manometry, endoanal ultrasonography, and rectal sensory testing were included. The participants were categorized into 3 BMI groups: normal (BMI 18.5-24.9 kg/m2), overweight (BMI 25.0-29.9 kg/m2), and obese (BMI ≥30.0 kg/m2).

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The cohort included 1,155 patients (median age, 52 [IQR, 40-63] years; women, 84.0%), of which 387 patients had normal BMI (33.5%), 402 had overweight (34.8%), and 366 had obesity (31.7%).

Patients with obesity had positive odds (ratio >1.0) for all assessed incontinence symptoms. The odds ratios (OR) were significantly increased for incontinence to liquid stools (OR, 1.96; 95% CI, 1.43-2.70; P >.0001), use of pads or plugs (OR, 1.81; 95% CI, 1.31-2.51; P =.0003), and fecal urgency (inability to defer defecation for 15 minutes: OR, 1.54; 95% CI, 1.11-2.14; P =.011) compared with patients who had normal BMI.

Among patients with obesity, all constipation symptoms except for digitation had ORs less than 1.0. Significantly lower odds were found for hard stools greater than 25% of defecation episodes (OR, 0.49; 95% CI, 0.32-0.76; P =.002). Patients with obesity had significantly greater odds for vaginal digitation (OR, 2.18; 95% CI, 1.26-3.86; P =.006).

Of the cohort, 81.0% of participants had Rome IV criteria for functional constipation, 64.3% of patients had Rome IV criteria for FI, and 45.3% met the criteria for both diagnoses. A significantly increased proportion of patients had overweight (33.8%) and obesity (37.3%) vs those with normal BMI (28.9%, P =.0005) among patients who met the Rome IV criteria for FI.

A positive linear association was observed between BMI and rectal resting pressure (b0.19, SE 0.019, R2 0.12, P <.0001) and anal resting pressure adjusted for anal sphincter morphology (b 0.45, SE 0.12, R2 0.25, P =.0003), as well as a negative relationship with maximum squeeze increment adjusted for anal sphincter morphology (b -1.18, SE 0.18, R2 0.23, P =.005).

Defecography was conducted in 1035 (89.6%) patients. Patients with obesity had greater odds for a rectocele (OR, 2.42; 95% CI, 1.66 to 3.57; P <.0001), which was more likely to be large and clinically significant (OR, 2.62; 95% CI, 1.51-4.55; P =.0006) vs patients with normal BMI.

Study limitations include the inability to control for potential confounders, such as the effect of diet and exercise. Also, abdominal circumference and intravesicular pressure may be a better indicator of central obesity and intraabdominal pressure than BMI and rectal resting pressure, respectively. In addition, the participants were predominantly women from a single tertiary center.

“Our findings may point to a typical clinical and pathophysiologic phenotype in obesity,” researchers wrote. “Prospective studies are required to determine if obesity is a modifiable risk factor for incontinence and constipation.”

Disclosure: Some study authors declared affiliations with medical technology or device companies. Please see the original reference for a full list of authors’ disclosures.


Chaichanavichkij P, Vollebregt PF, Keshishian K, Knowles CH, Scott SM. The clinical impact of obesity in patients with disorders of defecation: a cross-sectional study of 1,155 patients. Am J Gastroenterol. Published online July 7, 2023. doi:10.14309/ajg.0000000000002400

This article originally appeared on Gastroenterology Advisor