Evidence map›Paper›PMID 42752963›Full record

ArticleAbdominal radiology (New York)2026

Thickening of the internal anal sphincter: correlation with external rectal intussusception and associated features at MR proctography and anal manometry.

Mariana Yalon, David J Bartlett, Ramesh Lamichhane, David N Jacobson, Avinash K Nehra, Kristina T Flicek, Michael L Wells, Shannon P Sheedy, Ahmed O El Sadaney, Yong S Lee and 4 more

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Article in Abdominal radiology (New York), 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

Authors and funding

14 authors.

Mariana YalonDepartment of Nuclear Medicine, Cleveland Clinic, Cleveland, Ohio, USA.
David J BartlettDepartment of Radiology, Mayo Clinic, Rochester, USA.
Ramesh LamichhaneDivision of Gastroenterology and Hepatology, Mayo Clinic, Rochester, USA.
David N JacobsonDepartment of Radiology, Mayo Clinic, Rochester, USA.
Avinash K NehraDepartment of Radiology, Mayo Clinic, Rochester, USA.
Kristina T FlicekDepartment of Radiology, Mayo Clinic, Rochester, USA.ORCID https://orcid.org/0000-0002-3526-6103
Michael L WellsDepartment of Radiology, Mayo Clinic, Rochester, USA.
Shannon P SheedyDepartment of Radiology, Mayo Clinic, Rochester, USA.
Ahmed O El SadaneyDepartment of Radiology, Mayo Clinic, Rochester, USA.
Yong S LeeDepartment of Radiology, Mayo Clinic, Rochester, USA.
Blake A KassmeyerDepartment of Quantitative Health Science, Mayo Clinic, Rochester, USA.
William R G PerryDivision of Colon and Rectal Surgery, Mayo Clinic, Rochester, USA.
Adil E BharuchaDivision of Gastroenterology and Hepatology, Mayo Clinic, Rochester, USA.
Joel G FletcherDepartment of Radiology, Mayo Clinic, Rochester, USA. fletcher.joel@mayo.edu.ORCID https://orcid.org/0000-0002-8941-5434

Funding

NIDDK NIH HHS R01 DK78924
6 · The paper itself

Abstract

objectivesTo determine if internal anal sphincter (IAS) thickness can be reproducibly measured with endoanal MRI in conjunction with MR defecography, and if IAS thickening is associated with external rectal intussusception (i.e., external rectal prolapse) at MR defecography or high-resolution anal manometry (HRM) measurements.

methodsIn this case-control study, 119 patients underwent clinical endoanal MRI, dynamic MR defecography, and HRM. Patients with intra-anal or external rectal intussusception (cases) were matched to those who had neither (controls). Five radiologists, blinded to all clinical information and MR defecography images, measured the maximum lateral IAS thickness on endoanal MR images (≤ 3 mm considered normal). Intraclass correlation coefficient (ICC) estimated inter-rater reliability. Between-group differences and associations among IAS thickness, external rectal intussusception, and anorectal pressures at HRM were analyzed.

resultsAmong 52 cases, 40 had external and 12 had intra-anal rectal intussusception. Median IAS thickness was 2.5 mm (1.1-7.3) with good/moderate inter-rater agreement/reliability (ICC = 0.623). IAS thickening was more frequent in patients with external rectal intussusception (18/40; 45%) than in patients with intra-anal, intra-rectal, or no rectal intussusception (25%, 17%, 10%, respectively; p < 0.002). External rectal intussusception was associated with lower mean anal resting pressure (48 ± 29 mmHg), compared to controls and patients with other degrees of intussusception (75-81 mm Hg, p < 0.004). Anal resting pressure was also lower in patients with thickened IAS (53.5 mmHg vs. 73.8 mmHg; p =0.003). In multivariable analysis, only external rectal intussusception independently predicted anal resting pressure (β-coefficient = -28.9 mmHg, P < 0.0001). IAS thickening was associated with increased anterior-posterior separation of the sphincters and circumferential morphology of external rectal intussusception (P[Formula: see text] 0.015).

conclusionIAS thickening can be reliably measured on endoanal MRI and is strongly associated with external rectal intussusception on MR defecography and reduced anal resting pressure at HRM.

Indexed as

Anal manometryAnal sphincterFecal incontinenceMR defecographyMRIRectal intussusceptionRectal prolapse

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.