The London Classification: Improving Characterization and Classification of Anorectal Function with Anorectal Manometry

Functional Constipation and Obstructed Defecation

Constipation encompasses symptoms of decreased colonic motility or difficulty with the defecation process. As a broad definition, this can be inclusive of functional constipation (FC) or colonic inertia, obstructed defecation (OD), and irritable bowel syndrome-constipation type (IBS-CS). After excluding IBS-C, FC and OD diagnosis and management require a multidisciplinary approach often involving nutritionists, pelvic floor therapists, urogynecologists, and colon and rectal surgeons. Differentiating the presence or absence of each can direct therapy and prognosticate chances for improvement in this often complex combination of disorders.

Constipated patients with functional defecatory disorder have secondary rectal hyposensitivity due to altered rectal biomechanics

BACKGROUND AND AIM

Rectal hyposensitivity (RH) is common in constipation and often coexists with functional defecatory disorder (FDD). Rectal sensory thresholds are routinely evaluated with the anorectal manometry probe; however, the gold standard for the assessment of rectal sensitivity is with a barostat, use of which is limited by time constraints and availability. A novel rapid barostat bag (RBB) may facilitate measurements of rectal sensitivity. The aim is to evaluate the relationship between RH (measured by the RBB) and FDD (defined as any minor disorder of rectoanal coordination by the London classification) in constipated patients.

METHODS

Consecutive constipated patients referred for anorectal function testing underwent anorectal manometry with the 3D-HDAM probe as well as rectal sensation testing with the RBB pump. RH was defined by volume to first sensation >30%, urge to defecate >80%, or discomfort >100% (normalized to rectal capacity).

RESULTS

Fifty-three percent of constipated patients had RH. Patients with FDD had a significantly increased volume to first sensation (134.5 mL vs 102.0, P = 0.02), urge to defecate (187.0 mL vs 149.0, P = 0.04), and rectal capacity (253.5 mL vs 209.0, P = 0.04) compared to constipated patients without FDD. There was no difference in normalized sensory thresholds (percent of rectal capacity) nor the prevalence of hyposensitivity to each sensory threshold nor overall hyposensitivity.

CONCLUSION

Patients with FDD, when measured with the RBB, have increased sensory thresholds on volumetric distension, but RH was not observed when sensory threshold volume were normalized to rectal capacity. This may reflect "secondary" RH due to altered rectal biomechanics.

Increased Grades of Rectal Intussusception: Role of Decline in Pelvic Floor Integrity and Association With Dyssynergic Defecation

INTRODUCTION

The natural history of rectal intussusception (RI) is poorly understood. We hypothesized that decline in pelvic floor integrity and function leads to increasing RI grades.

METHODS

Retrospective analysis of a registry of patients with defecatory disorders with high-resolution anorectal manometry and magnetic resonance defecography was performed. Association of risk factors on increasing RI grades was assessed using logistic regression.

RESULTS

Analysis included a total of 238 women: 90 had no RI, 43 Oxford 1-2, 49 Oxford 3, and 56 Oxford 4-5. Age ( P = 0.017), vaginal delivery ( P = 0.008), and prior pelvic surgery ( P = 0.032) were associated with increased Oxford grades. Obstructive defecation symptoms and dyssynergic defecation were observed at relatively high rates across groups. Increased RI grades were associated with less anal relaxation at simulated defecation yet, higher rates of normal balloon expulsion ( P < 0.05), linked to diminished anal sphincter. Indeed, increased RI grades were associated with worsening fecal incontinence severity, attributed to higher rates of anal hypotension. Levator ani laxity, defined by increased levator hiatus length and its excessive descent at straining, was associated with increasing RI grades, independent of age, history of vaginal delivery, and pelvic surgeries and could independently predict increased RI grades. Concurrent anterior and posterior compartments, and visceral prolapse were associated with higher Oxford grades.

DISCUSSION

Our data suggest that decline in pelvic floor integrity with abnormal levator ani laxity is associated with increased RI grades, a process that is independent of age, history of vaginal deliveries, and/or pelvic surgeries, and perhaps related to dyssynergic defecation.

Diagnostic value of balloon expulsion test and anorectal manometry in patients with constipation: a systematic review and meta-analysis

This study aims to compare the diagnostic value of balloon expulsion test and anorectal manometry in patients with constipation through meta-analysis. Databases, encompassing PubMed, EMBASE, Cochrane Library, Web of Science, etc. were searched for all English publications on the diagnosis of constipation using balloon expulsion test and anorectal manometry. The publication date was restricted from the inception of the databases until December 2022. Data analysis was carried out utilizing Stata 15.0 and Meta-Disc 1.4 software. Thirteen studies involving 2171 patients with constipation were included. According to the meta-analysis, the balloon expulsion test showed a pooled sensitivity of 0.75 (95% CI: 0.72-0.77), a pooled specificity (Spe) of 0.67 (95% CI: 0.62-0.72), a pooled positive likelihood ratio (+LR) of 3.24 (95% CI: 1.53-6.88), a pooled negative likelihood ratio (-LR) 0.35 (95% CI: 0.23-0.52) and a pooled diagnostic odds ratio (DOR) of 9.47 (95% CI: 3.27-27.44). For anorectal manometry, the pooled Sen, Spe, +LR, -LR and DOR were 0.74 (95% CI: 0.72-0.76), 0.73 (95% CI: 0.70-0.76), 2.69 (95% CI: 2.18-3.32), 0.35 (95% CI: 0.28-0.43), and 8.3 (95% CI: 5.4-12.75), respectively. The area under the summary receiver operating characteristic curve areas for balloon expulsion test and anorectal manometry were 0.8123 and 0.8088, respectively, with no statistically significant disparity (Z = -0.113, P > 0.05). Both the balloon expulsion test and anorectal manometry demonstrate comparable diagnostic performance, each offering unique advantages. These diagnostic procedures hold significance in the diagnosis of constipation.

London Protocol under water-perfused HRM in a healthy population, towards novel 3D manometric parameters in an evaluation of anorectal functional disorders

BACKGROUND/AIM

London Protocol (LP) and Classification allied to high-resolution manometry (HRM) technological evolution has updated and enhanced the diagnostic armamentarium in anorectal disorders. This study aims to evaluate LP reproducibility under water-perfused HRM, provide normal data and new parameters based on 3D and healthy comparison studies under perfusional HRM.

METHODS

Fifty healthy (25 F) underwent water-perfused 36 channel HRM based on LP at resting, squeeze, cough, push, and rectal sensory. Additional 3D manometric parameters were: pressure-volume (PV) 104mmHg2.cm (resting, short and long squeeze, cough); highest and lowest pressure asymmetry (resting, short squeeze, and cough). Complementary parameters (CP) were: resting (mean pressure, functional anal canal length); short squeeze (mean and maximum absolute squeeze pressure), endurance (fatigue rate, fatigue rate index, capacity to sustain); cough (anorectal gradient pressure); push (rectum-anal gradient pressure, anal canal relaxation percent); recto-anal inhibitory reflex (anal canal relaxation percent).

RESULTS

No difference to genders: resting (LP, CP, and 3D); short squeeze (highest pressure asymmetry); endurance (CP); cough (CP, highest and lowest pressure asymmetry); push (gradient pressure); rectal sensory. Higher pressure in men: short squeeze (maximum incremental, absolute, and mean pressure, PV, lowest pressure asymmetry); long squeeze (PV); cough (anal canal and rectum maximum pressure, anal canal PV); push (anal canal and rectum maximum pressure). Anal canal relaxation was higher in women (push).

CONCLUSIONS

LP reproducibility is feasible under water-perfused HRM, and comparative studies could bring similarity to dataset expansion. Novel 3D parameters need further studies with healthy and larger data to be validated and for disease comparisons.

KEY POINTS

• London Protocol and Classification allied with the technological evolution of HRM (software and probes) has refined the diagnostic armamentarium in anorectal disorders. • Novel 3D and deepening the analysis of manometric parameters before the London Classification as a contributory diagnostic tool. • Comparison of healthy volunteers according to the London Protocol under a perfusional high-resolution system could establish equivalence points.

Rectal Sensory and Compliance Testing: A Method Comparison Study between High-Resolution Anorectal Manometry and Barostat Investigations

Abnormal visceral perception and motor function are often observed in patients with fecal incontinence, evacuation disorders and irritable bowel syndrome. The international anorectal physiology working group has proposed a standardization for anorectal function assessment, where rectal sensitivity testing is performed using an elastic balloon attached to a high-resolution anorectal manometry (HRAM) catheter. Rectal compliance, another component of rectal function evaluation, is a pressure-volume relationship that refers to the rectum's ability to stretch and expand as it receives and holds fecal matter. There are no data available regarding the possibility of compliance testing using HRAM, although this is theoretically possible by correcting for the elastic balloon's intrinsic properties. The gold standard for measurement of visceral sensitivity and compliance is the rectal barostat, according to the procedure described by the European COST action GENIEUR group. Data on the agreement between the two different procedures are scarce. Hence, we performed a comparative study of the HRAM and barostat investigations in 26 healthy individuals. We hypothesized that by inflating the balloon before the examination, rectal compliance can be measured with HRAM investigations, and we examined correlations and levels of agreement between the methods. Our results demonstrate that assessing rectal compliance with HRAM is technically possible; however, a strong correlation with the rectal barostat was only observed at the maximum tolerable volume (Spearman's rho = 0.7, p = 0.02). We only found moderate correlations (Spearman's rho = 0.562, p = 0.019) for compliance according to the barostat methodology and for rectal sensibility testing (Spearman's rho = 0.57, p = 0.03 for maximum tolerable volume). Bland-Altman plots showed poor levels of agreement between the methods. We conclude that HRAM and the rectal barostat cannot be used interchangeably for compliance or sensitivity assessments. We suggest the development of a non-elastic balloon with a fixed size and shape to assess rectal sensory function and compliance in HRAM testing.

Faecal incontinence-a comprehensive review

Introduction

Faecal incontinence (FI) is a distressing and often stigmatizing condition characterised as the recurrent involuntary passage of liquid or solid faeces. The reported prevalence of FI exhibits considerable variation, ranging from 7 to 15% in the general population, with higher rates reported among older adults and women. This review explores the pathophysiology mechanisms, the diagnostic modalities and the efficiency of treatment options up to date.

Methods

A review of the literature was conducted to identify the pathophysiological pathways, investigation and treatment modalities.

Result and discussion

This review provides an in-depth exploration of the intricate physiological processes that maintain continence in humans. It then guides the reader through a detailed examination of diagnostic procedures and a thorough analysis of the available treatment choices, including their associated success rates. This review is an ideal resource for individuals with a general medical background and colorectal surgeons who lack specialized knowledge in pelvic floor disorders, as it offers a comprehensive understanding of the mechanisms, diagnosis, and treatment of faecal incontinence (FI).

Anorectal Manometry in Patients With Fecal Incontinence After Ileal Pouch-Anal Anastomosis for Ulcerative Colitis: A Cohort Study

Background

Fecal incontinence commonly occurs in patients with ulcerative colitis and ileal pouch-anal anastomosis. There is a paucity of manometric data in pouch patients. We aimed to better define manometric parameters in pouch patients with fecal incontinence.

Methods

We compared clinical and manometric variables in ulcerative colitis patients with pouch and fecal incontinence to ulcerative colitis patients with pouch without fecal incontinence and to non-ulcerative colitis patients with fecal incontinence. Manometric data for the 3 cohorts were compared to established normative data. An independent-samples t-test was performed for continuous variables, and chi-square test was used for categorical variables. Logistic regression was performed to identify predictors of incontinence in pouch patients (P < .05).

Results

Among 26 pouch patients with fecal incontinence (73% female), 26 pouch patients without fecal incontinence (35% female), and 84 patients with fecal incontinence without ulcerative colitis (68% female), there were no differences in anorectal pressures between patients with fecal incontinence. Lower pressures were observed in pouch patients with fecal incontinence compared to those without fecal incontinence. Resting pressure was similar between pouch patients with fecal incontinence and healthy controls (60.9 ± 36.1 mmHg vs. 66.9 ± 3.2 mmHg, P = .40). Female sex (P = .019) and defecatory disorders (P = .033) each independently predicted fecal incontinence in pouch patients.

Conclusions

Pouch patients with fecal incontinence have lower anorectal pressures compared to pouch patients without incontinence, though have similar pressures to non-ulcerative colitis patients with fecal incontinence. Pouch patients with fecal incontinence have similar resting pressures as healthy controls. Distinct manometric normative values for pouch patients are needed.

Differential Findings on Anorectal Manometry in Patients with Parkinson's Disease and Defecatory Dysfunction

Introduction

Gastrointestinal dysfunction, particularly constipation, is among the most common non-motor manifestations in Parkinson's Disease (PD). We aimed to identify high-resolution anorectal manometry (HR-ARM) abnormalities in patients with PD using the London Classification.

Methods

We conducted a retrospective review of all PD patients at our institution who underwent HR-ARM and balloon expulsion test (BET) for evaluation of constipation between 2015 and 2021. Using age and sex-specific normal values, HR-ARM recordings were re-analyzed and abnormalities were reported using the London Classification. A combination of Wilcoxon rank sum and Fisher's exact test were used.

Results

36 patients (19 women) with median age 71 (interquartile range [IQR]: 69-74) years, were included. Using the London Classification, 7 (19%) patients had anal hypotension, 17 (47%) had anal hypocontractility, and 3 women had combined hypotension and hypocontractility. Anal hypocontractility was significantly more common in women compared to men. Abnormal BET and dyssynergia were noted in 22 (61%) patients, while abnormal BET and poor propulsion were only seen in 2 (5%). Men had significantly more paradoxical anal contraction and higher residual anal pressures during simulated defecation, resulting in more negative recto-anal pressure gradients. Rectal hyposensitivity was seen in nearly one third of PD patients and comparable among men and women.

Conclusion

Our data affirms the high prevalence of anorectal disorders in PD. Using the London Classification, abnormal expulsion and dyssynergia and anal hypocontractility were the most common findings in PD. Whether the high prevalence of anal hypocontractility in females is directly related to PD or other confounding factors will require further research.

Clinical Characteristics of Adult Functional Constipation Patients with Rectoanal Areflexia and Their Response to Biofeedback Therapy

Background: The London Classification for anorectal physiological dysfunction specifically proposes rectoanal areflexia (RA), which means the absence of a rectoanal inhibitory reflex (RAIR) based on a manometric diagnosis. Although RA is not observed in healthy people, it can be found in adult patients with functional constipation (FC). This study describes the clinical manifestations of adult patients with FC and RA and their response to biofeedback therapy (BFT). Methods: This retrospective study reviewed the reports of high-resolution anorectal manometry (HR-ARM) and the efficacy of BFT in adult patients with FC. In addition, the Constipation Scoring System (CSS) scale, Patient Assessment of Constipation Symptoms (PAC-SYM) scale, Patient Assessment of Constipation Quality of Life (PAC-QOL) scale, Zung’s Self-Rating Anxiety Scale (SAS), Zung’s Self-Rating Depression Scale (SDS), balloon expulsion test (BET), and the use of laxatives were assessed. Results: A total of 257 adult patients diagnosed with FC were divided into the RA group (n = 89) and the RAIR group (n = 168). In the RA and RAIR groups, 60 (67.4%) and 117 (69.6%) patients, respectively, had dyssynergic defecation (DD) during simulated defecation. Type II pattern of dyssynergia was most frequently observed in both groups. Compared with the RA group, the RAIR group showed a higher CSS score, physical discomfort score, and prevalence of inadequate relaxation of the anal sphincter (p < 0.001, p = 0.036, and p = 0.017, respectively). The anxiety and depression scores were not different between the two groups. The proportion of patients using volumetric and stimulant laxatives and their combination was significantly higher in FC patients with RA, whereas the efficacy of BFT was significantly lower (p = 0.005, p < 0.001, p = 0.045, and p = 0.010, respectively). Conclusion: Adult FC patients with RA may suffer more severe constipation and have a lower efficacy of BFT compared with those with RAIR.

Comparison of Anorectal Manometry, Rectal Balloon Expulsion Test, and Defecography for Diagnosing Defecatory Disorders

BACKGROUND & AIMS

The utility of high-resolution anorectal manometry (HR-ARM) for diagnosing defecatory disorders (DDs) is unclear because healthy people may have features of dyssynergia. We aimed to identify objective diagnostic criteria for DD and to ascertain the utility of HR-ARM for diagnosing DD.

METHODS

Constipated patients were assessed with HR-ARM and rectal balloon expulsion time (BET), and a subset underwent defecography. Normal values were established by assessing 184 sex-matched healthy individuals. Logistic regression models evaluated the association of abnormal HR-ARM findings with prolonged BET and reduced rectal evacuation (determined by defecography).

RESULTS

A total of 474 constipated individuals (420 women) underwent HR-ARM and BET, and 158 underwent defecography. BET was prolonged, suggesting a DD, for 152 patients (32%). Rectal evacuation was lower for patients with prolonged vs normal BET. A lower rectoanal gradient during evacuation, reduced anal squeeze increment, and reduced rectal sensation were independently associated with abnormal BETs; the rectoanal gradient was 36% sensitive and 85% specific for prolonged BET. A lower rectoanal gradient and prolonged BET were independently associated with reduced evacuation. Among constipated patients, the probability of reduced rectal evacuation was 14% when the gradient and BET were both normal, 45% when either was abnormal, and 75% when both variables were abnormal.

CONCLUSIONS

HR-ARM, BET, and defecography findings were concordant for constipated patients, and reduced rectoanal gradient was the best HR-ARM predictor of prolonged BET or reduced rectal evacuation. Prolonged BET, reduced gradient, and reduced evacuation each independently supported a diagnosis of DD in constipated patients. We propose the terms probable DD for patients with an isolated abnormal gradient or BET and definite DD for patients with abnormal results from both tests.

Current and future perspectives on the utility of provocative tests of anal sphincter function: A state-of-the-art summary

BACKGROUND

The maintenance of fecal continence depends upon coordinated interactions between the pelvic floor, anorectum, and anal sphincter complex orchestrated by central and peripheral neural activities. The current techniques to objectively measure anorectal function rely on fixed diameter catheters placed inside the anal canal with a rectal balloon to obtain measurements of anal resting and squeeze function, and rectal compliance. Until recently it had not been possible to measure the distensibility of the anal canal, or in other words its ability to resist opening against an increasing pressure, which has been proposed as the main determinant of a biological sphincter's function. Anal acoustic reflectometry (AAR) and the functional lumen imaging probe (FLIP) are two novel, provocative techniques that dynamically assess the anal sphincter complex under volume-controlled distension. In doing so, both provide information on the viscoelastic properties of the anal canal and offer new insights into its function.

PURPOSE

This review details the current and potential future applications of AAR and FLIP and highlights the unanswered questions relevant to these new technologies.

Anal Sphincter Defect and Fecal Incontinence

Anal sphincter defects can lead to fecal incontinence. The relationship between the extent of defect and continence is controversial. Magnetic resonance imaging (MRI) of the pelvis can assess anal sphincter defects. Transrectal ultrasonography (TRUS) is used to assess sphincter integrity in adults. We present a 17-year-old male with history of sexual abuse, rectal prolapse, and fecal incontinence. MRI showed a small defect that did not explain his clinical presentation. TRUS identified more extensive defects which were not picked up by MRI. The patient had rectopexy, and his rectal prolapse and fecal incontinence resolved. TRUS was superior in identifying sphincter defects compared with MRI. Our case also highlights that continence is possible despite large sphincter defects in pediatric patients. This may reflect the compensatory mechanism of residual sphincter in the absence of the aggravating factors like rectal prolapse.

Manometric parameters, when measured with the 3-dimensional high-definition anorectal manometry probe, poorly predict prolonged balloon expulsion time

BACKGROUND

There are little data evaluating the performance of the 3-dimensional high-definition anorectal manometry (3D-HDAM) system in the diagnosis of dyssynergic defecation. Physical properties of the thicker, rigid, 3D-HDAM probe may have implications on the measurements of anorectal pressures.

AIM

Our aim was to compare 3D-HDAM to balloon expulsion test and magnetic resonance (MR) defecography.

METHODS

Consecutive constipated patients referred for anorectal function testing at the Calgary Gut Motility Centre (Calgary, Canada) between 2014 and 2019 were assessed. All patients underwent anorectal manometry with the 3D-HDAM probe, and a subset underwent BET or MR defecography. Anorectal manometric variables were compared between patients who had normal and abnormal BET.

RESULTS

Over the study period, 81 patients underwent both 3D-HDAM and BET for symptoms of constipation. 52 patients expelled the balloon within 3 minutes. Patients with abnormal BET had significantly lower rectoanal pressure differential (RAPD) (-61 vs. -31 mmHg for normal BET, p = 0.03) and defecation index (0.29 vs. 0.56, p = 0.03). On logistic regression analysis, RAPD (OR: 0.99, 95% CI: 0.97-0.99, p = 0.03) remained a negative predictor of abnormal BET. On ROC analysis, RAPD had an AUC of 0.65. There was good agreement between dyssynergic patterns on 3D-HDAM and defecographic evidence of dyssynergia (sensitivity 80%, specificity 90%, PLR 9, NLR 0.22, accuracy 85%).

CONCLUSIONS

Manometric parameters, when measured with the 3D-HDAM probe, poorly predict prolonged balloon expulsion time. RAPD remains the best predictor of prolonged balloon expulsion time. The 3D-HDAM probe may not be the ideal tool to diagnose functional defecatory disorders.

Anorectal dysfunction in multiple sclerosis patients: A pilot study on the effect of an individualized rehabilitation approach

BACKGROUND:

Anorectal dysfunction (ARD), especially bowel incontinence, frequently compromises the quality of life in multiple sclerosis (MS) patients. The effect of rehabilitation procedures has not been clearly established.

OBJECTIVE:

To determine the effect of an individualized rehabilitation approach on bowel incontinence and anorectal pressures.

METHODS:

MS patients with ARD underwent 6-months of individually targeted biofeedback rehabilitation. High resolution anorectal manometry (HRAM) and St. Mark’s Fecal Incontinence Scores (SMIS) were completed prior to rehabilitation, after 10 weeks of supervised physiotherapy, and after 3 months of self-treatment.

RESULTS:

Ten patients (50%) completed the study. Repeated measures analysis of variance (ANOVA) demonstrated significant improvement in the SMIS questionnaire over time [14.00 baseline vs. 9.70 after supervised physiotherapy vs. 9.30 after self-treatment (p = 0.005)]. No significant improvements over time were noted in any HRAM readings: maximal pressure [49.85 mmHg baseline vs. 57.60 after supervised physiotherapy vs. 60.88 after self-treatment (p = 0.58)], pressure endurance [36.41 vs. 46.89 vs. 49.95 (p = 0.53)], resting pressure [55.83, vs 52.69 vs. 51.84 (p = 0.704)], or area under the curve [230.0 vs. 520.8 vs. 501.9 (p = 0.16)].

CONCLUSIONS:

The proposed individualized rehabilitation program supports a positive overall effect on anorectal dysfunction in MS patients.

Evaluation of constipation in children using high-resolution anorectal manometry

This prospective, cross-sectional study, conducted from July 2018 to March 2019, aimed to determine the causes of constipation using high-resolution anorectal manometry. Among 33 children enrolled in the study, 31 (94%) children presented with complaints of constipation with mean duration of 2.3 ± 2.5 years and 12 (36.4%) children also had associated complaints of faecal incontinence with mean duration of 3.5 ± 2.8 years. Seven children (21.2%) had normal high-resolution anorectal manometry parameters; anal sphincter hypotonia with decreased squeeze in one child, anal sphincter hypertonia with other abnormal parameters were noted in 25 and absent recto-anal inhibitory reflex in two. The causes of constipation determined were functional constipation in 30 (91%) children, suspected Hirschsprung's disease in two and suspected dyssynergic defecatory disorder in one. Almost 90% had functional constipation of which anal hypotension and anal hypertension may be a part of chronic functional constipation.

Diagnostic approach to faecal incontinence: What test and when to perform?

Faecal incontinence (FI) is a debilitating common end result of several diseases affecting the quality of life and leading to patient disability, morbidity, and increased societal burden. Given the various causes of FI, it is important to assess and identify the underlying pathomechanisms. Several investigatory tools are available including high-resolution anorectal manometry, transrectal ultrasound, magnetic resonance imaging, and electromyography. This review article provides an overview on the causes and pathophysiology of FI and the author’s perspective of the stepwise investigation of patients with FI based on the available literature. Overall, high-resolution anorectal manometry should be the first investigatory tool for FI, followed by either transrectal ultrasound or magnetic resonance imaging for anal internal sphincter and external anal sphincter injury, respectively.

Assessment of Gastrointestinal Autonomic Dysfunction: Present and Future Perspectives

The autonomic nervous system delicately regulates the function of several target organs, including the gastrointestinal tract. Thus, nerve lesions or other nerve pathologies may cause autonomic dysfunction (AD). Some of the most common causes of AD are diabetes mellitus and α-synucleinopathies such as Parkinson’s disease. Widespread dysmotility throughout the gastrointestinal tract is a common finding in AD, but no commercially available method exists for direct verification of enteric dysfunction. Thus, assessing segmental enteric physiological function is recommended to aid diagnostics and guide treatment. Several established assessment methods exist, but disadvantages such as lack of standardization, exposure to radiation, advanced data interpretation, or high cost, limit their utility. Emerging methods, including high-resolution colonic manometry, 3D-transit, advanced imaging methods, analysis of gut biopsies, and microbiota, may all assist in the evaluation of gastroenteropathy related to AD. This review provides an overview of established and emerging assessment methods of physiological function within the gut and assessment methods of autonomic neuropathy outside the gut, especially in regards to clinical performance, strengths, and limitations for each method.