Characteristics of Fecal Incontinence Using High Resolution Manometric assessment in Viet Duc hospital

r-u -ÍM CỊỈ ugc VHl Figure 1.2: Anatomy of anorectal area...4 Figure 1.3: Nerves of the anorectal area...5 Figure 1.4: High-resolution anorectal manometry...12 Figure 1.5: Filling the ba

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***.„

NGUYEN HUU TRI

CHARACTERISTICS OF FECAL INCONTINENCE USING HIGH RESOLUTION MANOMETRIC ASSESSMENT IN

VIETDƯC HOSPITAL

Major: General DoctorCode : 52720201

GRADUATE THESIS2015-2021

Supervisors: M.S Nguyen Ngoc Anil

Hanoi - 2021

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First of all I gratefully acknowledge the Board of President, the University Training andManagement Department of Hanoi Medical University and the Colorectal surgery center ofViet Due University Hospital for giving me the precious opportunity to do this study

Throughout the diesis I wish to express my deepest gratitude to my supervisors M.S.Nguyen Ngoc Anil for her excellent guidance, inspiration, encouragement, extremely helpfulcomments and supporting me during the process of the study

I also want to send my special thanks to all the participants My research would not havebeen possible without their cooperation

Finally I would also like to thank my friends and family who always beside me supportand encourage me

Hanoi May lOtli 2020

Student

Nguyen Huu Tri

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I hereby declare Thar the work entitled is my original work and have not been published

in any other dissertation, thesis for qualifications or any medical literature I did not copy fromany other's work or from any other sources except the attached references which were listedclearly in the text I also pledge the data collected in the thesis is completely honest

If there is anything wrong I would bear all responsibilities

Hanoi May 10th 2021

Student

Nguyen Huu Tri

CHAPTER 1: LITERATURE REVIEW 3

1.1 Anatomy and physiology of the anorectal area 3

1.1.1 General anorectal anatomy 3

1.12 Anorectal physiology and incontinence mechanism 5

1.2 General introduction of fecal incontinence 7

1.2.1 Definition and classification 7

1.22 Etiology 8

1.23 Pathophysiology 9

1.2.4 Risk factors 10

1.3 Diagnosis of fecal incontinence 10

1.3.1 Clinical manifestation 10

1.3.2 Fecal incontinence’s investigation tests 11

1.4 Treatment of FI 21

1.4.1 Nonoperative management 21

1.42 Surgery7 24

1.5 Previous researches on FI 25

1.5.1 World 25

1.52 Vietnam 27

CHAPTER 2: SUBJECTS AND METHOD 28

2.1 Subjects 28

2.1.1 Sampling method 28

2.12 Inclusion criteria 28

2.13 Exclusion criteria 28

2.2 Study settings 28

2.3 Study method 29

2.4 Research variables and indicators 30

2.5 Data analysis 31

2.6 Ethical consideration 31

CHAPTER 3: RESULTS 32

3.1. General features of study population 32

3.2. Risk factors 33

3.3. Etiology of fecal incontinence 34

3.4. HR AM in study population 36

3.4.1 Comparing men and women 36

3.42 Comparing men and women 38

3.5 Severity of FI hi research population 39

3.6. Influence of severity of FI on HRAM 39

CHAPTER 4 DISCUSSION ~ 41

4.1 General features of study population 41

4.1.1 Age 41

4.12 Gender 41

4.13 BMI 42

4.2 Risk factors 42

4.2.1 Vaginal deliver’ 42

4.3 Etiology’ of fecal incontinence 43

4.4 HR AM in FI patients 45

4.4.1 Pressure values 45

4.42 HPZ andRAIR 47

4.43 Rectal balloon volume 48

4.4.4 HR AM results comparing urge and passive incontinence 48

4.5 Severity of FI 49

4.4.1 Severity of FI comparing urge and passive incontinence 49

4.42 The correlation between FI severity and HRAM 49

CHAPTER 5: CONCLUSION -51 REFERENCES

APPENDIX 1

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EAƯS: Endoanal ultrasound

EAUS: Endoanal ultrasound

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Figure 1.2: Anatomy of anorectal area 4

Figure 1.3: Nerves of the anorectal area 5

Figure 1.4: High-resolution anorectal manometry 12

Figure 1.5: Filling the balloon during rectal sensibilty test 15

Figure 1.6: Anterior defect in external anal sphincter visualized on endoanal ultrasonography 18

Figure 1.7: MRI defecography 19

Figure 1.8: Stimulating the pudendal nerve 20

Figure 1.9: The nerves stimulator is implanted beneath the buttocks skin 24 Figure 3.1: HRA.M results comparing men and women 37

Fig 3.2: Bivariate distribution between Wexner score and maximum anal resting pressure(a) maximum anal squeeze pressure (b) 39

Fig 3.3: Bivariate disttibution between Wexner score and first sensation volume (a), max tolerable volume(b) 40

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Table 3.1: General features of study population 32Table 3.2: Risk factors comparing uige and passive Fecal Incontinence 33

Table 3.3: Causes of Fecal incontinence comparing urge and passive incontinence 34

Table 3.4: Causes of Fecal Incontinence comparing women and men 35

Table 3.5: HR AM results comparing men and women 36Table 3.6 Values of HRAM comparing passive and urge incontinence 38

Table 3.7: Wexner score in 2 different types of FI 39Table 4.1 Values of HRAM in FI and asymptomatic people 45Table 4.2 MARP and MASP comparing urge and pasive incontinence 48

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trên do áp lực hậu mòn trực tràng (ALIIMTT) độ phân giái cao tại bệnh viện Việt Đửc

Kết quà nghiên cứu: Sa tạng chậu lã nguyên nhãn phố biến nhất ờ nữ 5/9 (55.6%) trongkhi ờ nam là phẫu thuật hậu mòn trực trảng 7/9 (77.8%) ĐTKTC cẩp ki: 8/18 (44.4%) và thụđộng: 10/18 (55.6%) Khõng có sự khác biệt VC ket qua đo ALHMTT giừa 2 nhóm trừ the tíchbom bóng tối da thắp lum ớ nhõm cấp ki (90.0 ± 28.3 so vói 123.0 X 26.7 ml; p<0.05) Áp lựctrung binh cũa hậu môn khi nghi nhíu, rặn, ho lần lượt là 47,7 mmHg, 100,9 mmHg 61,1mmHg và 63.0 mmHg Ngường nhận cam cua trực tràng và khả nâng chịu đựng tối đa cua trụctràng lần lượt là 27.2 ml vã 108.3 ml Có sự tương quan rõ ràng giìra sự giam ãp lực khi nghi vànhíu cua hậu môn và the tích chịu dựng tối da cùa trực tràng vởi mức độ nặng cua bộnh (r = -0,48, - 0,50,-0,55; p<0.05)

Kết luận vã đề xuất: Đo áp lực hậu môn trực tràng độ phân giái cao cỏ giã trị trong chânđoán, đánh giã mửc độ tôn thương, lẽn kế hoạch diêu trị vã tiên lượng với bệnh nhân dại tiệnkhông tự chu

c) Từ khóa: đại tiện không tự chu do áp lực hậu môn trực tràng, cơ thắt hậu món

a) Title: Characteristics of fecal incontinence (FI) using High- resolution manometricassessment (HRAM) in Viet Due hospital

b) Abstract:

Reason for willing: Fecal incontinence lias a considerable impact on patients' quality oflife in both mental and physical well-being However in Vietnam FI has been considered as a

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patients with fecal incontinence

Methods: Case series study, IS patients diagnosed with fecal incontinence completedquestionnaire assessing clinical history’, symptoms and HRAM Statistical analysis was used toevaluate causes, risk factors, symptoms and HR AM results

Results: Pelvic organ prolapse was the main cause of FI in women: 5/9 (55.6%) whilecolorectal/anorectal surgery’ was the main cause of FI in men: 7/9 (77.8%) Urge incontinence:8/18 and passive incontinence: 10/18 In terns of anorectal manometry, no statistical differencefound between two groups, except max tolerable volume was lower in urge incontinence (90.0

= 28.3 vs 123.0 ± 26.7 mL: p<0.05) Anal pressures during resting, squeezing, straining,coughing were 47.7 mmHg 100.9 mmHg 61.1 mmHg and 63.0 mmHg First sensation volumeand max tolerable volume were 27.2 and 108.3 mL Maximum anal resting pressure, maximumanal squeeze pressure, max tolerable volume decreased significantly with increasing FI severity(r = -0.48 -0.50 -0.55; p<0.05)

Conclusion: High-resolution anorectal manometiy is valuable in diagnosis, assessment,treatment and prognosis in patients with fecal incontinence

c) Keywords: Fecal incontinence, high-resolution anorectal inanom?try analsphincters

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INTRODUCTIONFecal incontinence (FI) is defined as the unintentional leakage of solid or liquid stool

FI is a common disease with a prevalence ranging from 7 to 15% in the community,depending on the definition and the survey methods used [1] In elderly population, theprevalence is higher, up to 47% [2]

Fl has a considerable impact on patients' quality of life Fear of public humiliation canlead to social isolation, loss of employment as well as ruining relationships and lower self-esteem Physical complications include pain, infection and skin-ulcer which is more severe inolder patients

The incidence of FI is elevated in recent years associated with risk factors such asdiabetes mellitus lower gastrointestinal surgery and stroke Because FI is a significant issue,many studies are conducted annually However, in Vietnam Fl has been perceived as a non-serious problem by both healthcare providers and scientists Therefore FI patients often seekhealth care in severe leakage conditions

A thorough assessment of fecal incontinence is critical for the evaluation andmanagement of the anorectal disorder Anorectal manometry is an important diagnostic tool toevaluate anorectal motor and sensory function In patients with FI anal resting and squeezepressures help determine the presence of internal anal sphincter (IAS) and external analsphincter (EAS) dysfunction Measurements of anorectal function can help to establish a properdiagnosis for effective management Initial treatments include patient education for dietchanges, bowel training and exercises to sttengthen pelvic floor muscles Some researches showthose treatments can improve the symptoms about 60 percent [3] Conservative treatment withbiofeedback therapy, electrical stimulation were also recommended Surgery' like sacral nen estimulation may be an option for patients that fails with conservative treatments, or for fecalincontinence caused by pelvic floor muscles or anal sphincter injuries

In the world, there have been many studies on fecal incontinence because ofsignificant effect on quality of life In Vietnam due to rhe lack of data on diagnosis and

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management of fecal incontinence, it requires more studies to evaluate different characteristics

of patients with FI for an optimal individualized treatment plan Thus, we conducted this study

"Characteristics of Fecal Incontinence Using High-Resolution Manometric assessment in VietDue hospital" with two aims:

1 Evaluate clinical characteristics of patients with fecal incontinence.

2 Evaluate characteristics of high-resolution anorectal manometry assessment in patients with fecal incontinence.

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CHAPTER 1: LITERATURE REVIEW

1.1 Anatomy and physiology of the anorectal area

The rectum and anal canal are tile terminal parts of the large bowel The anorectal canalhas the important function of regulating defecation and the role of controlling fecal continence

1.1.1 General anorectal anatomy

The rectum is a hollow muscular tube, 12 to 15 cm long, composed of a continuous laser

of longitudinal muscle that internsine ssith the underlying circular muscle The anus is a tube ofmuscle ssith a length of 2 to 4 cm At rest, it forms an angle of roughly 90 degrees with the axis

of the rectunt.[4] During defecation, the anorectal angle becomes more obtuse, whereas during

voluntary squeeze, this angle becomes more acute (Figure 1.1)

Source: Satish S.C.Rao- 2016 [5]

• The Anal Sphincter

The anal sphincter is formed from 2 muscles: the internal anal sphincter

(IAS) and tlie external anal sphincter (EAS) (Figure 1.2) The IAS is a mostly

Resting defecation Normal

Figure 1.1 Anatomical Struct toe of the anorectum

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fatigue-resistant smooth muscle [6].[7] The IAS contributes approximately 70% to 85% of the resting sphincter pressure [8] In this way the IAS is primarfly responsible for maintaining anal continence at rest Normally the anus is closed by tile contraction of the IAS This barrier is strengthened during voluntary' squeeze by the EAS During defecation the IAS is relaxed and become vertical, the lumen is opened which allows the stool to pass distally.

The EAS is a cylindrical striated muscle under voluntary control and comprisespredominantly slow-twitch muscle fibers which enables it to have prolonged contraction [9].Sex-related differences include a fundamentally shorter external sphincter in women than inmen both laterally and anteriorly [10] The EAS lias a resting contraction that conưibutes about20% of anal resting pressure (8) EAS activity is innervated by somatic nenes, the right and leftinferior rectal nerves, each derived directly from the corresponding pudendal nene (S2-S4)

Source: Frank H Nett er Atlas of Human Anatomy [11]

Ọạndi and Haws in Penanal Skin External sptuncter

HuKle

F/gi/re 1.2: Anatomy of anorectal area

Internal StAexter Mwtcte

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• Nen e Structure and Sensation

The anorecrum is richly innervated by the sensory; motor, and autonomic nerves and bythe enteric nervous system The principal nerve is the pudendal nerve, which arses from the

second, third, and fourth sacral nerves (S2, S3, S4) and innervates the EAS (Figure 1.3).

Pudendal nerve block can lead to a loss of sensation in the perianal and genital skin andweakness of the anal sphincter muscle but rectal sensation is not affected [8Ị

Figure 1.3: Nenes of the anorectal area

Source: Frank H Neuer Atlas of Human Anatomy[11]

The sensation of rectal distention is most likely transmitted along the S2 S3, and S4parasympathetic nerves which are independent of the pudendal nerve [4] If parasympatheticinnervation is impaired, rectal filling is only- perceived as a vague sensation of discomfort [4].Thus, the sacral nerves play an important role in the maintenance of fecal continence

1.1.2 Anorectal physiology and incontinence mechanism

The recto-anal canal serves two important functions, the fecal continence and defecation

Normal anal continence allows emission voluntarily conuolled periodic, and selective ofthe various contents: gas or liquid and solid stool In normal conditions and during the filling ofthe rectal ampulla, continence is achieved by the conttaction of the internal anal sphincter Thedistension of the rectum activates the recto-anal inhibitory reflex with consequent relaxation of

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the internal spliincter and this causes a small amount of fecal material to come in contact withthe mucous membrane This is rich in nerve endings and can differentiate the feces from the gasand decide whether or not to defecate [12] If defecation should be delated, the voluntarycontraction of the external anal sphincter sends back fecal material, postponing the stimulus.Continence is based on two main elements: the ability of the rectum to host feces and anal lockmechanism (the ability of closing anal canal), which, together with the ability of sensor)'discrimination of the anal canal, prevents the involuntary leakage of stool

The defecation reflex is an act that takes place under the control of will When the fecesreach the rectum this is stretched When the person decides to defecate: Illis decision implies asitting position with hip flexion that results in the disappearance of the angle between the analcanal and rectum and a complex defecator)' mechanism begins The first occurs when the rectum

is distended by feces; a peristaltic wave is generated to push the stool from the sigmoid colonand rectum to the anus This reflex is however, weak and to cause defecation must be reinforced

by the reflection of the parasympathetic that amplifies peristaltic waves and transform the reflex

of defecation in a powerful process to allow emptying of the rectum and anus The afferentimpulses arriving at the spinal cord give rise to other effects: deep breathing

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closure of the glottis, and contraction of the abdominal muscles, to increase the abdominalpressure, which in turn increases the rectal pressure to push out the feces For defecation tooccur, the voluntary' mechanism is indispensable as it inhibits the external anal sphincter becauseIllis normally contracts with the arrival of stool

• Incontinence mechanism

The ability to control evacuation is guaranteed by many factors These include intact analsphincter mechanism, stool volume and consistency, intestinal motility, pelvic floor structuralintegrity, cortical awareness, cognitive function, mobility' and access to facilities Incontinenceoccurs when one or more of these mechanisms are impaired and the remaining mechanisms areunable to compensate Although the integrity of the sphincteric mechanism plays a major part,tliere a re other important aspects, such as stool volume and consistency, colonic transit, rectalcompliance and sensation, anorectal sensation and anorectal reflexes

1.2 General introduction of fecal incontinence

1.2.1 Definition and classification

Fecal incontinence is the inability' to control bowel movements causing stool (feces) toleak unexpectedly from the rectum

There is no widely accepted approach for classifying FI Currently FI is classified byseparated systems based on etiology', pathophysiology (i.e., bowel disturbances, anorectaldysfunctions), type of leakage (urge, passive, or combined), or symptom severity' scales

Commonly, the classification based on the type of leakage is used:

-r Urge incontinence: tire patient has a sudden urge to use the bathroom but is unable toget there in time

* Passive incontinence: Because of the loss of sensations in anorectal area, patients can'tconsciously control their defecation and stool is passed without their knowledge [13]

+ Combined incontinence: Patients have both urge and passive incontinence

1.2.2 Etiology

There are many different causes of FI in a patient FI is often the result of a combinations

• Nen e damage

If the nerves that innervate sphincter motor are injured, the sphincter muscles won’tclose properly Moreover, patients may lose the sensation of the urge to go to the bathroom.Some causes of nene damage are trauma from giving birth, chronic constipation, stroke, diabetesmellitus multiple sclerosis

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• Pelvic floor dysfunction

Women can experience damage to the muscles and nenes in their pelvis while givingbirth, but symptoms of peine floor dysfunction may not be immediately obvious They mayoccur after years Besides fecal incontinence, two common complications of this condition arerectal prolapse or rectocele

I.2J Pathophysiology

A majority of patients with FI have reduced anal resting and/or squeeze pressures,reflecting the weakness of the internal and/or external anal sphincters respectively [14] Analsphincter damage, which is most frequently caused by obstetric or iatrogenic trauma, orneurogenic injury can cause anal weakness Neurogenic lesions can occur at any level of the axisextending from the central nervous system to the external anal sphincter In addition to analsphincter injury FI is also associated with atrophy, denervation and impaired function of thepuborectalis muscle Excessive straining may cause increased perineal descent, which can stretchand thereby damage the pudendal nen e and also make the anorectal angle more obtuse

Patients with FI may have normal, reduced, or increased rectal sensation [14], Whenrectal sensation is leduced the external anal sphincter may not contract promptly when rherectum is distended by stool, predisposing to FI Conversely, rectal hypersensitivity in FI may bepartly secondary to an exaggerated contractile response to distention, and/or reduced rectalcapacity, and may explain the symptom of rectal utgenev [15]

In summary, multiple physiological mechanisms preserve continence Deficits in any ofthese mechanisms may contribute to FI and as a consequence no single physiological measure isconsistently associated with FI

1.2.4 Risk factors

According to Norton et al FI had a lot of risk factors [16]:

- Patient characteristics: Increasing age gender women, obesity, poor general healthand physical limitations

- Neurological disease or injury (learning disability, dementia, spinal cord injury,multiple sclerosis, stroke head injury, diabetes msllitus)

- Surgical procedures: Sphincterotomy, hemorrhoidectomy

- Urinary incontinence and pelvic organ prolapse

- Dings (antibiotics, laxatives, digoxin, orlistat) dietary supplements (lactose, fructose,artificial sugars)

13 Diagnosis of fecal incontinence

1.3.1 Clinical manifestation

Fecal incontinence can involve recurrent or infrequent involuntary leakage, an inability tohold in gas silent leakage of feces during daily activities or exertion, or not reaching thebathroom in time

The consistency' of stools passed during bowel incontinence can vary solid, liquid, gas.The leakage may occur daily, weekly, or monthly

Associated signs and symptoms may include abdominal pain, bloating, flatulence orboth, constipation or diarrhea the anus is irrflated or itchy, urinary incontinence

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Fecal incontinence can be a relatively small medical issue, bringing about the occasionalsoiling of underwear or it can be severe, with a total lack of bowel control

1.3.2 F'ecal incontinence's investigation fests

A -wide range of tests is available to facilitate the diagnosis and management of FI.Imaging tests, physiology tests, and nerve studies have all been described In Vietnam high-resolution anorectal manometry and endoanal ultrasound are two budget-friendly tests thatprovide useful information are mostly used in clinical practice

1.3.2.1 High-resolution anorectal manometry

• Introduction

High-resolution anorectal manometry (HRAX1) was first introduced in 2008 [17] is aninstrumental examination evaluating the pressure of the anal canal and the distal rectum givingmotor and sensory information on functional phases of defecation the continence of tíreanorectal tract and of tire pelvic floor muscles It measures the luminal pressure along 6-8 cmabove the anal verge [18] and in particular, it allows to evaluate:

The high-pressure zone (which refers to the length of the anal sphincter muscles)

The involuntary function of the anal canal at rest

The voluntary anal function on squeezing

The rectoanal reflexes

The rectal sensitivity and compliance

The rcctoanal coordination during simulated defecation ("push”)

The capacity to expel a balloon

• Equipment

Firstly, the pressure is recognized by a solid-state catheter (probe) which has an outerdiameter of 4.2 mm (figure 1.2a) There are 2 versions of this catheter: The regular probe has 12circumferential sensors, including ten sensors at 6-mm intervals along the anal canal and twosensors in the rectal balloon (3.3 cm long, maximum capacity of 400 mL) The small probe lias 8circumferential sensors in total with 1 balloon sensor A latex-free rectal balloon that is 3.3 cm

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long and lias a maximal capacity of 400 niL is recommended to be used In both types of probe,each sensor has 36 circumferentially oriented, pressure-sensing elements that generate anaveraged single value at 35 Hz

The manometry and topographic images are shown on a computer screen using specializedsoftware (Figure 1.2b) The system operates at a frequency response of > 20 Hz and an outputresolution of 0.1 mmHg The probe is calibrated immediately before the procedure by putting it

in a calibration chamber, where it becomes zeroed to atmospheric pressure and set to a scope ofpressures up to 300 mmHg [17]

- *

Figure 1.4: Higỉì-resoluíion anorectal manometry

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At rest, during squeeze, and rectal distention the software recognizes the highest of allpressures recorded by anal sensors at every point in rime T1ŨS value is then used to identify theaverage and maximum anal resting pressure and the maximum squeeze pressure In addition,rectal pressure is also reported to evaluate other anorectal functions

The patient (who should do an evacuation enema a few hours before the examination) isplaced in left lateral decubitus with overlapping thighs atri bent at 90° on tile trunk: the catheter

is then inserted into the rectum

• Procedure of high-resolution anorectal manometry

- Patient preparation: Bowel preparation with Fleet enema or defecation 2 hours beforethe test

- Patient position: left lateral decubitus with overlapping thighs and bent at 90° on tiletrunk

- Implementing: After digital rectal examination, a lubricated catheter with a balloonattached is then inserted into the rectum until only the 8th sensor is outside the anus

- Rest: Give tire patients time to relax for 5 minutes

-Squeeze: The patient is instructed to squeeze the anal sphincters for 20 seconds or aslong as possible

- Push (Bearing-down): Strain as forcefully as possible, hold on 10 to 20 seconds

- Cough: The subject is asked to give 5 to 7 coughs

- Recto-Anal Inhibitory Reflex (RAIR): Inflate the balloon with 10 mL of air throughcenter canal (balloon was attached to the head of catheter), after 3 to 5 seconds fast withdraw theair to deflate the balloon totally

- Repeat this maneuver several times (in 20-second gaps) and each time, inflate theballoon with an additional volume of 10 ml air

- Inflate the balloon to evaluate rectal sensitivity balloon volume for the first sensation,for constant desire to defecate, for maximum tolerable sensation

+ Finish the test: Air withdrawal and catheter extraction, data analysis and then print out

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tile result

• Interpretation of high-resolution anorectal manometry results

Functional anal canal length (cm): determined by length of the zone in which pressure ishigher 5 mmHg than atmospheric pressure

Resting pressure: the pressure in the high-pressure zone at rest after a period ofstabilization Physiologically the anal resting tone is predominantly generated by internal analsphincter (70-85% pressure) Measuring the resting pressure is to evaluate function of IAS

Squeeze pressure: is the pressure increment above resting pressure following voluntatysqueeze contraction and is a calculated value that is tile difference between the maximumvoluntary’ pressure and the resting pressure at the same level of the anal canal Squeeze pressure

is related to function of the EAS

Strain pressure: the patient is asked to sưain or bear down, as during defecation, whilepressures of anus and rectum are detected simultaneously; normally an increase in intrarectalpressure is detected, due to the Valsava maneuver associated with a decrease in intraanalpressure, due to coordinated relaxation of the E AS

Cough pressure: the patient is asked to cough several times In particular, coughincreases abdominal pressure and rectal pressure triggers a reflex contraction of the EAS Theintegrity of Valsava reflex acts to maintain anal continence in urgency This contraction isrecorded with an increase in the pressure recognized by the manometer, and cough pressure iscalculated

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as the difference between the maximum pressure recordid during cough and the restisig pressure

at the same level in the anal canaL Cough pressure and rectoanal inhibitory reflex (RAIR) areused to assess the integrity of neural reflex pathway

Rectoanal inhibitory reflex (RAIR): the transient decrease in resting anal pressure inresponse to rapid inflation of a rectal balloon with subsequent return to baseline The balloon isinflating with air (up to about 50- 00 cc or higher volumes in some cases with chronicconstipation and megarectum); in this way is recorded the threshold volume needed to elicit thereflex

Rectal sensibility test: A balloon distention, positioned in the rectum, filled (manually

using a hand-held syringe or pump assisted) with air or water (Figure 1.5) During the test,

patient is instructed to report the first sensation that is the minimum rectal volume perceived bythe patient, constant that is the volume associated with the initial uige to defecate, maximumtolerated volume tliat is the volume at which the patient experiences discomfort and an intensedesire to defecate, and pain

Figure 1.5: Filling the balloon during rectal sensibilry test

Source: Bruno - 2015 [19]

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Defecation index: Ratio of maximum rectal strain pressure/ minimum anal strainpressure During normal defecation, it is intuitive that rectal pressure should exceed analpressure The defecation index is a simple and useful quantitative assessment ofrecto>anal co-ordination during defecation

Table 1.1: Normal Values of anorectal manometry

Mean Values Asymptomatic people Mean(SD)

al

Source: Mion etal [20]: NgocAnh et a [21]; Yuwei Jet al [22]

• High-resolution anorectal manometry in Fl

There is general agreement that the anal sphincter mechanism is the most importantbarrier against leakage of rectal contents [23]

According to Rasmussen et al., typical anorectal manometry' results of FI are [24]:

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- Low anal resting pressure: weak IAS

- Low anal squeeze pressure: weak E AS

- Low first sensation volume

- Low maximum tolerable volumes

Mion et al conducted a prospective multicenter study in three groups of subjects: healthyasymptomatic controls, patients with FI and patients with chronic constipation to evaluate howHRAM could differentiate patients with FI or chronic constipation from asymptomatic subjects

To distinguish FI from asymptomatic women, tlie most important discriminant variable wasmaximum squeeze pressure [20] Rectal constant defecatory sensation and maximum tolerablevolumes were significantly lower in the FI women, compared to asymptomatic women

In another study, the authors developed and evaluated a robust prediction model todistinguish patients with FI from controls FI severity index scores correlated with low restingpressure (r = 0.34) and maximum squeeze pressure of the anal canal (r = 0.28) The combination

of pressure values, anal sphincter area, and reflective symmetry values differentiated FI patientsand controls with good accuracy (AƯC: 0.96) [25],

1.3.2.2 Endoanal Ultrasound

Since its first introduction ini 989 endoanal ultrasound (EAƯS) has played a firm role indie diagnostic work-up of FI [26] It provides an objective assessment of the of anorectalmuscles integrity and can promptly diagnose injuries or anatomic defects of the internal andexternal anal sphincters

EAƯS is performed utilizing a hal'd probe that rotates 360 degrees creating a circularimage of the anal sphincter complex The anal canal is visualized from the proximal to distalaspect and has several distinctive findings Throughout its length The IAS is showed hypoechoic.whereas the EAS appeal’s both of mixed echogenicity and hyperechoic due to being made ofskeletal muscle These differences result from the increased connective tissue present in skeletalmuscle [2Ó] The proximal anal canal is easily recognized by the conspicuous puborectalismuscle, which forms a posterior sling around the anal canal The mid-anal canal is recognized byboth IAS and EAS whereas the distal anal canal is characterized by a tliinness-to- disappearance

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of tile IAS Muscular injuries are visualized as breaks in either the hypoechoic band of the IAS

or as a break in the hyperechoic band of the E AS {Figure 1.6).

Figure J 6: Anterior defect in external anal sphincter visualized on endoanal

ultrasonography

Note: Area of interiuption of external anal sphincter marked by white aiTOws

Source: Olson, C.H (2014) Diagnostic testing for fecal incontinence Clin

Colon Rectal Surgery 27 S3-90 1.3.2.3 Defecography

Fluoroscopic defecographv shows the motion of anorectal area during defecation This test

is routinely performed in the seated position subsequent

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to inserting radio-opaque material into the rectum The patient is then asked to defecate whilereal-time fluoroscopic images are gathered to form a set of photos arranged in chronologicalorder In general, these images require expertise to interpret, and can be misleading at times [27].For these reasons, there is interest in magnetic resonance (MR) defecographv; where real-timecine-MR techniques are used to evaluate the rectum and pelvic organs during the act of

defecation (Figure, 1,7), MR imaging (MRI) lias the advantage of showing Ollier pelvic

anatomy, including the vagina, bladder, uterus, and small intestine, which supports theinterprelation of the images [28] In addition, it can uncover anatomic information about the analsphincter muscles

Figure 1.7: MRJ defecography

Note: (A) Anatomy before act of defecation: (B) Internal intussusception as

seen as a chevron sign (arrow) observed during the act of defecation

Source: Olson C.H (2014) Diagnostic testingfor fecal incontinence.

Clin Colon Rectal Surg 27 85-90 1.3.2.4 Pudendal Motor Nerve Terminal Latency

Sensory and motor nenes signal from or to the anal canal is transmitted by the pudendalnene Nene damage can occur with pregnane}* or several medical disorders, such as diabetesmellitus and multiple sclerosis While at first, tills may present as a solitary problem, it is oftenassociated xxith decreased resting and squeeze pressures as the absence of innervations leads todefects of muscle functions

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In this test, the technician applies the gloved finger fixed with a St Mark's elecnode in

the rectum on pudendal canal (Figure 1.8) A small electrical stimulus is applied to the pudendal

nerve in this area and results in contraction of the external anal sphincter, which is measured byelectrodes on the palm of the St Mark’s device This is then used to measure a “latency" or howlong it takes the nerve to conduct the stimulus external anal sphincter to contract Normalpudendal motor nene terminal latency (PMTNL) is 2.2 - 0.2 ms [26]

PMTNL testing has been stated to proxide prognostic data for patients before undergoingsphincteroplasty in one study, where an abnormal PMTNL was shown to have a significantlyhigher rate of failure of sphincteroplasty surgery to restore continence [29]

Figure 1.8: Stimulating the pudendal nene

Note: The nerve stimulator mounted on the finger

1.3.2.5 Electromyelography

This testing involves direct testing of the external anal sphincter by placing an electrode inthe muscle; a surface variant has also been described [30] Gix-en the lack of comfort associatedxxith the exam, it is infrequently used

1.4 Treatment of fecal incontinence

So far the treatment of FI is challenging and needs to be individualized [31].[32] Apartfrom conservative and supportive measures, a number of interventions are available tliat vaiy inefficacy and morbidity So tiiat options introduced below are only ones recommended inguidelines [33].[34] In general, treatment options of FI can be separated into two groups:nonoperative options and surgical options [34],

1.4.1 Conservative management

to increased volume and liquid consistency of stools [36].[37].[38] Besides, concerns of dietmanipulation are nutritional deficiencies and subsequent frailty.

1.4.1.2 Drug Treatment

The pharmacological administration of FI lias focused on three approaches

+ Treatment of Diarrhea-Associated FI With Anti-Diarrheal Drugs: The most widelytested medication for diarrhea-associated FI is loperamide All studies support the efficacy ofloperamide for decreasing diarrhea associated FI One study recommends that amitriptyline is ofpossible advantage for treating FI [39] There are two possible mechanisms of action recognized

in these studies: decreasing bowel movement frequency through an effect on motility andabsorption or increasing resting anal canal pressures

4* Increasing anal canal pressure in patients with passive FI: Phenylephrine gel and ervthro methoxamine gel, an alpha-1 adrenoreceptor agonist have been shown to improveinternal anal sphincter resting pressure, which is low in ARM of patients with passive FI [40],[41]

L-+ Drug Treatment of Constipation-Associated FI: Constipation- associated FI sometimesreferred to as "overflow incontinence”, occurs more frequently at the end of the lifespanConstipation-associated FI in nursing homes is regularly treated with the prescription of daily orfrequent laxatives Treating with sorbitol was found to significantly decrease the patients’nursingtime [42]

1.4.1.3 Biofeedback therapy

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Bio-feedback treatment of fecal incontinence was introduced by Engel and coworkers 30years ago [43] The term bio-feedback training refers to the utilization of various devices(mechanical, electrical) that are supposedly able to increase the awareness of a biologicalresponse, so that patients can learn to improve their voluntary control of anorectal function [44].Bio-feedback training sessions are usually associated with home practice training (Kegelexercises), with the purpose of strengthening muscle strength through an increase in the number

of muscle fibers innervated by existing nerves It is commonly believed that biofeedback is notable to repair or form new neural pathways For instance, a cause of fecal incontinence is the loss

of the ability' to feel rectal fullness, a major point for contracting the pelvic floor muscles toavoid incontinence In these patients, the objective of bio-feedback training is to improve dieability to recognize rectal filling through sensory retraining [45].[46]

Patients were taught to improve their ability to voluntarily contract the external analsphincter during rectal filling, either by improving the strength

of the sphincter (motor skills training) or by improving the ability- to perceive weak rectaldistention (discrimination training) or by combining the previous two mechanisms (training inthe coordination of sphincter contractions with rectal sensation) No side effects were found, andthe treatment was generally well accepted

1.4.1.4 Electrical stimulation therapy

Electrical stimulation is administered in different ways, utilizing many differentstimulation parameters and is often used in conjunction with other therapies One populartechnique is using a catheter which was placed into the anal canal The stimulation effect wasgenerated through two approaches One was the endo-anal method mostly used and the other wasthe external approach used only if the patient could not tolerate the endo-anal method Electricalstimulation comprises of pulses that trigger action potentials controlling muscle contraction.Contraction is sustained by perhaps 20 to 120 action potentials per second (Hz) Pulses of thatfrequency are applied for some seconds at a time with some seconds rest in between

The purpose of electrical stimulation is stated variously as enhancing the strength, speed,

or endurance of voluntary anal sphincter contraction, or to enhance sensation and tiius the ability

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to perform exercises or voluntarily contract the anal sphincter in response to an uige to defaecate.The precise mechanisms by which electrical stimulation can restore fecal control are notwell-understood Elecưical stimulation is known to improve muscle function by transformingfatigable fast-twitch muscle fibers to less- fatigable slow-twitch ones and it also increasescapillary density will ch supports the efficient working of these slow, oxidative fibers However,apart from physiological changes, the most important mechanism of improved fecal control is anenhanced sensation of the anal sphincter

Muscle transposition: In the rare situations where sphincteroplasty is not available because

of extensive injury to the pelvic floor or to its nerve innervation, a neosphincter may beperformed by wrapping the anal canal with one of the gracilis muscles or with a flap of glutealmuscle The outcomes for these operations are dramatically improved by implanting an electricalstimulator which artificially keeps the neosphincter in a state of contraction The electricalstimulator is turned off when patients desire to defecate Successful outcomes have been reported[49].[50]

Sacral nerve stimulation (SNS): During sacral nene stimulation, a surgically implanteddevice delivers electrical impulses to the nerves that regulate intact but functionally deficient

sphincter The unit is placed beneath the skin of the buttocks, near the sacral nenes (Figure 1.9).

Figure 1.9: The nerves stimulator is implanted beneath the buttocks skin

Source: Mayoclinic - 2019

SNS was first reported for the treatment of fecal incontinence by Matzel and colleagues in

1995 [51] The technique includes two stages In the first stage, an intraoperative peripheral neneevaluation is used to identify- the most efficient spinal nerve of sacral nerves for stimulation,followed by a temporary stimulation period of 1 to several weeks In the second stage, if fecal

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incontinence improves during this evaluation period, patients are then offered permanentelectrode implantation In a studs- conducted bv Mellgren et al 110 FI patients were treated bySNS, after 3 years follow-up 86% of patients (p < 0001) reported >50% reduction in thefrequency of incontinent compared with baseline, the number of incontinent episodes per weekdecreased from a mean of 9.4 at baseline to 1.7 times per week 40% of patients achieved perfectcontinence

1.5 Previous researches on fecal incontinence

The statements about the prevalence of fecal incontinence differ significantly in theliterature In 2002 Jamshid s Kalantar stated that 11% of people were suffered from fecalincontinence in the community aged 18 years and older which included 2% and 9% for solid andliquid fecal incontinence respectively [52] In 2010 in a multi center study carried out on 5 18adults, the prevalence of fecal incontinence was reported to be 10.8% [53] In Illis study,although the proportion for men (8.6%) is lower than that of women (12.0%) there is nostatistical noticeable difference between genders In 2016 in a systemic review A Sharmafound that the overall fecal incontinence prevalence was lower, ranging from 4.2-7.6% of thecommunity [54 ]

In ait attempt to assess the severity of fecal incontinence, several scales were introduced

In 1983 Browning and Parks produced one of the first scoring systems [55] This scale had theadvantage of simplicity but only assessed whether the patient was incontinent for solid or liquidstool or flatus

In 1993 Wexner developed the first incontinence scoring system to take into accountusage of pads and lifestyle alteration as well as the consistency and frequency of incontinence[56] In this scale, the total score ranges from 0 to 20 where score 0 means perfect continenceand 20 means complete incontinence

Regarding the application of HRAM in fecal incontinence, in 2014 Manuel A AmarisSphincter found that anal sphincters defects could be evaluated by HRAM which were defined

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by non-physiological localized gaps in resting pressure (internal anal sphincter defect) and/orsqueeze pressure (external anal sphincter defect) in topographic pressure maps In 2019 Zifandeveloped and evaluated a prediction model to differentiate fecal incontinence patients fromhealthy ones using HR AM FI severity index scores are stated to correlate with low restingpressure (r = 0.34) and peak squeeze pressure of tire anal canal (r = 0.2S) [25]

In terms of ưeatment in 1990 in a review study, Vera Loening-Bauke concluded thatbiofeedback had a greater impact on FI caused by anorectal surgery than nonsurgical causes [57].Besides, biofeedback training was reported to result in continence or significantly reduce thefrequency of incontinence in 70-83% of patients However, in 2003 Norton et al concluded thatthere was no difference between the biofeedback and general incontinence advice on any of thefecal incontinence outcomes recorded at 12 months follow-up [58] In comparison with othertreatment options, biofeedback shows no statistical differences with pelvic floor muscle warning[59] [60] and medication treatment [61]

In 2000 in a study about sacral nerve stimulation Vaizey found a significant increase insphincter pressures in the treated group, and

interestingly, this increase was maintained when the stimulator is turned off [62] In 2004.O'Brien Ct al reported the results of 14 adults with severe fecal incontinence who wererandomized to placement of an artificial anal sphincter (n=7) or supportive care (n=7) At 6months follow-up there was a significant difference between groups in the Cleveland ClinicIncontinence Score and in the American medical systems quality of life score favoring the artificial anal sphincter group [63]

Viet Due University Hospital had several studies evaluating the efficacy of suigical