Anorectal manometry

There are limitations to the reproducibility and reliability of anorectal manometry across institutions. However, a standardized protocol should be used within each institution. Tests are helpful in predicting realistic expectations from surgery and also in explaining the scope of problems to patients.

Anal manometry is not a single test but a series of measurements used to assess anal sphincter function, rectal sensation, rectoanal reflexes and compliance of the rectum (Kourakalis and Andromanakos 2004). The use of pull-through anal manometry allows assessment of the length of the functioning sphincter, resting pressures give a good estimation of internal sphincter function, and squeeze pressures assess external sphincter function. The patient is usually placed in the left lateral position, and manometry can be performed either using stationery pull-through or continuous pull-through techniques. Many catheters have four or eight channels, and these can therefore record different pressures in different parts of the external sphincter and internal sphincter at different levels. Using vector analysis, it is possible to look at the symmetry of the anal canal pressure, and combining this with anal ultrasonography can show whether there is a structural as well as a functional problem in either of the sphincter muscles. The rectoanal inhibitory reflex is usually assessed during the physiology. Absence of this may indicate a longstanding problem such as Hirschsprung’s disease. Rectal distension is assessed by inflating a balloon within the rectum; measurements are taken when the patient first feels the sensation of rectal filling, the feeling when there is maximum fullness, and then the feeling of urgent desire to defaecate. This can be extended to when the volume is unbearable. If the rectal threshold is low, even with a normal anal pressure, continence may be impaired.

Anal skin sensation is usually assessed by some form of electrical stimulation. Pudendal nerve terminal motor latencies are performed by stimulating the pudendal nerve transanally through the lateral wall of the rectum as the nerve transverses the ischial spine, using a St Mark’s electrode on the tip of the examining finger. The normal delay between stimulation and recording is less than 2.2 ms and a longer delay suggests that there has been damage to the pudendal nerve. A lengthening of the pudendal nerve latency is often associated with poorer outcomes after surgery, and may suggest that the patient’s incontinence is associated with nerve damage. An important outcome measure for sphincter repair is whether there is any pudendal neuropathy, as patients with pudendal neuropathy only have a 10% chance of success compared with 80% in patients without pudendal neuropathy (Laurberg et al 1988).

Ultrasound and dynamic imaging

The investigation of choice for structural abnormalities within the anal sphincter is a three-dimensional anal ultrasound. A data set can be captured and then manipulated at a later date to look at structural abnormalities throughout the anal canal (Figure 59.1).

Figure 59.1 Three-dimensional anal ultrasound.

Length of sphincter, damage to internal and external sphincters, and presence of sepsis or abnormalities can all be assessed.

Using the same anal probe transvaginally, it is possible to examine the levator plate and many other anatomical aspects of the pelvic floor. Asymmetry within the levator plate suggests damage during childbirth and often leads to the anus being diverted to the side of the damage (Figure 59.2).

Figure 59.2 Transvaginal scan of pelvic floor.

Dynamic images of the bladder and rectum can be taken using an 8848 transvaginal scanner, looking for perineal descent as well as enteroceles, rectoceles and rectal intussusception.

Further assessment of the pelvic floor often requires some form of proctography. In order to assess the whole pelvic floor using defaecating proctography, patients require not only contrast within the rectum but also in the small bowel, vagina and bladder. Defaecatory magnetic resonance imaging (Figure 59.3) can show all these parts of the pelvic floor. There are very few open magnets where a patient can sit and defaecate; therefore, the majority of these studies are performed with the patient lying prone.

Figure 59.3 Rectocele seen on dynamic magnetic resonance imaging.

It has been shown that magnetic resonance proctography shows increased evidence of other pelvic floor abnormalities over defaecating proctography. However, it underestimates the size of rectoceles and intussusception (Pilkington et al 2009).

Shapes study

By marking and counting the passage of ingested radio-opaque markers on a plain abdominal X-ray, it is possible to make an estimate of segmental and total colonic transit times. In a simplified method, 20 radio-opaque markers are ingested and an X-ray is taken at 60 and 96 h. Transit through the whole colon of more than 67 h is considered abnormal. Transit time is prolonged in 80% of patients suffering from constipation.

It is essential that all of these investigations are taken into consideration along with a full pelvic floor history and diary of bowel habit problems. Discussion at a pelvic floor multidisciplinary team (MDT) meeting allows every compartment to be assessed in equal relevance.

Haemorrhoids

The term ‘haemorrhoids’ (also known as ‘piles’) is generally used to describe enlarged anal cushions which become symptomatic through symptoms of either bleeding or prolapse. However, correlation between symptoms and the treatment of haemorrhoids is poor. Haemorrhoids and associated symptoms are an extremely common problem, presenting in patients at general practitioners’ surgeries and coloproctology clinics. During their lifetime, many patients will present with symptoms of rectal bleeding and many of these will have bleeding secondary to piles. It is most important to ensure that there is no other treatable or more serious problem relating to this bleeding, such as cancer, polyps or inflammatory bowel disease.

Piles often present with a combination of symptoms, including itching, soreness, postdefaecatory leakage and lumps around the anus. It is thought that the sliding anal canal theory proposed by Thompson (1975) is the most likely cause of piles, where Treitz’s muscle is stretched repeatedly resulting in fragmentation of the connective tissue. Haemorrhoids may be small and highly symptomatic, or large and asymptomatic. This is especially so in elderly female patients where normal anal canal pressures are low, and this can result in prolapse but little in the way of symptoms. Several classifications of haemorrhoids have been used over time. Goligher’s classification (Goligher 1976) describes the degree of prolapse and whether these reduce spontaneously (grade 2), require manual reduction (grade 3) or are permanently prolapsed (grade 4). However, although this is good for the description, it does not consider the symptoms of the piles. Work by Lunniss and Mann (2004) has produced a more accurate and useful classification of haemorrhoids, dividing them into non-prolapsing and prolapsing, looking at not only the morphological presentation but also any additional features such as pruritus or pain.

The diagnosis of haemorrhoids relies on a good history, exclusion of other possible causes of these problems and then a thorough clinical assessment. Anal pain may be associated not only with haemorrhoids but also abscesses, fistulae or fissures. Discharge and pruritus may be associated with warts, hypertrophied anal papillae or rectal prolapse. Anal incontinence is usually secondary to internal sphincter dysfunction and a lump or prolapse. Inspection of the perianal area may be done with the patient either lying in the left lateral position or with legs up in a gynaecology chair. The presence of anal skin tags is often suggestive of previous episodes of haemorrhoidal prolapse. If the haemorrhoids are associated with a predominant feature of itching, skin may be macerated or discoloured, and the presence or absence of scars or previous surgery should also be determined.

Second- or third-degree piles may become evident on asking the patient to bear down, and fourth-degree piles should be obvious at the time of examination. Palpation of the rectum is essential in order to exclude any other pathology, although the piles themselves are not easily examined as, by virtue of the nature of the anal canal and the soft tissues, no lumps will usually be felt. However, at the time of digital examination, it is also prudent to examine both the squeeze and the resting pressure associated with the anal canal. A proctoscopy is essential in examining for haemorrhoids, although internal haemorrhoids may be well visualized using an internal flexible sigmoidoscope.

Anal fissures

Patients with pelvic floor straining and post childbirth often present with anal pain associated with an anal fissure. An anal fissure is a tear running longitudinally in the epithelium of the anal canal, the majority of which lie posteriorly in the midline. Acute fissures are usually superficial, whereas chronic fissures may be associated with secondary changes including a sentinel tag or hypertrophied anal papilla. As with all acute and chronic anal conditions, efforts should be made to identify any precipitating causes or associated diseases (Crohn’s disease or anal carcinoma). A recent consensus statement from the Association of Coloproctology of Great Britain and Ireland covers aspects of diagnosis and treatment (Cross et al 2008). The most common presenting features are pain during defaecation which may last for several hours afterwards, as well as rectal bleeding. The most consistent finding on examination is spasm of the anal canal, and it is uncertain whether this is the result of or due to ischaemia. Many of the management options have been based around reducing the internal anal spasm, but as with many benign anal conditions, one of the most important measures is to increase dietary fibre and adequate fluid intake. The majority of fissures, especially posterior fissures, are associated with a high resting pressure and a low blood flow to the anoderm resulting from this spasm. However, postpartum fissures are usually anterior and may be associated with a rectocele. The scar formation may be associated with ischaemia; however, the resting pressures in these patients are usually low. If there are multiple fissures or the fissures are not in the midline, a differential diagnosis of Crohn’s disease, ulcerative colitis, human immunodeficiency virus and associated infections as well as neoplasia should be considered. An anal fissure may occur at any time in life but is most common between the second and fourth decades, with an equal distribution between men and women and a lifetime incidence of just over 11%. Inspection of the anus will usually reveal the fissure, and it is not usually possible to carry out any further examination due to the pain associated with the fissure.

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