Introduction

Gastrointestinal symptoms are very common within the general population (Thompson et al., 2003). There is a high prevalence of rectal bleeding (Crossland and Jones, 1995; Thompson et al., 2000), change in bowel habit (Everhart et al., 1989) and abdominal pain (Sandler, 1990). Since any one of these symptoms alone can be due to benign, transient disease, symptom complexes are more useful for predicting serious pathology (Thompson et al., 2007). In the UK, this has led to the ‘two week wait guidelines’ for suspected cancer (Department of Health, 2000). This means that patients with symptoms most predictive of colorectal cancer (Table 10.1) must be seen within 2 weeks from the date of referral.

Table 10.1 Criteria for urgent referral for suspected colorectal cancer under the two-week rule

This chapter will explore symptoms and symptom complexes of lower gastrointestinal disease, the possible diagnosis and the investigation performed for each symptom group.

Rectal bleeding

Bleeding from the gastrointestinal tract can be overt or occult. With overt rectal bleeding, the blood is recognized and is usually noticed on defecation. If this is the case, the origin of the bleeding is usually in the left colon or distal transverse colon. If the bleeding is occult, the blood loss is not recognized in the stool and the patient presents with anemia.

When a patient presents with rectal bleeding, there are features that can help locate the source of the bleeding, such as the color of the blood. Bright red rectal bleeding tends to originate from a distal source such as the rectum, whereas dark red blood tends to originate from a more proximal source but within the left colon or distal transverse colon. Another feature is whether the blood is separate to the stool or mixed in when it is passed. If the blood is separate to the stool, the patient notices it on the toilet paper or in the water in the toilet bowl, this usually suggests a very distal source such as hemorrhoids. If blood has had time to mix in with the stool, it suggests a more proximal source of bleeding.

Coexisting symptoms are also very important. A change in bowel habit to looser stools coupled with rectal bleeding is a symptom complex with a high predictive value for cancer (see above) or colitis. Anal pain may suggest a fissure. Change in bowel habit to constipation may merely mean that constipation has exacerbated hemorrhoids. Common combinations of symptoms associated with rectal bleeding, the possible causes and appropriate investigations are detailed below.

Bright red rectal bleeding with anal symptoms

Rectal bleeding with anal symptoms without a change in bowel habit is the lowest predictor of colorectal cancer (Thompson et al., 2007). It usually suggests hemorrhoids (associated with mucus, skin tags or prolapsing lumps) or an anal fissure (associated with anal pain on defecation). Distal proctitis (inflammation of the very distal rectum) may also be a cause. The exception to this is anal cancer that may present with these symptoms but is often associated with a lump or ulcer in the anal canal

Investigation: no radiological investigation may be necessary. This diagnosis can usually be made in the outpatient clinic on rigid sigmoidoscopy and/or proctoscopy. In the case of a fissure, examination may not be possible and a painful per rectum (PR) examination may be diagnostic.

Bright red rectal bleeding without anal symptoms

This may suggest a distal rectal cancer, although this is often associated with change in bowel habit to looser stools, fecal leakage or a feeling of incomplete evacuation (tenesmus).

Investigation: radiological investigation may not be necessary for this symptom complex. It should be diagnosed on PR examination ± rigid sigmoidoscopy or proctoscopy. Flexible sigmoidoscopy would be appropriate in the over 40s to exclude malignancy. Should a stricture prevent the passage of the endoscope, a barium enema (Figure 10.1) or computed tomography (CT) should be considered.

Figure 10.1 Rectal synchronous tumors.

Although a barium enema may exclude cancer in a patient presenting with a symptom complex associated with bright red rectal bleeding, it may not diagnose the cause. Patients with these symptoms may need a rigid sigmoidoscopy to establish the cause of their bleeding.

Bright red rectal bleeding with change in bowel habit (CIBH) to looser stools

This carries the highest risk of bowel cancer (Thompson et al., 2007) but is also symptomatic of colitis, which may be infective, ischemic, ulcerative colitis (UC) or Crohn’s disease (Figures 10.2, 10.3 and 10.4).

Figure 10.2 Ischemic colitis.

Figure 10.3 Ulcerative colitis.

Figure 10.4 Crohn’s colitis.

Investigation: since recognizable rectal bleeding usually originates in the left colon, a flexible sigmoidoscopy will diagnose the cause of this symptom complex with the advantage of obtaining a tissue diagnosis. A barium enema or CT colonography is also a reasonable test to request. However, the disadvantage is that a tissue diagnosis will still be necessary, it is possible to miss mild/moderate colitis on barium enema and, if the barium enema is normal, as discussed above, it does not exclude a very distal cause of blood loss and the patient should have a coloproctological examination.

Bright red rectal bleeding with constipation

Often the constipation has exacerbated bleeding from hemorrhoids or a fissure, rarely due to cancer.

Investigation: the clinician may request a barium enema or CT colonography to find a cause for the change in bowel habit. Constipation alone is a poor predictor of cancer. However, it is a predisposing factor for diverticular disease and so this is a common finding in patients with constipation. A coloproctological referral will still be needed to assess the distal bleeding. If the constipation is long standing and an underlying functional bowel disorder is being considered, a colonic transit study (Figure 10.5) may be requested.

Figure 10.5 Normal colon transit study appearance.

Dark red rectal bleeding without a CIBH

Usually this presentation results from diverticular bleeding. This may present as a large bleed where dark blood and clots are passed with very little stool. The patient usually presents as an emergency or may give a history of a few large bleeds rather than continuing ongoing bleeding (see also Chapter 15).

Investigation: a flexible sigmoidoscopy may be useful but, in the acute situation, may be suboptimal if the colon is full of blood. A reasonable strategy is that once the bleeding has settled down, the clinician may request a barium enema, CT colonography or flexible sigmoidoscopy.

Dark red rectal bleeding with a CIBH

This may mean a more proximal tumor in the sigmoid, descending colon (Figure 10.6) or transverse colon or more proximal colitis.

Figure 10.6 Pedunculated neoplastic polyp with two smaller pedunculated pdyps in descending colon.

Investigation: recognizing their attendant advantages and disadvantages, barium enema, CT colonography, flexible sigmoidoscopy or colonoscopy can all be considered.

Change in bowel habit alone

While CIBH with rectal bleeding is often indicative of significant pathology, CIBH alone is less predictive. This is because many of the population experience a CIBH at some point (Everhart et al., 1989) and 10–20% (Longstreth et al., 2006) have irritable bowel syndrome. When asking about change in bowel habit, it is essential to ascertain what the patient means. For example, does diarrhea mean more frequent stools, looser stools or both? Some patients describe diarrhea as a slightly looser stool; others will only use the term if they are passing watery stools. It is the same with constipation. Some patients describe this as hard stools, some as less frequent stools and some mean they are not going at all. In fact, patients with an obstructing malignancy may describe ‘constipation’ and, although they may be hardly passing any stool, when they do so, it may be watery.

Constipation

True constipation is described as less than three stools per week. Patients who present with a very infrequent bowel frequency may have had problems since childhood. In these patients, a colonic transit study may be appropriate or even a rectal biopsy to exclude a late diagnosis of Hirschsprung’s disease. If the bowel habit change is less dramatic, a barium enema or CT colonography is a reasonable request and diverticular disease will be a common finding.

Absolute constipation means no passage of stool or flatus and is a sign of bowel obstruction. This rarely presents in an outpatient and is more likely to be a symptom experienced by a patient admitted as an emergency. However, these patients should not have a prepared double contrast barium enema as the stimulant bowel preparation carries a risk of perforation. These patients should have an unprepared (Gastrografin) enema or a CT scan to elucidate the site of obstruction.

CIBH to looser stools alone

Again, the investigation chosen depends on the severity of the symptoms. A barium enema or CT colonography is a very good first choice in patients who may have a slight increase in bowel frequency. Most clinicians would expect the change to have persisted for at least 6 weeks before investigation for the reasons described above and infection to be excluded by a negative stool sample. If the diarrhea is severe, i.e. 10–20 times a day, this suggests a diagnosis of colitis and so a colonoscopy or flexible sigmoidoscopy is a better investigation as a tissue diagnosis can be obtained.

Irritable bowel syndrome (IBS)

It is worth mentioning this as a separate entity as it probably accounts for many of the patients with a negative barium enema who present with symptoms. It is not a diagnosis of exclusion and has very specific diagnostic criteria based on the Rome Criteria (Sandler, 1990). In 2008, the National Institute for Clinical Excellence (NICE) produced guidelines for the diagnosis and management of IBS.

The positive diagnostic criteria are:

Investigation: NICE has ruled that for patients who meet the positive diagnostic criteria for IBS, neither barium enema nor colonoscopy is necessary (NICE, 2008).

Iron deficiency anemia

This may be diagnosed on a routine blood test as defined above or the patient may present with shortness of breath, fatigue or fainting. It is usually related to occult blood loss from either the upper GI tract or the right colon where it may be associated with a mass.

Investigation: The British Society of Gastroenterology Guidelines (Goddard et al., 2005) recommend investigation of both the lower and upper GI tract in men and post-menopausal women. This can consist of a barium enema then esophagogastroduodenoscopy (OGD) or an OGD and colonoscopy at the same sitting. It is important that, if tests are done consecutively, that the lower GI tract is examined as anemia can be mistakenly attributed to mild gastritis. If the patient is frail or elderly and will not withstand bowel prep, a CT scan is a good first line test as it has good sensitivity for the diagnosis of right-sided colonic tumors (Figure 10.7) (Ng et al., 2002).

Figure 10.7 CT carcinoma cecum.

Melena

This is the passage of altered blood per rectum. Patients may describe black stools. True melena is very distinctive. It has an offensive smell and is described as black and tarry and is usually a reflection of a large bleed, most commonly due to an upper GI source such as a gastric or duodenal ulcer. It can be due to a right-sided colonic tumor.

Investigation: an OGD is essential in the acute situation to exclude a bleeding ulcer. If this is normal and a right-sided colonic tumor is suspected, the investigations are the same as for iron deficiency anemia.

Abdominal pain

Abdominal pain alone is rarely discriminatory for problems affecting the lower GI tract. In general, pain from the large bowel presents as lower abdominal pain, whereas pain from the small bowel presents as upper or central abdominal pain. Pain from an obstructing lesion is generally colicky and comes in waves, whereas pain from an inflammatory process, e.g. diverticulitis, is usually constant (see also Chapter 15). The features of the pain such as exacerbating and relieving factors, radiation (whether it spreads anywhere) and any associated symptoms also help determine the cause. In obstruction, (Figures 10.8, 10.9A and 10.9B), the pain may be exacerbated by eating and may be associated with vomiting and a change in bowel habit.

Figure 10.8 Large bowel obstruction.

Figure 10.9 (a) Distal large bowel obstruction. (b) Obstruction caused by a twisted loop of bowel.

In an inflammatory process, the pain may be made worse by moving or coughing or anything that causes peritoneal irritation.

Investigation: if the pain is obviously related to the gut and associated with gastrointestinal symptoms, the investigations of the large bowel described above will be appropriate. If not obviously intestinal, an ultrasound scan or abdominal and pelvic CT with oral contrast is a good first line investigation, as it will identify common extracolonic causes of abdominal pain such as abscess formation or that originating from the gallbladder, pancreas or gynecological tract.

Incontinence

This is a distressing symptom, which is either due to a weak anal sphincter, a change in bowel habit to loose stools or a combination of both. If the bowels are loose, correcting the underlying cause can often improve the incontinence.

Investigation: if damage to either the internal or external sphincter is suspected, anorectal physiology tests and an endoanal ultrasound will be necessary.

Rectal prolapse

Rectal prolapse is described as ‘something coming down’ or protruding out from the anal canal. There are degrees of prolapse that can affect bladder, uterus, vagina and rectum and the underlying cause is a weak pelvic floor, commonly due to childbirth. Prolapse is thought to be a gradual condition, which may start as the rectum prolapsing within itself (intussuscepting). The symptoms of this may be tenesmus, inability to defecate (obstructed defecation), passage of blood or mucus and a heavy feeling in the rectum.

Investigation: if the prolapse is extending beyond the anal canal the diagnosis is obvious, but if it is internal, radiological investigation may be necessary. In this case, a defecating proctogram will give information on the degree of prolapse if present and give information to help plan appropriate surgery (see Chapter 13).