Symptoms and signs of lower gastrointestinal disease
SergioCoda
Andrew V. Thillainayagam
Andrew V Thillainayagam MD FRCP is a Consultant Physician at HammersmithHospital and Honorary Senior Lecturer in Medicine at ImperialCollege London, London, UK. Competing interests: none declared.
Sergio Coda MD PhD is a Consultant Surgical Gastroenterologist and Specialist Gastrointestinal Endoscopist at the North East London NHS Treatment Centre and Honorary Post-doctoral Academic Visitor at Imperial College London[RE1], London, UK[X2]. Competing interests: none declared.
Abstract
Symptoms of lower gastrointestinal disease are common and frequently trigger consultation in primary and secondary care. Diarrhoea, abdominal pain and constipation are presentations of a wide range of different underlying pathologies, from chronic, benign, functional conditions to acutely life-threatening emergencies. Lower GI bleeding is often due to serious pathology and requires rational investigation based on a systematic clinical assessment. Extra-intestinal manifestations of lower GI disease can often give a clue to the underlying diagnosis. In this contribution, we review the aetiology, clinical features, investigations and management for a range of lower gastrointestinal symptoms, namely diarrhoea, constipation, lower GI bleeding, bloating and abdominal pain.
Keywords
abdominal pain; bloating; constipation; diarrhoea; lower GI bleeding
Diarrhoea
Definition
The strict definition of diarrhoea is stool volume of more than 200 ml per day, or a stool frequency of more than three times per day. This is widely accepted as the technical definition of diarrhoea and is frequently used in clinical studies. However, it may be of less utility in the clinical assessment of an individual patient. A simpler and less arbitrary definition is ‘a decrease in consistency or increase of liquidity of stool’; this is widely accepted in clinical practice and accords well with what patients understand by ‘diarrhoea’. Diarrhoea is defined as acute when it has been present for less than four weeks, chronic if longer. Chronic diarrhoeaprevalence in the developed world is approximately 5% in symptom questionnaire population studies.
Aetiology and classification
There are four mechanisms of diarrhoea:
•reduced absorption of osmotically active substances
•abnormal secretion
•inflammatory damage to the mucosa
•reduced transit time.
Most diarrhoeal conditions result from a combination of these processes.
It is useful to classify diarrhoea as acute or chronic to narrow the differential diagnosis and allow rational investigation (Table 1).
Important clinical features
A detailed history is essential. The onset, duration, frequency, and volume of stool should be estimated. Bloody diarrhoea with pus or mucus suggests a predominantly inflammatory process. A bulky, greasy, foul-smelling stool is highly suggestive of steatorrhoea. Urgency to defecate is a feature of proctitis, particularly when associated with blood or pus per rectum, as is tenesmus. Nocturnal symptoms, continuous symptoms, duration of over 3 months and significant weight loss all point to an organic rather than a functional process. Associated symptoms, such as abdominal pain, bloating, nausea and vomiting, should be sought.
A history of HIV disease or other immunosuppressant states should trigger investigation for an infective cause, including atypical organisms. Radiotherapy to the abdomen or pelvis, or previous bowel surgery can lead to bacterial overgrowth. A history of biliary or small bowel surgery raises the possibility of bile salt malabsorption. Individuals with diabetes are prone to dysmotility or bacterial overgrowth. Recent antibiotic use predisposes to Clostridiumdifficile infection. The drug history may be relevant as many commonly prescribed medications can cause diarrhoea(Table 2), as can recreational drugs, such as alcohol and cocaine. A history of dietary indiscretion or foreign travel may point towards an infective cause. Anal intercourse can lead to HSV or gonococcalproctitis. Long-standing alcohol excess may indicate an underlying pancreatic abnormality.
A family history of inflammatory bowel disease (IBD) or gastrointestinal (GI) malignancy should be sought. General examination may reveal jaundice, hepatomegaly, cachexia or extraluminal signs of GI disease that may give clues to the cause of the diarrhoea. A palpable mass may result from malignancy or Crohn’s disease. Fluid status should be checked carefully, and dehydration, sepsis, peritonism or shock should be recognized and treated promptly.
Investigations
Uncomplicated acute diarrhoea requires no investigation, but simply supportive measures. Severe or prolonged symptoms should trigger stool microscopy and culture. Full blood count, erythrocyte sedimentation rate, and serum C-reactive proteinand albumin should be measured. Flexible sigmoidoscopy and biopsy, and plain abdominal radiography are necessary in those patients with bloody diarrhoea, systemic disturbance or significant abdominal tenderness, and in those whose symptoms do not settle promptly.
Investigation of chronic diarrhoea is guided by the history and likely underlying diagnosis. Further blood tests include anti-endomysial or anti-tissue transglutaminase antibodies (for coeliac disease), amoebic serology, thyroid function tests (TFTs), iron studies, and serum folate and vitamin B12.
Colonoscopy to exclude colonic neoplasia is almost mandatory in patients over the age of 45 with persistent diarrhoea. Younger patients with associated red-flag features, such as weight loss, bleeding per rectumor anaemia, also warrant full colonoscopy to exclude colonic neoplasm or inflammatory bowel disease. In very elderly patients, or those with extensive co-morbidity, computed tomographic(CT)pneumocolonography is a less invasive test that can reliably exclude colonic neoplasm. However, it does not offer the same sensitivity for mucosal disease or very small lesions. In young patients with typical features of functional bowel disease, normal physical examination and normal blood screen, no further investigation is necessary. Measuring faecalcalprotectin, a white cell protein that is elevated by intestinal inflammation and neoplasia, can further help reduce unnecessary colonoscopy in low risk cases. Small bowel imaging, with magnetic resonance (MR)enterography or barium follow-through should be undertaken in patients with suspected small bowel disease such as Crohn’s disease.
Repeat stool microscopy and culture should be sent. A 3-day stool collection can be performed and a volume of ≤200 ml/day (roughly equivalent to a mass of 200 g) is highly suggestive of a functional disorder. A sample can be sent to measure faecalelastase,to assess pancreatic exocrine function.Any suspicion of factitious diarrhoea should trigger a laxative screen. [JM3][X4]In patients with symptoms of malabsorption, CT imaging of the pancreas may be undertaken to exclude pancreatic pathology and hydrogen methane breath testing to exclude lactose intolerance, fructose malabsorption and bacterial overgrowth (Thomas 2003). The gold standard for proving steatorrhoea is the 3-day stool collection on a controlled fat intake to measure the coefficient of fat absorption. However, this test is quite unreliable if not correctly collected and is not undertaken in many hospitals because it is unpleasant for laboratory staff to perform. Most institutions now make do with pancreatic faecalelastase measurements or, where available, the 13C-mixed triglyceride breath test (Dominguez-Munoz 2007). A 23-seleno-25-homo-tauro-cholic acid (SeHCAT) scan can exclude bile salt malabsorption, an underdiagnosed cause of chronic diarrhoea. Enteropathies such as coeliac disease can be confirmed by endoscopy with duodenal biopsy. A trial of empirical treatment with, for example, pancreatic supplements or a bile salt sequestrant, may be necessary when no obvious cause is demonstrated, or when ready access to appropriate investigations is not available.
Constipation
This is a common lower GI complaint with an estimated prevalence of 2–28%. Most cases can be managed successfully with reassurance and dietary advice.
Definition
A number of symptoms can be used to define constipation, and patients will often complain of a combination of the following:
•infrequent stools (<3 per week)
•difficult passage of hard stool
•need for manual manoeuvres, including digitation of rectum and/or vagina, to aid evacuation
•sense of incomplete defecation (tenesmus)
•excessive straining or time spent on the toilet (more than four to five minutes)
Absolute constipation is the inability to pass stool or flatus per rectum, which is suggestive of bowel obstruction, particularly if accompanied by concurrent vomiting, and is a medical emergency.
It is important to elicit any alarm symptoms present, particularly weight loss, bleeding, distension and new-onset constipation in the elderly.
Aetiology and classification
It is useful to consider the contributory mechanisms to constipation, particularly:
•increased absorption/reduced consumption of osmotically active substances
•mechanical obstruction of the bowel lumen
•secondary causes of prolonged transit times.
Constipation may also be a behavioural response secondary to painful defecation or maladaptive learning from childhood.
It is important to distinguish functional constipation from constipation that has an organic cause. The former is common in patients who present with a long history of constipation without any alarm symptoms. These patients usually have normal colonic transit, require no investigation, and typically respond to dietary modification and osmotic laxatives.
Slow-transit constipation may have an organic cause, such as an adverse effect of drugs (Table 3), or neurogenic disorders like diabetes mellitus, autonomic neuropathy or Hirschsprung’s disease. Idiopathic slow-transit constipation is more common in young women. Whatever the aetiology, slow transit usually means that long-term use of an osmotic laxative will be required.
Constipation may also be a dominant feature of irritable bowel syndrome, a functional disorder comprisingchronic abdominal pain and deranged bowel habit (Drossman 2000). Long-term avoidance of pain associated with the passage of hard stools, the presence of anal fissures or haemorrhoids, along with structural abnormalities, such as a rectocoele, are other causes of constipation.
Causes of constipation, although often multifactorial, are shown in Table 3.
Important clinical features
A detailed history is required to exclude organic causes, and to decide whether the patient is indeed constipated and which patients require further investigation. Attention should be paid to themedical history, including obstetric history in women, current medications and dietary history. The psychosocial history can be relevant, as a history of psychiatric illness or sexual abuse is a risk factor for non-organic constipation. Features suggestive of a functional cause include a long (often lifelong) history, other symptoms compatible with irritable bowel syndrome (IBS) and presentation in a younger patient (<50 years of age). A recent sudden change in bowel habit in older patients (>50 years of age) or the presence of alarm symptoms such as bleeding or weight loss warrants further investigation, as does the acute onset of absolute constipation. Problems with initiating defecation, prolonged straining or manual manoeuvres with digitation may indicate a severe structural or functional evacuatory disorder.
A thorough examination of the abdominal system is required in all patients, and should always include careful inspection of the perineum for scars, fissures, fistulae and external haemorrhoids. Digital rectal examination is required to assess the anal reflex, sphincter tone, and any evidence of structural abnormality or faecal impaction.
Investigations
Basic tests: a detailed history, examination and simple screening blood tests (full blood count, serum electrolytes, calcium and glucose, and thyroid function) will help exclude most secondary causes and identify those who require further investigation. Colonoscopy is reserved for patients in whom colorectal cancer or inflammatory disease needs to be excluded (alarm symptoms, new onset after 50 years of age, significant family history of colorectal neoplasia or IBD). In acute-onset constipation with abdominal pain and vomiting, a chest and abdominal X-rayis always necessary to exclude obstruction and/or perforation.
Specialist tests: various physiological tests can be performed in those patients who do not respond to a high-fibre diet and are refractory to laxatives. Colonic transit studies (normal transit time <72 h) will help identify slow-transit constipation or a defecatory disorder. Balloon expulsion, anorectalmanometry and defecography with barium or by magnetic resonance (MR) scan may be required to diagnose disordered evacuation.
Management
Education regarding diet, exercise and what is a ‘normal’ bowel habit is essential. Secondary causes, anorectal abnormalities and systemic disease should be identified and treated appropriately.
In those with severe, intractable constipation, an initial bowel purge using any potent osmotic laxative regimen followed by regular high doses of a gentler osmotic laxative and stimulant laxative may be necessary.
Surgery (subtotal colectomy and ileorectal anastomosis) remains controversial and should be considered only in those who have severe refractory slow-transit constipation with no evacuation disorder. It should be considered only after all medical therapies have failed and when more than one expert opinion has been sought.
Lower gastrointestinal bleeding
Definition and causes
Haematochezia is the passage of fresh or partially altered blood per rectum. Most bleeding will be either colorectal or anal in origin; small bowel lesions are rarely the cause. Rarely, it can be the consequence of massive upper GI bleeding, where rapid transit results in minimal digestion. An upper GI source should be excluded in all shocked, anaemic patients with acute onset of haematochezia.
Melaena is the passage of substantially digested blood that appears black. Melaena is a consequence of upper or midgut bleeding and is not considered further in this article. Acute lower GI bleeding is common, although massive bleeds are rare and usually secondary to diverticular disease or ischaemic colitis. Chronicblood loss per rectumoften relates to perianal disease, colonic inflammation or neoplastic disease. Causes are listed in Table 4.
Important clinical features
The patient’s history will give clues as to the cause and site of the bleeding. Questions should focus on:
•the colour of the blood
•exactly when and where the blood is seen
•duration
•any change in bowel habit or diarrhoea
•presence of abdominal pain
•any associated symptoms
•travel history
•previous episodes
•risk factors for bleeding.
Bright red blood seen either separate from the stool or after wiping,or dripping into the pan after evacuation of stool is likely to be secondary to anorectal disease. Bloody diarrhoea with or without mucus suggests an inflammatory, neoplastic or infective aetiology. Colorectal carcinoma and polyps may present with minor, intermittent rectal bleeding. Occult lower GI bleeding may be detected by testing stool samples for faecal occult blood in screening programmes for colorectal neoplasia.
The age of the patient will influence the likely differential diagnosis; malignancy, ischaemic colitis, diverticular disease and arteriovenous malformations are much more common in older patients.
Examination may reveal the presence of a mass or identify anorectal disease. A digital rectal examination should always be performed, although benign anorectal lesions are common and further colonic investigation is often still required.
Investigations
Basic tests: blood tests should include full blood count, electrolytes, clotting and iron studies. Colonoscopy to assess the large bowel, with or without gastroscopy if an upper gastrointestinal source is thought possible, will identify the cause in the majority of cases.
Specialist tests:patients in whom the source of bleeding cannot be identified readily often require referral to a specialist centre, where upper and lower GI endoscopy is usually repeated. Assessment of the small bowel can be performed with an enteroscopy, barium follow-through or MR enteroclysis. Video-capsule endoscopy is now widely available and is a more sensitive technique to identify small bowel mucosal lesions. A technetium99m (Tc99m)-labelled red cell scan can localize the source of ongoing bleeding in the acute situation but is rarely used. Mesenteric angiography can reliably identify the site of brisk bleeding (>1 U/4 h) and offers the opportunity for embolic therapy. In younger patients, a Tc99m-pertechnetate (Meckel’s) scan,to detect gastric mucosa in a Meckel’s diverticulum,should be performed early.
Management
Inmost cases, acute lower GI bleeding resolves spontaneously; the patient should be resuscitated as necessary and managed conservatively with blood products, if required, without the need for surgery. Once the bleeding has resolved, further investigation to identify the site of bleeding, usually with colonoscopy, can be undertaken. Where bleeding is ongoing and not resolving, urgent gastroscopy and colonoscopy are required, followed if necessary by mesenteric angiography, during which selective embolization can be performed. Surgical resection is indicated for severe, persistent bleeding where the sourcehas been localized.
Abdominal pain
Abdominal pain, both chronic and acute, is a common presenting complaint in primary and secondary care. The differential diagnosis is broad and the clinician must ensure that those with serious underlying pathology, such as visceral perforation, receive prompt treatment whilst those with more benign conditions, such as IBS, are not submitted to excessive investigation.
Definition
Pain is a sensory perception to noxious stimuli, often with an associated emotional response. In the abdomen, pain may be categorized into visceral, parietal or referred pain.
The causes of abdominal pain are detailed in Table 5.
Aetiology and classification
The character of abdominal pain is important in narrowing the range of differential diagnoses. Visceral pain is poorly localized, tends towards the midline and is often described as dull, cramping or burning. Stretching of hollow viscera is the key mechanical stimulus in visceral nociception. Pain is roughly localized to the epigastrium, peri-umbilical or suprapubic regions if the origin is in the embryological foregut, midgut or hindgut respectively. This pain may be colicky, worsening with each episode of peristalsis of the hollow viscus, as is seen in renal colic with ureteric stones or early intestinal obstruction. Associated autonomic phenomena, such as sweating, pallor, vomiting and nausea, are common.
Somatoparietal pain originates from the peritoneum and is better localized and sharper in character than visceral pain. This pain tends to be more constant and is often associated with inflammation. [X5][JM6]Referred pain is pain perceived to be originating from a site distant from the affected organ. This occurs because visceral afferent nerve fibres enter the spinal cord adjacent to somatic inputs, activating the same spinothalamic pathways. The visceral afferent signal is wrongly perceived as a somatic one, localizing the pain to the cutaneous dermatome at the same level as the visceral input. In early cholecystitis, there may be referred pain to the scapula, localization to the right upper quadrant appearing only later when the gallbladder inflammation involves the peritoneum.