chapter 30 Gastroenterology
COMMON PRESENTATIONS
ACUTE ABDOMINAL PAIN1,2
Nature of pain
• Visceral pain—abdominal organs are not sensitive to touch. However, stretching or distending the bowel does cause pain that is poorly localised, usually to the midline. Distension of the capsule of the liver also causes pain.
• Peritoneal pain—the parietal peritoneum has pain fibres, but the visceral peritoneum does not. Pain from inflammation of the parietal peritoneum is well-localised to the area of inflammation. It is exacerbated by movement such as coughing or respiration.
• Referred pain—referred pain is pain felt distant from the site of the problem that is causing the pain. For example, right shoulder tip pain is referred from the parietal peritoneum under the diaphragm, with these areas both innervated by somatic C4 nerves. Cardiac pain may be felt in the epigastrium, and pelvic pain in the umbilical area.
Mechanisms of abdominal pain
• Obstruction—pain tends to be colicky unless there is a complication such as secondary infection or perforation, when it becomes continuous.
Type and chronicity of pain
• Colicky—felt in the midline, associated with forceful smooth muscle contraction related to stomach (epigastric), intestine (small bowel and right hemicolon colic felt periumbilically; left hemicolon colic felt suprapubically) or uterus (suprapubic). Repetitive cyclic pattern of intense pain, then relief.
Biliary ‘colic’ is continuous rather than intermittent, in the epigastrium or RUQ.
GENERALISED ABDOMINAL PAIN
• Perforated appendix—history suggestive of appendicitis: initially central colicky abdominal pain later localising to the RIF, fever, tachycardia. Tenderness and rebound in RIF. Tenderness on the right on digital rectal examination. Neutrophilia and raised C-reactive protein. Requires immediate surgical referral.
• Perforated peptic ulcer—sudden prostration with severe generalised peritoneal-type abdominal pain. Symptoms may improve after 2–6 hours. Peritonitis develops after 6–12 hours with generalised tenderness and guarding, maximal in the epigastrium, board-like rigidity, loss of bowel sounds and loss of liver dullness to percussion. Gas under diaphragm may be seen on erect abdominal X-ray. Limited gastrograffin meal may help diagnosis. Initial treatment: resuscitation, nasogastric suction, antibiotics. Urgent surgical referral.
• Perforated diverticulum—history of diverticular disease or preceding undiagnosed pain in LIF. Tenderness and rebound in LIF, gas under diaphragm in erect abdominal X-ray.
• Ruptured ectopic pregnancy—suspect in a woman of childbearing age with a late period and sudden onset of pelvic or lower abdominal pain. Symptoms and signs are maximal in the pelvis; sometimes pain is felt in region of rectum. This is sometimes reported as increase in pain when woman tries to sit down. Tender mass may be evident on vaginal examination. Shock is common. Usually elevated β-hCG levels are found and ectopic implantation seen on ultrasound at 5–6 weeks of amenorrhoea. Urgent gynaecological surgery referral.
• Ruptured solid organ—a history of trauma is usually present. Symptoms and signs will include significant blood loss and also be organ-specific.
• Ruptured aortic aneurysm—patient usually elderly with risk factors for cardiovascular disease. Pain is central, constant and radiates through to the back. Not usually signs of peritonism, as bleeding is retroperitoneal. Pulsatile mass in central abdomen. May sometimes present with sudden pain followed by shock and loss of consciousness. Surgical emergency.
• Strangulated bowel—site of pain depends on area of strangulation. Is there a history or signs of a hernia or previous abdominal surgery? May be associated signs and symptoms of small bowel obstruction. Urgent surgical referral required.
• Superior mesenteric artery thrombosis or embolism—causes massive small bowel ischaemia. Often preceded by a history of atrial fibrillation or myocardial infarction. CT scan will define the problem but should not delay urgent surgical referral.
LOCALISED ACUTE ABDOMINAL PAIN
Left iliac fossa
CONSTIPATION
While the cause of constipation may be a simple matter of diet, drug side effect or behavioural bowel habit, constipation may be an indication of a serious underlying disorder.
Investigation
Therapeutics
• Dietary fibre 20–30 g per day, especially fresh fruit and vegetables and whole cereals (especially oatmeal).
• In high doses, magnesium exerts a laxative effect (Epsom salts or milk of magnesia) for short-term relief.
DIARRHOEA
Acute diarrhoea
• Acute watery diarrhoea is most often due to viral or bacterial gastroenteritis/enteritis or protozoal infection.
• Bloody diarrhoea may be a result of infectious colitis, drug-induced colitis, inflammatory bowel disease, ischaemic colitis or antibiotic-associated diarrhoea.
• Acute diarrhoea may be a first presentation of coeliac disease, Crohn’s disease or inflammatory bowel disease.
• History should elicit symptoms of volume depletion such as dry mouth, orthostatic hypotension, tachycardia, especially when vomiting is associated.
• History should include recent travel, medications (especially antibiotics and vitamin supplements), dietary history, consumption of fast food or leftovers and whether other members of family or a dining group developed diarrhoea, and any history of immune deficiency.
Investigation
• General physical examination will include cardiovascular assessment, signs of toxicity (fever, tachycardia, shock), abdominal palpation for mass or tenderness, and digital rectal examination for tenderness, mass or faecal impaction.
• Patients presenting with diarrhoea will need to be assessed for volume depletion, and this is particularly important in children and the elderly.
• For minor resolving episodes of diarrhoea without systemic features, no investigations will be necessary.
• Stool examination for blood, and stool culture looking for ova, cysts and parasites, may help to target therapy in cases of severe or prolonged acute diarrhoea. However, standard stool examination can be unreliable. Special requests for identification of pathogens may need to be made for suspected Campylobacter, Clostridium difficile and toxin, Yersinia, and Cryptosporidium or amoebic dysentery.
• Blood tests can give valuable information about the cause and/or the effects of the diarrhoea. These might include full blood count, ESR, iron studies, folate, vitamin B12, calcium, electrolytes and thyroid function.
• Sigmoidoscopy or colonoscopy may be indicated where colitis or inflammatory bowel disease is suspected.
Viral gastroenteritis/enteritis
Treatment
• Rehydrate with fluid and electrolyte solution, and monitor fluid balance. Use the simplest route where possible (oral) but sometimes the nasogastric or IV route may be required in emergency situations (e.g. infants) or where oral rehydration is not possible. Avoid rehydration with sweet drinks such as lemonade unless diluted to one-third to one-quarter normal strength.
Bacterial gastroenteritis
Nausea, vomiting, diarrhoea and abdominal pain are common to most. Neurological, hepatic and renal complications can also occur. Rapid onset (hours) after ingestion of contaminated food suggests a pre-formed toxin, while a longer incubation period (1–3 days) suggests a bacterial or viral cause.
Enterotoxigenic E. coli
A leading cause of traveller’s diarrhoea. Adheres to the gut wall and produces enterotoxins.
• Norfloxacin 400 mg b.i.d. p.o. or ciprofloxacin may be used for moderate to severe symptoms. Cotrimoxazole can be used for children.
