Disorders of the large bowel Flashcards
Discuss diverticular disease
Virtually unknown in countries with high fibre diets. Diverticla fortm where the colon wall is penetrated by the vasa recta. Patient with diverticular disease exhibit normal resting colonic pressure but higher peak pressure.
The high peak pressure causes the intestinal mucusa to herniate at the sites of vasa recta penetration. These diverticula are usually asymptomatic and only develop symptoms with inflammation.
The course of diverticulitis is not influenced by antibiotics but is by anti-inflammatories
Uncomplicated diverticulitis occurs when only the pericolonic fat is inflamed. With time a phlegmon, abcess or gross perf can occur. Any extension beyond the pericolonic fat is termed a complicated diverticulitis.
Diverticula can also bleed with svere haemorrhage occuring in 3-5% of all patient with diverituclosis and accounting for approximatly 40% of lower GI bleeds.
Discuss clinical symptoms of diveritulitis
Because most diverticula in the west form in the left side of the colon symptoms are usual persistent left lower quadrant pain and tenderness. May begin in the hypogastrium before localising to the left.
Referred pain may occur in the penis scrotum and suprapubic region
Diffuse tenderness is associated with perforation and peritonitis, dysuria is associated with colovesciula fistula
Care must be taken with older patient as signs are much less dramatic and disease is often more severe
Discuss management
Uncomplicated diverticulitis in an immunocompetent non older patient without comorobid illness or significant social problems can be treated on oral antibiotics as an outpatient.
Bactrim + metronidazole
Cipr + metronidazole
Augmentin
Complicated diverituclitis should be hospitalized and treated with IV ABs and bowel rest. Bowel obstruction during an attack of diverticulitis is usually self limited and resolves with conservative management.
Of patient treated medically for the first attack of diverticulitis 90% remain asymptomatic for the next 2 years and 80-90% remain symptom free permanently
Discuss large bowel obsturction
LBO much less common than SBO but more ominous as is usually associated with malignancies
Other causes include
-volvulus, diverticular disease, faecal impaction, strictures, adhesions, hernias and psuedo- obstruction
When mechanical obsturction cause either by an intrinsic lesion (carcinoma) or an extrinsic mass eg. diverticular abcess occur the bowel becomes increasing dilated with air and fluid and pressure builds. Once pressure reaches systolic blood flow is compromised and odema occurs. Transudation along with decreased reabsorption leads to dehydration and eventially arterial flow can be compromised enough to lead to ischemia.
Discuss pseudo-obstruction (ogilivie’s sydnrome)
LBO without obstruction lesion. Usually found in a patient with significant acute co-morbidities such as spine or retroperitoneal injury, narcotic abuse or electrolyte disturbance
Is due to disruption in autonomic control of the bowel.
Discuss clinical features of LBO
Abdominal pain, distension, obstipation and vomiting
Timeframe depends on cause –> volvusus rapid onset, maligant mass slow onset
in those who symptoms took a long time to develop severe dehydration may accompany patient
Discuss management of LBO
Rehydration, electrolyte replacement, pain relief, gastric decrompression. ABS are indicated if signs of perforation or abcess.
Definitive management depends on causes, abcess can be drained but volvulus or pseudoobstruction can be decrompressed endoscopically `
everyone come in as most need surgical intervention
Discuss volvulus
Occurs when a loop of bowel twists and obstructs the intestinal lumen, Volvulus account for 1-7% of all LBO. They can occur in all age groups but are more common in the older age group
Most cases are divided roughly equally between the sigmoid and the caecum
Sigmoid voluvus typical is a disease of the elderly and if gangrene is present has a 50% morality
Discuss intussusception
Primary cause of bowel obstruction in children and the second most common cause of abdominal pain followed by appendicitis
Peak incidence is between 4-10months of age.
Is rare in adults accounting for 5% of all intussusception cases and is usually asociated with neoplasms of malignancies.
Is associated with rotavirus in children.
The exact mechanisms of intussusception is unknown however it is believed that a lead point lesions alters the motility properties of the distal end allowing the proximal portion to invaginate along with its mesenteric vessles and mesentery. As blood supply is compromised odema can lead to functional obstruction
if not treated can lead rapidly to ischaemia and necrosis
Most infant intussessption involves the ileum invaginating through the ileocaecal valve. 95% of cases in children are idiopathic but are commonly assoicated with hyperplasia of payers patches secondary to cocurrent viral infection.
Adult intussusception has a cause in 95% pf cases. 60% of SB cases are due to benign lesiosn compared to 60-65% of cases being due to malignat lesions in the large bowel
Discuss clinical features of intussusception
Manifest as two patterns
1: acute pattern –> paediatrics -abrupt onset of intermittent colicky abdominal pain which causes episodes of cyring and pulling knees up
2: acute partial intestinal obsrtucion –> seen in adults –> abdominal pain with vomiting and rectal bleeding. abdo may be distended and bowel sounds are often decreased.
the classic triad of abdominal pain, mass and haemepositive stools noted in children is found in less than 50% of paediatric intussusceptions and rarely inadlts.
Dicuss ix of intussusception
Ultraouns is helful in detecting intussusception but not in picking up alternative diagnosis
CT most useful in adults but does not pick up the actual intussescption in 50% of caess
Discuss management of intussusception
In a stable child a trial of pneumatic or hydrostatic reduction where appropriate radiologic facilities are available. this may prevent the need for surgery in children.
Surgery is almost always required in adults as there is normally a secondary precipitant
