o Hyperchloraemic acidosis
ASSOCIATED CONDITIONS
I. Familial adenomatous polyposis (FAP) - 1 in 10,000, autosomal dominant inheritance - Germline mutation of APC gene on 5q21
- >100 adenomatous polyps all over colon; polyps take 5-6 yrs to turn malignant - 50% patients will have polyps by 16yrs; 90% will have colorectal CA by 45yrs - Other sites for polyps: stomach, duodenum
- Extraintestinal manifestations Skin: Epidermoid cysts, Lipoma
Bone: Osteoma of skull/ mandible, Dental abnormalities
Eye: Congenital hypertrophy of retinal pigment epithelium (CHRPE) Other tumours:
Desmoid tumours (intra-abdominal tumours, treated with CT, RT or HT.) Thyroid cancer (follicular or papillary type)
Periampullary CA - Diagnosis
Colonoscopy showing >100 polyps Genetic testing
- Surveillance
Yearly colonoscopy for at-risk family members from 12y onwards 5 yearly OGD for surveillance of Periampullary Cancer.
Genetic testing of at-risk family members
Affected members should undergo prophylactic proctocolectomy with ileal pouch anal anastomosis (IPAA – involves folding loops of ileum back on themselves and stitching or stapling them together to form a reservoir pouch which is them anastomosed to the anus) at ~ 20 YO
Subtotal colectomy is an option if the rectum is relatively spared of polyps II. Hereditary Non-Polyposis Colorectal CA (HNPCC)
- Divided into Lynch syndrome I or Lynch syndrome II based on clinical features - Tumours usually proximal to splenic flexure (~70% proximal to splenic flexure) - Tumours tend to arise from polyps which are commonly flat, with villous histology - Resultant tumour is often poorly differentiated
- Lynch syndrome type II is associated with increased risk of cancer elsewhere, most commonly endometrial cancer, and also ovarian, gastric, small bowel, hepatobiliary, and renal pelvis/ureter cancers
o Offer a THBSO with total colectomy if CRC detected - Diagnosis is based on the Amsterdam criteria – see above - Surveillance – 1-3yrly colonoscopy starting at 20 years old
III. Ulcerative colitis
- Screening – yearly colonoscopy starting after 10 years of UC
3. STOMAS
Stoma: opening of a luminal organ into the external environment Indications
1. For input: feeding (Percutaneous endoscopic gastrostomy)
2. For output: decompression/ lavage, defunctioning/ diversion, draining/ exteriorization (urine, faeces) Nursing intervention
- Stoma nurse to perform counselling & discuss best site for stoma placement Stoma siting
- Over the rectus sheath decreases the risk of prolapse,
- Away from the surgical incision risk of wound contamination and infection
- Away from skin creases or bony prominences stoma wafer can be flush with the skin (any gaps between skin and wafer leakage of fluid skin excoriation & infx)
- Away from old surgical scars risk of hernia
- Sited for easy accessibilty i.e. not under a large fold of abdominal fat
- Intra-operatively, avoid tension over the stoma to marked site causes vascularity of the stoma stoma necrosis Types of stomas
Permanent (end colostomy)
- When patient or surgeon factors are against reversal of stoma (relative) - When no distal bowel remaining (absolute)
After abdomino-perineal resection for Low rectal/ anal tumor After Panproctocolectomy without ileal pouch anal anastomosis
Temporary
- Decompression – relief of bowel obstruction causing proximal dilatation - Defunctioning – to reduce effects of anastomotic leak
Esp. after low anterior resection, where risk of anastomotic leakage is high 2o to poor blood supply to anastomotic site Usually loop ileostomies or colostomies with 2 openings (ileostomies usually on the right side, colostomies in the
epigastric/hypochondriac [transverse colostomy] or left side) - To rest an inflamed distal portion e.g. acute Crohn’s
Colostomy (vs ileostomy)
?usually flushed with skin, (vs protrudes 3cm ‘spout’, as ileal contents are corrosive, to prevent contact with skin) firm brown faceal output (vs watery greenish ilieal output)
larger diameter of stoma (vs smaller diameter in ileostomy) Stoma Complications
Early
- Necrosis of terminal bowel (stoma appears dusky (grey black); check by intubating with a glass tube into the stoma to look at colour of mucosa) refashion stoma
- Obstruction (fecal impaction explore with finger, enema / secondary to adhesion – more in ileostomy) - Leakage skin erosion, parastomal infection resite
- Bleeding
- Stoma diarrhoea (high output) correct water & electrolyte imbalance (hypoK), add anti-motility agent to thicken output (loperamide +/- codeine)
http://www.wjgnet.com/1007-9327/7/741.asp
Late
- Prolapse of bowel refashion/refresh
- Parastomal hernia (+ve cough impulse) refashion - Stenosis (unable to pass finger through) refashion - Retraction refashion
- Fistulae - Skin excoriation - Psychological problems
End colostomy This procedure is most commonly performed to manage carcinoma of the lower rectum or anus, diverticular disease, and rare cases of faecal incontinence that do not respond to medical mx.
For example, a very low rectal cancer will require resection of the rectum and anus
(abdominoperineal excision of rectum). The remaining descending and sigmoid colon is mobilised and the cut end brought to the abdominal surface at an opening about 2 cm across.
This is usually sited in the left iliac fossa.
Abdominoperineal excision of the rectum If the anus, rectum, and a portion of the lower colon have not been removed, as in Hartmann's procedure, two outcomes are possible. In the first, the distal, non-functioning part of the colon and the rectum can be stapled or sewn closed and left inside the abdomen as a rectal stump. The proximal colon is then taken out as an end colostomy.
Because the rectum has not been removed, the urge to have a bowel movement may occur. Mucus and some old stool, if present, will be passed.
If the colostomy is temporary, a second operation is needed to reconnect the two ends.
Hartmann's procedure Less commonly, two separate stomas may be created.
One stoma is the exit of the functioning part of the colon through which stool and gas pass. The second stoma opens into the non-functioning portion of the colon and rectum and is called a mucous fistula. The second stoma is usually small, flat, pink-red in colour, and moist, and it produces only mucus.
Loop colostomy A loop colostomy was traditionally created to defunction an inflamed sigmoid in diverticular disease or to defunction a distal anastomosis.It has largely been replaced by loop ileostomy. A loop of colon is brought to the surface of the body and may be supported on a rod, which is removed after about five days. The bowel wall is partially cut to produce two openings—of an afferent limb and an efferent limb. The opening of the afferent limb leads to the functioning part of the colon, through which stool and gas pass out. The opening of the efferent limb leads into the non-functioning part of the colon. The stoma site was usually high on the abdomen above the waistline because the transverse colon was commonly used.
Currently, loop colostomies are more often fashioned from the sigmoid colon to defunction the rectum (for example, in cancer) or anus (for example, in incontinence).
A loop colostomy may be temporary or permanent.
End ileostomy When the entire colon, rectum, and anus must be removed (panproctocolectomy) an end ileostomy must be employed. This occurs most commonly in severe ulcerative colitis but also in familial polyposis and some cases of colorectal cancer (for example, hereditary non-polyposis colorectal cancer).
The ileum is resected just short of its junction with the caecum, and 6-7 cm of the small bowel is brought through the abdominal wall, usually in the right iliac fossa. It is everted to form a spout and then sutured to the bowel wall to protect the skin from the irritating content of the ileal fluid. After a panproctocolectomy the ileostomy is permanent. Temporary end ileostomy is often used after an emergency subtotal colectomy, which leaves part of the sigmoid colon and rectum left in place; for acute ulcerative colitis; acute ischaemic bowel; or neoplastic obstruction of the sigmoid . Loop ileostomy This type of stoma allows for defunctioning of an obstructed colon (in cancer), defunctioning of a
distal anastomosis (after resection and primary anastomosis either as an emergency or after radiotherapy), or defunctioning of the anus (in incontinence or perineal involvement in Crohn's disease). Loop ileostomy has largely replaced loop colostomy because it is easier to site, less bulky, and easier to surgically close. A loop ileostomy has two openings, and most are temporary.
End-loop ileostomy This less commonly performed procedure is used when an end ileostomy cannot be fashioned safely because the patient is obese or because of unfavourable mesenteric anatomy. The formation of this stoma is similar to a loop ileostomy, but the efferent limb is short and blind ended. On inspection at the bedside this type of stoma is indistiguishable from a loop ileostomy. Double barrel stoma When the caecum is removed, the surgeon might create a double barrel stoma. In essence, this is
an end ileostomy (small bowel) and a mucous fistula (the remaining colon) sited beside each other. On examination this will look almost identical to a loop ileostomy, however, closer inspection will show two separate stomas.
Urostomy This is a general term for the surgical diversion of the urinary tract. The main reasons for a urostomy are cancer of the bladder, neuropathic bladder, and resistant urinary incontinence. The bladder is usually removed, but this may depend on the underlying condition. Formation of an ileal conduit is the most common procedure, which constitutes isolation of a segment of ileum. One end of the ileum is closed and the two ureters are anastomosed to it. Finally, the open end of ileum is brought out onto the skin as an everted spout and will look similar to an end ileostomy. Urine drains almost constantly from the kidneys through the ureters and ileal conduit into a bag.
Stoma bags
Stoma bags are of two main types.
Single piece systems stick straight on to the patient's skin. Two piece systems have a separate base (a flange) that sticks to the skin, and the bag attaches to this. This enables the bag to be changed wo removing the flange.
Some bags have a second opening at the bottom to allow emptying. These are most useful in the period immediately after operation and in patients who have had ileostomy, who need to drain their bag regularly. Closed bags are used when the faeces are well formed and are usually only changed once or twice a day. Most patients with a stoma will use an opaque bag, but in the period immediately after operation a transparent bag is used to observe the new stoma for complications such as persistent oedema or necrosis. Modern stoma bags are fitted with a carbon or charcoal flatus filter that allows gas to escape to prevent the bag from ballooning or detaching and neutralises odour.
Complications
Functional problems, such as skin excoriation and stoma noises, are the most common complications and are usually managed by the stoma nurse. Patients with stoma admitted to hospital with increased or decreased output should be appropriately managed to exclude any abdominal emergency, with particular emphasis on careful history taking to establish the normal bowel pattern, and attention to fluid balance.
Most structural problems, such as stoma prolapse, retraction, and parastomal hernia formation can be managed conservatively with modified bags and specialised belts. Only about 10% of patients with these complications will require further surgery. Patients should be alert to any change in colour of their stoma. Stomal oedema is normal for several days after surgery, but if the mucosa becomes dusky or necrotic the surgeon should be contacted promptly.
Question Answer Stoma
Where is the stoma? Left iliac fossa Most likely a colostomy Right iliac fossa Most likely an ileostomy How does the bowel lie in relation to
the external skin? Flush with skin Most likely a colostomy
Raised spout Ileostomy; less commonly a urostomy How many lumens are present? One End colostomy; end ileostomy; urostomy
Two (adjacent)—efferent limb may be difficult to see
Loop colostomy; loop ileostomy; end-loop ileostomy
Two (separate stomas) Most likely end colostomy with a mucous fistula; double barrel stoma; rarely bowel stoma and urostomy What are the contents of the stoma
bag (don't be afraid to feel it)? Fully formed stool Colostomy
Semisolid or liquid stool Most likely ileostomy; colostomy
Urine Urostomy
Mucus Mucous fistula
Examining a patient with an abdominal stoma and bag
4. DIVERTICULAR DISEASE
PATHOLOGY – acquired herniation of colonic mucosa through muscular wall, with a covering of colonic serosa TERMS
- Diverticulosis coli – presence of acquired pseudodiverticula - Diverticular disease – symptomatic diverticulosis coli - Diverticulitis – inflammation of diverticula
EPIDEMIOLOGY
- Increases with age; up to 25% in >70YO (2-5% are <40YO, more in obese M) - Majority are asymptomatic; 10-30% are symptomatic
- Risk factors – dietary fibre & genetics - Site
o majority are in the sigmoid colon, right sided are thought to be genetic; o Asians: 40% right, 60% left, Caucasians: 20% right, 80% left o not in rectum as taeni coli has fused
PATHOGENESIS
1. Increased intraluminal pressure - Associated with lack of dietary fibre 2. Degenerative changes in colonic wall
- Usually at point of entry of terminal arterial branches where serosa is weakest - Associated with weakening of collagen structure with age
PRESENTATIONS - depends on location of the affected diverticulum, the severity of the inflammatory process, and presence of complications 1. Acute diverticulitis
- Symptoms: LLQ pain, N/V, Constipation / diarrhoea, flatulence/bloating - Signs: Low grade fever, Tender palpable mass
- Investigation: WBC 2. Chronic diverticulitis
- Recurrent LIF pain - Irregular bowel habit - Passage of mucus PR
3. Complicated diverticulitis (dangerous) a. Perforation
b. Paracolic abscess / inflammatory mass – 2o to localized perforation c. Bowel obstruction – 2o to stricture or adherence to a diverticular mass d. LGIT haemorrhage – ulcerated vessel @ neck of diverticulum; torrential
e. Fistula formation (commonest: colovesical fistula) – 2o to pericolic abscess discharging, operation or drainage of pericolic abscess. May present with urinary symptoms. Others – colo-cutaneous, colo-uterine, colo-enteric, colo-vaginal
Elderly and patients on steroids may have no sign even in severe diverticulitis.
There is an increased rate of free perforation (43% vs. 14% in immunocompetent patients), increased need for surgery (58% vs. 33%), and increased postoperative mortality (39% vs. 2%).
STAGING
- Hinchey classification of complicated acute diverticulitis – need for surgery is reflected by degree of infective complications
Stage 1 Pericolonic / Mesenteric
abscess (small) - ABx, NBM, IV fluids - Consider 1 stage surgery after acute episode – resection of affected bowel segment with primary anastomosis