Bowel obstruction

Main Signs And Symptoms Of Bowel Obstruction:

Obstruction of the small bowel causes symptoms shortly after onset: abdominal cramps centered around the umbilicus or in the epigastrium, vomiting, and—in patients with complete obstruction—obstipation. Patients with partial obstruction may develop diarrhea. Severe, steady pain suggests that strangulation has occurred. In the absence of strangulation, the abdomen is not tender. Hyperactive, high-pitched peristalsis with rushes coinciding with cramps is typical. Sometimes, dilated loops of bowel are palpable. With infarction, the abdomen becomes tender and auscultation reveals a silent abdomen or minimal peristalsis. Shock and oliguria are serious signs that indicate either late simple obstruction or strangulation.

Obstruction of the large bowel usually causes milder symptoms that develop more gradually than those caused by small-bowel obstruction. Increasing constipation leads to obstipation and abdominal distention. Vomiting may occur (usually several hours after onset of other symptoms) but is not common. Lower abdominal cramps unproductive of feces occur. Physical examination typically shows a distended abdomen with loud borborygmi. There is no tenderness, and the rectum is usually empty. A mass corresponding to the site of an obstructing tumor may be palpable. Systemic symptoms are relatively mild, and fluid and electrolyte deficits are uncommon.

Volvulus often has an abrupt onset. Pain is continuous, sometimes with superimposed waves of colicky pain.

Radiological Appearance Of Bowel Obstruction:

Supine and upright abdominal x-rays should be obtained and are usually adequate to diagnose obstruction. Although only laparotomy can definitively diagnose strangulation, careful serial clinical examination may provide early warning. Elevated WBCs and acidosis may indicate that strangulation has already occurred.

On plain x‑rays, a ladderlike series of distended small-bowel loops is typical of small-bowel obstruction but may also occur with obstruction of the right colon. Fluid levels in the bowel can be seen in upright views. Similar, although perhaps less dramatic, x‑ray findings and symptoms occur in ileus (paralysis of the intestine without obstruction—see Acute Abdomen and Surgical Gastroenterology: Ileus); differentiation can be difficult. Distended loops and fluid levels may be absent with an obstruction of the upper jejunum or with closed-loop strangulating obstructions (as may occur with volvulus). Infarcted bowel may produce a mass effect on x‑ray. Gas in the bowel wall (pneumatosis intestinalis) indicates gangrene.

In large-bowel obstruction, abdominal x‑ray shows distention of the colon proximal to the obstruction. In cecal volvulus, there may be a large gas bubble in the mid-abdomen or left upper quadrant. With both cecal and sigmoidal volvulus, a contrast enema shows the site of obstruction by a typical “bird-beak” deformity at the site of the twist; the procedure may actually reduce a sigmoid volvulus. If contrast enema is not done, colonoscopy can be used to decompress a sigmoid volvulus but rarely works with a cecal volvulus.

Differential Diagnosis:

• Abdominal pain and vomiting can occur with gastroenteritis but if the abdomen is bloated and there is little or no bowel movement, obstruction must be considered. Diarrhoea and vomiting will also cause very active bowel sounds that may be confused with the tinkling of obstruction
• Ischaemia of the gut can cause pain and distension but there is usually bloody diarrhoea.
• The pain of acute pancreatitis tends to radiate to the back. There may be an associated paralytic ileus. Amylase is often raised in obstruction but levels are very high in pancreatitis.
• Perforation of the gut can produce an acute abdomen with pyrexia and vomiting. Peptic ulcer disease, perforated diverticular disease and a perforated carcinoma are all possible causes.
• Intussusception should be considered in children.
• Tuberculosis can present as gastrointestinal disease.
• Non-gastrointestinal conditions to bear in mind include myocardial infarction (small bowel) ovarian cancer (large bowel).

Describe The Differences In Presentation Between Left-Sided And Right-Sided Colonic Carcinoma:

Left-sided colonic carcinoma is characterised by a change in bowel habit due to obstruction. Pain is felt in the left side of the abdomen because there is commonly involvement of the sigmoid colon and the rectosigmoid junction, and there is gross blood in the stool. The carcinoma tend to be small, annular and ulcerated. It appears as a fixed filling defect with an annular “apple core” configuration on barium enema. Usually, the patient is over 40 and commonly, over 70 years of age. Men are affected slightly more than women.

The patient with left-sided colonic carcinoma may be pale due to chronic blood loss and anaemia, and may show weight loss. The left supraclavicular lymph nodes may be enlarged.

The abdomen may be distended and the caecum palpable. The liver may be enlarged due to metastases.

Masses may be felt in the left iliac fossa which may be hard and indentable because of faeces above the tumour. They will be tender if there is surrounding inflammation, and will be dull to percussion, but the abdomen will feel normal on palpation if the mass is small and lying in the paravertebral gutter. A mass may be noted anteriorly on rectal examination if the tumour is down into the pelvis.

Hyperactive bowel sounds indicate chronic intestinal obstruction. During an attack of colic, loud high-pitched continuous gurglings are heard.

Possible symptoms of right-sided colonic carcinoma include:

• pallor, debility, breathlessness – due to iron deficiency anaemia caused by prolonged bleeding
• loss of weight and anorexia
• occult blood in faeces
• persistent, dull ache in right iliac fossa, often postprandial and mistakenly attributed to gallbladder or gastroduodenal disease. This is a late symptom.

Less commonly:

• intestinal colic and intestinal obstruction if the growth occludes the ileocaecal valve
• acute appendicitis if the tumour blocks the mouth of the appendix, causing it to dilate
• change in bowel habit, either constipation or diarrhoea but not both alternately

The patient with a right-sided colonic carcinoma may be pale and thin, possibly jaundiced.

The supraclavicular nodes may be palpable.

The abdomen may be generally distended or ‘full’ in the right iliac fossa. The right iliac fossa is often tender with some guarding of the covering muscles. A firm irregular mass may be felt which may be fixed or freely mobile. When it is mobile it tends to slip upwards into the paravertebral gutter or medially and downwards into the pelvis. It is dull to percussion.

The liver may be palpable and irregular.

The bowel sounds should be normal. Hyperactivity indicates obstruction of the ileo-caecal valve.

The faeces may contain blood.

The patient with carcinoma of the transverse colon presents with a picture intermediate between that of left-sided and right-sided lesions.

A palpable mass may be noticed in the abdomen which is freely mobile in the early stages. A distended caecum indicates obstruction.

The tumour may be treated surgically by transverse colectomy

Describe The Steps In The Pre-Operative Management Of A Patient Presenting With Malignant Large Bowel Obstruction:

1. Correction of fluid loss by aggressive intravenous fluid hydration using crystalloid solutions, e.g. normal saline, with possible addition of potassium supplements (based on estimated fluid loss, blood results and urine output).

2. Passage of naso-gastric tube to drain stomach and small bowel contents.

3. Analgesia via intramuscular or parenteral route.

4. Passage of urinary catheter to monitor urine output (>0.5 ml/kg/hr)

5. Blood should be cross-matched in preparation for surgery.

6. Consent should be obtained for surgery as well as discussion about possible stoma formation.

7. Prophylactic antibiotics, DVT prophylaxis (TEDS and s/c low molecular weight heparins)

Patient must be warned of the risks of the procedure, anaesthetic and possible permanent stoma formation.

Treatment of colonic carcinoma consists of wide surgical resection of the lesion and its regional lymphatic drainage after preparation of the bowel. The primary tumour is resected, even if distant metastases have occurred, since prevention of obstruction or bleeding may offer palliation for long periods.

The abdomen is explored to determine resectability of the tumour and to search for multiple primary carcinomas of the colon, distant metastases, and associated abdominal disease. Care is taken not to contribute to the spread of the tumour by unnecessary palpation. Some authors have even advocated occlusion of the bowel with encircling tape on either side of the lesion in order to contain exfoliated cancer cells within the segment to be resected.

The cancer-bearing portion is mobilised and removed.

Right hemicolectomy is used to treat unobstructed carcinomas of the caecum, ascending colon and hepatic flexure.

The abdomen is opened and the terminal ileum, ascending colon and hepatic flexure are mobilised. The mesentery is divided and the growth and surrounding bowel removed. An anastomosis is made between the ileum and the transverse colon. The anastomosis is drained when possible.

The operation is performed under general anaesthetic. The patient will stay in hospital for 7-10 days and be off work for 6 weeks.

A transverse colectomy is used to treat an unobstructed carcinoma of the transverse colon.

The transverse colon is excised and after full mobilisation, an end-to-end anastomosis performed between the right and the left colon. If the operation is for malignant disease, the transverse mesocolon and omentum are included in the resection.

A left hemicolectomy is used to treat unobstructed carcinoma of the splenic flexure or descending colon, or more rarely for widespread diverticulitis.

The left side of the colon is mobilised and the growth resected. An end-to-end anastomosis is performed. The more common radical left hemicolectomy involves regional lymph node clearance followed by the anastomosis of transverse colon to rectosigmoid colon.

If done as an emergency, the bowel ends may be brought out as a left iliac colostomy and closed later. If a stoma is to be fashioned electively, the patient must have full explanation and counselling.

The operation is done under general anaesthetic. The patient will be in hospital for 7-10 days and off work for 6 weeks.

Colorectal carcinomas are relatively unresponsive to chemotherapy but liver metastases may occasionally be controlled by 5-fluorouracil (5 FU).

NICE recommend options for the adjuvant treatment of patients with stage III (Dukes- C) colon cancer following surgery for the condition as either:

• capecitabine as monotherapy
• oxaliplatin in combination with 5-fluorouracil and folinic acid

NICE has also made recommendations related to the treatment of advanced colorectal cancer (2,3):

irinotecan and oxaliplatin, within their licensed indications, are recommended as treatment options for people with advanced colorectal cancer as follows:

• irinotecan in combination with 5-fluorouracil and folinic acid as first-line therapy, or irinotecan alone in subsequent therapy
• oxaliplatin in combination with 5-fluorouracil and folinic acid as first-line or subsequent therapy

raltitrexed is not recommended for the treatment of patients with advanced colorectal cancer. Its use for this patient group should be confined to appropriately designed clinical studies (2)

Metastatic colorectal cancer, where the tumour has spread beyond the confines of the lymph nodes to other parts of the body, is generally defined as stage IV of tumour node metastases (TNM) system or stage D of Dukes’ classification:

• management of metastatic colorectal cancer is mainly palliative and involves a combination of specialist treatments (such as palliative surgery, chemotherapy and radiation), symptom control and psychosocial support. The aim is to improve both the duration and quality of the individual’s remaining life
• clinical outcomes such as overall survival, response and toxicity are important, but alternative outcomes such as progression-free survival, quality of life, convenience, acceptability and patient choice are also important
• most frequent site of metastatic disease is the liver. In up to 50% of patients with metastatic disease, the liver may be the only site of spread. For these patients surgery provides the only chance of longer-term survival. Approximately 10% of patients with metastatic colorectal cancer present with potentially resectable liver metastases and for approximately 14% chemotherapy may render unresectable liver metastases operable
• first-line active chemotherapy options include infusional 5-fluorouracil plus folinic acid or leucovorin (calcium folinate) (5-FU/FA, 5-FU/LV), oxaliplatin plus infusional 5-FU/FA (FOLFOX), and irinotecan plus infusional 5-FU/FA (FOLFIRI). Oral analogues of 5-FU (capecitabine and tegafur with uracil) may also be used instead of infusional 5-FU

NICE suggest that:

• bevacizumab in combination with 5-fluorouracil plus folinic acid, with or without irinotecan, is not recommended for the first-line treatment of metastatic colorectal cancer (4)
• cetuximab in combination with irinotecan is not recommended for the second-line or subsequent treatment of metastatic colorectal cancer after the failure of an irinotecan containing chemotherapy regimen (4)
• cetuximab as first-line therapy (5):
• cetuximab in combination with 5-fluorouracil (5-FU), folinic acid and oxaliplatin (FOLFOX), within its licensed indication, is recommended for the first-line treatment of metastatic colorectal cancer only when all of the following criteria are met:
• primary colorectal tumour has been resected or is potentially operable
• metastatic disease is confined to the liver and is unresectable
• patient is fit enough to undergo surgery to resect the primary colorectal tumour and to undergo liver surgery if the metastases become resectable after treatment with cetuximab
• manufacturer rebates 16% of the amount of cetuximab used on a per patient basis
• cetuximab in combination with 5-FU, folinic acid and irinotecan (FOLFIRI), within its licensed indication, is recommended for the first-line treatment of metastatic colorectal cancer only when all of the following criteria are met:
• primary colorectal tumour has been resected or is potentially operable
• metastatic disease is confined to the liver and is unresectable
• patient is fit enough to undergo surgery to resect the primary colorectal tumour and to undergo liver surgery if the metastases become resectable after treatment with cetuximab
• patient is unable to tolerate or has contraindications to oxaliplatin
• patients should receive treatment with cetuximab for no more than 16 weeks. At 16 weeks, treatment with cetuximab should stop and the patient should be assessed for resection of liver metastases

survival estimates for patients with metastatic colorectal cancer receiving best supportive care are approximately 6 months

o use of infusional 5-FU/FA can increase survival to approximately 10-12 months, whereas combinations of FOLFIRI followed by FOLFOX, or FOLFOX followed by irinotecan, have been reported to increase survival to 20-21 months

The response to radiotherapy is limited by the difficulty of directing the radiation beam at the tumour without damaging surrounding bowel. Also, if radiotherapy is to be useful, there must be only local invasion – sterilization of local lymph nodes will have no effect on prognosis, for example, if there is already hepatic involvement.