Sunday, January 13, 2008

11 - surgery mcqs - 71 to 80

71. Regarding local anaesthesia

a. Local anaesthetics act on large before small nerve fibres

b. Their main toxic effects are seen on the central nervous and cardiovascular systems

c. Adrenaline reduces absorption and prolongs the local effects

d. Preparations containing adrenaline are safe to use on digits and appendages

e. Lignocaine has a longer duration of action than bupivicaine


only b and c are right . local anaesthetics act on small pain and autonomic C fibres . the use of adrenaline on digits can cause ischemic necrosis . duration of action for lignocaine is one and half hours ( 1 and 1/2 hrs ) where as for bupivacaine it is 8 hours .


72. With an iron deficiency anaemia

a. Both serum iron and total iron binding capacity are reduced

b. The blood film shows a hyperchromic microcytic picture

c. The reticulocyte count is low in relation to the degree of anaemia

d. Serum ferritin levels are increased

e. The platelet count may be increased


c and e are true . total iron binding capacity is increased . serum ferritin levels are decreased . blood film shows a hypochromic anaemia . platelet count is increased.


73. Regarding abdominal aortic aneurysms

a. They commonly remain symptomless until they rupture

b. The risk of rupture increases with aortic diameter

c. Elective repair should have a 30-day mortality of less than 5%

d. Emergency repair has a 30-day mortality of less than 10%

e. The benefits of surgery for small (4.0-5.5 cm) is proven


a , b , c only are true . emergency AAA repair usually has a 30 day mortality approaching 50 % . the benefits of surgery for small aneurysms is unproven.


74. Regarding hepatitis B

a. It is due to an RNA virus

b. It has an incubation period of 2 to 6 days

c. It can be transmitted via blood products

d. About 1% of the UK population are Hepatitis B Surface Antigen positive

e. About 10% of infected patients become chronic carriers


c , d , e are true . hepatitis B is a dna virus . it has an incubation period between 2 and 6 months .

75. Regarding vascular grafts

a. PTFE grafts are less porous than Dacron

b. Vein grafts have better long-term patency

c. Graft failure less than a month after surgery is usually due to a surgical error

d. Graft failure within the first year is often due to neo-intimal hyperplasia

e. Graft failure beyond one year is due to progression of the underlying disease


all are true .


76. Regarding colorectal carcinomas

a. About 40% present as surgical emergencies

b. Right-sided tumours often present with a change in bowel habit

c. 75% of tumours can be reached with a flexible sigmoidoscope

d. Over 20% of patients present with more than one primary tumour

e. A Duke's B tumour has nodal metastases


only a and c are true . right sided tumors usually present with anaemia and abdominal mass . about 5 % patients have synchronous tumors. a duke's C tumor is node positive.


77. Regarding colonic polyps

a. Metaplastic polyps are pre-malignant

b. Adenomatous polyps are pre-malignant

c. Villous adenomas are more common than tubular adenomas

d. Genetic mutations can result in epithelial metaplasia

e. Most carcinomas arise in adenomatous polyps


only b and e are true . metastatic polyps are not pre-malignant . tubular adenomas account for about 70 % of adenomatous polyps . genetic mutations result in epithelial dysplasia in the adenoma - carcinoma sequene .


78. In patients with carotid artery disease

a. A bruit is a reliable sign of the degree of stenosis

b. Atheroma is most commonly seen in the external carotid artery

c. An embolic event often results in an ipsilateral hemiplegia

d. Prophylactic aspirin reduces the risk of a stroke

e. Surgery is of proven benefit in those with asymptomatic stenoses


only d is true . bruits are unreliable signs . complete occlusions are silent . atheroma commonly occurs at the carotid bifurcation .


79. Regarding acute limb ischaemia

a. Arterial occlusion has less dramatic effects in those with underling occlusive disease

b. Occurs more often in patients in sinus rhythm

c. Objective sensory loss requires urgent treatment

d. Fixed skin staining is an early sign

e. Intra-arterial thrombolysis is invariably successful with no morbidity


a and c are true . the effects of acute arterial occlusion depends on the state of collateral supply . emboli often arise in the left atrium in those in AF . fixed staining is a late sign of irriversible ischemia . thrombolysis is about 60 % succesful and has significant risks associated with it .


80. Regarding muscle relaxants

a. Suxamethonium is a non-depolarising agent

b. Vecuronium is a depolarising agent

c. Suxamethonium induces histamine release and can produce a 'scoline rash'

d. Suxamethonium has a duration of action of about 5 minutes in most people

e. Scoline apnoea is due to pseudocholinesterase deficiency


only c , d , e are true . vecuronium and tubocurarine belong to non-depolarising muscle relaxants . where as suxamethonium and scoline are depolarising muscle relaxants .


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