DNB surgery Questions 11-15

DNB surgery Questions 11-15

 General Surgery Questions from DNB SS

Questions 1-10      Q16-20         21-30 (Neurosurgery)

Q 11) On T2 W MRI image, what appears bright

a) Water

b) Bone

c) Air

d) Fat

Q12) All  body parts have very low signal on all pulse sequences of MRI except

a. Water
b. Bone
c. Hemosiderin
d . Ferromagnetic particles

Q13) All are interventional procedures except

Q14. Harmonic  scalpel frequency of vibration is 
A. 20000-50000
B. 50000-80000
C. 80000-100000
D. >100000

Q15 ) Commonest cause of breathing difficulty in unconscious patient is 

a) Foreign body 

b) Tongue

c) Blood

d) Impacted teeth

Q16 ) Out of the following which will require Spinal immobilization most?
a. 22 yr Female had a high-speed motor vehicle collision who complains of backpain and no
b.16 yr male jumped from 6ft landed on both foot denies back pain and weakness
C. Gunshot injury
D. Abdominal injury

A11) a 


MRI consists of T1 weighted image and T2 weighted image. Both depends on the timing of radiofrequency pulse sequence. In T2 images water appears bright. In T1 images fat is bright and so are methemoglobin and mucinous fluid. 

In general T1 images is for finding the anatomy and T2 are for finding the pathology.

Bone and Air have low intensity on both T1 and T2

A12) a

In MRI, a brief radiofrequency pulse is applied to alter the protons and electrons in the uniform magnetic field. These protons and electrons have a particular motion and this is altered in MRI. Once the signal is removed, the particles realign and give characteristic images.


Cortical bone, air, haemosiderin and ferromagnetic materials are of very low signal on all pulse sequences

Water has high signals and as discussed in previous question appears bright in T2

Bailey page 178


Easy answer

A14) A 

Its 20K to 50 k Hz

Read about techniques of liver resection here

Harmonic scalpel cuts through tissues and causes coagulation by protein denaturation caused by vibrating force. As compared to cautrey harmonic scalpel

  1. takes longer time 
  2. produces less smoke
  3. Cause less tissue edema, swelling

Ref : bailey page 49

Answer 15 

b Tongue

In an unconscious patient tongue falls forwards with gravity and blocks the airway, more so in supine position. Unconscious patients should always be nursed in prone or semi prone positions.

Airway protectors are available which prevent the tongue falling forwards.

Other causes of air way obstruction are broken teeth, food and gastric secretions. 

Bailey page 341 

Answer 16 ) a

Spinal cord injuries are a common cause of morbidity and expenditure. Mortality is associated with cervical injuries but not lower spinal cord injuries.

Motor vehicle accidents are the most common cause and gunshot injuries the least common for spinal cord injuries.

Mechanism of injury 

  1. Blunt trauma - Direct impingement, Ischemia, compression or bleeding 
  2. Penetrating - Laceration of spinal cord

Chance fracture - is a type of spinal cord fracture in which there is transverse fracture of all vertebral elements


1 Complete immobilisation

2. Management of associated neurogenic shock ( due to loss of sympathetic tone) with vasopressors  and fluids

Sabiston page 420

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