This presentation gives basic principles of port position in laparoscopy

1. Baseball Diamond Concept for
Port Position in Laparoscopy
Jibran Mohsin
Resident, Surgical Unit I
SIMS/Services Hospital, Lahore

2. Where should I insert the port?
 First query and common problem which the beginners encounter
 Common cause of stressful surgery is wrong port position
 If one port is at wrong place, surgeon will struggle throughout surgery due to bad
ergonomics
 May be sometime one of causes of complication and more rate of conversion

3. Answer lies in Baseball Field

4. Target of Dissection
Outer Arc
Inner Arc
Working/Secondary
Port
Working/Secondary
Port
Primary/Optical Port
(Telescope)

5. First Principle of Baseball Diamond
Concept
 Half of the instrument should be in and half out.

6. 1st Rationale for 1st Principle
 Laparoscopic instruments works on Lever action.
 Type I Lever……….Fulcrum in the center and load is equal and opposite to the force
applied
 Generally all laparoscopic instruments should behave like type 1 Lever

7. 1st Rationale for 1st Principle
 If fulcrum is very close to load arm:
 i.e. maximum length of instrument outside (Port very near to target of dissection)
 Force is magnified……………leading to tissue tear or avulsion of CBD
 movement will be rectified.

8. 1st Rationale for 1st Principle
 If fulcrum is very close to force arm:
 i.e. maximum length of instrument is inside abdomen (Port very far from target of
dissection)
 Little movement outside leads to magnified distance moved inside  again leading
to collateral damage(diaphragm, bowel) i.e. overshooting
 Force will be rectified inside.

9. 2nd Rationale for 1st Principle
 If port is very close to target of dissection………………elevation angle will be 90O
……surgery can’t be performed….as instrument will not lift the tissue e.g. fork at 90o can’t
turn the omelette
 If port is very far from target of dissection………….elevation angle will be less i.e.
10o……handle of instrument will touch the body of the patient
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 Elevation Angle = angle between instrument and body of patient
 Ideally it should be 60o and equals the manipulation angle
 during cooking, stirring etc 60o elevation angle is used

10. 3rd Rationale for 1st Principle
 If port is very close to target of dissection………metallic cannula of port will touch
the non insulated part of instrument….direct coupling occur….injury to nearby
bowel or bladder
 If port is very far away from target of dissection…………………entry and exit will not
be witnessed by telescope as cannula will be behind the telescope and long
pathway of entry/exit is blind and bowel damage may occur
 If half is out and half is in………no chance of direct coupling and no blind long
pathway

11. How to get 1st Principle?
 Step I: Find out the target of dissection (defined as most critical part of dissection,
requiring most attention and linked with max anxiety)
 E.g. calot triangle , base of appendix, splenic artery/vein
 Step II: Find the length of instrument
 Neonatal………..20 cm
 Pediatric……..28 cm
 Adult………….36 cm
 Morbid Obese………..45 cm

12. How to get 1st Principle?
 Step III: Draw the line of optimum area
 Keeping target at center, draw 2 arcs
 1st arc at 18 cm (half the length of instrument)
 2nd arc at 24 cm (2/3rd of length of instrument)
 All ports including telescope MUST ALWAYS be placed anywhere in between these
2 arcs.

13. Second Principle of Baseball Diamond
Concept
 Telescope should be in middle of working instruments i.e. Azimuth angle (defined
as angle between telescope and working port/hand instrument) must be equal i.e.
30o (normal range 15o to 45o)
 i.e. contralateral port position
Etymology: Azimuth  Arabic al-sumūt, meaning "the directions"

14. Rationale for 2nd Principle
 Contralateral Port Position  Depth Perception
1. Linear Parallax

15. Rationale for 2nd Principle
 2. Motion Parallax
 Object near will appears to move more and vice versa

16. Rationale for 2nd Principle
 3. Relative Size
 Object far will appears to be small and vice versa

17. Rationale for 2nd Principle
 4. Aerial gradient/persecption
 Object near will appear to have better contrast and better color

18. Rationale for 2nd Principle
 5. Correct Shadow

19. Rationale for 2nd Principle
 6. Texture Gradient
 Near object appears to have more rough and detailed surface

20. Rationale for 2nd Principle
 Versus ipsilateral port position
 DEMERIT:
 Less depth perception…….1 instrument too near to telescope and other away from
telescope.
 Acceptable only for simple procedures such as appendectomy, ventral hernia
 but doesn’t works for advanced surgery such as fundoplication, inguinal hernia repair,
hiatus hernia + knotting/suturing.
 MERIT:
 Allows sectorisation i.e. surgeon can move freely as camera is away from operative field
 no physical contact between surgeon and camera holder

21. Third Principle of Baseball Diamond
Concept
 Manipulation angle(defined as angle between two working hand
instruments)should be 60o ± 15o

23. How to get 3rd Principle?

24. How to get 3rd Principle?
 Put tip of index finger over target of dissection
 Put tip of thumb over site of telescope
 Position of anatomical snuff box will give you rough estimation of secondary port
position in adult on both sides
Target of dissection
Optical port
ANATOMICAL SNUFF BOX
Working port position

25. How to get 3rd Principle?
 LIMITATIONS:
 Not applicable for pediatric patients
 Measurements are for average adult male surgeon………..in female reference point
is approximately radial styloid process

26. SUMMARY
 1st Principle: Half (i.e. 18 cm in adult) of the instrument should be in and half out so
that elevation angle is 60 degree.
 2nd Principle: Contralateral port position with equal Azimuth angle is ergonomically
better
 3rd Principle: Manipulation angle should be 60 degree.

27. Available at surgicalpresentations