Reliability of the reported size of removed colorectal polyps.
BACKGROUND
The size of colorectal polyps is important in the clinical management of these lesions.


OBJECTIVE
To audit the accuracy in calculating the size of "polyps" by various specialists.


METHODS
Eighteen pathologists and four surgeons measured, with a conventional millimetre ruler, the largest diameter of 12 polyp phantoms. The results of two independent measurements (two weeks apart) were compared with the gold standard-size assessed at The Royal Institute of Technology, Sweden.


RESULTS
Thirty-one percent (83/264-trial 1) and 33% (88/264-trial 2) of the measurements underestimated or overestimated the gold standard size by >1 mm. Of the 22 experienced participants, 95% (21/22-trial 1) and 91% (20/22-trial 2) misjudged by >1 mm the size of one or more polyps. Values given by 13 participants (4.9%) in trial 1 and by 15 participants (5.7%) in trial 2, differed by > or = +/-4 mm from the gold standard size. In addition, a big difference between the highest and the lowest values was recorded in some polyps (up to 11.4 mm). Those disparate values were regarded as a human error in reading the scale on the ruler.


CONCLUSIONS
Using a conventional ruler (the tool of pathologists worldwide) unacceptably high intra-observer and inter-observer variations in assessing the size of polyp-phantoms was found. The volume and the shape of devices, as well as human error in reading the scale of the ruler were confounding factors in size assessment. In praxis, the size is crucial in the management of colorectal polyps. Considering the clinical implications of the results obtained, the possibility of developing a method that will allow assessment of the true size of removed clinical polyps is being explored.
Rubio
Carlos A
CA
Department of Pathology Karolinska University Hospital, Stockholm, Solna, Sweden. Carlos.Rubio@onkpat.ki.se
Grimelius
Lars
L
Lindholm
Johan
J
Hamberg
Hans
H
Porwit
Anja
A
Elmberger
Göran
G
Höög
Anders
A
Kanter
Lena
L
Eriksson
Elina
E
Stemme
Sten
S
Orrego
Abiel
A
Saft
Leonie
L
Petersson
Fredrik
F
De La Torre
Manuel
M
Ekström
Christina
C
Astrom
Kristina
K
Rundgren
Asa
A
Djokic
Miroslav
M
Chandanos
E
E
Lenander
Claes
C
Machado
Mikael
M
Nilsson
Per
P
Mattsson
Lars
L
D003108:Colonic Diseases / Q000473:pathology*; D006801:Humans; D007417:Intestinal Polyps / Q000473:pathology*; D015588:Observer Variation; D010336:Pathology / Q000379:methods / Q000592:standards; D012002:Rectal Diseases / Q000473:pathology*; D015203:Reproducibility of Results