The total number of CT scans of the abdomen and pelvis performed within the Greater Glasgow and Clyde Health Board over the 4 year period analysed was 65,393 giving an overall incidence of intussusception of under 0.3%,
comparable to that documented in the literature [3,4,5].
Overall,
the majority were enteroenteric 91/177 (51%),
followed by colocolic 53/177 (30%) and ileocolic 30/177 (17%),
Table 1.
Of the 177 intussusceptions identified on CT,
a lead point was identified in 67/177 (38%).
There was no lead point in 110 (62%),
Figure 1.
Identified lead points in our cohort include colorectal cancer (Figure 2),
adenomatous polyps,
Meckel’s diverticulum,
intramural lipoma (Figure 3) and mesenteric lymph nodes.
Another interesting case involved a long segment intussusception in a young patient with cystic fibrosis (Figure 4).
Of those with a lead point on CT,
33/67 (49%) proceeded to surgery whilst 34 (51%) were managed conservatively.
Indications for conservative management were that the patient was deemed unfit for surgery,
further treatment was declined by the patient,
the patient died or in only 1 case,
that the intussusception was not believed to be the cause of their symptoms.
In the surgical group,
the positive predictive value (PPV) of CT was 97% with 32/33 patients having lead points confirmed whilst only 1(3%) did not (Figure 5).
In the group where no lead point could be visualised on CT,
83/110 (75%) were managed expectantly and 27 (25%) proceeded to operation (Figure 6).
Of those taken to theatre,
17/27 (63%) had a lead point demonstrated intra-operatively or on pathology whilst 10 cases had no lead point giving a negative predictive value (NPV) of 37% (Figure 7).
In the subgroup with no CT identified lead point and who did not undergo surgery,
70/83 (84%) were deemed incidental based on imaging (Figure 8) and received clinical follow up alone; while the remainder either refused further intervention or were deemed for palliative care and therefore not investigated further or died of other causes.
On further analysis,
the PPV was 100% in the non-surgical group with no obstruction,
ischaemia or lead-point on CT.
The majority of these were entero-enteric,
67/83 (81%).
Overall,
the sensitivity of CT in predicting lead-point intussusception was 65% with a specificity of 90%.