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Keywords:
Outcomes, Diagnostic procedure, Normal variants, Nuclear medicine conventional, Gastrointestinal tract, Quality assurance
Authors:
V. M. Rhodes, N. Moffitt, T. Toma; SOUTHEND ON SEA/ESSEX/UK
DOI:
10.1594/ecr2016/C-1199
Aims and objectives
Cholecystectomy is one of the most common operations in the world and diarrhoea developing after this is a well-known and documented clinical problem.
However the aetiology of post cholecystectomy diarrhoea is not fully understood,
and can often be the most distressing post-operative,
non-painful,
symptom.
Determining the incidence of occurrence and the likely severity of post cholecystectomy diarrhoea could,
therefore,
identify whether cholecystectomy itself may be a cause for bile acid malabsorption induced diarrhoea after surgery (Farahmandfar et al 2012).
There has been a recent revival of 75Se-23-selena-25-homotauro-cholic acid (SeHCAT) testing in order to diagnose diarrhoea associated with bile acid malabsorption (BAM) as this isotope is absorbed and circulates in a manner equivalent to that of cholic acid and has the benefit of being able to be measured externally (Suhr et al 1988).
It has a half-life of 120days and decays emitting a gamma radiation of 136 and 265 keV (Notta 2011).
This test has developed due to new advances in understanding BAM and the realisation that it is more prevalent than first understood.
Although BAM is not a life threatening disease it is most often a life-changing one as it can have a significant impact on how the patients live on a day to day basis.
The diarrhoea associated with BAM can be frequent and uncontrollable which limits the patient’s movement and impedes on the patient being able to lead a normal life (Notghi et al 2011,
Pattni & Walters 2009).
In normal patients 95% of the bile acids secreted by the liver are reabsorbed in the terminal ileum through the enterohepatic cycle.
This cycle can repeat between 4-12 times a day (Barkum et al 2013).
By the seventh day about 35 enterohepatic cycles will have occurred and in normal patients it is expected that the retention percentage should be >15%,
this can be calculated by measuring how much 75SeHCAT remains at day seven using the formula as described by Notghi et al (2011).
However in patients with BAM a higher than normal percentage of bile acid may not be absorbed in the terminal ileum and can reach the colon which may induce diarrhoea (Walters & Pattni 2010,
Suhr et al 1988).
In addition Fort et al’s (1996) report found that patients who had had post-cholecystectomy diarrhoea also had markedly shortened total colonic transit times.
It has therefore been suggested that after cholecystectomy the total storage capacity of bile acid may be lost,
which in turn could lead to increased loss of bile acid.
This reduction might then increase the daily turnover of bile acid by allowing bile acid to enter the duodenum as soon as it has been excreted by the liver,
shortening the colonic transit time (Eusufzai 1993).
Bile acid malabsorption has been split into 3 distinct classifications depending on the aetiology.
Type 1 BAM is associated with ileal Crohn’s disease,
ileal resection or ileal bypass,
and involves the complete failure of the terminal ileum to re-absorb the bile acids resulting in bile acid reaching the colon.
Type 2 BAM is associated with a rare genetic defect in the apical sodium bile acid transporter protein and is responsible for most of the reabsorption of bile acids.
Its main diagnostic characteristics are the lack of change in ileal and/or clinical histology/ pathology.
Type 3 BAM encapsulates all other causes for malabsorption such as diabetes,
post-cholecystectomy,
gastric surgery,
coeliac disease and post-vagotomy (Wedlake et al 2009,
Pattni & Walter 2009).
The aim of this study was to assess the prevalence and severity of post cholecystectomy diarrhoea in patients undergoing SeHCAT testing and to determine if there was any correlation between the clinical severity of the patient’s diarrhoea and a positive result for type 3 bile acid malabsorption. A retrospective study was performed on consecutive past patients,
which investigated the diarrhoea complaints that had been documented in the patient files and in the referrals from the requesting doctors.
From these details it was possible to obtain patient acquired observational data on the degree of diarrhoea each patient suffered after their cholecystectomy.