10.1055/a-1005-6602Over the last few years, we have seen an increasing number of reports about use of
endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) as an option for drainage
of the gallbladder in patients suffering from acute cholecystitis who are at high
risk for cholecystectomy [1]. Other indications for the procedure include conversion of permanent cholecystostomy
to internal drainage or drainage of the biliary tract when endoscopic retrograde cholangiopancreatography
and EUS-guided biliary drainage fails [2]
[3]
[4]. Multiple studies and meta-analyses have shown that the procedure is associated
with reduced adverse events (AEs), reinterventions and re-admissions [5]
[6]
[7]
[8]
[9]. Nevertheless, the procedure is still mostly performed in tertiary centers with
vast experience in interventional EUS and the learning curve for it is still undefined.
In the current study by Tyberg et al [10], outcomes in 48 patients who received US-GBD by a single operator over a 5-year
period were reported. The gallbladder was drained using a variety of stents including
lumen-apposing stents (LAMS) (37.77 %), fully-covered self-expanding metal stents
(FCSEMS) (19 %) or plastic stents (4 %). AEs occurred in 19 % of patients and evenly
throughout the study period. Median procedural time was 41 minutes and was achieved
on the 19th procedure. Procedural duration declined further, with the last 10 procedures taking
20 minutes or less. The authors concluded that the learning curve for EUS-GBD should
be around 19 cases.
The amount of experience required to obtain competency with a procedure is an important
concept, as it is vital for standardization and credentialing purposes. However, many
factors could influence the learning curve for a procedure, including the endoscopist’s
prior experiences, institutional volume, presence of prior training on models, and
availability of dedicated devices. Thus, to measure what makes the individual competent
for a procedure is extremely difficult, given that many of these factors may introduce
different biases. Hence, investigators often have to resort to measuring surrogate
outcomes like procedure time and AEs to quantify the learning curve for a procedure.
In another recently published manuscript on the learning curve of gallbladder drainage,
the authors attempted to quantify the number of procedures required to gain competency
by comparing outcomes of EUS-GBD in endoscopists experienced with fewer than 25 versus
25 or more procedures [11]. The authors also had an interesting outcome parameter that is known as unplanned
procedural events (UPE). UPEs were defined as any deviations of the procedure from
the planned steps. These events include dislodged guidewires or mis-deployment of
the stents, where subsequent proper placement of the stent may not lead to any clinical
sequalae. UPEs are a new classification of events that are particular to interventional
EUS procedures and do not occur in other endoscopic procedures. In this study, UPEs
were significantly more common in patients with EUS-GBD performed for conversion of
cholecystostomy (P < 0.001); and by endoscopists with experience with fewer than 25 procedures (P = 0.033). Both presence of clinical failure (P = 0.014; RR 8.69 95 %CI [1.56–48.47]) and endoscopist experience with fewer than
25 procedures (P = 0.002; RR 4.68 95 %CI [1.79–12.26]) were significant predictors of 30-day AEs.
Presence of 30-day AEs was a significant predictor of mortality (P < 0.001; RR 103 95 %CI [11.24–944.04]). The authors concluded that the number of
cases required to gain competency with EUS-GBD by experienced interventional endosonographers
was 25 procedures.
Both of the above studies have flaws in the method of measuring learning curves. The
procedures were also performed by highly experienced and specialized endoscopists,
and outcomes reported may not be applicable to those just beginning the procedure.
Nevertheless, they still provide some guidance as to the minimal number of procedures
required to gain competency with EUS-GBD. In those already experienced in interventional
EUS, the number should be around 19 to 25 procedures. However, apart from mere numbers,
when learning a new procedure, perhaps the more important aspect is to follow a standard
protocol. An example could be starting with understanding background about the procedure,
followed by hands-on training in ex-vivo or animal models, and then observing the
procedure being performed in humans, followed by performing the procedure under supervision
by those experienced in the procedure [12]. Only by introducing new procedures in a step-wise manner can we continue to educate
our junior colleagues without jeopardizing patient safety.
In conclusion, EUS-GBD is gaining popularity as the procedure of choice in treatment
of acute cholecystitis in patients who are at very high risk of surgery. To introduce
the technique effectively and safely to the wider endoscopic society, a standardized
training program is essential. Thereafter, we should validate the numbers required
to gain competency by trainees who have undergone these training programs.
