Accuracy of Surgeon-performed Ultrasound in Detecting Gallstones - a Validation Study
Accuracy of Surgeon-performed Ultrasound in Detecting Gallstones - a Validation Study
Aims: To prospectively investigate the accuracy of surgeon-performed ultrasound for the
 detection of gallstones.

 Methods: 179 adult patients, with an acute or elective referral for an abdominal ultrasound
 examination, were examined with a right upper quadrant ultrasound scan by a radiologist as
 well as surgeon. The surgeons had undergone a four-week long education in ultrasound before
 participating in the study. Ultrasound findings of the surgeon were compared to those of the
 radiologist, using radiologist-performed ultrasound as reference standard.
Enrolment of patients:

 Three hundred patients, with an acute or elective referral to the radiology department at
 Stockholm South General Hospital, Sweden, for any diagnostic abdominal US examination,
 including both patients admitted to in-hospital care and out-patients, were prospectively
 enrolled between October 2011 and November 2012. Eligible patients were identified in the
 radiology department by a study surgeon and informed consent was obtained. Six US educated
 surgeons participated in the enrolment of patients. Exclusion criteria were age <18 years or
 inability to communicate with the examiner. Referrals concerning metastases of the liver or
 contrast-enhanced examinations were considered not suitable for the study and were also
 excluded. The surgeons examined patients consecutively if time was available, but mostly they
 didn't have time to examine every patient referred per day, hence a certain prioritisation
 between referrals was done.

 Data collection:

 Enrolled patients received one US examination by the study surgeon as well as the standard US
 examination by the on-duty radiologist. In a majority of cases the two examinations were
 performed consecutively and the time interval between the surgeon-performed US and
 radiologist-performed US never exceeded 24 hours. The surgeon's examination took place either
 before or right after the radiologist's examination. The examining surgeon and radiologist
 were blinded to each other's findings. The surgeon's US examination followed a standardised
 protocol, which included a full abdominal scan, regardless of the nature of the referral. The
 presence of gallstones was marked as a 'yes' (positive finding, regardless of number or size)
 or 'no' (negative finding) by the surgeon. In cases where a full abdominal scan could not be
 performed, due to urgent patient management, a focused examination based on the referral as
 well as a right upper quadrant (RUQ) scan was advised. The on-duty radiologist performed a
 standard care US focusing on the individual referrals. The radiologist's statement was
 collected from the patient's medical record and transferred to the study protocol by a
 separate radiologist, who was also blinded to the surgeon's examination. Among the
 radiologists the major part of the scans was done by US specialised radiologists with several
 years of training (56% US specialists, 73% specialists in radiology).

 The surgeons used a portable US machine of the model LOGIQ e with a convex (1.6-4.6 MHz) or
 linear (5-13 MHz) transducer, GE Healthcare, WuXi, China. All scans were saved on a separate
 hard drive, which was kept together with the study protocol. The radiologists used Philips
 iU22 with a convex C5-1 or a linear L12-5 transducer.

 US training of surgeons participating in the study:

 Six study surgeons, five in the final years of their specialist training and one specialist
 in surgery, with limited or no previous US training, attended a one-week course, comprising
 US physics, technique, anatomy and hands-on training, led by specialists in US. After
 attending the course the surgeons received three weeks of training in the radiology
 department under the guidance of an US specialist. The surgeons were expected to perform a
 minimum of 50 supervised scans, which was obtained in all cases but one. The training focused
 on detecting gallbladder stones, widened bile ducts, thickened wall of the gallbladder,
 lesions in the liver parenchyma, hydronephrosis, abdominal aortic aneurysms, free abdominal
 fluid and appendicitis. After the training was completed, each surgeon spent a minimum of two
 weeks enrolling and scanning patients during office hours in the hospital's radiology
 department.

 Ethics:

 The patients received oral and written information from the study surgeon and were included
 after informed consent. The study was approved by the Ethical Review Board, at Karolinska
 Institutet, Stockholm, Sweden.
Inclusion Criteria:

 -  Patients referred to the radiology department for an abdominal ultrasound

 -  Age > 18 years

 Exclusion Criteria:

 -  Inability to communicate with the examiner

 -  Referral for intervention

 -  Metastasis screening

 -  Referrals concerning contrast enhanced examinations