Family Practice Advance Access originally published online on June 21, 2006
Family Practice 2006 23(5):507-511; doi:10.1093/fampra/cml027
Upper abdominal ultrasound in general practice: indications, diagnostic yield and consequences for patient management
a Department of Radiology, University Medical Centre Utrecht Utrecht, The Netherlands
b Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht Utrecht, The Netherlands
c Department of Radiology, ‘Onze Lieve Vrouwe Gasthuis’ Amsterdam, The Netherlands
d Department of Radiology, Gelre Hospitals Apeldoorn, The Netherlands
e Department of Radiology, Jeroen Bosch Hospital's-Hertogenbosch The Netherlands
Correspondence to Anouk M Speets, Department of Radiology, E01.335, University Medical Centre Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands; Email: a.speets{at}umcutrecht.nl
Received 12 October 2005; Accepted 23 May 2006.
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Abstract |
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Background. Abdominal ultrasound (US) is frequently performed in Western societies. There is insufficient knowledge of its diagnostic value in terms of changes in patient management decisions in primary care.
Objective. To assess the influence of upper abdominal US on patient management in general practice.
Methods. A prospective cohort study with 76 GPs and three general hospitals in The Netherlands. A total of 395 patients aged 
18 years referred by their GPs for upper abdominal US were included. The main outcome was change in anticipated patient management assessed by means of questionnaires filled in by GPs before and after abdominal US.
Results. Mean age of the patients was 54.0 ± 15.8 years, 35% were male. Clinically relevant abnormalities were found in 29% of the abdominal US, mainly cholelithiasis. Anticipated patient management changed in 64% of the patients following abdominal US. Main changes included fewer referrals to a medical specialist (from 45 to 30%); and more frequent reassurance of the patient (from 15 to 43%). However, this reassurance was not perceived as such in almost 40% of these patients. A change in anticipated patient management occurred significantly more frequently in patients with a prior cholecystectomy (82%).
Conclusion. Anticipated patient management by the GP changed in 64% of patients following upper abdominal US. Abdominal US substantially reduced the number of intended referrals to a medical specialist, and more patients could be reassured by their GP.
Keywords. Abdominal ultrasound, general practice, patient care management.
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Introduction |
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Abdominal ultrasound (US) is an important diagnostic method for evaluation of many structures in the abdomen, such as the liver, gallbladder, biliary tract, pancreas and kidneys. Indications include abdominal, flank and/or back pain, palpable abnormalities, abnormal laboratory values suggestive for abdominal pathology, follow-up of known or suspected abnormalities and search for metastatic disease or occult primary.1 Abdominal US is frequently performed in Western societies. Annually, about 200 000 abdominal ultrasounds are requested by GPs in The Netherlands, usually performed in referral hospitals.
The frequency with which even relatively inexpensive and non-invasive diagnostic tests are performed clearly places a burden on health care. Therefore it is important that their influence on patient management is assessed. Unnecessary diagnostic investigations may lead to incidental findings, or to additional unnecessary diagnostic procedures or even over treatment.
Evaluations of abdominal US in patients referred by GPs have been reported scarcely in the scientific literature. There is insufficient knowledge of its diagnostic value in terms of changes in patient management decisions in primary care. We are aware of four retrospective studies that examined abdominal complaints and referral by GPs for abdominal US.2–5 The percentages of clinically relevant abnormalities detected on abdominal US ranged from 25 to 30%. Clearly, the full value of abdominal US cannot be assessed in terms of positive findings alone. Firstly, the relevance of detected abnormalities must be assessed with respect to clinical practice, because positive findings may be incidental and without any consequences. Positive findings are relevant only when they result in changes of patient management. On the other hand, negative examinations can also have potential value when they result in changes of patient management and can be very helpful in reassuring patients. Neither of these studies however cited both positive and negative findings in detail, nor assessed the value of abdominal US in terms of changes in patient management. Also, the consequences of abdominal US according to the patient were not studied before.
The objective of this study was to assess the influence of both positive and negative findings of upper abdominal US on the change in patient management in general practice and to evaluate the consequences of the abdominal US according to the patient.
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Methods |
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Population
This prospective cohort study was conducted from April 2003 to December 2004. In total, 76 GPs in the catchment area of one of three participating general hospitals located in three main cities in The Netherlands (Jeroen Bosch hospital in 's-Hertogenbosch; Gelre hospitals in Apeldoorn; ‘Onze Lieve Vrouwe Gasthuis’ in Amsterdam) were involved; 25 GPs (33%) worked in a solo practice, 54 (71%) were male, 32 GPs (42%) graduated between 1968 and 1980, 23 (30%) between 1980 and 1990, and 21 (28%) between 1990 and 1997. All patients of 18 years and older who were referred for upper abdominal US by their GP to one of these hospitals were included in the study. The patients received an exclusion form from their GP, which they could return to the study coordinator if we were not allowed to use their data for this study. This study was approved by the Medical Ethics Review Board.
Measurements
All GPs were asked to fill in a standardized form before requesting an upper abdominal US, including information on history, physical examination, indication, suspected diagnosis and proposed patient management. The anticipated patient management was filled in as if no abdominal US would be performed. The management options included referral to a medical specialist; initiation or change in therapy; follow-up by the GP (watchful waiting or additional diagnostic testing); and reassurance of the patient. The GP could choose only one of these management options. After the GP received the report (within 1–4 days after the US) he or she filled in a second questionnaire; again including the suspected diagnosis and anticipated patient management plan.
The reports of upper abdominal US were collected in the three hospitals to determine the findings of the US. These findings were categorized into six groups: (i) malignancy; (ii) cholelithiasis; (iii) nephrolithiasis; (iv) other significant abnormalities (e.g. abdominal aortic aneurysm and unclear abnormalities that required further investigation according to the radiologist); (v) follow-up of abnormalities detected previously on abdominal US; and (vi) no abnormality. The first four groups were considered clinically relevant abnormalities.
Six months after the abdominal US a short questionnaire was sent to all patients, in order to assess the value and consequences of abdominal US according to the patient (response rate 81%). They could choose one of the following options: definite diagnosis; better treatment; reassurance; nothing; or other. With this information we could check whether reassurance of the patient as reported by the GP was really perceived as reassurance by the patient.
In total, 430 patients of 18 years or older were referred for upper abdominal US. Patient management plans for 35 patients (8%) were not filled in by the GP before and/or after abdominal US. These patients were excluded from the study, resulting in a study population of 395 patients. Their patient characteristics were comparable with the included patients.
Statistical methods
The primary outcome measure for our study was the proportion of patients in whom there was a change in anticipated patient management by the GP following upper abdominal US. This proportion and the corresponding 95% confidence interval were calculated using the statistical program Confidence Interval Analysis.6 Additionally, subgroup analyses were performed to assess whether the patient and GP characteristics influenced the proportion of change in anticipated patient management. Associations were tested with chi-square tests and regarded as significant when the P-value was 
0.05. Data were analysed using SPSS for Windows version 11.0.
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Results |
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Mean age of the patients at time of the abdominal US was 54 years (SD 15.8) and 35% were male. Ten percent of the patients had a prior diagnosis of cholelithiasis or nephrolithiasis and 7% had a prior cholecystectomy. Almost 80% of the patients had complaints of abdominal pain. Abnormalities with physical examination were found in 44% of the patients. The most common indications for abdominal US were cholelithiasis (47%) and nephrolithiasis (13%) (Table 1).
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The radiology reports of abdominal US showed no abnormality in 269 patients (68%) and follow-up of an abnormality detected previously on abdominal US in 12 patients (3%). Clinically relevant abnormalities were found in 114 abdominal US (29%), these included malignancy (n = 9; 2%), cholelithiasis (n = 74; 19%), nephrolithiasis (n = 7; 2%) and other clinically relevant abnormalities that required further investigation according to the radiologist (n = 24; 6%). Five of the nine malignancies were detected in the liver, three in the pancreas and one in the kidney. The other clinically relevant abnormalities were eight solid lesions of the liver, six other abnormalities of the kidney (e.g. large cysts), three gallbladder polyps, three abnormalities of the bowels (e.g. Crohn disease), one AAA, one umbilical hernia, one patient with small nodular lesions of the spleen and one patient with ascitis.
As expected, all patients with a malignancy were referred to medical specialists after abdominal US. Fifty-two patients (70%) with cholelithiasis and two of the seven patients with nephrolithiasis were referred to a medical specialist by their GP after abdominal US. Noticeable was that 16 patients (4%) with no abnormalities detected on the abdominal US were referred to a medical specialist. In 10 patients the GP was not able to come to a diagnosis after abdominal US and they were referred to a medical specialist for further diagnostic workup, and in six patients the suspected diagnosis of the GP was confirmed by exclusion of other pathology and these patients were subsequently referred to a specific medical specialist, e.g. gastroenterologist.
The proportion of patients in whom upper abdominal US resulted in a change in anticipated patient management was 64% (95% CI 59–68%). Main changes in patient management plans after abdominal US included a reduction in anticipated referrals to a medical specialist from 179 (45%) to 119 (30%); and more frequent reassurance of the patient, from 58 (15%) to 170 (43%) patients (Table 2).
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The proportion of patients in whom abdominal US resulted in a change in the anticipated patient management was significantly higher in patients with a negative US finding, compared to patients with a clinically relevant finding on abdominal US, 72% (95% CI 68–76%) and 43% (95% CI 36–51%), respectively. Subgroup analyses revealed that the proportion of patients in whom the patient management changed after upper abdominal US was significantly higher among patients with a prior cholecystectomy (82%) (Table 3). This was mainly caused by a larger decline of anticipated referrals to a medical specialist after abdominal US (from 48 to 22%), because no abnormalities were detected with the US examination in almost 90% of these patients. None of the other patient characteristics influenced the proportion of management changes. The characteristics of the GPs (solo or group practice, gender and year of graduation) had little influence on the proportion of change in management of 64%.
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Almost one-third of the patients who returned the questionnaire reported that abdominal US had no consequences for him/her. In total 46% of the patients with a negative finding on abdominal US felt reassured by the US. It was noted that 37% of the 170 patients who were reportedly reassured by their GP after abdominal US failed to perceive the result of the US as reassurance.
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Discussion |
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The proportion of patients for whom the anticipated patient management changed following upper abdominal US was 64%. Main changes included fewer intended referrals to a medical specialist (from 45 to 30%); and more frequent reassurance of the patient (from 15 to 43%).
To our knowledge this is the first study that has investigated the influence of upper abdominal US on patient management in general practice. The studies of Charlesworth et al.2, Colquhoun et al.3, Connor et al.4 and Mills et al.5 reported numbers of clinically relevant abnormalities in 25, 30, 28 and 27%, respectively, of patients referred for abdominal US by GPs. The 29% clinically relevant abnormalities found in our study is comparable. In addition, our study showed that the full value of upper abdominal US cannot be assessed in terms of positive findings alone. Negative findings are important for exclusion of diseases and, therefore, for reassurance of the patient. However, such findings can also result either in referral of patients to a medical specialist for further evaluation of their complaints when an abdominal US fails to show any abnormalities, or in the referral of patients to a suitable medical specialist, when specific pathology is excluded.
Subgroup analyses revealed that the proportion of patients in whom patient management changed after upper abdominal US was significantly higher among patients with a prior cholecystectomy (82%). This was mainly caused by a larger decline of anticipated referrals to a medical specialist after abdominal US. Obviously, in those patients hidden postcholecystectomy gallstone pathology was excluded by the absence of choledochus dilatation or intrahepatic stones.
Over 80% of the questionnaires were returned by the patients, which increased the validity of these results. It was noted that almost 40% of the 170 patients who were reportedly reassured by their GP after abdominal US failed to perceive the result of the US as reassurance. Therefore, it seems abdominal US did not have much value for these patients, because no referral or treatment followed after the radiological investigation and reassurance was not achieved.
Before we can reach a conclusion, it is important to note that this study has several limitations. It was impossible to verify whether or not the GP really would have conducted the anticipated patient management in accordance with the plan made on the standardized form before abdominal US was performed. This could result in an overestimation of intended referrals to medical specialists. Furthermore, this study does not prove that the patient actually benefits from the diagnostic procedure, e.g. in terms of morbidity, mortality or quality of life. However, this study is the first to show that the procedure often leads to changes in anticipated patient management, which is one of the prerequisites for successfully influencing clinically relevant patient outcomes.
In conclusion, the GP's anticipated patient management strategy was changed for 64% of patients following upper abdominal US. Abdominal US substantially reduced the number of intended referrals to a medical specialist and more patients could be reassured by their GP.
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Declaration |
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Funding: none.
Ethical approval: this study was approved by the medical ethics review board of the University Medical Centre Utrecht.
Conflicts of interest: none.
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Acknowledgments |
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It would not have been possible to conduct this study without the participation of all GPs from the catchment areas of the three hospitals. We wish to thank the three trial nurses, Han de Koning working in the Jeroen Bosch hospital in 's-Hertogenbosch, Ireen Brussee from the Gelre hospitals in Apeldoorn and Cecil Kressenhof from the ‘Onze Lieve Vrouwe Gasthuis’ in Amsterdam, for their help with all the logistics in the three hospitals. Finally, we thank Cees Haaring from the University Medical Centre Utrecht for making the database and his assistance with the data management.
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Notes |
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Speets AM, Hoes AW, van der Graaf Y, Kalmijn S, de Wit NJ, Montauban van Swijndregt AD, Gratama JWC, Rutten MJCM and Mali WPThM. Upper abdominal ultrasound in general practice: indications, diagnostic yield, and consequences for patient management. Family Practice 2006; 23: 507–511.
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References |
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1 American College of Radiology. (2001) ACR Standards. ACR Standard for the performance of an ultrasound examination of the abdomen or retroperitoneum pp. 1–5.
2 Charlesworth CH and Sampsom MA. (1994) How do general practitioners compare with the outpatient department when requesting upper abdominal examinations? Clin Radiol 49:343–345.[CrossRef][Web of Science][Medline]
3 Colquhoun IR, Saywell WR, Dewburry KC. (1988) An analysis of referrals for primary diagnostic abdominal ultrasound at a general X-ray department. Br J Radiol 61:297–300.
4 Connor SEJ and Banerjee AK. (1998) General practitioner requests for upper abdominal ultrasound: their effect on clinical outcome. Br J Radiol 73:1021–1025.
5 Mills P, Joseph AEA, Adam EJ. (1989) Total abdominal and pelvic ultrasound: incidental findings and a comparison between outpatient and general practice referrals in 1000 cases. Br J Radiol 62:974–976.
6 Altman DG, Machin D, Bryant TN, Gardner MJ. (2000) Statistics with Confidence: Confidence Intervals and Statistical Guidelines (BMJ Books, London).
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