ACCURACY of Ultrasound in the Diagnosis of Upper Abdominal Pain

Sabina Imran

Department of Radiology, Ayub Medical College, Abbottabad

Background: Upper abdominal pain is one of the commonest complaints in patients seeking medical advice, and in majority of the cases the aetiology is simple and treatable. Ultrasonography is hazard free and cost effective investigation. This study was designed to evaluate the accuracy of ultrasound in the diagnosis of upper abdominal pain. Methods: Ultrasonography using 3.5 MHz convex transducer was performed in patients presenting with upper abdominal pain. Results: Five hundred consecutive cases with upper abdominal pain underwent ultrasonic examination. Positive findings were there in 248 patients while 252 had normal studies. Conclusion: This study showed that ultrasound is an easy and quick investigation in the diagnosis of upper abdominal pain with slightly less than 50% accuracy.

Key Words: Ultrasonography, Upper abdominal pain, 3.5 MHz convex transducer.

INTRODUCTION

Patients presenting with upper abdominal pain comprise the largest group of people reporting to medical and surgical out-patient department/OPDs. Following the history and clinical examination, ultrasonography has become one of the first and most useful methods of investigation¹. Upper abdominal pain whether acute or chronic, is caused by diseases of the liver, gall bladder, kidneys, pancreas, stomach, duodenum, spleen, pleura, pericardium and basal lung segments^1,2. Rare causes include aortic aneurysm and acute myocardial infarction. All these conditions have useful sonographic features which help in their diagnosis except uncomplicated peptic ulcer disease, acute myocardial infarction and basal pneumonitis^1,2.

MATERIAL AND METHODS

The study included 500 consecutive patients who were sent to the radiology department, Ayub Teaching Hospital for ultrasonography with the complaints of upper abdominal pain. Ultrasonography, using high resolution 3.5 MHz convex transducer with depth adjustment facility, was performed in these patients. Few patients with increased gut gases or contracted gall bladder were advised to come 8 hours fasting next day. Similarly few patients were called for follow-up scans after 2-4 weeks.

RESULTS

In our study of 500 cases with upper abdominal pain, 248 patients had positive findings on ultrasound. This comes to slightly less than 50%. Bulk of the positive cases had liver, biliary tree and renal pathologies, all roughly with equal numbers.

                The final outcome of negative cases justified the failure of ultrasound as 157 of them were later found to have gastrointestinal problems like gastritis, uncomplicated peptic ulcer disease, worm infestation and intestinal tuberculosis. Eighteen patients had problems above the diaphragm like basal pneumonitis and myocardial infarction. Fifteen patients had urinary tract infection. The cause of upper abdominal pain was not clear in 62 patients but they however, responded well to ordinary analgesics and smooth muscle relaxants.

                Table-1 shows the ultrasound diagnosis in patients with upper abdominal pain and Table-2 shows the incidence of organ involvement in upper abdominal pain.

DISCUSSION

Abdominal pain is a common problem in all age groups and whether chronic or acute it is caused by a divers group of diseases. Differential diagnosis is sometimes difficult and often requires the use of many modalities including the history and physical examination, laboratory tests, ultrasonography, computerized tomography scan and nuclear medicine. Magnetic resonance imaging is at present of limited value in upper abdomen. Its major limitations are motion and prolonged scanning time³.

                Upper abdominal ultrasound examination takes about 20 minutes and costs thirty rupees per case (excluding the equipment investment, maintenance and staff salaries). When upper abdominal pain is acute, rapid and accurate diagnosis on an emergency basis may be crucial. Many of the internal disasters that precipitate an acute abdomen are readily detectable with ultrasound.

The role of ultrasonography in hepatitis is to evaluate parenchymal changes. Sonographic patterns have been reported to correlate with histologic changes⁴. In the acute phase the appearance range from normal to enlarged liver. While the fibrosis resulting from chronic hepatitis produce a hyperechoic texture.

Table-1: Ultrasound diagnosis in patients with upper abdominal pain.

Ultrasound is a useful imaging modality in the diagnosis of focal hepatic lesions. The cause of a hepatic abscess is usually bacterial infection or amoebiasis. The ultrasonographic appearance of a pyogenic liver abscess varies with the stage at which it is seen. Initially it is less echogenic and has irregular margins. As necrosis progress the abscess becomes more spherical, well defined and cystic. The differential diagnosis include haematoma, necrotic tumour and metastatic cyst adenocarcinoma^5,6. An amoebic abscess is characteristically round, subcapsular and contains fine echoes which may layer dependently⁸. The mortality rate can be 100% in untreated cases⁹. Sonographic examination can non-invasively locate, measure and characterize such masses. Ultrasound guided aspiration is carried out in large abscesses.

Table-2: Organ distribution of diseases in patients with upper abdominal pain

Cirrhosis is diagnosed with 99% confidence if the ratio of caudate lobe width to right lobe width on a transverse section is greater than 0.73 and if the ratio is less than 0.60, cirrhosis is less likely¹⁰. Sonographically, the cirrhotic liver appears atrophic, echogenic and with irregular contour secondary to nodular regeneration¹¹. Ultrasound is an excellent imaging modality for liver tumours¹². Cavernous haemangioma is the most common benign hepatic tumour. The classic sonographic appearance is a homogeneous hyperechoic mass with well defined margins in sub-capsular position or closely related to the hepatic veins¹³ (Fig-1).