Assessment of ARC patients

Added on - 19 Sep 2019

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Plain Computed Tomography of Kidneys, Ureters and Bladder as aFirst Diagnostic Option for Renal Colic Patients in Sohar HospitalAcute Renal Colic:Acute renal colic (ARC) is one of the most common patients symptoms seen in theaccident and emergency (A&E) departments and urology clinics worldwide. Renal colicis caused by a urinary stone that affects about 10% to 15% of the population in theirlifetime, 50% of these people are predicted to experience a recurrence of urinary stonein the first 10 years after the first incidence (Ahmed et al., 2010; Smith, 2012; Moore etal., 2013; Moore et al., 2014; Lukasiewicz et al., 2014).According to Vijayaraghavan et.al. (2009), over 7 million patients were seen in the A&Edepartments in the United States of America (USA) in 2008 which resulted in anestimated cost of 2.1 Billion dollars. There are approximately 360000 annual visits ofARC in Oman hospitals (Al-Marhoon et al., 2013).Generally, renal stone affects moremale than females with a ratio of 3:1. The clinical presentation is usually symptoms ofcolicky flank pain that irradiates to the groin, and sometimes is associated withhematuria or single sided abdominal pain (Taourel et al., 2008; Sayani et al., 2011;Nadeem et al., 2012; Leveridge et al., 2015). Generally, there are several methods ofdiagnosing ARC which includes good patient`s history, clinical examination, laboratoryinvestigation and radiological investigation1
The Role of Imaging in the Assessment of ARC:Various imaging techniques can be used to diagnose renal stones. These includeradiography of the kidneys, ureters and bladder (KUB), intravenous urography (IVU),ultrasound (US) and computed tomography of the KUB (CT-KUB).Plain KUB radiography:In the last century plain radiography of the KUB was the initial radiological assessmentof ARC. This technique was not so accurate in detecting renal stones due to missing50% of stones smaller than 5mm in size and their location in the lower portion of theurinary tract system. Also, the stones may be obstructed by faecal matter and gases inthe bowel. It has been reported that the sensitivity and specificity of this technique indetecting urinary stone was 18.3% and 77% respectively. However, the radiationburden is very low (0.7mSv) in comparison to IVU (1.5 mSv) and CT (4.7 – 6.5 mSv)which obviously is a benefit as it can be used for follow-up cases (Chuwdhury et al.,2007; Kenniish et al., 2008; Peddu & Desai, 2009; Song et al., 2010).Intravenous urography:Intravenous urography involves the injection of a contrast agent into the anterior cubitalvein of the arm to opacify the kidneys and ureters in relation to the surrounding softtissue structures within the abdomen because the contrast has high atanomic numberwhich make it easily visualized in the x-ray image (Wang et al., 2008;Quirke et al.,2011). Although IVU’s sensitivity and specificity of 59.1% and 94% is higher than forplain KUB radiography, the technique has the following drawbacks; it provides limitedinformation about intra-abdominal pathology, very long examination time, risk of patient2
reaction to contrast agent such as collapse, itching and vomiting, and specialconsiderations are needed for diabetic patients and those with kidney disease as thecontrast agent needs to be excreted from the body to avoid any complications (Kenniishet al., 2008; Lauritsen et al. in 2008; Mccombie et al., 2011).Ultrasound imaging:Ultrasound is basically a device which uses a high frequency sound waves to produceimages of the internal structures of the body without the use of ionization radiation(Nicolau et al., 2015). Ultrasound is capable to visualises hydronephrosis which is anindication of obstruction caused by stone, in addition it can identify large urinary stonesof 5mm diameter and above. The advantages of US include its portability which meansthat it can be used at patients’ bed side, wide available, not invasive and it is cheapcompared with CT. Its major advantage is the lack of ionizing radiation and itsassociated hazards (Patatas et al., 2012; Nicolau et al., 2015). On the other hand, USlimitations include low detection rate for small stones less than 5mm in size, andinability to provide accurate anatomical location which can lead to misdiagnosis. Itsreported sensitivity is 45% and specificity of 88% (Pal and Mellon, 2008; Masselli et al.,2015). It is also operator dependent since the accuracy can be differ from one operatorto another in terms of knowledge, experience andskills (Chen et al., 2015).However,US remains the first line of assessing ARC when there is lack of CT equipment orradiologists to interpret the images produced, and also for pregnant women and childrento avoid ionizing radiation risk. It is also recommended when either IVU or MRI iscontraindicated (Sayani et al., 2011; Curhan, 2014; Leveridge et al., 2015).3