Volume 7, Case 5
Daniel C.H. Kidani, Medical Student
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
Three cases will be presented:
This is a 16 year old female who presents to the emergency department with a one day history of severe right flank pain with associated vomiting. She denies any fever, urgency, or dysuria. Her past medical history is unremarkable.
Exam: VS T 36.8 degrees C, P53, RR 24, BP 120/80. She is alert, cooperative, in moderately severe discomfort. HEENT unremarkable. Heart regular. Lungs clear. Abdomen Diffuse tenderness on the right. Guarding and rebound are present on the right. She has severe right CVA tenderness.
UA: >100 RBCs, 20-50 WBCs, positive nitrite. UCG negative. WBC 10.1, Hgb 13. BUN 11, Creat 0.8. An abdominal flat plate is ordered.
View her abdominal radiograph.
This abdominal flat plate demonstrates a possible renal stone on the patient's right at the level of L3 and L4.
View the arrow to see where the stone is. It is not easy to see.
An IVP is ordered.
View her IVP at 5 and 20 minutes.
IVP at 5 minutes (below)
IVP at 20 minutes (below)
The first IVP image is taken at 5 minutes following IV contrast. This shows prompt excretion of contrast from the left kidney. Contrast is seen excreted from the right kidney, but the ureter is not well visualized suggesting an obstruction in ureter. The calyces are blunted indicating hydronephrosis. The second IVP image is taken at 20 minutes following IV contrast. This shows delayed retention of contrast on the right. The calyceal blunting of the right kidney indicating hydronephrosis is more evident. There is a narrowing of the ureter on the right in the area of the suspected stone.
View a close-up of this.
This view shows a close-up of the same 20 minute IVP on the right in the area of the suspected stone. The black arrow points at this area.
This is a 15 year old male who presents to the emergency department with abdominal pain, vomiting and spots on his legs. He vomited 15 times. He also noted a red spot on his eye. His pain is intermittent (crampy).
Exam: VS T 37.5 degrees C, P70, R20, BP 125/80. He is alert and comfortable. He has a subconjunctival hemorrhage. HEENT otherwise unremarkable. Heart regular without murmurs. Lungs clear. Abdomen soft, non-tender with normal bowel sounds. No CVA tenderness. He has a moderate degree of purpuric lesions mostly on his lower extremities.
His CBC and coagulation studies are normal. His UA shows 5-10 RBCs. An abdominal series is ordered.
View his abdominal series.
Supine view (below)
Upright view (below)
View a close-up of the supine view.
His abdominal radiographs demonstrate an incidental finding of a two calcifications superimposed on the right kidney, which are suggestive of kidney stones. These are best seen on the supine (flat) view. The calcifications are present on the upright view, but they are superimposed over his 12th rib, making it more difficult to see.
A CT scan is done.
View his CT scan.
His CT scan is unremarkable except for the incidental finding of stones in his right kidney. The arrow points to a stone in his right kidney.
He is discharged with a diagnosis of probable anaphylactoid purpura, subconjunctival hemorrhage and nephrolithiasis. Lithotripsy is considered.
This is a 19 year old female who presents to the emergency department with a chief complaint of abdominal pain. She has a two-day history of abdominal pain progressing to right CVA tenderness with radiation to the groin region. She also has fever, vomiting, nausea, chills, dysuria, urinary frequency, diarrhea, and general malaise.
Exam: VS: T 37 degrees C, P 67, RR 20, BP 105/68. She is alert, oriented, not toxic and in no apparent distress. Her oral mucous membranes are pink and moist. Heart regular without murmurs or extra heart sounds. Lungs clear to auscultation and percussion bilaterally. She has mild CVA tenderness on the right side. Abdomen is soft and nondistended with normal bowel sounds. She has some RUQ tenderness. No rebound tenderness or peritoneal signs. No masses were palpated. Her pelvic exam is significant for mild right adnexal tenderness. There is no cervical motion tenderness. Extremities unremarkable.
Her lab studies show: WBC 17.0, Hgb 13, platelet count 295,000. UA 1+ protein, 4+ blood, positive leukocyte esterase, many bacteria, 20-50 WBCs and 5-10 RBCs per high power field. UCG negative. An abdominal series is ordered.
View her abdominal series.
Supine view (below)
Upright view (below)
There is nothing obvious on the supine (flat) view. The upright view is significant for a calcification overlying the right kidney. Another abdominal flat plate is ordered to see if the calcification has moved.
View later abdominal radiograph.
This follow-up radiograph shows persistence of the calcification over the right kidney. A CT scan is ordered.
View the patient's CT scan.
The first CT image shows a contrast enhanced left kidney with prompt excretion of contrast. The right kidney is excessively contrast enhanced with no excretion of contrast. The black arrow points at two stones in the renal collecting system.
The second CT image shows a dilated ureter on the right kidney (black arrow). The third CT image shows a dilated ureter on the right without contrast flow compared to the normal sized contrast filled ureter on the left. The fourth CT image shows another stone in the right ureter just as it enters the bladder.
The patient is diagnosed with pyelonephritis, hydronephrosis and urolithiasis. She is hospitalized and treated with IV antibiotics, fluids and ketorolac. Her urine culture later grows proteus species which is a urea splitting organism suggesting that these are struvite stones.
Discussion
Urolithiasis affects 2-10% of industrialized populations, with a lower incidence in non-industrialized countries. Most, 80%-85%, of stones pass spontaneously; however, 20% of patients require hospitalization. Recurrence rates are 14%, 35%, and 52% at 1, 5, and 10 years respectively, after the first stone is passed. The peak onset of symptomatic kidney stones is in the 3rd and 4th decades of life, with a male to female ratio of 3:1(1). High humidity and elevated temperatures seem to be contributing factors to the development of renal calculi. Symptomatic stones also have their highest incidence in the higher temperatures of the summer months (4).
Nephrolithiasis is rare in children; however, the incidence of urinary calculi in the United States is increasing. Approximately 5-10 cases of urolithiasis between 10 months and 16 years of age are seen at a typical US pediatric center annually (1). Although urolithiasis is uncommon in children younger than 2 years of age, the incidence does not seem to favor any age group or gender (2). Approximately 66% of urinary calculi in North American children are found in the kidneys at the time of diagnosis, the remaining 1/3 are located in the ureters (2).
The etiology of kidney stones is derived from an imbalance of a delicate equilibrium within the kidneys. The kidneys must both conserve water and excrete substances with a low solubility, two opposing factors. This balance must be maintained with the adaptation to diet, climate, and activity. When this balance is disrupted, the urine may become supersaturated with insoluble materials which may aggregate into a calculus (3).
There are four basic types of renal calculi: calcium, struvite, uric acid, and cystine stones. Calcium stones, which account for 75%-85% of all renal calculi, consist of calcium oxalate, calcium phosphate, or calcium urate. Since most renal calculi are composed of calcium, most urinary stones are radioopaque (4). They are more common in males, often arise in the 3rd decade of life, have a recurrence rate between 2 and 3 years, and is frequently familial. They are associated with idiopathic hypercalciuria, hyperuricosuria and primary hyperparathyroidism which accounts for 50%, 20% and, 5% of calcium stones, respectively. Another 20% are idiopathic (3).
Struvite (magnesium ammonium phosphate) stones are relatively common, making up 10%-15% of all renal calculi (3). These stones are due to chronic urinary tract infections with gram-negative urease-producing bacteria and therefore are commonly found in women and in those patients requiring chronic bladder catherization (3). Common organisms are Proteus, Pseudomonas, and Klebsiella species. Struvite is visualized on radiograph when it complexes with calcium carbonate or calcium phosphate. These stones are capable of obtaining large sizes, large enough to fill the renal pelvis and calyces to produce staghorn calculi (3).
Uric acid stones make up 5%-8% of renal calculi (3). They are radiolucent, are more common in males, and are commonly familial. Since pure uric acid stones are radiolucent, CT, ultrasound, or intravenous ultrasonography may be implemented for detection; however, uric acid frequently complexes with calcium oxalate making these stones radioopaque via radiograph (4). About 25% of patients with uric acid stones have gout.
Cystine stones are rare and account for approximately 1% of all renal calculi (3). Because of their sulfur content, cystine stones are only slightly radioopaque, so are poorly visualized on x-ray. They are due to a hereditary metabolic defect resulting in proximal tubular and jejunal transport of the dibasic amino acids: cystine, lysine, arginine, and ornithine. Thus, a large amount of these amino acids are lost in the urine; however, because of its relative insolubility, cystine is the only one of these amino acids to form stones (1).
Stones initially form on the renal papillae or within the collecting system. Stones need not be symptomatic; however, pain and obstruction arise when stones break loose and enter the ureter or ureteropelvic junction (3). It is not uncommon for struvite, cystine, or uric acid stones to grow too large to enter the ureter; these stones gradually fill the renal papillae and even the renal calyces, forming staghorn calculi (3).
As the stone traverses the ureter it commonly produces severe colicky pain and bleeding, termed renal colic (5). The pain develops gradually, manifesting initially in the flank progressing downward and anteriorly toward the lower back and genitalia. Stones obstructing the ureteropelvic junction may present with mild to severe flank pain without radiation due to distention of the renal capsule. Pain which migrates downward suggests that the stone has passed to the lower third of the ureter. In the absence of migrating pain, the position of the calculi cannot be predicted. If the stone makes its way to the ureterovesical junction, symptoms consistent with urinary tract infection may manifest; frequency, urgency, dysuria (3). When the stone passes into the bladder, the pain subsides; however, unique symptoms arise if the stone enters the urethra (5). There is no correlation between stone size and severity of symptoms (4). The symptoms surrounding urolithiasis in the pediatric patient varies with age. The excruciating flank pain associated with stone passage in the adult patient is rarely seen in children; however, 50% of children experience abdominal, flank, or pelvic pain. The pain from renal calculi may mimic colic in infants. Pre-school aged children commonly experience the symptoms of urinary tract infections while adolescents more commonly experience pain similar to adults (2).
The patient who presents with a renal stone may be mistaken for a patient with an aortic dissection, acute appendicitis, mechanical back pain, bowel obstruction, cholecystitis and biliary colic, constipation, epididymitis, gastritis or peptic ulcer disease, UTI and pyelonephritis, PID, pneumonia, testicular torsion, or urinary obstruction (1). Thus, these differential diagnoses must be considered.
Upon physical examination, the patient with renal colic is typically writhing in pain and is unable to keep still; in contrast to patients suffering from peritoneal irritation who remain motionless to minimize the pain (4). Fever is absent in uncomplicated cases of urolithiasis. Pyelonephritis, pyonephrosis, or perinephric abscess should be suspected if fever is present. An abdominal examination is typically unremarkable; although hypoactive bowel sounds may indicate an ileus, which is common in patients suffering from severe, acute pain. In male patients, pain may radiate to the testicles; however, the testicles should appear normal and be only mildly tender. One should be wary of the older patient (>60 years old) with a suspected primary case of nephrolithiasis and should take care to rule out an aortic aneurysm (1).
The evaluation of a patient with a suspected renal calculi should consist of a metabolic evaluation, urine and dipstick, as well as imaging. Recovered stones should be examined for composition, as treatment differs according to stone type. Controversy exists as to which patients require a thorough metabolic work-up; however, abnormalities of serum calcium, phosphate, electrolytes, and uric acid should be screened for in first time stone formers. In recurrent stone formers or patients with a family history of stone disease, a more extensive evaluation is required. An initial 24 hour urine collection on a random diet should be analyzed for volume, urinary pH, and calcium, uric acid, oxalate, phosphate, and citrate excretion. If necessary, a second 24 hour urine collection can be made on a restricted calcium diet. PTH and calcium load tests can be performed to further clarify metabolic abnormalities (4).
Urinalysis may reveal microscopic or gross hematuria. 85% of patients with ureterolithiasis have hematuria on microscopic exam of the urine, while 95% have hematuria when both microscopy and urine dipstick are used (1). Although hematuria is commonly associated with urinary calculi, the degree of hematuria is not predictive of stone size or passage.
Infection must be excluded in cases of renal calculi. If a urinary tract infection is present with hydronephrosis, hospital admission is mandatory unless follow-up is readily available within 24 hours (1).
Non-contrast helical CT is currently the gold standard imaging study for the diagnosis of ureterolithiasis in the emergency department. Non-contrast helical CT has been shown to have a sensitivity of 95%-100% and a specificity greater than that of an intravenous pyelogram (IVP). Advantages of non-contrast helical CT are that it can be done in less than 5 minutes and avoids the use of IV contrast. However, helical CT does not provide information on kidney function, the degree of obstruction, and does not visualize indinavir stones well (1).
Prior to helical CT, IVP was the gold standard imaging technique. Since IVP is dependent on the flow of IV contrast from the kidney to the ureters, both kidney function and degree of obstruction can be assessed. It is also the test of choice for diagnosing indinavir stones. However, an IVP is not as rapid as a helical CT and exposes patients to both radiation and the risk of nephrotoxicity or anaphylactoid reactions due to contrast agents. The cost of an IVP is comparable to a helical CT (1).
Although less sensitive or accurate than either an IVP or helical CT in diagnosing ureteral calculi, ultrasound is useful in the pregnant or unstable patient. It is also a useful imaging modality in the course of ruling out an abdominal aortic aneurysm in patients older than 60 who present with a first or atypical nephrolithiasis. Ultrasound may also be able to elucidate stones at the ureterovesical junction that may have been missed by helical CT or IVP (1).
Treatment of nephrolithiasis is dependent on stone type. However, IV access should be obtained to administer pain and antiemetic medications. IV hydration is controversial as some believe fluid loading forces the stone through the urinary tract at a faster rate; however, some feel as if this may increases renal colic (1). However, it is generally accepted that increased fluid intake is beneficial in diluting the urine and impeding stone formation.
In some instances, purely medical treatment is not sufficient and surgical intervention is indicated. Ureterolithiasis coupled with a fever, suggesting a urinary tract infection represents a true medical emergency. IV antibiotics and immediate drainage of the infected hydronephrosis are indicated, either through percutaneous nephrostomy or ureteral stent placement. Antibiotics alone, in this situation, may be insufficient (1).
When stones fail to pass spontaneously and impede urine flow, surgical measures are often indicated. Typically, stones lodge at three main sites: the ureteropelvic junction, the point at which the ureter crosses the iliac vessels, and the ureterovesical junction. Although stones less than 6mm in diameter commonly pass spontaneously, it is difficult to determine which stones will pass. Conservative observation with the proper pain medications is appropriate for the first 6 weeks; if the stone has not passed by the 6th week, more aggressive intervention is required. Indication for intervention before the 6th week includes severe pain that does respond to medication, fever, chronic nausea and vomiting that requires IV hydration, and social factors (e.g. need to return to work or travel) (4).
Distal ureteral stones are best extracted via ureteroscope or in situ extracorporeal shock wave lithotripsy (ESWL). Ureteroscopic extraction involves passing an endoscope through the urethra into the ureter. With the aid of direct visualization, the stone is removed via basket extraction. In situ ESWL involves the use of external energy that is focused at the point of the stone, resulting in stone fragmentation and eventually stone passage. This technique is not advised for women of childbearing age with stones in the lower ureter since the effects of such treatment on the ovaries is unknown (4).
Proximal and midureteral stones (i.e. above the inferior margin of the sacroiliac joint) can also be treated with ureteroscopy or in situ ESWL. With ESWL, the stone can be pushed back via a retrograde ureteral catheter into the renal pelvis so as to provide a larger area for stone fragmentation. Stents may be placed in the ureter to facilitate passage and prevent obstruction (4).
Renal stones that are asymptomatic do not need to be treated. However, they should be monitored via serial abdominal radiographs or renal ultrasound. If the stone is growing and becomes symptomatic, the appropriate procedures should be undertaken. Stones less than 3cm in diameter should be treated with ESWL; while larger stones, and stones that reside in the inferior calyx are best treated with percutaneous nephrolithotomy (4).
References