Chapter 56. Urologic Stone Disease

The acute phenomenon of renal stones migrating down the ureter is referred to as renal colic. Adults and children can develop kidney stones. In adults, the condition is 3 times more common in males than in females; kidney stones usually occur in the third to fifth decade of life. Children under the age of 16 years old constitute 7% of cases seen, with the distribution being equal between the sexes.

Patients usually present with an acute onset of severe pain, which may be associated with nausea, vomiting, and diaphoresis. Patients are frequently anxious, pacing, or writhing and are unable to hold still or converse. The pain is sharp and episodic in nature due to the intermittent obstruction of the ureter and is relieved after the stone passes. The pain typically originates in either flank with subsequent radiation around the abdomen toward the groin. However, as the stone passes into the distal ureter, where 75% of stones are diagnosed, the pain may be located in the anterior abdominal or suprapubic area. Vesicular stones may present with intermittent dysuria and terminal hematuria. Children may present in a similar fashion, but up to 30% have only painless hematuria. Vital signs may demonstrate tachycardia and an elevated blood pressure, which are secondary to pain. Pyrexia may be present if there is a concomitant urinary tract infection. Examination may show costovertebral tenderness or abdominal tenderness, guarding, or rigidity. Hematuria may be present in 85% of patients with renal colic.

The diagnosis of urologic stones and renal colic is based on clinical judgement. A urinalysis will help rule out infection and assess for microscopic hematuria.

All females of childbearing age should have a pregnancy test. Imaging is controversial. It allows confirmation of the ureteral stone, rules out other diagnoses, identifies complications, establishes the location of the stone, and assists with the management if the stone fails to pass spontaneously. The use of noncontrast helical computed tomography is the mainstay of diagnosis in the emergency department (ED). Positive findings include changes in the ureteral caliber, suspicious calcifications, stranding of perinephric fat, and dilation of the collecting system (Fig. 56-1). It has a PPV of 96% and a NPV of 93% to 97%. The greatest advantage is the speed at which it can be performed, no need for intravenous contrast administration, and the benefits of excluding other diagnoses. The disadvantages are that it does not evaluate renal function and has radiation exposure.

The use of plain kidney-ureter-bladder film (KUB) is limited by the visibility of the stone; the KUB cannot rule out a ureteral stone. The KUB is useful in following the progression of a stone, if visualized, in the outpatient setting.

Ultrasound, an anatomic rather than a functional test, is useful in patients who are not candidates for intravenous pyelogram (IVP) or computed tomography. It detects hydronephrosis and larger stones but is not sensitive for midureteral stones or small stones (< 5 mm).

It is critical to consider vascular etiologies in the differential diagnosis for abdominal-flank pain, including abdominal aortic aneurysm and aortic dissections. Other concerning differentials include appendicitis, mesenteric ischemia, cholecystitis, ectopic pregnancy, gonadal torsion, renal infarction, incarcerated hernia, epididymitis, salpingitis, pyelonephritis, papillary necrosis (sickle cell disease, diabetes, nonsteroidal analgesic abuse, or infection), herpes zoster, drug-seeking behavior, and musculoskeletal strain. Patients receiving outpatient extracorporeal shock wave lithotripsy for urolithiasis may present to the ED with renal colic because the resulting “sludge” is passed in the urine.

1. Analgesia: nonsteroidal anti-inflammatory drugs administered parenterally are considered the primary analgesic choice. The prostaglandins promote dilation of the ureter and thus aid in the alleviation of the source of the pain. Ketorolac 30 milligrams IVP is the recommended starting dose. Caution should be used in the elderly, those with bleeding tendencies, and renal impairment. Opioids, in titrated doses of morphine 5 milligrams IV or hydromorphone 1 milligram IV, may also be used to assist in pain control.

2. Antiemetics: metoclopramide, 10 milligrams IV, the only antiemetic drug studied for the treatment of renal colic has been shown to be effective in providing relief in nausea and pain. Other antiemetics may also be used.

3. Medical expulsion therapy: α-blockers demonstrate a 2- to 6-day improvement in time to expulsion. Options include tamsulosin (0.4 milligram daily up to 4 weeks), terazosin (5 to 10 milligrams daily), and doxazosin (4 milligrams daily).

4. Antibiotics: if the urinalysis shows evidence for an infection, the choice of antibiotic is dictated by the local resistance patterns to gram-negative rods. Patients with an infected ureteral stone without significant obstruction, fever or systemic illness, may be discharged with a fluoroquinolone such as ciprofloxacin (500 milligrams twice a day for 10 to 14 days) or levofloxacin (500 milligrams daily for 10 to 14 days) or a third-generation cephalosporin such as cefpodoxime (200 milligrams twice a day for 10 to 14 days). Follow-up is essential.

5. Those patients who have a more complicated clinical situation should be admitted. Intravenous antibiotic selections to consider include gentamicin or tobramycin (1.0 milligram/kilogram/dose every 8 hours) and ampicillin (1 to 2 grams every 4 hours); piperacillin-tazobactam (3.375 grams every 6 hours); cefepime (2 grams every 8 hours); ticarcillin-clavulanic acid (3.1 grams every 6 hours), or ciprofloxacin (400 milligrams every 12 hours).

6. Discharge is appropriate for patients with small unilateral stones (< 6 mm), no complicated infection, and pain controlled by oral analgesics. It is recommended that patients be given a urinary strainer, prescriptions for oral analgesics and medical expulsive therapy, and urologic follow-up within 7 days. If the stone is passed in the ED, no treatment is necessary other than elective urologic follow-up. Patients should be instructed to return if they develop fever, persistent vomiting, or uncontrolled pain. On average, the stone may take 7 to 20 days to pass.

7. Urologic consultation on an emergent basis is needed in those patients with a complete obstruction complicated by a solitary or transplanted kidney, fever, and/or urosepsis. Disposition should be discussed with a urologist in patients with a stone larger than 6 mm, renal insufficiency, severe underlying disease, extravasation or complete obstruction, sloughed renal papillae, UTI, or failed outpatient management.

8. Hospitalization is absolutely indicated for those patients who have a solitary or transplanted kidney with obstruction, uncontrolled severe pain, intractable emesis, acute renal failure, hypercalcemic crisis, severe medical comorbidities, and urosepsis. Those individuals with a fever, solitary or transplanted kidney without obstruction, obstructing stone with infection, urinary extravasation, significant medical comorbitidies, or large proximal ureteral stones should be considered for admission.