This is part of the four part PEMBlog series on kidney stones. Throughout you’ll learn about diagnosis and management of an increasingly recognized problem in the Pediatric Emergency Department.
What is the spontaneous passage rate?
The best estimate is 90%. Stones <5mm are highly likely to pass. 10mm stones are not. One adults only study showed that the rate of urologic intervention increased with stone size – up to 50% with stones 4-6mm in size needed an intervention. See Miller et al for more.
The size and location of the stone and its relation to the likelihood of passage is only truly estimated in adults and if patients have uncontrolled symptoms, hydronephrosis and signs of an obstructing stone with UTI. So, in general, 90% of patients will pass stones regardless of size.
What is the best pain medicine?
In general both NSAIDs and opiates are appropriate. Comparison of the two has not been studied to a satisfactory degree in pediatrics. If renal function is normal/not suspected (you don’t need a creatinine first in kids) start with NSAIDs. IV or IM Ketorolac rules the day heer, reducing inflammation and promoting ureteral dilation. The dosing is 0.5mg/kg, 30mg max. Opiates are also a good choice, and I would recommend using them after ketorolac or in patients with renal insufficiency. Morphine at 0.05 to 0.1 mg/kg IV max 5mg is the dose. It lasts longer than fentanyl and is IMHO a better choice in the ED. Some adult studies have indicated that the combo of the two (NSAID + opiate) is better still, but a stepwise approach in first time stone formers is prudent in the pediatric population.
In patients who can be discharged home regular NSAIDs (ibuprofen 10mg/kg/dose or Naproxen) are first line. Opiates (like the acetaminophen/oxycodone combo) are for breakthrough pain. If pain is significant enough to require multiple doses of IV pain meds (especially morphine) you should admit.
Are antiemetics helpful?
If the patient is nauseous and vomiting then yes. Ondansetron 0.15 mg/kg IV or PO (either ODT or suspension) would be a good first choice in children.
What about IV hydration?
If the patient is euvolemic/not dehydrated you do not need to give a 20 mL/kg NS bolus. Altrernatively it is appropriate to start IV hydration with D5 1/2NS at 1.5-2x maintenance rate ASAP.
What about alpha blockers?
Tamsulosin and doxazosin, alpha blockers both may lead to increased passage rate in children. A summary of the evidence is as follows;
- Aydogdu et al. studied 39 children with distal ureteral stones <10mm and randomized to either doxazosin or ibuprofen. There was no significant difference in the overall stone passage rate or mean time for passage. 84 vs 70% and 5.9 vs 6.1 days respectively for the alpha blocker vs NSAID.
- Ertuhan et al noted that in their trial of 45 children and reported increased passage rates for patients getting both doxazosin and ibuprofen vs those that received ibuprofen alone (71% vs 29%).
- A prospective controlled trial of 61 children with distal ureteral stones <12 mm in diameter was conducted by Mokhless et al. Children that got tamsulosin (alpha blocker) and pain meds vs those who only got pain meds had a higher stone-free rate after 4 weeks (88% vs 64%) and a decreased passage time (8.2 days vs 14.5 days)
- Tasian et al conducted a retrospective review of 274 patients and noted a greater likelihood of stone passage overall in those that had received tamsulosin (99/274) – (OR 3.31, 95% CI 1.49-7.34).
In general, discussion with Urology is assumed prior to starting these drugs. A sample regimen would be 0.4 mg of tamsulosin (Flomax) before bedtime each night. This one is a good choice for even younger kids since it is a capsule and can be opened and sprinkled into something yummy. If stone passage hasn’t occurred in 1-2 weeks then other interventions are needed. This is on top of aggressive hydration and oral pain meds of course. First dose hypotension – though reported in adults mostly – should be discussed but the risk of it is not a contraindication.
patients with signs of UTI on urinaysis should be treated with appropriate antibiotics (like cephalosporins, TMP/SMX or other agents). Consider admitting febrile or ill appearing patients with stone + UTI. IN general the threshold to amdit these patients is lower than non-infected stones. Often the stone will obstruct and serve as a veritable petri-dish for infection.
Who needs to be admitted?
- Needing lots of IV pain meds
- Can’t tolerate oral fluids
- Large stone >>10mm and urology is considering intervention
- UTI + stone and ill appearing
What is the best urologic intervention?
Though techniques like ESWL (external shock wave lithotripsy), Percutaneous nephrostolithotomy and ureteroscopy are often successful medical management is generally indicated for 1-2 weeks. If the stone is obstructing and has caused renal injury (elevated creatinine, imaging findings etc,.) or if there is a UTI and urosepsis intervention is indicated sooner. Stones obstructing at the uretero-vesical (UVJ) or uretero-pelvic junction (UPJ) may benefit from temporary stents.
- ESWL is good for stones <1-2cm. This requires general anesthesia as children need to remain motionless. It is generally the “first-line” in kids. It should not be done if the stone is in the pelvis and the patient is a female (ovaries)
- Stents are good for stones >2cm
- Percutaneous nephrolithotomy is comparable to ESWL inc limited studies in children
- Ureteroscopic instrumentation is first-choice for children that fail ESWL