38 year old male with a history of kidney stones c/o severe right flank pain, radiating to the groin, “feels just like my kidney stones” with small amount of blood in his urine, begging for pain meds. Ok, I know this is not the most mysterious case, but when I looked over his chart he has a radiology list of 8 CT scans over the last 5 years to evaluate for kidney stones! Why? Do we really work in an era where we MUST know the diagnosis instead of just being able to screen for the emergent conditions, and treat by using our clinical judgement… and bedside ultrasound? I sure hope not, because that’s not how I practice. This is not the first-time flank pain patient, although some would argue that you dont need to get a CT for that either if labs and ultrasound are clear/negative. This is also not the elderly patient that could have belly-badness that will die soon – but not from CT scan-radiation-induced cancer, that’s for sure.
If the creatinine shows no evidence of new renal failure and the urine shows no evidence of infection, then performing a bedside renal US to evaluate for signs of – or the degree of -obstruction (hydronephrosis) – and maybe even making sure that aorta is a normal size in the appropriate patient – should be enough (in addition to IV fluids and pain meds, of course). Study after study after study after study after study has shown that with all else being ok with adequate pain control, even if there is hydronephrosis on your bedside US, outcomes don’t necessarily change if no CT is done – and, more importantly, doing the CT does not add that much value: “without an associated change in the proportion of diagnosis of kidney stone, diagnosis of significant alternate diagnoses, or admission to the hospital.” However, the ability of renal ultrasound to detect mild levels of hydronephrosis has less sensitivity and specificity – but who cares? I would argue that if the patient has 2 kidneys, a normal creatinine, and negative urine for infection with pain control – they could be discharged home – even with moderate hydronephrosis – with urology follow up and specific ED return precautions. Let’s face it, when is the last time a urologist admitted anyone with the above?
Using the curvilinear or phased array low frequency probe perform the renal ultrasound by placing the probe in the right and left midaxillary line at the lower rib cage and slowly fan up and down to evaluate the longitudinal view of the kidney for dilation of the collecting system and renal pelvis. Then rotate 90 degrees, indicator toward the ceiling, to see the transverse view of the kidneys and slowly fan to evaluate for hydronephrosis.
Mild hydronephrosis: renal pelvis dilation; moderate hydronephrosis – renal pelvis and calyces dilated; severe hydronephrosis – the entire thing is effaced. Don’t forget to look at the bladder too! With bilateral mild hydro and a full bladder – they may just have to pee (or they have a bladder outlet obstruction, or maybe just pregnant). With unilateral hydro, be aware of stones or a mass obstructing the ureter.