Diagnosing and imaging renal calculi: what can be done in the pre-hospital environment?

Renal calculi are common in the UK with an incidence of 2–3%, with 0.5% of the population experiencing an acute episode of renal colic every year (British Association of Urologic Surgeons, 2015). These episodes are responsible for over 12 000 hospital admissions yearly and incidence rates have been rising (British Association of Urologic Surgeons, 2015). Anecdotal evidence suggests that these patients are seen commonly in the pre-hospital environment; however, due to diagnostic uncertainty they are often conveyed to the emergency department.

This article seeks to evaluate the current evidence for diagnosing renal calculi in the pre-hospital environment and address the requirement for, and timing of, computerised tomography (CT) scanning in the renal colic patient. The case study discussed is an example of confident diagnosis resulting in appropriate management and avoidance of unnecessary hospital admission.

The case study describes a 48-year-old female who called 999 with symptoms descriptive of renal colic. The pain had started during the night, coming in waves and had worsened throughout the morning. The patient described her pain as sharp with associated nausea but no vomiting. Her previous medical history consisted of chronic obstructive pulmonary disease, previous mastectomy and a left-sided kidney stone 2 years earlier. Observations revealed a respiratory rate of 21 breaths per minute, heart rate of 98 bpm, blood pressure of 152/90 mmHg, oxygen saturations of 98% and a temperature of 36.8°C. On inspection, the patient's abdomen showed no signs of scars, peritoneal bruising or asymmetry. Auscultation revealed active bowel sounds; percussion, tympany throughout and palpation elicited mild tenderness over the site of pain and over the right renal angle.