The present series shows that conservative management is feasible even for higher grade injuries with blunt and penetrating injuries.
At our institution the decision to treat a renal injury is primarily based on haemodynamic instability whilst considering the grade of renal injury and the presence of concomitant injuries.
Over the 9-year period, conservative management was successful in all grade 1 and 2 renal injuries, and 94.9%, 90.7% and 35.1% of grade 3, 4 and 5 injuries, respectively.
The present study included 54 patients with grade 4 injuries, of which 4 (7.4%) had angioembolisation, one (1.9%) underwent nephrectomy and 90.7% were treated conservatively. This is consistent with published data [5, 14].
Whilst conservative management has been widely accepted for blunt renal injuries in haemodynamically stable patients, the management of penetrating injuries remains controversial. A non-operative approach has been advocated in selected stabbing injuries and to a lesser extent in gunshot injuries . Currently at our institution, penetrating injury does not mandate operative intervention and haemodynamically stable patients will undergo CT imaging. Patients with entry wounds anterior to the mid-axillary line undergo laparoscopy to determine whether the peritoneum has been breached, followed by laparotomy if confirmed. If there is evidence of retroperitoneal injury from an anterior penetrating injury, the retroperitoneum is explored only if there is concern of perforated viscous or there is an expanding haematoma.
At our institution over the 9-year period, 13 patients were seen with penetrating renal injuries. Seven patients underwent emergency laparotomy, of which one patient with a grade 5 injury after a stabbing went on to have a nephrectomy. The renal injuries in the remaining 12 patients were successfully managed conservatively.
There has been variable success of angio-intervention for blunt renal injuries. In one study of 434 patients with blunt renal injuries from 2002 to 2008, six (27.2%) of 22 had failed angioembolisation requiring laparotomy . Another study using the USA National Trauma Data Bank examined the use of diagnostic angiography and angioembolisation, identifying 9002 renal injuries between 2002 and 2007 . Angioembolisation was performed in 77 patients, of whom 68 required successive therapy (commonly repeat angioembolisation), including all patients with grade 4 and 5 renal injuries. The overall renal salvage rate was 92%, including 88% for grade 4 and 5 injuries. The high rate of successive therapy was not experienced in our institution, although overall there was a similar renal salvage rate. Haemostasis was successfully attained during the first procedure in the 10 patients treated with angioembolisation. This suggests that the success of angioembolisation varies amongst institutions, potentially influenced by patient selection, the level of experience of the interventional radiologist and the volume of renal trauma seen at the institution.
The impact of angioembolisation vs nephrectomy on the patient's recovery is difficult to determine in the context of trauma, where renal injury infrequently occurs in isolation. The present study found that the median (IQR) LOS for patients who underwent angioembolisation was 12.7 (10.5–23.4) days, compared with 10.7 (6–18.2) days for those treated conservatively and 20 (13–34.3) days for those who underwent nephrectomy. However, the median renal injury grades were 2, 4, and 5, and the median (IQR) ISS were 25 (16.5–36), 25 (16.3–29) and 38 (29–50) for those treated conservatively, by embolisation and nephrectomy, respectively.
Similar demographic data have been reported in other studies, with most injuries affecting males and being incurred due to blunt trauma. Although higher rates of penetrating injuries have been reported in some regions, e.g. a prospective study conducted in Pakistan between 2005 and 2007, 22% (11/50) of patients had penetrating injuries, most commonly due to firearm, reflective of the civil instability in their region .
The present study found that survival is related to age and ISS, with no correlation to the grade of renal injury. Given that renal injury commonly occurs with concomitant abdominal injuries, the latter is not surprising as ISS will more accurately reflect the patients' overall condition.
However, in an ageing society, the difference in outcomes between patients of different ages is of interest. A USA study examining outcomes in geriatric genitourinary trauma found that patients aged ≥ 65 years had more ICU admissions, longer ICU stays and twice the mortality rate of patients aged 18–65 years; however, there was no difference in mean ISS between the groups . This is consistent with the findings at our institution. Interestingly we also found a correlation between the age of the patient and the grade of injury, with increasing age being associated with lower injury grades, although no associated correlation between age and ISS. This is likely to be attributed to the different pattern of injury mechanism, in that younger people are more frequently involved in higher impact mechanisms (e.g. motor vehicle accidents), as opposed to lower impact mechanisms, e.g. low-level falls in older patients.
The lowest complication rate was seen amongst the patients managed conservatively. Of the high-grade injuries, there was a complication rate of 10 of 136 (7.4%) in the conservatively managed group vs two of eight for embolisation, and three of 24 (12.5%) for nephrectomy patients. This supports the adoption of a non-operative approach in appropriate patients, despite the presence of high-grade injuries.
The strengths of the present study are that it is a large single-centre series, and that the data were collected from a database that is recorded prospectively and maintained by dedicated data registry staff. The present study focuses on the contemporary management of renal injuries.
We accept that there are controversies on how to treat grade 4 and 5 injuries.
A significant limitation of the present study is a lack of data about long-term renal function in the patients managed conservatively. A formal assessment of creatinine clearance as part of the long-term follow-up would help to identify whether there is improved preservation of renal function in this group, and whether it is counterbalanced by an increase in incidence of post-traumatic hypertension and associated nephropathy.
There is potential selection bias in the present study. There are two adult and one paediatric Level 1 Major Trauma Services (MTS) in Victoria, and triage guidelines for rural, metropolitan and air ambulance services direct all patients with major or potentially major trauma to an MTS if one is accessible within 30 min . Non-MTS hospitals are also directed to transfer patients to an MTS if they fulfil major trauma criteria. Major trauma is defined by any of the following criteria; death due to injury, an ISS of >15, injury requiring urgent surgery, or an ICU stay of >24 h requiring mechanical ventilation. The Alfred is one of the two adult MTS in Victoria, and it receives most of the road trauma cases. As such the present results are likely to over represent the proportion of; high-grade renal injuries, multisystem injuries and road trauma.
Patients with haematuria and normal urological studies were excluded from the present study, although they meet AAST grade 1 criteria, thus further underestimating the true incidence of low-grade injuries.
Follow-up data on the effect that renal injury grade and management have on long-term complications, e.g. renal function, hypertension and chronic pain, were beyond the scope of the present study.
In conclusion, road trauma is the greatest cause of renal injury. Renal injury may be a life-threatening event but if managed correctly can be managed safely without the need for nephrectomy in most cases. Blunt trauma accounts for most renal injuries, of which a greater proportion are a less severe injury grade.