Value of Doppler ultrasonography in predicting deteriorating renal function after spinal cord injury

Comparing the role of renal ultrasound vs MAG3 renal scans for evaluation of neurogenic bladder after spinal cord injury

OBJECTIVE

Compare ability of renal ultrasound and Tc-99m mercaptoacetyltriglycine (MAG3) renal scan to identify upper urinary tract stasis.

DESIGN

Retrospective chart review.

SETTING

Outpatient Neuro-urology clinic serving a large SCI population.

PARTICIPANTS

One hundred and sixty-five individuals with spinal cord injury, presenting for annual evaluation.

INTERVENTIONS

Renal ultrasound, MAG3 renal scan.

OUTCOME MEASURES

Radiologic evidence of upper urinary tract stasis as reviewed by independent radiologist. For renal ultrasounds, this included: mild hydronephrosis, dilation of collecting systems, pelviectasis, or caliectasis. For MAG3 renal scans, this included evidence of slow drainage of radioisotope, dilation of collecting systems, or reverse peristalsis.

RESULTS

Forty-five individuals with spinal cord injury demonstrated upper tract stasis, with 12 identified by renal ultrasound and 43 identified by MAG3 renal scan. There was a strong relative correlation between test results (Yule's Q = 0.90), though MAG3 renal scan identified a significantly higher rate of upper tract stasis within the same patients (P < 0.0001). The odds ratio of improved identification using MAG3 renal scan was 16.5 (95% CI 3.96-68.76).

CONCLUSIONS

While renal ultrasound is more effective at evaluating renal anatomy, MAG3 renal scan identifies significantly more upper urinary tract stasis than renal ultrasound and should be considered for SCI individuals with risk factors of upper tract injury.

Incidence of Renal Tract Abnormalities on Ultrasonography in Patients with Spinal Cord Injury: A Retrospective Pilot Study of a Military Cohort Undergoing Long-Term Institutional Rehabilitation

Study Design

Retrospective pilot study.

Purpose

To assess the incidence of renal tract abnormalities using ultrasonography (US) in a military cohort with traumatic spinal cord injury (TSCI) at a tertiary level spinal cord injury center.

Overview of Literature

Neurogenic bladder in TSCI patients results in significant urological morbidity. There is lack of data for these patients during the first 18 months of long-term rehabilitation in an institutional setting.

Methods

We retrospectively reviewed patient records to collect data on demographic characteristics, injury level, injury severity, time since injury, bladder management methods (such as an indwelling catheter [IC], clean intermittent catheterization [CIC], or self-voiding [S]); we correlated these data with the findings of the renal tract US.

Results

The study included 73 out of 81 male participants. The mean patient age was 29.99 years; the study group included 34.2% tetraplegics and 65.8% people with paraplegia. The time since injury was 6–12 months for 42.5% of the subjects and 12–18 months for 57.5% of the subjects. A normal US scan was recorded in 65.7% patients, and bladder trabeculation was the commonest finding in 15.1% of the subjects, followed by hydronephrosis (HDN) in 12.3%, and renal calculus and atrophy in 1.3% participants each. We found 22.22% of the IC group participants had higher US abnormalities than those in the reflex voiding group (statistically non-significant difference, p=0.7). Trabeculations (21.4%) and HDN (19%) were more common in those who had sustained the injury 12–18 months previously as compared to that in those who had injured themselves 6–12 months previously (p=0.04). The proportion of patients who had a normal US scan was higher in the group who sustained the injury 6–12 months previously versus those who had sustained the injury 12–18 months previously; the difference was statistically significant (p=0.02). There was no significant (p=0.72) correlation in the bladder management method, injury level, and renal tract abnormalities between the groups.

Conclusions

This retrospective study shows that 65% of TSCI participants had no renal tract abnormality on US scan and bladder trabeculation ruled out as the most common finding. Long-term supervised rehabilitation may help achieve good renal quality of life; however, further prospective trials are required on this subject.