Postoperative bladder distention: measurement with bladder ultrasonography

The effectiveness of implementing a bladder ultrasound programme in neurosurgical units

AIM

This paper reports an evaluation of the differences among rates of unnecessary catheterization, urinary retention and urinary tract infection before and after implementing a bladder ultrasound programme to assess urine volume.

BACKGROUND

Bladder ultrasound is a non-invasive alternative to urethral catheterization for the determination of bladder urine volume. Much of the literature available on bladder ultrasound technology addresses the accuracy of the equipment, with little research on the clinical outcomes or benefits of the intervention.

METHODS

A quasi-experimental design was adopted. Data were collected from March 2001 to May 2001 in a control group in two neurosurgical units in Taiwan. During July and August 2001, nurses were taught how to operate a portable ultrasound machine and how to implement the programme. Data were collected from September to November 2001 in the study group.

RESULTS

The rates of unnecessary catheterization in the control group and the study group were 35.3% and 7.0%, respectively. The urine volume (more than 500 mL) in the control group and the study group were 13.4% and 20.3%, respectively. The study group had a statistically significantly lower average catheterization volume than that of the control group (676.9 mL vs. 777.1 mL, t = 1.84, P < 0.05). During 3 months before and after the implementation of the programme, the urinary tract infection rates in the control group and the study group were 3.47% and 2.87%, respectively. After 6 months the urinary tract infection rates decreased to 1.39%.

CONCLUSION

The bladder ultrasound programme was successful and could be used to manage patients with urination disorders in neurosurgical units.

Screening test model using duration of labor for the detection of postpartum urinary retention

AIMS

To construct a screening test model for postpartum urinary retention (PUR), using the duration of labor, which was shown to be the risk factor for PUR.

METHODS

A group of 691 consecutive patients were recruited at postpartum day 1. Of the 691 patients, 101 (14.6%) had PUR. The 691 patients were computer-randomized into two groups, 'A' and 'B.' A receiver operating characteristic (ROC) curve was constructed for Group A to determine the optimum cutoff value for screening PUR using the duration of labor. The cutoff value was then applied to Group B to determine the screening test characteristics of the duration of labor: sensitivity, specificity, predictive values, and likelihood ratios.

RESULTS

An ROC curve with an area under curve (AUC) of 0.63 (95% CI 0.57-0.69, P < 0.0001) was constructed. A range of cutoff values (with specificity ranging from 0.60 to 0.99) for the duration of labor was determined and the test characteristics computed. According to the test characteristics the optimal cutoff value for the duration of labor was 700 min. This cutoff value for the duration of labor has a specificity of 0.95, negative predicative value of 0.86, and likelihood ratio for a positive test of 0.88.

CONCLUSION

A screening test model using the duration of labor can be constructed to predict PUR.