Postoperative urinary retention may be becoming more common among patients undergoing primary total knee replacement and could be associated with a higher risk of complications and longer hospital stays, according to a new analysis of over 1.2 million cases across the United States.
Using data from 2005 to 2014, the investigators found that the incidence of postoperative urinary retention (POUR) rose from 1.51% to 2.29%. Over the 10-year period, the cumulative rate was 1.91%. While the overall rate remains under 2%, the upward trend signals a growing concern in clinical practice.
POUR is the inability to urinate following surgery despite having a full bladder. If not promptly managed, it can lead to overdistension and other complications. Although POUR didn't significantly increase inpatient mortality (0.1% vs 0.07%, P = .12), the condition was associated with a higher likelihood of adverse outcomes and longer hospital stays.
Patients who developed POUR were more likely to be older, male, and have underlying health conditions. The strongest risk factor was male sex (odds ratio [OR] = 3.40), followed by fluid and electrolyte disorders (OR = 2.02), age over 60 years (OR = 1.97), paralysis (OR = 1.78), and psychoses (OR = 1.57). White patients had a higher incidence compared with Black or Hispanic patients.
POUR was also linked to higher rates of several complications, including acute myocardial infarction (0.42% vs 0.20%), pulmonary embolism (0.80% vs 0.42%), acute renal failure (6.06% vs 1.49%), and posthemorrhagic anemia (28.89% vs 19.45%)—all with P < .0001.
Hospital costs were notably higher for the patients who experienced POUR, with median charges of $44,338 compared with $41,228 in the non-POUR group. The length of stay was also modestly longer.
Notably, obesity appeared to reduce the risk of POUR (OR = 0.88). The investigators suggested this could be because of the more frequent use of preoperative catheterization in patients with obesity, though further studies are needed.
The findings highlighted the need for better risk screening and targeted preventive measures, especially in older male patients and those with multiple comorbidities. Early bladder scanning and optimized fluid management may help reduce incidence.
The study was based on the National Inpatient Sample, which provides data from a broad mix of hospitals nationwide. Its large sample size enhanced the reliability of the findings, although the investigators acknowledged potential limitations in coding accuracy and missing data.
As more total knee replacements shift to outpatient settings, monitoring and prevention of POUR may become increasingly critical to patient safety and recovery.
The authors reported no competing interests.
Source: BMC Surgery
