A bladder scan is a medical procedure that uses a small, portable ultrasound device to non-invasively measure the volume of urine inside the bladder. This quick and painless assessment utilizes harmless sound waves traveling through the lower abdomen to calculate the fluid volume in milliliters. It is a simple diagnostic tool employed across various healthcare environments to gain insight into a patient’s urinary function. The primary goal is to determine how completely the bladder is emptying.
Why a Bladder Scan Is Necessary
The main reason for performing this scan is to measure the post-void residual (PVR) volume, which is the amount of urine left in the bladder after urination. A high PVR volume suggests incomplete bladder emptying, known as urinary retention. Identifying retention is important because it can indicate underlying issues such as bladder outlet obstruction or weakened bladder muscles.
The scan helps medical teams determine whether a patient requires a urinary catheter, reducing the risk of catheter-associated urinary tract infections (CAUTIs) by avoiding unnecessary invasive procedures. For patients experiencing symptoms like urgency, frequency, or unexplained incontinence, the scan helps differentiate between an overactive bladder and retention-related overflow incontinence. The scan is also routinely used to monitor bladder function following surgery, especially after anesthesia, as temporary suppression of bladder reflexes can lead to retention.
Settings Where Scans Are Routinely Performed
The portability of the device means bladder scans can be performed virtually anywhere a patient is receiving care. In Emergency Departments, the scan provides a rapid assessment for patients presenting with lower abdominal pain or an inability to urinate. Quick results help physicians determine if acute urinary retention is the cause, allowing for immediate triage and intervention.
Acute Care Hospital Units, including post-surgical recovery and general medical floors, rely heavily on bladder scanning to monitor inpatients. Staff proactively check for PVR to ensure the bladder is emptying correctly after anesthesia or to track fluid output. This helps prevent overdistension and supports a smoother recovery. The non-invasive nature of the scan makes it suitable for frequent monitoring.
In Primary Care and Urology Clinics, the scan is a standard part of evaluating chronic urinary symptoms like difficulty voiding or long-term incontinence. These clinical settings use the scan during routine check-ups to assess bladder health and track the effectiveness of medications or behavioral therapies. Long-Term Care and Nursing Facilities frequently utilize the device at the bedside to monitor residents for signs of retention or to guide decisions regarding catheterization.
Specific Anatomical Considerations for Females
Scanning a female patient requires specific anatomical awareness due to the proximity of other pelvic organs. The female bladder is situated directly in front of the uterus and the vagina. These structures can sometimes interfere with the ultrasound signal or be mistaken for the bladder itself. The scanner must be correctly calibrated to the “female” setting, which adjusts the algorithm to account for the typical size and positioning of the female bladder.
Proper probe placement is achieved by locating the symphysis pubis, the joint at the front of the pelvis. The probe is applied approximately 2.5 to 4 centimeters above this bone on the midline of the lower abdomen. The healthcare provider must angle the probe slightly downward toward the tailbone to ensure the sound waves are directed into the pelvic cavity where the bladder is located. This precise angling is important to visualize the maximum diameter of the bladder and avoid capturing fluid-filled structures like the uterus or ovarian cysts, which can lead to falsely high volume readings.
Anatomical changes, such as a severe pelvic organ prolapse or the presence of fibroids, can also complicate the scan by distorting the bladder’s shape. In the postpartum period, the recently vacated uterus may still contain fluids or be enlarged, which can affect the accuracy of the volume measurement. In situations where the reading is questionable due to complex anatomy, the provider may need to use anatomical landmarks on the screen to confirm the visualized structure is indeed the bladder.