Retrograde Cystography Health Article

Definition

A retrograde cystogram is a radiographic study of the bladder, made after a direct injection of a radiopaque contrast material by means of a urethral catheter.

Purpose

A retrograde cystogram is performed to evaluate the structure of the bladder and identify such bladder disorders

as cystitis, polyps, stones, and tumors. It may also be used to diagnose recurrent urinary tract infections due to urine reflux (backward flow) into the ureters. This examination is commonly performed as an emergency procedure on patients with gross hematuria (blood in urine) due to a pelvic fracture or severe trauma to the abdomen, in order to detect rupture of the bladder. Retrograde cystography is frequently done on children being evaluated for a congenital abnormality, obstruction, or urethral stricture. When the urethra is also being evaluated, the study is called a cystourethrogram. If the bladder or urethra is evaluated while the patient is voiding (urinating), the study is called a voiding cystourethrogram or VCUG. A voiding cystourethrogram is often performed when the bladder is full to check for any reflux or other problems during urination.

Complications

The physician should be alerted to any previous history of an allergic reaction to an iodine-based contrast material. Since the contrast medium is injected directly into the bladder instead of the venous circulation, allergic reactions are extremely rare. A retrograde cystogram should not be performed, however, on patients who have had recent bladder surgery or an obstruction that interferes with the placement of a urinary catheter. Patients with an active urinary tract infection or who may be pregnant should not be given a retrograde cystogram.

Description

To administer a retrograde cystogram, a doctor or nurse will insert a thin tube-like instrument called a Foley catheter through the patient's urethra and into the bladder. The contrast medium is then injected through the catheter into the bladder. The catheter can be inserted in an outpatient clinic before the patient is taken to the radiology department. It may also be inserted by an emergency physician when a retrograde cystogram is ordered on a severe trauma patient. The cystogram can be performed in the emergency department using a portable xray machine.

After the Foley catheter is inserted, 250–300 mL of a water-soluble contrast medium is injected into the bladder and the catheter is clamped. A diluted contrast agent (usually 30% sodium iodide) is used since the contrast medium is not injected intravenously. An AP (anteroposterior) view of the full bladder is taken with the tube angled 10–15 degrees caudal (in the direction of the patient's feet) to project the pubic symphysis away from the base of the bladder. The patient is turned 45 degrees onto each side for two oblique views of the bladder and completely sideways for a true lateral view. The films are reviewed by the radiologist. If no other films are needed the catheter will be removed and a post-void film is taken. If the patient is unable to urinate, the clamp will be removed, the contrast medium will then empty from the bladder through the tube, and a post-drainage film will be taken. During a voiding cystogram, films are taken by the radiologist under fluoroscopy while the patient is voiding in order to image any urethral abnormalities or urinary reflux.

A retrograde cystogram usually takes from 30 minutes to one hour, depending on how many films are requested by the radiologist.

This examination can also be performed with a radioactive tracer (isotope) in the nuclear medicine department. A cystogram performed with a tracer is known as a radionuclide retrograde cystogram.

A CT scan of the bladder may also be ordered after the injection of a radiopaque contrast material.