Cystocentesis. Small Animal Diagnostic and Treatment Techniques

	Cystocentesis can be performed with the animal in dorsal recumbency (shown below), lateral recumbancy, standing or being held standing on its hindlimbs by elevating its forequarters. The position of the animal is primarily based on personal preference. Cystocentesis is usually performed with a 25-22 gauge needle.
Although some veterinarians perform cystocentesis without preparation of the puncture site, (they just wet the site with alcohol) it is the preference of the author to clip the puncture site of hair and clean the area with an antiseptic solution such as Betadine^TM.

The bladder is palpated and immobilized. The bladder should not be squeezed tightly as the puncture is being made as this can cause urine to leak from the puncture site into the abdominal cavity.

The needle should be inserted at a 450 angle, a short distance cranial to the junction of bladder and urethra (a) If the needle is inserted at the apex of the bladder (b), as urine is removed, the bladder gets smaller and moves away from the needle. The needle should be inserted into the bladder while creating negative pressure by pulling back on the plunger of the syringe. The needle should not be redirected if urine is not obtained, due to the risk of penetrating a bowel loop and subsequently taking the contaminated needle into the bladder. If a sample is not obtained on the first attempt, change the needle before making another attempt. If a sample is not obtained on 3 attempts, the bladder is probably small and in the pelvic canal. If a sample is obtained, the syringe plunger is released, and the needle is removed from the abdomen.

If you cannot palpate the bladder, you can perform "blind" cystocentesis with the dog in dorsal recumbancy. Pick a point on the midline, midway between the umbilicus (u) and brim of the pelvis (p) . Notice when you are preparing the puncture site, this is the same point at which the antiseptic solution will pool when the patient is in dorsal recumbancy. This is the starting point of cystocentesis. If urine is not obtained with the first puncture, two additional punctures can be attempted from 1 to 2 centimeters cranial and 1 to 2 centimeters caudal to the initial puncture site. If urine is not obtained on the first attempt, change the needle before making another attempt. If a sample is not obtained on 3 attempts, the bladder is probably small and in the pelvic canal. Try again later to collect a sample.

Cystocentesis can be performed on the midline in male dogs by retracting the penis and prepuce off the midline.