Chapter 143. Suprapubic Bladder Aspiration

Suprapubic bladder aspiration is the introduction of a needle through the anterior abdominal wall and into the bladder to obtain a urine specimen under strict sterile technique. It is performed primarily to diagnose urinary tract infections.1–9 It is most commonly performed in children under the age of 2 years as part of the septic work-up.7 The procedure is quick, simple to perform, safe, and has a low rate of complications. The main advantage of suprapubic bladder aspiration is that it bypasses the urethra and minimizes the risk of obtaining a contaminated urine specimen.

Urinary sampling remains the cornerstone for the diagnosis of many disease processes including metabolic derangements, infectious processes, catabolic states, and neoplastic conditions. In cases when the usual means of voided urine collection or bladder drainage is not possible or preferable, suprapubic bladder aspiration becomes a viable option both therapeutically and diagnostically. If properly performed, this technique can yield an uncontaminated urine sample without urethral or skin flora contamination.

The urinary bladder of the neonate and infant begins as an abdominal organ (Figure 143-1A). As the child grows the pelvis enlarges and the bladder migrates down into the pelvis. The bladder eventually assumes its retropubic position that is maintained throughout life (Figure 143-1B).

The anatomic knowledge required to perform this procedure is minimal. The pubic symphysis is in the midline and forms the anterior border of the bony pelvis. The bladder resides posterior and superior to the pubic symphysis in the young child. The needle will pass through the skin and subcutaneous tissue of the lower abdominal wall, the rectus sheath, the peritoneum, and the bladder wall.

The adult urinary bladder resides behind the pubic symphysis and has both retroperitoneal and intraperitoneal attachments (Figure 143-1B). A working knowledge of this anatomy makes percutaneous bladder manipulation both safe and possible. The rectum lies just inferior and posterior to the urinary bladder. This relationship must be kept in mind when attempting percutaneous access. The bladder dome has peritoneal attachments and access in this area carries the potential for bowel injury and intraperitoneal bladder perforation.

Multiple major vascular structures, including the common iliac and hypogastric vessels, reside in the bony pelvis alongside the bladder. These structures are lateral to the bladder and eccentric percutaneous access may result in troublesome hemorrhage.

Suprapubic bladder aspiration is the preferred method of urinary sampling and drainage in instances where voided specimens are undesirable or unattainable, and when urethral catheterization is not technically possible or contraindicated.1–10 It offers a means of obtaining an uncontaminated urine sample from the bladder. Obtaining a urine sample by urethral catheterization in the neonate or young child may be technically difficult, in which case suprapubic aspiration is a viable alternative. Although urethral catheterization may be an easier method of urine collection in the child or adult, suprapubic aspiration may be required to isolate infravesicular infections, to rule out contamination with asymptomatic bacteriuria, or in cases of urinary retention from a phimosis. The procedure may be performed to temporarily relieve acute urinary retention.

The single most important aspect of suprapubic bladder manipulation is the presence of an identifiable (by palpation, percussion, transillumination, and/or ultrasonography) and distended urinary bladder. Under no circumstances should “blind” percutaneous access be attempted if the bladder is not palpable or visualized with the aid of ultrasonography.

Any physical alteration, spinal deformities, extremity contractures, truncal obesity, or other conditions that would preclude patients from lying supine and inhibiting bladder palpation are contraindications to this procedure. Skin infections overlying the puncture site are a contraindication to bladder aspiration. Abnormalities in genitourinary anatomy or enlargement of pelvic structures (e.g., ovarian cysts, uterine fibroids) increase the chance of complications with bladder aspiration. Known neoplastic processes of the lower genitourinary tract heighten the possibility of complications. Similarly, distention or enlargement of the abdominal viscera can increase complication rates. The return of ascitic fluid may lead to a false sense of security when the needle is actually intraperitoneal.

Patients with a coagulopathy are at an increased risk for troublesome hemorrhage from any percutaneous procedure, including suprapubic bladder access. Patients with a bleeding diathesis, anticoagulant therapy, or thrombocytopenia should be corrected prior to performing the procedure. In individuals with prior abdominal surgery, the peritoneal cavity has been violated and the bowel may be displaced more caudal and extend to the level of the urinary bladder. This heightens the risk of inadvertent bowel injury. The procedure should not be performed in patients with abdominal distention or the suspicion of an intestinal obstruction. An uncooperative patient should be sedated and/or restrained for the procedure.

• Povidone iodine or chlorhexidine solution
• Sterile gloves
• 22 to 24 gauge needle or spinal needle, 1½ to 3 inches long for neonates, infants, and young children
• 22 to 24 gauge needle or spinal needle, 3 inches long for older children, adolescents, and adults
• 10 mL syringe
• Injectable local anesthetic solution, most commonly 1% lidocaine
• 4 × 4 gauze squares
• 25 gauge needle and 3 mL syringe for anesthetic administration
• Sterile towels or drapes
• Specimen containers for urine analysis and culture
• Bandage
• Ultrasound (US) machine (recommended)
• Sterile US gel
• Sterile US probe covers
• 5 to 10 MHz linear US probe for neonates, infants, and children
• 2 to 5 MHz curvilinear abdominal US probe for adolescents and adults

Explain the risks, benefits, and alternative procedures to the patient and/or their representative. Obtain an informed consent for the procedure and place this in the medical record. When performing the procedure on a neonate or child, it is advisable to give the parent the option to leave the room or look away as the procedure can be disconcerting to some parents.

It is important to identify the distended bladder by palpation, percussion, transillumination, or ultrasonography. Transillumination of the full bladder may be conducted in the neonate. Place the patient supine (Figure 143-2). Ultrasonography should be used, if available, even if the bladder is readily palpable. Ultrasound can be used to identify the bladder, confirm the bladder is distended with urine, guide the needle aspiration, and increase the success of the procedure.10–13 If the bladder is readily distended, it appears on ultrasound as an anechoic (black) square-like structure just below the abdominal musculature.6 Placement of a gel-filled sterile glove over the probe maintains sterility during ultrasound-guided procedures. Identify and mark the skin location immediately above the bladder where it is closest to the skin.

Prepare and drape the abdomen in a sterile fashion from the umbilicus to the pubis. Clean the skin of any dirt and debris. Apply povidone iodine or chlorhexidine solution and allow it to dry. Apply sterile drapes. Inject a local anesthetic agent, usually 1% lidocaine, to raise a subcutaneous wheal in the area of the intended skin puncture site. Many consider this step to be optional in the neonate as the amount of discomfort caused by placement of the anesthetic is similar to the actual puncture for bladder aspiration. Slight differences in technique are required for suprapubic bladder aspiration of the infant, child, and adult.

Neonates and Infants

Have an assistant place and hold the infant supine in the frog-leg position (Figure 143-2A). Identify the needle insertion site in the midline and 2 cm cephalad to the pubic symphysis (Figure 143-3). The use of US is recommended to assist in determining the proper needle insertion site. Inject 1 mL of local anesthetic solution subcutaneously and into the abdominal wall musculature at the needle insertion site.

Place a 22 or 24 gauge spinal needle onto a 10 mL syringe. Occlude the urethra to prevent reflexive micturition. Apply manual pressure to the urethral meatus of the female (Figure 143-4A) or the glans penis in the male (Figure 143-4B). Insert the needle through the insertion site and at a 20° angle from the true perpendicular to the skin (Figure 143-4). Advance the needle cephalad while applying negative pressure to the syringe. Stop advancing the syringe when urine is aspirated. The bladder appears to tent as the needle pierces its anterior wall when ultrasonographic guidance is used.6 If no urine is aspirated, withdraw the needle to the subcutaneous tissue and readvance it in a slightly different direction (e.g., 0° to 10° to the true perpendicular). If the procedure is unsuccessful on the second attempt, delay further attempts until the bladder is more distended, consult a Urologist, or obtain urine through urethral catheterization. After urine is obtained, remove the needle and apply a bandage to the skin puncture site.

Older Children

The positioning of the older child is similar to that of the neonate or infant (Figure 143-2B). The procedure is similar to that of the infant, although it is more important to identify the location of the distended bladder to assure a successful aspiration. The use of US is recommended to assist in determining the proper needle insertion site. The urinary bladder of the older child may be in the abdomen or may have migrated into the pelvis.

Adolescents and Adults

Place the patient supine. Identify the bladder by palpation or ultrasonography. Identify the needle insertion site in the midline and 2 to 4 cm cephalad to the pubic symphysis. Inject 1 to 3 mL of local anesthetic solution subcutaneously and into the abdominal wall musculature at the needle insertion site.

Place a 3 inch, 22 to 24 gauge spinal needle onto a 10 mL syringe. Insert the needle through the insertion site and at a 60° angle to the skin of the abdominal wall (Figure 143-5). Advance the needle caudally while applying negative pressure to the syringe. Stop advancing the needle when urine is aspirated. If no urine is aspirated, withdraw the needle to the subcutaneous tissue and readvance it in a slightly different direction (e.g., 50° to the skin of the abdominal wall). After urine is obtained, remove the needle and apply a bandage to the skin puncture site.

Ultrasound can ensure there is sufficient urine to aspirate and locate a bladder that is located off midline or deep in the pelvis. It is especially helpful in infants and toddlers, who have small bladders. There are no contraindications to using ultrasound other than those for the procedure itself. For adults, a general-purpose curvilinear abdominal or phased-array probe provides the best combination of penetration and field of view into the abdomen. A linear probe can be used for children. Either a static or dynamic (real-time) technique can be used. The static technique is preferred as it is the easier technique to learn and master. The dynamic technique will increase the success rate for small bladders with minimal urine.

Image the bladder to ensure there is sufficient urine to aspirate. Place the US probe transversely and just superior to the pubic symphysis. If the bladder is not immediately visible, slowly fan the probe cephalad and caudal until it appears. If the bladder is not visible, repeat the scan just off the midline. The bladder will appear anechoic (Figure 143-6). Moderate to large bladders are amenable to the static US technique. Bladders smaller than 2 cm in anteroposterior or transverse diameter have a lower success rates for aspiration and the dynamic US technique may be necessary to obtain urine.11

Static US Technique

Identify the bladder using US and center the image on the US machine screen. Angle the US probe so that the largest dimensions of the bladder appear on the screen. Note the angle of the US probe as this will correspond to the angle of entry for the needle. Make sure that the bladder is centered on the screen. Move the probe off midline, if necessary, to minimize lateral angulation. This will prevent the need to angle the needle laterally to reach the bladder. Note the depth on the screen from the skin to the bladder in order to gauge the necessary needle length. Mark the entry point on the skin where the middle of the probe meets the skin. Prep the skin and proceed with procedure as described previously.

Dynamic US Technique

Prepare the skin, apply sterile single-use US gel to the patient's skin, and apply a sterile US probe cover. Stand to the side of the patient so that your dominant hand is cephalad (Figure 143-7). Position the US monitor on the opposite side of the patient so that it is easy to see (Figure 143-7). A longitudinal US probe orientation is preferred for the dynamic approach since it allows visualization of the entire needle as it courses toward the bladder. In infants and toddlers, there may not be enough space to place the US probe longitudinally and a transverse probe orientation may be necessary. In either case, place the US probe marker to your left. This will ensure that the left–right orientation on the US screen matches the real-world orientation.

Place the longitudinally oriented US probe in the suprapubic area and move it from side to side to locate the largest bladder dimension. Place the procedure needle on a 10 mL syringe. Position the procedure needle on the cephalad side of the US probe and angle it caudally (Figure 143-8). Insert and slowly advance the needle. Look for the needle on the US screen as it is inserted and advanced. If the needle is a narrow gauge and the US probe is low frequency, the needle will not necessarily be visible in the tissue. Rather, look for movements in the tissue as the needle is advanced (Figure 143-9). Adjust the needle and the US probe side to side as needed to keep the needle in the same plane as the US beam. Aspirate as the needle is advanced. When the needle appears to enter the bladder, aspiration should result in urine return. Remove the US probe once urine is aspirated. The remainder of the procedure can proceed as previously described.

For the transverse orientation, position the US probe so that the image of the bladder is centered on the screen. Position the procedure needle attached to a syringe just superior to the center of the US probe (Figure 143-10). Slowly advance the needle toward the bladder. Angle the needle slightly more caudal than the US probe since the entry point of the needle is superior to the US probe. The needle will be seen on screen in cross section and will appear as an echogenic point with a ring-down artifact or bright shadow (Figure 143-11). As the needle is advanced toward the bladder, the US probe may need to be fanned slightly cephalad or caudal to keep the needle tip in view. Aspirate as the needle is advanced. When the needle appears to enter the bladder, aspiration should result in urine return. Remove the US probe once urine is aspirated. The remainder of the procedure can proceed as previously described.

If the first attempt at aspiration is unsuccessful, withdraw the needle to a subcutaneous position and redirect it at a different angle. This should be done only if the bladder is clearly identified. If the procedure is unsuccessful on the second attempt, the procedure should be delayed until the bladder is more distended. Consultation with a Urologist may be necessary.

No specific care is required after performing a suprapubic bladder aspiration. Microscopic hematuria can occur following the procedure although gross hematuria is uncommon. The patient may complain of mild pain or soreness in the suprapubic area. This can be relieved with acetaminophen or nonsteroidal anti-inflammatory drugs. The patient, if discharged, should be given specific instructions to return immediately if they develop gross hematuria, abdominal pain, fever, nausea, vomiting, or infection at the puncture site.

Numerous complications can be associated with suprapubic bladder aspiration.1–16 Fortunately, these are rare occurrences. Bowel perforation, intraabdominal viscera injury, uncontrolled hemorrhage, and needle misplacement are the major complications of suprapubic bladder aspiration. Infectious complications include abdominal wall cellulitis, abdominal wall abscess, sepsis, and peritonitis. Hematomas of the abdominal wall, bladder wall, and pelvis are usually self-limited and require no treatment.

In the unfortunate situation when bowel contents or continuous blood is aspirated, the appropriate surgical consultant should be contacted. Generally, simple penetration of the bowel is considered harmless and requires no specific treatment. Observe the patient for the development of signs and symptoms of peritonitis.

To avoid complications, it is key that the bladder be clearly identified prior to inserting the spinal needle. The use of ultrasonography may aid in substantial reduction of complications arising from needle misadventure. The use of strict aseptic technique should avoid most infectious complications. Delaying the procedure for infants who have urinated within the last hour and the correction of any bleeding diathesis before performing the procedure can help avoid complications.

Do not mistake ascites as urine on ultrasonography. Ascites will outline the bowel and appears in many places around the abdomen. Fluid in the bladder has rounded borders and is localized. It is easy to lose sight of the needle tip and misdirect the needle as it advances through the tissue. Always fan the US probe to keep the tip of the needle in sight. In some cases, the needle may not be visible. Look instead for tissue movement.

In those clinical situations when transurethral urine collection is not desired or possible, suprapubic bladder aspiration is an alternative. A thorough understanding of the pelvic and abdominal anatomy, along with a complete history and physical examination, is necessary to assure patient safety and avoid complications. This procedure is safe and effective to obtain urine as long as the bladder can be properly identified by palpation, percussion, or ultrasonography. Suprapubic bladder aspiration provides urine that is free from urethral contamination.