Gastrointestinal and Genitourinary Procedures

Fig. 10.1

Position of the probe for paracentesis

Procedure

Clean the procedure site with antiseptic (chlorhexidine, betadine, etc.), and sterilely drape the patient. Apply the sterile probe cover to the ultrasound probe. Inject a wheal of lidocaine or other anesthetic into the procedure site. Anesthetize down to the peritoneum along the desired catheter tract, always applying negative pressure when advancing the needle. Superficially incise the previously determined site with a scalpel, and slowly insert the 8F fenestrated catheter into the peritoneal cavity. The procedure is done in out-of-plane or in-plane needle visualization approach. Once past the epidermis, track the needle tip to the peritoneal wall. If using the out-of-plane approach, carefully track the catheter by fanning the probe in the direction of the catheter movement while keeping the probe in place on the patient’s skin. If visualizing the catheter tip becomes difficult, attempt to place the probe and sound waves in a perpendicular orientation to the catheter tip, fanning again until you have discovered and demarcated the tip of the catheter. If using the in-plane guidance approach, the catheter and needle tip should remain visible at all times. When the tip is close to entering the peritoneal cavity (which can be visualized as tenting of tissue on ultrasound), the catheter and probe can be laterally/inferiorly/superiorly displaced with gentle pressure in order to form a discontinuous tract from the abdominal peritoneal cavity to the external environment (Z-track), and the needle can then be advanced, all the while maintaining negative pressure on the syringe piston and awaiting aspiration of fluid. After aspiration has been observed, advance the catheter. Drain the desired amount of fluid. When finished remove the catheter, apply slight pressure, and place a bandage over the procedural site (Fig. 10.2) [1, 2].

../images/323313_1_En_10_Chapter/323313_1_En_10_Fig2_HTML.png — Fig. 10.2

Visualization of the needle (arrow) during a paracentesis. (Courtesy of Srikar Adhikari, MD)

Complications

Complications from paracentesis are uncommon but may include hemorrhage (0.93%), abdominal wall and mesenteric hematomas, bladder or bowel perforation, inferior epigastric artery aneurysm, vessel laceration (aorta, mesenteric artery, iliac artery), hypotension, infection (0.58–0.63%), and persistent ascitic fluid leak (5%). The clinician can reduce all of these with ultrasound guidance [2, 4].

Pearls/Pitfalls

Allowing the patient to move after abdominal fluid surveying and evaluation has occurred, possibly leading to a shift in fluid and resulting in a dry tap or bowel injury
Accidentally assuming a large fluid-containing structure like a large bladder, fluid-filled loop of bowel, bladder, or cyst is peritoneal fluid [1]

Integration into Clinical Practice

Ultrasound assists clinicians in the performance of abdominal procedures both by improving patient safety and satisfaction and by decreasing failed attempts. Paracentesis is frequently performed in high-risk populations with coagulopathies and in those who are at increased risk for infectious complications of the procedure. Ultrasound allows the clinician to identify vascular structures, both superficial and deep, at risk of being damaged during the procedure. It aids in prevention of accidental bowel and mesenteric injury by assisting in dynamic needle visualization. Ultrasound guidance brings similar benefits to diagnostic peritoneal lavage (DPL) and G-tube placement. With practice it is not difficult to become proficient with ultrasound-guided paracentesis. Inexperienced users can start with the static approach. As one becomes more accustomed to procedural ultrasound, they may begin to see the benefits of dynamic guidance and add into their clinical practice.

Evidence

In 1 prospective randomized study where 100 patients were enrolled, 56 into the ultrasound-assisted group and 44 into the traditional technique, 95% of the ultrasound group were successfully aspirated, and only 61% of the traditional group were successfully aspirated. Key pathology was noted in two of the interventional group patients (a large left lower quadrant cystic mass and a ventral hernia). Of the traditional group’s 17 unsuccessful aspirations, 15 patients had a “break” in the study where they had intervention with ultrasound resulting in 13/15 successful aspirations; of the 2 remaining patients, 1 did not have enough fluid to be sampled, and the other had no fluid visualized [5]. Complications from bleeding during ultrasound-guided abdominal paracentesis are uncommon and appear to be very mild, regardless of pre-procedure INR or platelet count. Routine correction of prolonged INR or thrombocytopenia before abdominal paracentesis may not be necessary. In a 2-year study period, a total of 410 abdominal paracenteses in 163 patients were investigated. The pre-procedure INR for prothrombin time was more than 1.5 in 142 paracenteses; the pre-procedure platelet count was less than 50 × 10³ μL⁻¹ in 55 paracenteses. Only 2 out of 410 procedures (0.5%, 95% confidence interval = 0.1–1.8%) were associated with minor complications of cutaneous bleeding in the same patient (0.6%, 95% confidence interval = 0.1–3.4%) at different visits [6].

Key Points

Ultrasound-guided paracentesis is safer than the traditional blind approach.
Ultrasound-guided paracentesis increases patient satisfaction and procedural success rates.
Visualize the tip of the procedural catheter the entire time.
Do not let your patient shift position after the fluid contents have been surveyed.
Do not mistakenly attempt to drain an abdominal fluid-filled structure.

Diagnostic Peritoneal Lavage (DPL)

In the setting of trauma, diagnostic peritoneal lavage has traditionally been fused in the assessment of intraperitoneal injury and bleeding. When practicing in an austere environment, physicians do not always have access to CT. Additionally, traditional trauma imaging modalities such as CT and ultrasound may yield equivocal findings.

Anatomy

Anatomy of the abdomen for ultrasound-guided procedures has several key elements: location of the stomach and other major organs, the epigastric vessels, mesentery, areas of dependency for fluid collection, and the layers of soft tissue leading to the peritoneal cavity. The epigastric blood vessels traverse the rectus abdominis muscles posteriorly and can be easily injured during blind procedures. The deep inferior epigastric artery and branches can come close to the umbilical area, and providers should maintain an awareness of the variability in apparent anatomy between patients, especially ones who have had prior abdominal surgery.

Indications

Trauma patient in a remote location or a location that lacks computed tomography (CT)
Hemodynamically unstable trauma patient who has a negative or equivocal FAST examination
Should be considered in patients who have an unreliable examination or those at high risk for hollow viscus injury (HVI)
Trauma where CT or ultrasonography detects minimal fluid or when the patient manifests fever, peritonitis, or both with concern for HVI [7–9]

Contraindications

Any obvious need for laparotomy is an absolute contraindication.
Unstable patient with a positive Focused Assessment with Sonography in Trauma (FAST) examination in the setting of trauma.
Unstable patient with an open wound to the abdomen or chest at locations with trauma surgery.
Relative contraindications include:
- No training in DPL
- Prior abdominal surgery
- Morbid obesity
- Second to third trimester pregnancy
- Morbid obesity
- Coagulopathy [2]

Equipment/Probe Selection

A low frequency curved and a high frequency linear array transducer with sterile probe cover are essential to perform DPL. Abdominal wall blood vessels will be best identified using a high-resolution linear array probe with color or power Doppler. Most of the equipment required can be found in a peritoneal lavage kit. See the equipment as follows:

Gloves, gown, mask, and cap
Ultrasound machine
Ultrasound probe cover
Sterile gel (surgical lubricant)
Antiseptic
Fenestrated drape
Suture tray and suture
Injection needles and syringe: 25ga, 22ga
Sterile 4 × 4 sponges
Anesthetic
Scalpel, #15 blade
Peritoneal dialysis set
Intravenous (IV) pole, peritoneal dialysis tubing, and 1 liter of normal saline (NS) or Ringer’s lactate (RL) solution
Three-way stopcock
Tubing set with drainage bag or vacuum container/bulbs
Tape
Specimen vials (cell count, gram stain, culture) [2]

Preparation/Pre-procedural Evaluation

The patient should lie as flat on the bed as possible. The abdomen should be mapped with the ultrasound probe at one-third the distance from the umbilicus to the pubic symphysis (PS). Make note of any hernia, blood vessel, or cystic structure that should be avoided going forward. The depth of the peritoneal cavity should be recorded during this process as well.

Procedure

A nasogastric tube and Foley catheter should be placed in order to minimize complications of the procedure prior to the start of the procedure. We will discuss closed percutaneous technique here. Patients should be placed flat on their back with the head of the stretcher at zero-degree incline. The procedure area can then be sterilely prepped with antiseptic. The IV should be flushed with the sterile fluid chosen to prepare the line free of air, and the clinician should retain the sterile cap in order to maintain a sterile column of fluid and tip of the IV tubing. DPL can be done with static ultrasound guidance after the site has been mapped prior to procedure, as recommended in the paracentesis section above. Dynamic guidance is recommended and is especially valuable when only small amount of free fluid is suspected. In the case of the latter, the sterile probe cover should be applied to the ultrasound probe, and one can evaluate the placement of the needle dynamically into the peritoneal cavity. The clinician can then begin by sterilely injecting a wheal of lidocaine or other anesthetic into the procedure site. Anesthetize down to the peritoneum along the desired needle tract. A small vertical skin incision is made one-third of the distance from the umbilicus to the pubic symphysis (approximately 2-3 cm below umbilicus). A supraumbilical incision is preferred in the presence of pelvic fracture or pregnancy. Then the needle is inserted through the linea alba and peritoneum with real-time ultrasound guidance. Ultrasound can help ensure bowel is not adherent to the anterior peritoneum. The guidewire and catheter are also inserted into the peritoneal cavity under dynamic ultrasound guidance (Fig. 10.3), thus ensuring advancement of the catheter into the peritoneal cavity and prevention of intra-abdominal organ injury. When using ultrasound guidance for this procedure, the needle tip should always be in view if using the out-of-plane approach, and the entire shaft of the needle should be in view using the in-plane approach. Upon passage of the catheter or needle into the peritoneum, aspiration of 10 ml of blood indicates a positive examination, and operative exploration is warranted. If no blood is aspirated, the liter of fluid is flushed into the abdomen, and then the bag is placed below the patient in a gravity-dependent location, which will then allow the fluid to reenter the bag. The bag is then agitated, and 10–30 ml of fluid is sent for analysis, and a positive finding consists of 100,000 RBCs/mm³; 500 WBCs/mm³; any presence of bile, bacteria, or intestinal contents; and a serum amylase >175 IU/ml [7–9].

../images/323313_1_En_10_Chapter/323313_1_En_10_Fig3_HTML.png — Fig. 10.3

Catheter (arrow) introduced into the peritoneal cavity under dynamic ultrasound guidance. (Courtesy of Srikar Adhikari, MD)

Complications

Local or systemic infection
False-positive results, resulting in unnecessary laparotomy
Intraperitoneal injury or hematoma, which can be reduced by assistance with ultrasound monitoring the tip of the procedure needle
Inability to recover lavage fluid (catheter into preperitoneal space, internal adhesions compartmentalizing fluid, internal contents blocking return of flow into catheter, diaphragmatic injury pooling fluid into thoracic cavity), which can be investigated by the use of ultrasound evaluating the fluid location and obstructive issues or by aiding in repositioning the catheter to recollect the fluid

Pearls/Pitfalls

Placing fluid into the preperitoneal space
Bladder injury secondary to neglecting to place a Foley catheter
Fluid testing producing indeterminate results

Integration into Clinical Practice

The ultrasound-assisted DPL can limit the invasiveness of DPL and can help guide catheter placement. Given the prevalence of portable and handheld ultrasound devices, this procedure can potentially be performed in any settings where minimum requirements are met. This can be especially helpful in highly remote or austere environment and in case where patient evaluation brings severe hazards and high risk.

Evidence

Ultrasound may prove beneficial in returning the lavage fluid for testing as it can frequently be hard localize [7, 8].

Key Points

Ultrasound can make the invasive procedure of DPL less invasive.
Ultrasound can assist in returning fluid from the peritoneal cavity.
Ultrasound can decrease complications arising from DPL.

Gastrostomy Tube Placement

Traditionally, gastric tube placement has been confirmed with X-ray and injection of contrast into the newly replaced gastric tube. However, ultrasound can be used on a daily basis in the acute care settings to confirm placement of dislodged G-tubes decreasing time, radiation, and cost.

Anatomy

Anatomy of the abdomen for ultrasound-guided procedures has several key elements: location of the stomach and other major organs, the epigastric vessels, mesentery, and the layers of soft tissue leading to the peritoneal cavity. The epigastric blood vessels traverse the rectus abdominis muscles posteriorly and can be easily injured during blind procedures. Particular attention should be paid to the superior epigastric and superficial inferior epigastric artery branches given potential for variability between patients.

Indications

Those who are unable to safely move food from their oropharynx to the stomach are commonly those in need of a gastrostomy tube, in those that a lighted endoscope cannot pass ultrasound may prove beneficial:

Pre-existing G-tube tract and tube was dislodged
Oropharyngeal, esophageal, or other mass obstructing passage of an endoscope to aid in G-tube placement

Contraindications

Uncorrected coagulopathy
Sepsis, peritonitis, and abdominal wall infection
Gastric outlet obstruction
Gastroparesis
Peritoneal dialysis

Equipment/Probe Selection

Clinicians should opt for a curvilinear transducer with sterile probe cover.

Ultrasound
Percutaneous endoscopic gastrostomy (PEG) tube kit
- PEG tube
- Guidewire
- Nasogastric tube
- Surgical marker
- Partially water-filled syringe, 5 mL
- Sterile fenestrated drape
- Lidocaine or anesthetic of choice
- Anesthesia
- Needle and pigtail catheter assembly (can use one similar to the urology suprapubic pigtail catheter)
- #11 surgical blade
- Sterile 4 × 4 gauze
- Sterile gel (surgical lubricant)
- Antiseptic
- Suture kit with iris scissors
- Supplies for moderate sedation

Preparation/Pre-procedural Evaluation

In clinical settings, the most common indication for this procedure will be replacement of a dislodged tube with ultrasound confirmation. However, for those with upper gastrointestinal obstruction, one may need to place a percutaneous sonographic gastrostomy (PSG) tube. One can use the ultrasound to identify the stomach, which appears as an anechoic pouch with a hyperechoic rim that is the gastric mucosa. The experienced sonologist may be able to make out the gastric rugae. The thinnest layer of abdominal wall overlying the stomach can be identified. Pay special attention to the location of the colon, and map out regions where it will be safe to place the catheter without damaging the colon.

Procedure

Place the head of the bed at a 30-degree angle or greater. The patient should be administered a first-generation cephalosporin intravenously prior to beginning the procedure or some other antibiotic with gram-positive coverage for new PSG placement. After you have sterilely prepared the mapped procedure site with antiseptic, cover it with a fenestrated drape. Local anesthetic should be given to adequately anesthetize the abdominal wall. The stomach should be insufflated with water through a nasogastric tube or via direct puncture with a procedure needle. The procedure needle should be placed under direct ultrasound visualization into the gastric antrum; while holding negative pressure on the water-filled syringe piston, insert the needle until directly visualized in the stomach. If the air is aspirated into the water filled syringe prior to visualizing the needle puncture the stomach, the colon has likely been punctured. If this happens, the needle must then be redirected around the bowel and into the gastric lumen. A guidewire can then be placed through the procedure needle and a small incision is made at the skin in order to pass a trocar over the wire. While advancing the trocar, do not slowly place it into the stomach; instead, it should be advanced with a slight jab or poke in an attempt to not separate the gastric wall from the abdominal wall, and the results of this can be monitored by evaluating the trocar with ultrasound. After the trocar is advanced over the guidewire and removed, the pigtail catheter with balloon proximal to its last fenestration to enter the stomach can then be advanced over the wire. The balloon can be inflated and the stylet is removed. Successful placement can be verified with ultrasound, aspiration of gastric contents, and air insufflation. Real-time ultrasound guidance can be used to visualize a new G-tube inserted through a pre-existing stoma, through the previously fashioned tract, into the body of the stomach. This allows one to dynamically see the tube reenter the stomach and confirm accurate G-tube placement in one process (Fig. 10.4) [10–13].

../images/323313_1_En_10_Chapter/323313_1_En_10_Fig4_HTML.png — Fig. 10.4

Visualization of the gastrostomy tube (arrow) in the stomach

Complications

Aspiration
Peritonitis, infection, bleeding, and leakage
Colon injury
Oversedation leading to cardiopulmonary problems
Placement of tube into peritoneum or abdominal wall

Pearls/Pitfalls

The tube should be flushed and aspirated prior to completion of the procedure to ensure patency while the patient is still sedated.
Ensure that a slight jab or poke is used when introducing the dilator and pigtail catheter.
Ensure adequate sedation and anesthesia.

Integration into Clinical Practice

Ultrasound provides a higher degree of accuracy and safety when compared to traditional blind approaches. A practitioner can become reliant on the visualization of the tube in the antrum, aspiration of gastric contents, and the auscultation of air as reassurance of proper G-tube replacement.

Evidence

Real-time ultrasound guidance and manipulation increases provider certainty and confidence. Ultrasound allows for real-time confirmation of tube placement [10–13]. The confirmatory gastric contrast confirmatory study can be foregone and the patient safely dispositioned with a new feeding tube [7, 10–13].

Key Points

Ultrasound assistance of the procedure is sensitive and practical for evaluating G-tube placement.
Ultrasound helps to confirm stomach aspiration versus aspiration of bowel.

Nasogastric Tube Insertion

Nasogastric tube (NGT) insertion is one of the most commonly performed procedures in the acute care settings. The location of the NGT must be ascertained immediately after placement or with the presence of vomiting, coughing, severe retching, or a drop in oxygenation. The gold standard for proper nasogastric tube placement is the upright chest X-ray. Other methods for assessing placement include auscultation, measurement of NGT pH, colorimetric analysis of NGT carbon dioxide, and the use of sonography for direct visualization of the NGT in the stomach.

Anatomy

Placement of a NGT involves passing the flexible tube through the nares, the nasopharynx, and the oropharynx, past the larynx, and into the esophagus. The esophagus begins at the level of the cricoid cartilage; courses behind or to the left of the trachea, behind the aorta and heart in the posterior mediastinum, and through the diaphragm at the esophageal hiatus; and ends at the cardia of the stomach just below the diaphragm. Once the NGT passes into the esophagus, peristalsis will carry it into the stomach. Having the patient flex their neck will push the NGT to the posterior oropharynx allowing easier passage into esophagus. Having the patient swallow allows for the epiglottis to cover the larynx, the vocal cords to approximate together, and the larynx to pull up and forward stretching the esophageal walls to create a larger opening for the tube to go into as the first part of the esophagus relaxes. The average distance from the anterior nasal spine to the tracheoesophageal junction is about 20 cm. The average length of the muscular esophagus is about 25 cm. Ideally the tip of a nasogastric tube should lie approximately 10 cm below the gastroesophageal junction, making the ideal length for nasogastric tube insertion about 50 to 60 cm at the nasal vestibule [14].

Indications

Placement of the nasogastric (NG) tube allows for bowel decompression after intubation and in instances of acute bowel obstruction, confirmation of transdiaphragmatic hernia in trauma, lavage of pill fragments in acute overdose, or removal of blood in acute gastrointestinal bleeding.

Contraindications

Relative contraindications for this procedure include facial fractures, coagulopathy, history of esophageal strictures or caustic ingestion, esophageal varices, coma or lethargy with an unsecured airway, recent stomach or esophageal surgery, gastrectomy, and suspicion for elevated intracranial pressure.

Preparation and Pre-procedural Evaluation

An initial evaluation of the patient’s bilateral nares for patency is necessary to decrease patient discomfort during the procedure. Additionally, estimation of the required length for the NGT to be placed is required to ensure intragastric placement. This is done by placing the tube up against the patient’s face from the tip of the nose to the patient’s ear and then from the ear to the xiphoid process. This length plus 5 cm, a total length of approximately 55–65 cm, should correspond to the proper length for intragastric insertion. Mark this length on the NGT with a permanent marker. NGT size is selected for comfort and purpose. For the commonly used Levine tube, sizes range from 2 to 18 French; 2–12 French is for neonates, infants, children, and adult patients with small nares, while 14–18 French is for the typical adult.

Equipment/Probe Selection

Gloves
Towels (if patient gags and vomits)
Tincture of benzoin
Adhesive tape
Appropriate sized Levine nasogastric tube
Cetacaine spray or 4% nebulized lidocaine
Neosynephrine 0.5% or Afrin 0.5% spray
Wall suction set up with adapter for connection to NGT tube
Emesis basin
Small cup of water with a straw

Procedure

Instill a topical vasoconstrictor such as neosynephrine 0.5% or Afrin 0.05% into both nares to decrease risk of epistaxis secondary to nasal trauma and wait for 5 minutes. Apply Cetacaine spray or 4% nebulized lidocaine delivered via facemask 5 minutes prior to the procedure to anesthetize the oropharynx.

Examine the patient’s neck with ultrasound to view the position of the esophagus prior to NGT insertion by placing a linear, high-frequency probe (14–8 MHz) in transverse orientation, midline over the lower third of the neck, near the thyroid, with the indicator pointing to the patient’s right. To the right of the screen, the trachea will appear as a hyperechoic ring with posterior shadowing lying midline under overlying thyroid tissue. To the left of the trachea, the circular esophagus will appear as a hyperechoic ring (Fig. 10.5a). Adjacent to the esophagus, the internal jugular vein and carotid artery will appear. Lubricate the NGT with sterile lubricant and/or viscous lidocaine. Have the patient flex his or her neck with the chin touching the chest, and while they are simultaneously sipping water, insert the lubricated NGT through the most patent nostril, straight back, past the posterior pharynx to the oropharynx, esophagus, and stomach as noted by the marked area on the NGT reaching the nasal vestibule. Clean the nose with the tincture of benzoin, and tape the nasogastric tube in place to the nose.