Editing Reduction of Risk Potential (section)

== Diagnostic Testing: Preparation and Post-Procedure Care ==

=== General Principles ===

Before any invasive procedure, verify that informed consent has been obtained by the provider and correctly witnessed, confirm client identity with two identifiers, confirm allergies including latex and iodinated contrast, confirm nothing by mouth status, review anticoagulant and antiplatelet therapy and any hold orders, obtain baseline vital signs, have the client void when the procedure involves the abdomen or pelvis, and establish that laboratory studies including coagulation and renal function are on the chart. After the procedure, monitor vital signs on a defined schedule, assess the puncture or insertion site for bleeding, hematoma, and drainage, assess pain and neurovascular status distal to any arterial site, and observe for the specific complication that procedure is known to cause (Pagana et al., 2022; Potter et al., 2023).

=== Iodinated Contrast Studies ===

Includes computed tomography with contrast, intravenous pyelography, angiography, and cardiac catheterization. Screen for prior contrast reaction, asthma, and renal impairment. The historical practice of screening for shellfish allergy is not supported by evidence, since the reaction is to the contrast agent rather than to iodine content in seafood; a prior reaction to contrast itself is the meaningful risk factor (American College of Radiology [ACR], 2023). Assess creatinine and estimated glomerular filtration rate. Warn the client that a warm flushing sensation and a metallic taste are expected during injection. Afterward, encourage generous oral or intravenous fluids to promote contrast excretion, and monitor urine output and renal function. '''Metformin''' is generally withheld at the time of contrast administration and for approximately 48 hours afterward in clients with impaired or at-risk renal function, with renal function reassessed before restarting, because of the risk of lactic acidosis if contrast-associated kidney injury occurs; follow facility protocol (ACR, 2023).

=== Endoscopic Procedures ===

Esophagogastroduodenoscopy and colonoscopy require nothing by mouth beforehand, bowel preparation for lower endoscopy, and moderate sedation. Afterward keep the client '''nothing by mouth until the gag reflex returns''' following upper endoscopy, position on the side to protect the airway during recovery, and monitor for the shared major complication of '''perforation''': severe or worsening abdominal or chest pain, abdominal distension and rigidity, fever, tachycardia, and hypotension. Report frank rectal bleeding after colonoscopy; small amounts of blood after biopsy or polypectomy may be expected but increasing bleeding is not. Endoscopic retrograde cholangiopancreatography carries an additional risk of post-procedure pancreatitis, signaled by severe epigastric pain radiating to the back with elevated amylase and lipase (Harding et al., 2023; Pagana et al., 2022).

=== Cardiac Catheterization ===

Before: nothing by mouth, assess and mark distal pulses, screen for contrast reaction and renal function, and review anticoagulants. After: maintain bed rest with the accessed extremity straight for the ordered interval, keep the head of the bed low for femoral access, assess the site for bleeding and hematoma, assess distal pulses, color, temperature, capillary refill, and sensation frequently, monitor cardiac rhythm, and encourage fluids. Report immediately any expanding hematoma, loss of a distal pulse, a cool or pale extremity, chest pain, or '''back or flank pain with hypotension''', which suggests retroperitoneal hemorrhage (Ignatavicius et al., 2021; Pagana et al., 2022).

=== Lumbar Puncture ===

Position the client laterally with the knees drawn to the abdomen and the chin tucked, or sitting and leaning over a table, to widen the intervertebral spaces. Have the client void first. Afterward, keep the client flat for the ordered period, encourage fluids, and monitor for post-dural puncture headache, which is worse upright and better lying flat, as well as for site leakage of cerebrospinal fluid and new neurologic deficits (Pagana et al., 2022).

=== Thoracentesis ===

Position the client sitting upright leaning over a bedside table with the arms supported. Instruct the client to remain still and to avoid coughing or deep breathing during needle insertion. After the procedure, monitor for '''pneumothorax''': sudden dyspnea, pleuritic chest pain, diminished or absent breath sounds on the affected side, tachypnea, tachycardia, and in tension pneumothorax, tracheal deviation away from the affected side with hemodynamic collapse. A chest radiograph is typically obtained afterward. Removing a very large volume at one time raises the risk of re-expansion pulmonary edema (Harding et al., 2023; Pagana et al., 2022).

=== Paracentesis ===

Have the client void immediately before to reduce the risk of bladder puncture, and position upright or with the head of the bed elevated. Measure abdominal girth and weight before and after. Monitor for hypovolemia and hypotension from fluid shifts after large-volume removal, for hypoalbuminemia, and for signs of peritonitis or bleeding (Pagana et al., 2022).

=== Bronchoscopy ===

Nothing by mouth beforehand; a topical anesthetic suppresses the gag reflex. Afterward keep the client '''nothing by mouth until the gag reflex returns''', monitor for laryngospasm, bleeding, hypoxemia, and pneumothorax if a transbronchial biopsy was taken. Blood-tinged sputum can occur after biopsy, but frank bleeding must be reported (Harding et al., 2023; Pagana et al., 2022).

=== Liver Biopsy ===

Verify coagulation studies and platelet count beforehand and hold anticoagulants as ordered, since the liver is highly vascular. Have the client exhale and hold still during needle insertion. Afterward, position the client on the '''right side''' with a pillow or rolled towel against the biopsy site to apply pressure, maintain bed rest, and monitor for hemorrhage, hypotension, tachycardia, referred right shoulder pain, and peritonitis (Pagana et al., 2022).

=== Magnetic Resonance Imaging ===

Screen carefully for ferromagnetic implants, aneurysm clips, cochlear implants, retained metal fragments, and cardiac devices; many contemporary pacemakers are conditionally safe, but the determination belongs to the imaging team. Remove all metal objects, transdermal patches with metallic backing, and jewelry. Assess for claustrophobia and warn the client about loud knocking noises and the need to remain still. Gadolinium contrast is avoided or used with caution in advanced kidney disease (ACR, 2023; Pagana et al., 2022).

=== Other Common Preparations ===

* '''Barium studies''': after the study, give fluids and a laxative as ordered to prevent barium impaction, and tell the client that stools will be chalky white for a few days (Pagana et al., 2022).
* '''Tuberculin skin test''': inject intradermally to raise a wheal, do not massage, and read induration, not redness, at 48 to 72 hours (Pagana et al., 2022).
* '''Blood cultures''': draw before starting antibiotics whenever it does not delay treatment in sepsis, from two separate sites with strict aseptic technique (Potter et al., 2023).
* '''24-hour urine collection''': discard the first voiding, then collect all urine for the period, keep the specimen refrigerated or on ice as required, and end by having the client void at the exact final time and adding that specimen. A single discarded voiding invalidates the entire collection and it must restart (Pagana et al., 2022).
* '''Stool for occult blood''': depending on the test used, certain foods and drugs such as red meat, nonsteroidal anti-inflammatory drugs, and high-dose vitamin C may need to be withheld beforehand (Pagana et al., 2022).