Diagnostic Tests and Procedure Prep

In depth

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Why each complication happens

Most priority complications follow from what the needle or scope passes through. A needle into an artery, the liver or the kidney can bleed, so the nurse trends blood pressure and pulse and inspects the site or the urine. A needle through the chest wall can let air into the pleural space, so breath sounds, oxygen saturation and breathing effort come first after thoracentesis. Numbing the throat for a bronchoscopy or an EGD removes the cough and gag reflexes, so food or fluid could be aspirated until they return. Removing a large volume of fluid shifts blood volume, so a client can become hypotensive after paracentesis. Contrast agents bring two risks of their own: an allergic-like reaction within minutes and, in clients with poor kidney function, kidney injury or (with gadolinium) nephrogenic systemic fibrosis.

Cardiac catheterization in detail

MedlinePlus advises 6–8 h without food or drink, a signed and witnessed consent, and telling the team about contrast reactions, medicine allergies, erectile dysfunction drugs and possible pregnancy. The client is sedated but awake and able to follow instructions. After a groin approach the client usually lies flat for a few to several hours to prevent bleeding. Listed risks include bleeding, infection and pain at the site, vessel damage, clots, arrhythmia, tamponade, MI, stroke, contrast reaction and contrast kidney injury, which is more likely with diabetes or kidney disease.

Femoral access carries hematoma, pseudoaneurysm, limb ischemia, arteriovenous fistula and retroperitoneal bleeding (reported in 0.025% to 0.9% of femoral cases), which is linked to higher 30-day mortality; a puncture high in the groin makes it more likely because pressure there compresses the artery poorly (Attachaipanich 2026). Radial access has fewer bleeding complications; its typical late problem is radial artery occlusion, and compression held longer than 4 h is a strong predictor, so compression is kept short and patent, with blood still flowing through the artery.

Discharge teaching (MedlinePlus): if the site bleeds, lie down and press on it for 30 minutes; call if it does not stop. Keep the site dry for 24–48 h and avoid baths and swimming for a week. After a groin approach, no driving, yard work, heavy lifting or squatting for at least 2 days; after an arm approach, nothing over 10 lb. Call for a limb below the site that changes colour, feels cool or goes numb, chest pain or breathlessness that rest does not relieve, fainting, or fever over 101°F (38.3°C).

Chest, abdomen and spine

Thoracentesis: imaging is done before and usually after. The client sits on the edge of the bed with the head and arms on a table and must not cough or breathe deeply while the needle is in. Bleeding, infection, pneumothorax and respiratory distress are the listed risks; shortness of breath or chest pain during or after is reported at once (MedlinePlus).

Paracentesis: the client voids first, lies on the back with the head flat or a little raised, and an ultrasound guides the needle. A diagnostic tap takes about 25 mL; a therapeutic tap often removes about 5 L. Vital signs are watched for about an hour afterward. Risks are low blood pressure, infection, bleeding, ongoing leakage and, rarely, puncture of the bowel, bladder or a vessel. Chest pain, shortness of breath, light-headedness or severe abdominal pain or swelling needs emergency care (Cleveland Clinic).

Lumbar puncture: side-lying with knees drawn up and chin tucked, or sitting bent forward; moving can injure nerves. Usually 1–10 mL of CSF goes into four or more tubes. A brain mass makes the test dangerous because of herniation, and bleeding problems, low platelets and anticoagulants are also reasons for caution. Afterward the client rests for several hours but need not lie flat the whole time; caffeinated drinks may ease the headache, and a headache lasting more than a few days, worse on sitting or standing, suggests a CSF leak (MedlinePlus).

Liver and kidney biopsy

Liver biopsy (BSG 2020): the client lies supine with the right hand behind the head and holds the breath out while the needle is in. For a non-lesional biopsy in liver disease, an INR above 1.4 points to the transjugular route; fresh frozen plasma is not recommended to correct the INR. Afterward the client stays recumbent, on the right side or supine, with pulse and blood pressure checked regularly for at least 3 h; right-side lying caused more pain and no fewer complications in a small study. Teach rest for the rest of the day, no driving that day, no strenuous activity or heavy lifting for 48 h, and to call for fever, chills, breathing trouble, bright red bleeding, severe chest, shoulder or abdominal pain, blood in the stool or a swelling abdomen.

Kidney biopsy (MedlinePlus): the client lies prone, or supine for a transplanted kidney, and stays at least 12 h. Every urine is checked for heavy bleeding; a little blood is expected and bright red urine in the first 24 h is possible, but bleeding beyond that is reported. Bleeding can rarely need a transfusion. No lifting over 10 lb for 2 weeks.

Contrast: metformin, allergy and kidneys

Allergy (ACR): a prior allergic-like reaction to the same class of contrast raises the risk about fivefold and is the strongest predictor. Other allergies and asthma raise it modestly and do not justify premedication or withholding contrast, and shellfish or povidone-iodine allergy is no more a risk than any other allergy. There is no cross-reactivity between iodinated and gadolinium agents. An elective premedication is prednisone 50 mg by mouth 13, 7 and 1 h before, with diphenhydramine 50 mg 1 h before (optional), or methylprednisolone 32 mg 12 and 2 h before.

Kidneys (ACR): IV volume expansion with isotonic saline, typically starting 1 h before and continuing 3–12 h after, is indicated for clients with AKI or eGFR below 30 who are not on dialysis; weigh the risk of fluid overload in heart failure. It is not indicated for stable eGFR of 30 or more. For gadolinium, clients on dialysis, with eGFR below 30 or with AKI are the at-risk group for nephrogenic systemic fibrosis when a group I or III agent is used; group II agents are preferred for them. Breastfeeding need not stop after iodinated contrast.

Stress tests and PFTs in detail

Regadenoson (Lexiscan label) is given as 0.4 mg rapid IV push followed by a saline flush. Clients avoid caffeine and other methylxanthines (theophylline, aminophylline) for at least 12 h, and dipyridamole is held for at least 2 days if possible. It can cause myocardial ischemia, first- to third-degree AV block, bronchoconstriction in asthma or COPD, seizures and hypotension, so resuscitation equipment must be ready. Aminophylline 50–250 mg by slow IV injection can reverse severe or persistent effects, but not a seizure. It is contraindicated in second- or third-degree AV block or sinus node dysfunction without a working pacemaker.

ATS/ERS also asks clients to avoid smoking or vaping and vigorous exercise for 1 h and intoxicants for 8 h, and to wear loose clothing. Forced breathing raises chest, abdominal and intracranial pressure, so testing is a relative contraindication within 1 week of an MI or eye surgery, within 4 weeks of chest, abdominal or brain surgery, and with a pneumothorax. The test stops if the client has pain.

Common traps

• Offering water right after a bronchoscopy or EGD before checking the cough or gag reflex
• Assuming no bleeding after a femoral cath because the dressing is dry
• Treating a shellfish allergy as the contrast risk and missing a prior contrast reaction
• Giving metformin the morning after contrast without an eGFR result when the order says hold
• Letting a client have coffee before an EEG or a regadenoson stress test
• Giving a scheduled bronchodilator before PFTs when the order says to hold it