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Blood can often be taken from your line or port so you do not need a needle in your arm. The nurse cleans their hands and the end of the line, usually draws off a little blood first and throws it away, takes the samples and then flushes the line with salt water. If an infection is suspected, a sample is also taken from a vein in your arm.
Every access is a chance for infection, so the line is opened no more often than needed: a 2026 scoping review of six studies found that more frequent access for blood draws is associated with more line infections and that standard sampling times, phlebotomy teams and peripheral cultures reduce it. Hand hygiene (CDC IB), scrubbing the hub or needleless connector with an antiseptic and using only sterile devices (CDC IA) apply as for any access. For blood cultures, IDSA (2009) asks for the hub to be cleaned with alcohol, tincture of iodine or alcoholic chlorhexidine above 0.5%, allowed to dry (A-I), and, when line infection is suspected, paired cultures from the catheter and a peripheral vein before antibiotics, labelled by site (A-II); ESMO 2015 agrees ([II, A]). After any sample the line is flushed with saline (ESMO [II, B]).
How much blood to discard first, to avoid diluted or drug-contaminated results, is not set by any guideline that could be read; the INS Standards address it but were not reachable. Local policies commonly discard a few millilitres; an intensive-care study in 105 patients found 2 ml gave results agreeing with venepuncture for electrolytes and blood counts.
Why: Each time a line is opened, germs have a chance to get in.
“Increased frequency of CVC access is associated with a higher risk of CLABSI.”
Why: Hands are the commonest route by which germs reach a line.
“Hand hygiene should be performed before and after palpating catheter insertion sites as well as before and after inserting, replacing, accessing, repairing, or dressing an intravascular catheter.”
CDC/HICPAC 2011 · Category IB
Why: The connector is touched many times and is a main route for germs into the line.
“Minimize contamination risk by scrubbing the access port with an appropriate antiseptic (chlorhexidine, povidone iodine, an iodophor, or 70% alcohol) and accessing the port only with sterile devices”
CDC/HICPAC 2011 · Category IA
Why: The first blood drawn is mixed with the flush or drugs in the catheter and can give wrong results.
Common practice: No guideline that could be read sets a discard volume; the INS Standards do but were not reachable. A 2026 intensive-care study found 2 ml enough for electrolytes and blood counts (see variants).
Why: Skin and hub bacteria can contaminate the bottle and give a false result.
“If a blood sample is obtained through a catheter, clean the catheter hub with either alcohol or tincture of iodine or alcoholic chlorhexidine (>0.5%), allowing adequate drying time to mitigate blood culture contamination (A-I).”
IDSA (Clinical Infectious Diseases, Mermel et al.) 2009 · A-I
Why: Comparing the two shows whether the line is the source of the infection.
“For suspected CRBSI, paired blood samples, drawn from the catheter and a peripheral vein, should be cultured before initiation of antimicrobial therapy, and the bottles should be appropriately marked to reflect the site from which the samples were obtained (A-II).”
IDSA (Clinical Infectious Diseases, Mermel et al.) 2009 · A-II
Why: Blood left in the catheter can clot and block it or feed germs.
“Routine flushing with saline, after the completion of any infusion or blood sampling, is recommended [II, B]”
ESMO (Annals of Oncology) 2015 · [II, B]
How care is usually carried out, read from the guidelines and standards cited. Your own team's protocol and their judgement come first; this page is for understanding it, not for doing it yourself.
Open the line only when needed, with hand hygiene (CDC IB), a scrubbed hub and sterile devices (CDC IA), hub antisepsis allowed to dry before cultures (IDSA A-I), paired line and peripheral cultures before antibiotics when infection is suspected (IDSA A-II; ESMO [II, A]) and a saline flush after every sample (ESMO [II, B]). The discard volume for routine bloods is set by local policy: no guideline that could be read specifies it.
CDC/HICPAC 2011 · IDSA (Clinical Infectious Diseases, Mermel et al.) 2009 · ESMO (Annals of Oncology) 2015 · American Journal of Infection Control (Davis et al.) 2026
Where it differs: Discards 2 ml before routine sampling from a central catheter, rather than 3 ml or more, to reduce blood loss.
Evidence: In 105 intensive-care patients, results from the proximal lumen after a 2 ml discard agreed well with venepuncture for sodium, potassium, calcium and blood counts except white cells; acidosis explained some differences (Pushparaj 2026). Not studied in cancer outpatients or ports.
Where it differs: Takes routine bloods and cultures by venepuncture, or by a phlebotomy team, to keep the central line closed.
Evidence: A 2026 scoping review of six hospital studies found standard sampling times, phlebotomists for peripheral cultures and avoiding the line for both cultures and routine bloods lowered line infection rates. In cancer care this trades against repeated needle sticks in people with poor veins.
When blood is taken from a line, a small amount is usually drawn off and thrown away first. How much is needed has never been set by a guideline that could be read, and the only recent study was in intensive care, not in people with ports having chemotherapy.
| Recommendation | Grade, as printed | Source |
|---|---|---|
| If no peripheral sample can be drawn, take at least two samples through different lumens “If a blood sample cannot be drawn from a peripheral vein, it is recommended that ≥2 blood samples should be drawn through different catheter lumens (B-III).” | B-III | IDSA (Clinical Infectious Diseases, Mermel et al.) 2009 |
Shares Disinfecting caps for needleless connectors (Curos), PICC and tunnelled central line care: dressing, hub cleaning, flushing and living with the line, Peripherally inserted central catheters (PICC lines), Central venous access (port, PICC line).
Shares PICC and tunnelled central line care: dressing, hub cleaning, flushing and living with the line, Implanted port access, flushing and care in adults having cancer treatment, Peripherally inserted central catheters (PICC lines), Implanted ports for chemotherapy (port-a-cath, power-injectable, apheresis and intraperitoneal ports).
Shares Disinfecting caps for needleless connectors (Curos), PICC and tunnelled central line care: dressing, hub cleaning, flushing and living with the line, Peripherally inserted central catheters (PICC lines), Central venous access (port, PICC line).
Shares PICC and tunnelled central line care: dressing, hub cleaning, flushing and living with the line, Implanted port access, flushing and care in adults having cancer treatment, Peripherally inserted central catheters (PICC lines), Implanted ports for chemotherapy (port-a-cath, power-injectable, apheresis and intraperitoneal ports).
Shares Test the smallest safe discard volume for blood taken from ports and PICCs in cancer outpatients, Implanted port access, flushing and care in adults having cancer treatment, Implanted ports for chemotherapy (port-a-cath, power-injectable, apheresis and intraperitoneal ports), Central venous access (port, PICC line).
Shares Suspected central line infection in a person with cancer: paired blood cultures, first antibiotics and line removal or salvage, PICC and tunnelled central line care: dressing, hub cleaning, flushing and living with the line, Implanted port access, flushing and care in adults having cancer treatment, Peripherally inserted central catheters (PICC lines).
Shares Suspected central line infection in a person with cancer: paired blood cultures, first antibiotics and line removal or salvage, Peripherally inserted central catheters (PICC lines), Implanted ports for chemotherapy (port-a-cath, power-injectable, apheresis and intraperitoneal ports), Central venous access (port, PICC line).
Shares Suspected central line infection in a person with cancer: paired blood cultures, first antibiotics and line removal or salvage, PICC and tunnelled central line care: dressing, hub cleaning, flushing and living with the line, Peripherally inserted central catheters (PICC lines), Implanted ports for chemotherapy (port-a-cath, power-injectable, apheresis and intraperitoneal ports).