# Blood sampling from a central line or port

Source: https://onco.cc/protocols/blood-sampling-from-a-central-line/  
OnCo record `blood-sampling-from-a-central-line` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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.

## Summary

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.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: taking blood from a PICC; bloods from a port; CVAD blood sampling; discard volume; line bloods; blood cultures from a central line; paired blood cultures

## Connected records

- protocols: [Central line and port care in the community and at home](https://onco.cc/protocols/community-care-of-vascular-access-devices/), [Implanted port access, flushing and care in adults having cancer treatment](https://onco.cc/protocols/implanted-port-access-and-care/), [PICC and tunnelled central line care: dressing, hub cleaning, flushing and living with the line](https://onco.cc/protocols/picc-and-tunnelled-line-care/), [Suspected central line infection in a person with cancer: paired blood cultures, first antibiotics and line removal or salvage](https://onco.cc/protocols/suspected-central-line-infection/)
- technologies: [Disinfecting caps for needleless connectors (Curos)](https://onco.cc/technologies/needleless-connector-disinfecting-caps/), [Implanted ports for chemotherapy (port-a-cath, power-injectable, apheresis and intraperitoneal ports)](https://onco.cc/technologies/implanted-ports/), [Peripherally inserted central catheters (PICC lines)](https://onco.cc/technologies/picc-lines/)
- terms: [Central venous access (port, PICC line)](https://onco.cc/terms/central-venous-access/)
- ideas: [Test the smallest safe discard volume for blood taken from ports and PICCs in cancer outpatients](https://onco.cc/ideas/idea-upgrade-central-line-discard-volume-in-cancer-outpatients/)

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