In the early 1970’s, the three letters that a pediatric house officer hated to see on a slip returning from the lab were Q.N.S. Quality Not Sufficient meant that the minutes, which seemed like hours, you had invested torturing some poor sick child to obtain just a few cc’s of blood had been wasted. It also meant returning to the patient’s crib or bedside to explain to the child and her parents that the torture you had promised was over for the day was in fact not over.
Tourniquets were fished out of lapel buttonholes, and the search for a decent vein had to begin all over again. If the child was chubby or bloated with retained fluid, those veins were invisible. If the child had been ill for weeks – particularly if the patient had been on chemotherapy – all of the good veins had been blown or had clotted days ago.
Many of the patients were saintly and eerily cooperative despite your fumbling attempts at venipuncture, but most were not. Some parents were so supportive of your efforts that you wanted to hug them when the ordeal was over (and you did). A few parents amped up the tension at the bedside so much that you wanted to ask them to leave (but you didn’t). If a parent was understandably incapable of effectively restraining the child, you needed to find an experienced nurse to help. A few of the best nurses were so good that the house officer merely needed to hold the needle still, and the child was repositioned in just the right orientation so that the puncture occurred miraculously.
There were some last ditch efforts at phlebotomy that were so ghastly that you had to ask the parents to leave. I don’t know if the infamous internal jugular stick is still used, but it wasn’t pretty. And it was almost as frightening for the physician holding the needle as it was for the patient. Even in the big teaching hospitals, dedicated phlebotomists hadn’t been invented yet. A few nurses had earned reputations as good vein finders, but for the most part it was on-the-job training for the house officers.
It was not until 1973 that Dr. John Broviac’s central line catheters became available in some hospitals and 1979 until Dr. Robert Hickman’s version appeared. It took a few more years before techniques were perfected for safely drawing specimens from these lines that had been originally intended for infusion. But for me and my cohort of house officers and our unfortunate patients, it was years too late. I am sure that caring for hospitalized pediatric cancer patients today continues to be dominated by challenges. But for those of us tasked with drawing blood from patients without the benefit of central line catheters, it was gut wrenching.
Those battles for a few cc’s of blood left their scars. I have seldom ordered any blood test without asking myself whether there wasn’t a bloodless way of assessing the patient’s condition. Or couldn’t we just do the test on a drop or two of blood? Of course, as I as finishing my training, more tests were downsized so that they could be done “micro.” But as you know, getting enough blood from a heel stick or finger prick isn’t always as easy as it sounds. If the child is shocky or cold, a good blood flow is hard to obtain. Warming helps but squeezing doesn’t because tissue juices can dilute the sample, and the trauma of squeezing can contaminate the sample.
A study published in the American Journal of Clinical Pathology raises the question of how accurately even a single drop of blood reflects what is going on in the patient’s total blood pool (“Drop by drop variation in the cellular components of fingerprick blood: Implications for point-of-care diagnostic development” [ Am J Clin Pathol. 2015 Dec;144(6):885-94] ). Two bioengineers from Rice University discovered that six successive drops of blood from a single finger prick varied by a significant amount when analyzed for a variety of cellular components. For example, the drop-to-drop variability for hemoglobin was five times that of a sample collected by venipuncture.
You and I may dream of the day when just a drop will do it and we can put our needles away for good. Unfortunately, for now, the answer is that a single drop of blood is a Q.N.S.
Dr. Wilkoff practiced primary care pediatrics in Brunswick, Maine, for nearly 40 years. He has authored several books on behavioral pediatrics including “How to Say No to Your Toddler.”