Surgery – Diagnostic testing – Liquid collection
Reexamination Certificate
1999-04-20
2001-10-16
Hindenburg, Max (Department: 3736)
Surgery
Diagnostic testing
Liquid collection
C604S317000
Reexamination Certificate
active
06302854
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for collecting blood or other fluids from an organ or tissue through a vessel. The method according to the invention is used in the biological, medical and veterinary field for diagnostic and therapeutic purposes and for research purposes to collect blood or other fluids from organs or parts of organs or tissues. In particular, the method according to the invention is used to collect placental blood, that is to say, the blood that is present in the placenta, during childbirth, directly after the birth of the neonate.
In the biological, medical and veterinary fields it is necessary to collect fluids, particularly blood, from organs or tissues or containers in general, both for diagnostic and therapeutic purposes and for research purposes. Two non-limitative examples are: 1. the collection of blood from masses of tumoral tissue, since the blood contained in the tumoral tissue is potentially useful for therapeutic purposes after appropriate treatment; 2. the collection of blood from the placenta during childbirth directly after cutting the umbilical cord. In this second case, the blood is useful since it contains stem cells, which are hematopoietic precursor cells, that is to say, cells which are capable of reconstituting the hematopoietic system and therefore can be used, if the need arises, for transplanting to the same donor or to another compatible recipient.
The procedures currently used to collect placental blood from an umbilical cord are described hereinafter as a typical example of the recovery of fluids from an organ; it is important to note that the reference to this practice is not limitative and is merely an example of situations in which it is necessary to collect blood or another fluid from tissues, organs or other containers in general.
Placental blood from the umbilical cord is collected because it contains hematopoietic stem cells which can be used for transplants. To allow the collected blood and therefore the recovered cells to be truly and successfully usable, the following conditions must be met: 1. the largest possible amount of blood, that is to say, the highest possible number of cells, must be recovered; 2. the collected blood, which is fetal in origin, must not be contaminated by foreign cell populations, such as for example maternal cells; 3. during collection, contact of the blood with the outside (air or other potentially contaminated objects) must be minimized, or the collection procedure must occur in sterile conditions, possibly in a closed environment; 4. the possibility of human error must be minimized.
Steps of Collection
a. Before Expulsion of the Placenta
Blood is currently extracted from the placenta in the medical field, both for diagnostic and therapeutic purposes and for research purposes, as follows: during childbirth, directly after the expulsion of the neonate, the umbilical cord is closed (clamped) in two points and cut in a point which is intermediate between the two closure points. After cutting, the cut end of the umbilical cord which is connected to the placenta protrudes freely from the mother's vagina and is available for collection operations. Typically, blood is collected in the period between the cutting of the umbilical cord and expulsion of the placenta. During this period, the flow of blood is ensured by the pressure generated by uterine contractions, which by compressing the placenta facilitate the outflow of blood through the umbilical cord.
b. After Expulsion of the Placenta
Only a small number of authors reports collection procedures which provide for cord blood collection after expulsion of the placenta by placing the placenta on a frame and collecting the blood by gravity. The limited use of collection after expulsion of the placenta is certainly due to the low yield of collection by gravity and to difficulty in handling the placenta, especially when the sterility of the collected blood must be guaranteed.
Collection Systems
Collection of placental blood from the umbilical cord in the medical field, both for diagnostic and therapeutic purposes and for research purposes, is currently performed with methods which can be traced back to two categories: “open-circuit” systems and “closed-circuit” systems. Both systems are used for collection both before and after expulsion of the placenta.
a. “Open-circuit” Systems
“Open-circuit” systems collect placental blood from the cut umbilical cord in containers which contain anticoagulant. This collection is performed by making the blood flow out directly into the collection container without connecting the end portion of the cord, which is placed loosely at the inlet of the container.
Advantages
The main advantage of this system is the absence of resistances to flow, since there are no bottlenecks or sudden decreases in cross-section of the cord and of its vessels.
A second advantage is that the three vessels which are present in the umbilical cord are simultaneously pervious.
Another advantage of the system is the possibility to express the umbilical cord during collection.
Disadvantages
Various scientific papers have demonstrated that “open-circuit” systems do not ensure sterility and are in fact associated with a particularly high incidence of microbial contaminations. The cut end portion of the umbilical cord in fact has a loose consistency, and since it is simply rested on the inlet of the collecting container it can easily escape from it, consequently contaminating said end portion in addition to losing blood, which contaminates the outside environment.
Furthermore, the system inherently (being an “open” system) collects both the blood that flows out of the vessels of the cord and potentially contaminated liquids which flow along the outer surface of the umbilical cord; in particular, the maternal blood which is abundantly present along the outer surface of the placenta flows along the cord and mixes with the blood of the umbilical cord.
This collection system furthermore exposes the blood to the air of the outside environment, thus facilitating contaminations by microorganisms which are present in the outside environment.
Another drawback is the constant need for an operator assigned to keeping the umbilical cord in the correct position, particularly if repeated maneuvers for expressing and cleaning the cord are performed.
b. “Closed-circuit” Systems
Collection is performed by venipuncture of the cut and clamped end of the umbilical cord, after accurately disinfecting the entry point of the needle. The blood is collected in one or more syringes or in donation pouches.
Advantages
With respect to “open-circuit” systems, “closed-circuit” systems reduce the risks of microbial contamination of the collected blood and do not require continuous cleaning and disinfection of the cord.
Another advantage is reduction of the contamination of the sample with maternal blood or other liquids which flow along the outer surface of the cord.
Disadvantages
“Closed-circuit” systems entail handling needles and therefore expose the operators to the risk of accidental punctures.
Furthermore, the needle inserted in the umbilical vein is not stably fixed to it and can easily come loose, also in view of the highly dynamic nature of childbirth; this problem is particularly felt if collection is continued even after expulsion of the placenta. Accordingly, the continuous presence of an operator is required to ensure the correct placement of the needle during the various steps of collection.
If the needle leaves its seat, blood contaminations and accidental punctures of the operator are possible, and repetition of venipuncture is furthermore required in order to continue collection.
Owing to the limited cross-section of two of the three vessels of the umbilical cord (the arteries), collection is feasible only on one vessel (the vein), consequently reducing the collection potential.
The flow of blood is also hindered by the sudden decrease in cross-section (the needle, no matter how large, can never have the same cross-section a
CRB Nederland B.V.
Greer Burns & Crain Ltd.
Hindenburg Max
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