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OBGYN Skills Lab |
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Knot Tying High Resolution Version Suturing High Resolution Version |
Introduction to Knot Tying and Suturing in Obstetrics and Gynecology Watch a 6 minute Video on Knot Tying (14 MB WMV File) Watch a 6 minute Video on Suturing (16 MB WMV File) Knot tying and suturing are basic surgical skills that need to be learned and practiced so they become virtually automatic. In this lesson, we’ll learn how to tie knots and suture using medical instruments. During the lesson, you’ll need several items:
A ligature is a thread that is tightened around an object, such as a blood vessel, and is secured in place by tying the loose ends in a knot. For example, during surgery, a bleeding point might be identified and grasped with a hemostat. Then the surgical assistant elevates the hemostat so that the surgeon can see it’s tip. The assistant does this in a way that the assistant’s hand covers the ring of the hemostat to prevent the ligature from becoming entangled. The surgeon passes a ligature around the hemostat and encircles the clamped tissue. After placing a first throw with the ligature, the surgeon snugs down the ligature around the enclosed tissue. After the surgeon completes the knot with a second and sometimes third throw, the assistant releases the hemostat. Depending on the tissue, the surgeon may indicate to the assistant to release the tissue sooner than the final throw. The reason this technique works is that the knot is tied in such a way that it won’t relax or come loose. The best way to accomplish this is with a square knot. The square knot locks on itself so that with increasing tension, the knot gets tighter. There are a number of good ways to tie square knots. We’ll show one technique here, and you can later learn some of the other techniques if you wish. The granny knot, in contrast to the square knot. loosens when tension is applied. While there might be an occasional use for a granny knot in medicine, most surgical knots should be tied as square knots. I want you to start off using thick rope to learn the knots. Later, when you’ve got the basic techniques down, we’ll advance to actual ligatures. The square knot is tied using two different motions or throws. We’ll consider each throw separately.
Now watch the whole first throw a few times and then practice it on your own. If you just used first throws all the time, all of your knots would end up as granny knots. You need to learn the second throw, which will lock your knot in place.
Watch the whole second throw a few times, then practice tying this second throw. When you have mastered the second throw, try alternating first, then second, then first, then second throws. In this way, you will create a series of square knots that will be very strong. As you are laying down your throws, they should go down flat and not curled back on themselves. This may require you to briefly cross your hands before snugging down the throw. Alternatively, you can cross the thread before you start tying it. Either way, the throws need to go down flat or you won’t get the square knot you are seeking. When tightening your throws, apply the tension in line with the orientation of the thread. If you tighten at an oblique angle, you may tear the tissue and your knots generally won’t be as snug. Usually, the orientation of the thread is perpendicular to the line of the incision. This means that usually, you will exert your tension on the ends of the threads perpendicular to the line of the incision. When tightening your throws, exert your force equally in both directions and level with the knot. In other words, don’t pull up on the knot when you snug down your knots. If you pull up while tying, you may tear the tissue. Practice now tying knots so you are applying even tension at the level of the knot, perpendicular to the line of the incision. One important, useful variation on the square knot is called the Surgeon’s knot. With the surgeon’s knot, rather than completing the first throw, you double back after half the throw is done and make a second half throw, before moving on to the second throw. The purpose of a surgeon’s knot is to apply a better grip to the first throw so that it won’t loosen while you are putting in your second throw. While it does this very effectively, surgeon’s knots are used sparingly during surgery because they break more easily, they add extra bulk to the knot, and usually aren’t necessary. Sometimes they are. Watch this surgeon’s knot a few times, and then practice on your own. Now that you have a working knowledge of tying square knots and surgeon’s knots with the thick rope, I’ll want you to switch to tying your knots using thread. But first, a few words about suturing. Suturing is the act of using a needle to thread ligature material through tissue, either as a secure method to surround a blood vessel, or to approximate cut tissues next to each other to facilitate healing. During surgery, we use sutures to close the tissues. In the case of lacerations or trauma, we use sutures to restore the normal anatomy. There is an entire science involved in knowing when to suture something and when to not suture something, what type of suture to use, and what diameter to use. For today’s lesson, I’m going to ignore that science and just focus on the basic techniques. Occasionally, suturing is done with you holding the needle in your hand, but usually, you will hold it with a needle holder or needle driver. The needle holder has jaws to grip the needle. If you look closely at the inner surface of the jaws, you’ll see a fine grid that helps hold the needle in any position you put it. In contrast, a straight clamp usually has parallel grooves within its jaws. You can use a straight clamp for suturing, but it doesn’t work as well as a needle driver because the needles tend to slip within the jaws. At the opposite end of the needle driver are rings for your fingers and a ratcheting lock, with three positions. Grasp the needle holder with your 4th digit inserted into one ring, just to the first joint. Place the tip of your thumb into the other ring, and place your index finger on the body of the instrument. In this position, you will have the greatest control. Later, with more experience, you may find leaving your thumb out of the ring is smoother for you. Sutures come in a variety of lengths, thicknesses, composition, and packaging, but they all have in common the ability for an unsterile person to open them for access by a sterile person. They also all have in common a method of visualizing the butt end of the needle so it can be grasped by a needle holder before removing it from the sterile package. In this example, the clear wrapper is peeled open using two hands, exposing the sterile suture package that can be lifted out in a sterile fashion. If you hold the sterile pack in your left hand so you can read the lable, you’ll see a notch in the upper right hand corner. Tear open the package at the notch and you will see the butt end of the needle. Grasp the butt end with a needle holder and pull it straight out of the package. The suture material will deploy behind it. Don’t hit anyone with an overly enthusiastic pull. Load the needle in the needle holder so that the needle is grasped two-thirds the way back from the needle tip. If you are further back, the needle will tend to bend and break during use. If you are too close to the tip, it will restrict your suturing range. The needle should be loaded at a right angle to the needle holder’s axis. During surgery, there may be times when you change that basic orientation, but always start off with the needle loaded at right angles, two-thirds of the way back from the tip. Hold the forceps in your other hand as though it were a pencil. You can use the forceps to stabilize tissue you are about to sew, grasp tissue, grasp a needle, or as a pusher to let you see underneath structures. Remember that every time you pinch tissue with your forceps, you are traumatizing that tissue, so it is best to use the forceps sparingly as a grasping instrument, and more often as a pusher or stabilizer, without crushing the tissue. When passing the needle through tissue, try to follow the curve of the needle. Don’t just ram the needle straight through. If the tissue is thin enough, you will be successful in getting the needle through it, but you will traumatize the tissue, tearing it in order to force the needle through. If the tissue is thick, the needle won’t slide through and you may end up breaking or bending the needle. Use a simple supination motion of your wrist to push the needle through its natural, curved path. Once the needle is through the tissue, it is often best to release the needle holder, pronate your wrist, come over to grasp the exposed needle, and then continue the same curve of the needle. If you don’t reposition your wrist, it will be difficult for you to complete the curve of the needle. If you grab the exposed needle with your forceps, it will be very difficult to follow the curve of the needle. More likely, you will end up just yanking the needle out…not good for the tissue. In some situations, particularly tissue that is on tension from retraction, you may need to grasp the exposed needle with your forceps to hold on to it long enough for you to come over with the needle holder to complete the needle’s circular path. There is a difference between closing an incision that is oriented side-to side in front of you versus up and down in front of you. The important thing is to make sure your needle holder is oriented in line with the incision. That’s easy if the incision is vertical in front of you. But if the incision is transverse in front of you, you’ll need to swing your elbow out over the patient in order to get your needle holder to line up with the line of the incision. When sewing two edges together, make sure that the needle’s path through one edge is duplicated by a mirror image path on the other side. If you don’t get them to match, the edges will be uneven, slowing healing and sometimes resulting in a weaker scar and unsightly scar. A simple stitch is when you make a single pass through the tissues to bring them together or to secure them. When first learning, practice this stitch because it is basic to all the other more complex stitches. After the simple stitch is completed, the loose ends are tied using a square knot or surgeon’s knot. During surgery, 3 to 5 throws are generally employed, depending on the tissue and the suture material. When multiple interrupted sutures are placed, they are should be an even distance apart and usually an even distance back from the cut edge. For example, a common placement for sutures is 1/2 cm apart and 1/2 cm back from the cut edge. An important exception to that rule is when closing the fascia, which is the main strength of the wound. Fascial sutures should probably not be lined up perfectly, so as to avoid uniform perforations that could act like a postage stamp tearing out of it’s roll. Many surgeons prefer that some of the sutures be placed closer to the cut edge of the fascia and other sutures be placed further away, more evenly distributing and stresses that might be applied to the repair. Another commonly used technique of suturing during surgery is a running stitch. With this method, after completing one pass of the needle through the tissue, you move down a centimeter on the tissues and pass the needle through again, without stopping to tie the suture. This method has the advantage of speed, effectiveness, even distribution of tension, and decreased suture bulk, but it sometimes distorts the tissue through its obliquely applied forces. Further, should the suture break anywhere along its length, there is a tendency for the entire suture line to give way. Practice suturing now, with single stitches. If you have time after mastering single sutures, try suturing a continuous line of sutures. Now that you’ve mastered the basics, you will need to practice these techniques a lot, so they are very natural for you and you don’t have to think much about the mechanics of suturing. Borrow an old needle holder or straight hemostat and some surplus suturing materials from the surgical suite and carry them around in your lab coat pocket. Practice opening and closing the needle holder and practice grasping small objects with it. For the last century, medical students during their “down” times have practiced sewing two raised edges of their pant-legs together. When you’re finished, just cut out the sutures. |
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This information is provided by The Brookside Associates, a private organization, not affiliated with any governmental agency. The opinions presented here are those of the author and do not necessarily represent the opinions of the Brookside Associates. For educational simplicity, only one method is usually shown, but many alternative methods may give satisfactory or superior results. This information is provided solely for educational purposes. The practice of medicine and surgery is regulated by statute and restricted to licensed professionals and those in training under supervision. Performing these procedures outside of that setting is a bad idea, is not recommended, and may be illegal. The presence of any advertising on these pages does not constitute an endorsement of that product or service by the Brookside Associates. C. 2010 All Rights Reserved
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