DALLAS (FRONTLINE MEDICAL NEWS) – Using knotless barbed sutures to close the uterine incision after cesarean delivery reduced operating time and blood loss, according to a recent randomized controlled study.

“On average, knotless barbed sutures were 1 minute and 43 seconds faster,” said David Peleg, MD, discussing the study results at the meeting sponsored by the Society for Maternal-Fetal Medicine. Average uterine closure time with knotless barbed sutures was 3 minutes and 37 seconds; with smooth sutures, average closure time was 5 minutes and 20 seconds (103-second difference; 95% confidence interval, 67.69-138.47 seconds; P less than .001).

The rationale for the study, said Dr. Peleg, was that knots in smooth sutures decrease the tensile strength of the suture, are the weakest part of the suture, and also increase the volume of the suture, which can be problematic in some cases. With smooth sutures, usually made from braided material, slippage is more likely during the suturing process.

Barbed sutures, in contrast, are usually made of monofilament with barbs created by the addition of tiny diagonal cuts made just partway through the suture material. When the suture is pulled through with the angle of the barbs, it pulls smoothly, but pulling back against the barb angle causes the barbs to protrude and catch against tissue, preventing slippage and eliminating the need for knots.

The fact that the monofilament has been partially cut to create the barbs can also reduce tensile strength, but some of the other disadvantages of smooth sutures are avoided, said Dr. Peleg.

The suture material used for the study was bidirectional, with the barbs running in opposite directions from the midline and a needle swaged onto each end; other barbed suture systems have an integral loop at one end of a unidirectionally barbed length of suture material that is used to anchor the first suture. The brand used was Stratafix.

The prospective study was necessarily unblinded, and compared the knotless barbed sutures with smooth sutures using polyglactin 910 braided material (Vicryl) for use during closure of the uterine incision during cesarean section procedures.

Patients were eligible if they were having an elective cesarean section after at least 38 weeks’ gestation, or if they were having a cesarean for the usual obstetric indications after laboring. Women with previous cesareans who failed a trial of labor were eligible.

The primary outcome was the length of time to close the uterine incision, measured from the start of suturing until hemostasis was achieved; the time included hemostatic suturing.

After a small pilot study that established a baseline suturing time with polyglactin 910 sutures of 6 minutes (standard deviation, 2 minutes and 10 seconds), Dr. Peleg and his collaborators determined that they would need to enroll at least 34 women per study arm to detect a decrease of 25% in suture time – to 4.5 minutes – with barbed sutures.

“The decrease in closure time is not linear,” said Dr. Peleg, so they increased their sample size by 50%, to 51 patients in each group, to ensure statistical significance of the results.

One of the challenges of a surgical randomized controlled trial is ensuring uniform technique; for this study, all patients had epidural or spinal anesthesia and antibiotics before opening. Surgeon clinical judgment was used to determine whether a Pfannenstiel or low transverse incision was made. In either case, there was no closure of the parietal peritoneum or the rectus muscles, and subcutaneous closure was used if tissues were greater than 2 cm in depth. Subcuticular stitches were used if possible.

Looking at secondary outcomes, there was a trend toward shorter total operative time with barbed sutures that didn’t reach statistical significance (20.1 min for barbed sutures vs. 23.1 for conventional, P = .062). However, fewer hemostatic sutures were required when barbed sutures were used: Extra sutures were used in 16 of the barbed group vs. 41 who had conventional sutures (P less than .001). Those receiving barbed sutures also had significantly less blood loss and estimated total blood loss during uterine closure than the conventional suture group (P = .005 and P = .002, respectively).

No study patients experienced serious postoperative complications; there were no infections, hematomas, or other wound complications, said Dr. Peleg of Bar-Ilan University, Zefat, Israel.

On the pro side for wider implementation of the use of barbed sutures for uterine closure stand the quicker closure and better hemostasis, along with the theoretical benefits of having no knots. Additionally, said Dr. Peleg, “there’s a gentle learning curve – it’s relatively easy to get used to the technique” of using barbed sutures. And, he said, “surgeons find them satisfying to use.”

However, he acknowledged the extra expense of barbed suture material – depending on the location and supplier, he estimated the cost could run from 7- to 20-fold for the barbed sutures, which he said cost $23.50 apiece. Also, he said, though the results were statistically significant, “Are they clinically significant? Does a difference in closure time of one minute 43 seconds, and a decrease in blood loss of 47 milliliters matter?”

Other considerations, he said, will require longer-term study. Polydioxanone, used for the barbed sutures, has a longer absorption time – a factor with unknown clinical implications in this application. Other longer-term outcomes, such as vaginal birth after cesarean success rates, rates of uterine rupture, the thickness of the uterine scar, and rates of adhesions and placenta accreta, will need to be tracked for years.

The authors reported no conflicts of interest and specifically reported that they had no relevant consulting or research agreements with suture manufacturers or marketers.

SOURCE: Peleg D et al. The Pregnancy Meeting Abstract 32 .