1. Indications for cervical cerclage surgery and surgical route
1.1 Diagnostic criteria for cervical insufficiency (1) a clear history of multiple spontaneous abortions in midterm pregnancies; (2) no aura of abortion, no previous uterine contractions and disappearance of the cervical canal and protruding amniotic sac; (3) a No. 8 cervical dilator can be placed into the cervix up to the uterine cavity without resistance during non-pregnancy; (4) a tubular enlargement of the isthmus of the uterus confirmed by hysterosalpingography during non-pregnancy; (5) an endocervical width greater than 37.5 px as measured by ultrasound. The diagnosis of cervical insufficiency is confirmed by the presence of (1) of the above diagnostic criteria and any one of the other 4 criteria.
1.2. Surgical route Cervical cerclage is the main treatment for cervical insufficiency, which reduces the tension of the uterine fibers and the load on the lower uterine segment to maintain pregnancy. Currently, the two main routes of cervical cerclage are transabdominal and transvaginal. The traditional surgical approach is transvaginal cervical cerclage. Currently, the MacDonald procedure is mostly performed, with sutures at the cervicovaginal junction without incision of the tissue and removal of the sutures before delivery.
In 1965, Benson [4] proposed transabdominal cervical isthmus ligation for cervical insufficiency, which was initially reserved for cervical insufficiency combined with anatomical abnormalities (short cervix, missing tissue after conization or severe scarring, uterovaginal In 1982, Novy [5] expanded the indications for this procedure to include patients with repeated failed transvaginal cerclage.
Although laparoscopic laparoscopy has been reported in the national and international literature for patients with cervical insufficiency who have failed transvaginal laparoscopy, it should be the safest treatment option for patients with cervical insufficiency who have already had a mid-pregnancy miscarriage, especially those who need assisted reproductive technology for infertility, to avoid a second miscarriage. There are several reports in the literature on the success of laparoscopic and robot-assisted laparoscopic cervical cerclage [7-9], and it is indisputable that the success rate of laparoscopic isthmus cerclage is higher than that of transvaginal cerclage, and if translaparoscopic cervical cerclage is preferred in these patients it may reduce the rate of recurrent miscarriage and avoid the physical and psychological harm caused by recurrent miscarriage. Therefore, we believe that laparoscopic cerclage should be preferred once cervical insufficiency is diagnosed.
2. Timing of laparoscopic isthmus annuloplasty
Laparoscopic isthmic annuloplasty can be performed during non-pregnancy or pregnancy. In the non-pregnant period, the uterus is of normal size and the field of view is easily exposed, and the placement of manipulators in the uterine cavity is more conducive to the surgical operation. The literature reports that surgery during pregnancy is mostly performed during early pregnancy. Surgery performed during pregnancy has the potential to affect pregnancy, such as surgical stimulation can cause contractions and increase the rate of surgical failure; too loose sutures can increase the risk of premature rupture of fetal membranes, inevitable abortion or preterm delivery. The enlarged uterus during pregnancy restricts the field of view for surgical operation, making it more difficult to perform surgery. In addition, abundant pelvic blood flow, increased vascularity, and increased vascular area during pregnancy make intraoperative blood loss significantly higher[12] . Currently, there is no evidence that the success rate of circumferential ligation during pregnancy is higher than that of non-pregnant surgery[12-13] .
Whittle[13] conducted a prospective cohort study in which laparoscopic cervical cerclage was performed in 65 patients with cervical insufficiency, 31 of whom were operated during pregnancy (before 16 weeks) and 34 during non-pregnancy, to observe surgical complications and postoperative pregnancy outcomes. The results showed that 5 patients were converted to open surgery due to uterine vascular bleeding and 2 due to obesity affecting the surgical view, of which 6 were operated during pregnancy, and 2 spontaneous abortions occurred after surgery without other complications, and the mean gestational weeks of pregnancy maintenance were 32.9 and 34.5 weeks in the pre-pregnancy and pregnancy surgery groups, respectively, so the authors concluded that the timing of cervical ligation did not affect the duration of pregnancy maintenance, but in this study, In this study, however, the rate of conversion to open surgery during pregnancy was 19.4% and the rate of conversion to open surgery during non-pregnancy was 2.9%. The abortion rates before 24 weeks of gestation in both groups were 22.6% and 5.9%, respectively, although the differences were not statistically significant. Therefore, the operation before pregnancy is relatively easy and safe.
3.Surgical methods and points of trans-laparoscopic annuloplasty
3.1. Surgical method Laparoscopic isthmus annuloplasty during non-pregnancy is performed 3-7 days after menstrual cleansing. The patient was placed in a cystotomy position, and three puncture points were taken at the umbilicus and both sides of the lower abdomen, and the laparoscope and operating instruments were inserted for surgical operation. A transvaginal uterine lifter was placed to push up the uterus, and the peritoneal regurgitation of the bladder was incised with monopolar electrocoagulation under the microscope to push away the bladder and expose the uterine vessels in the isthmus and on both sides. A polypropylene ring ligature (Mersilene band) with stitches at both ends is then used to perform a cervical ring ligation. The stitches are straightened from curved to straight, and the needle is advanced from anterior to posterior in the avascular zone between the isthmus and the uterine vessels, with the exit point still chosen between the isthmus and the uterine vessels. After performing hysteroscopy to rule out that the ring-tie band is located in the cervical canal, the Mersilene band is pulled tight, the isthmus is ring-tied, and the knot is tied posteriorly to the isthmus. Sutures may not be necessary for peritoneal reflexion [11]. It is advisable to place two ring ties in the isthmus to strengthen the support of the isthmus.
If the isthmus ligation is performed during pregnancy, it is not necessary to place an intrauterine lifter in the uterine cavity. The procedure is performed as follows: The procedure is performed using a four-penetrating hole. The round ligament is cut with an ultrasonic knife, the assistant clamps the round ligament near the broken end of the uterus, pulls the uterus to one side, exposes the broad ligament on the operative side, cuts the avascular zone of the broad ligament to the level of the cystoperitoneum reflex, pushes up the cervix with a cervical clamp, the ultrasonic knife cuts the cystoperitoneum reflex, pushes away the bladder, exposes the parametrial vascular bundle of the uterine isthmus, and the curved needle of the mersilene loop ligature is used from the medial side of the uterine vascular bundle, from posterior to anterior, respectively. The knot was tied in front of the isthmus with the curved needle of the mersilene loop. After the knot is tied, without cutting the loop tie, the needle of the loop tie is punctured from the medial side of the vessels from anterior to posterior, bypassing the posterior aspect of the cervix, and then from the medial side of the vessels on the other side of the isthmus from posterior to anterior to reach the anterior aspect of the isthmus, and the isthmus is looped again to complete the double loop tie of the isthmus.
3.2. Surgical points
3.2.1 Suture selection Previously, 7- or 10-gauge double-stranded silk or nylon thread was used to perform the procedure, but since Novy adopted the polypropylene loop ligature (Mersilene tape) to ligate the isthmus in 1982, the Mersilene tape is now the preferred choice for cervical cerclage. This suture tape is 5 mm wide, has slightly higher resistance during suturing, and does not slip easily after knotting. A polypropylene mesh tape suture has been suggested to avoid suture erosion [13-14], or a No. 1 acrylic suture (A#1 Prolene, Ethicon), which is easy to manipulate during suturing and easier to remove [9,12-13,15]. However, its effectiveness and safety need to be confirmed by more studies.
3.2.2 Loop tie tightness control
The control of the non-pregnant loop ligature tightness is based on the diameter of the cervical canal after ligation. When the loop ligature is tied, a dilation strip is placed in the cervical canal with a dilation diameter ranging from 5-8 mm [12-13,16], and it is recommended that a 5-6 mm dilation strip be placed, and the diameter of the cervical canal after ligation is appropriate for a 6-mm dilation strip to pass without resistance. Avoid over-widening of the cervical canal, which may cause intrauterine infection or premature rupture of the membranes. It should not be tied too tightly to avoid difficulties in terminating the pregnancy and clearing the uterus when embryonic abnormalities are found in early pregnancy. Some scholars believe that tying in the front is likely to cause adhesions, but it is easier to identify and find when removing the sutures, and tying in the back is more spacious and less likely to cause adhesions, so it is recommended that the knot be tied in the back [17]. Some scholars have used silk thread to sew the most terminal knot against the lower segment of the uterus after tying the knot, which plays a role in reinforcing and preventing slippage on the one hand, and avoiding adhesions caused by a raised knot on the other [15]. In early pregnancy, the diameter of the cervical canal cannot be detected during cervical isthmus ligation, and the standard is to ligate the isthmus as tightly as possible; the softened isthmus makes it easier to ligate. In such patients, the diameter of the cervical canal must be checked at the time of cesarean delivery at full term of pregnancy, and if the canal is completely closed the sutures need to be removed so that the malignant fluid is not drained and retained in the uterine cavity.
4. Methods and effects of pregnancy termination
4.1. Patients with transvaginal cerclage can deliver vaginally by removing the sutures before delivery, but patients with full-term pregnancies or viable preterm infants with transabdominal cerclage need to terminate the pregnancy by cesarean delivery. In cases of midtrimester fetal anomalies, stillbirth, uncontrollable preterm delivery with non-viable fetuses, and when the fetus cannot be delivered vaginally at a large gestational age, three delivery options are available; the first is cesarean extraction, which is a more invasive procedure with an increased risk of uterine rupture in subsequent pregnancies and is generally not recommended; the second is incision of the posterior fornix to remove the sutures [13] and deliver the fetus vaginally. However, the position of this suture is higher, and when combined with adhesions there is some difficulty in removing the suture vaginally, the pelvic cavity is congested during pregnancy, there is more intraoperative blood loss, and there is an increased risk of injury to the intestinal canal. The third option is to cut the sutures laparoscopically or through a small abdominal incision, then deliver the fetus vaginally and perform a laparoscopic isthmus ligation when ready for another pregnancy. The latter two surgical approaches can maintain the integrity of the uterus, and the removal of the sutures through a small abdominal incision/laparoscopy and vaginal delivery of a nonviable fetus is the approach currently recommended by most authors.
4.2. Surgical outcome
Successful annuloplasty is defined as a single pregnancy delivery after reattachment with neonatal survival of 28 days or more.
In the literature, it has been reported that after laparoscopic laparoscopy, the patient’s gestational weeks were extended from 19.7 to 32.9 weeks and the live birth rate increased from 11.9% to 88.3% [13]. In recent studies, live birth rates of 90.9-100% were achieved above 34 weeks [12-14,16-17], and pregnancy rates after preconceptional cerclage ranged from 42.9-90.9% [12-14,16-17].Patient age and prior cervical surgery may affect pregnancy, although these factors cannot be ruled out, and laparoscopic isthmus cerclage has not been found to affect pregnancy or embryo transfer [In 2012, we reported 16 patients who underwent laparoscopic cervical cerclage prior to pregnancy and 8 patients who had undergone cesarean section to terminate their pregnancy, with a mean preoperative miscarriage of 20 weeks (18-22 weeks) and a mean delivery of 37.9 weeks (31-39 weeks). The average gestational week of miscarriage before surgery was 20 weeks (18-22 weeks) and the average gestational week of delivery was 37.9 weeks (31-39+1 weeks), and the cervical ligation resulted in an average extension of 17.9 weeks (13-19+1 weeks) with a 100% live birth rate [11].
4.3 Management of residual sutures
A single annuloplasty can result in more than one pregnancy, and there is a reported case of a patient with transabdominal annuloplasty who successfully delivered three full-term pregnancies after surgery, and the sutures were finally removed laparoscopically without difficulty because the patient requested removal of the sutures [3], which indicates that removal of the sutures is not difficult.Gibb [21] believed that preconception cervical annuloplasty would prolong the time of the sutures in the abdominal cavity, and later removal of the sutures would be difficult, but in practice, all pregnant women terminate their pregnancies by cesarean section, so the sutures can be removed intraoperatively and simultaneously, without the need for deliberate surgical removal prior to delivery. The sutures can be retained for patients with a requirement to continue the pregnancy. Erosion of the Mersilene band and penetration of the lower uterine segment have been reported in the literature [22].Whittle [13] reported a patient with suture erosion that was dislodged into the vagina via the posterior fornix and removed via the posterior fornix during delivery.Mark [17] reported two patients with chronic pelvic pain after delivery and relief of symptoms after laparoscopic removal of the sutures. However, no significant side effects have been seen with retention of the looped sutures for most women. Therefore, the loop-tie suture can be retained when asymptomatic, and laparoscopic removal of the suture can be considered when the patient has recurrent pelvic inflammatory disease and chronic pelvic pain.
In conclusion, laparoscopic surgery is more minimally invasive than open surgery and also has advantages that negative surgery does not have, with better efficacy than open or negative surgery, and the many advantages of laparoscopy make it easier for patients to undergo this type of surgery [12]. It is indisputable that the success rate of laparoscopic isthmus ligation is higher than that of transvaginal ligation; however, whether laparoscopic isthmus ligation can become the standard and procedure for the treatment of cervical insufficiency remains to be confirmed by the results of a multicenter randomized controlled clinical study.