**3.7 Single stitches versus continuous suture**

A small number of studies is available comparing continuous suture with single stitches to close the uterine incision.

One case–control study (n = 98) analysed the effect of prior uterine closure on placenta location and placentation disorders. Half of the double-layer group had continuous suture of the inner layer, the others had interrupted sutures of the inner layer. Continuous suture of the inner layer of the myometrium was an independent risk factor for subsequent placenta accreta, total placenta praevia and anterior location. The risk for morbidly adherent placenta was 6-fold higher after continuous suture compared to interrupted stitches [45]. An additional prospective randomized study in primiparae with an elective CS demonstrated larger and more numerous niches in patients after locked continuous sutures compared to interrupted sutures (95% niches and 77% niches after 12 months, respectively). In this study, the decidua was excluded and a single layer suture without closure of the visceral peritoneum was performed [46].

Overall, conclusive evidence in this topic is limited by the small size of the studies. Currently, interrupted stitches of the inner layer of myometrial closure might favour the healing process.

### **3.8 Inclusion versus exclusion of the decidua in the suture**

Including the decidua (endometrium) in the suture might lead directly to a worsened scar integrity and niche development. Roberge et al. observed, as mentioned before, that excluding the decidua in double-layer suture supports better scar healing than including it [36].

A recently published double-blind, randomised controlled study (2Close Trial) examined the presence of postmenstrual spotting after a single- versus a double- layer suture. In the double-layer group, the decidua was integrated in the scar, however, in the single-layer group, this integration was optional. Surprisingly, a significantly increased niche prevalence was found after double- compared to single-layer suture (73.6 versus 68.9%). The authors draw the conclusion that rather by the number of sutured layers this result was provoked by the integration of the decidua in the suture. In line with this, subgroup analysis of the single-layer group revealed a significantly lower niche incidence in cases of exclusion of the decidua (59.3 versus 71.8%) [47].

A retrospective cohort study showed no morbidly adherent placenta in a cohort of 109 patients with previous CS, although in 44% an anterior wall placentation was present. The authors concluded that the exclusion of the endometrium from the suture, which was a standard practice in the study center, chiefly contributed to the results. However, there was no control group and the study group was compared with historical cohorts [48].

A critical view on this approach raises the concern that less myometrium might be adapted if the endometrium is not included in the scar, probably contributing

#### *Prevention of Cesarean Scar Defects: What Is Possible? DOI: http://dx.doi.org/10.5772/intechopen.97618*

to a defect healing. Yazicioglu et al. observed a higher incomplete healing ratio in sutures that excluded the endometrium compared to those including all layers [49]. However, the examination was performed 6 weeks after the CS, which is known to be rather early for a final assessment of wound healing. Furthermore, cervical dilatation was performed at a lower percentage in patients with incomplete healing, probably explaining the results. This study also was part of a meta-analysis pooling two studies recording niches after sutures including or excluding the decidua [39]. The second study, which was included in this meta-analysis, showed contrary results [50]: Three study groups were compared (group A: inclusion of all layers; group B: double-layer suture with inclusion of the decidua, group C: double-layer suture with a separate suture of the decidua and a separate suture of the myometrial layer). The group with the separate suture of the endometrium showed significantly lower niche rates (34%, 16% and 5.6% niches in group A, B and C, respectively).

In summary, the exclusion of the decidua from the suture seems favourable in preventing niches.

#### **3.9 Closure of the peritoneum viscerale/parietale**

The closure of the peritoneum reveals no advantages with regards to operation time, pain and bleeding amounts, as currently recommended the German Guideline Cesarean Section [51]. But does the closure of the peritoneum help to prevent a niche?

Verwoort et al. discussed several hypotheses on niche development. During laparoscopic scar repair surgery dense fibrotic adhesions attached on top of the niches were found [11]. One hypothesis is that adhesions pull the uterine scar towards the abdominal wall and induce scar development due to traction. One explanation for this adhesion between the anterior uterine and the abdominal wall might be the incision of the utero-vesical fold and subsequent dissection of the urinary bladder with the aim to keep the bladder out of the surgical area. This may create adhesions and provoke niche formation as well as a fixed retroflexio uteri [52].

Moreover, a systematic review including 249 patients evaluated whether the parietal peritoneum should be closed. This study showed that closure of the peritoneum prevents adhesions from abdominal to uterine wall [53].

In conclusion, further investigation is needed to be able to answer the question about the contribution of closure of the visceral and parietal peritoneum to niche prevention.

#### **3.10 Dilatation of the cervix uteri**

The rationale of dilating the cervix uteri during elective CS is to facilitate the proper drain of blood and "products of conception" postpartum. On the one hand, retained blood after CS is ought to impair scar healing and results in scar defects [54]. On the other hand, a risk of infection by a possible transmission and contamination from vaginal microorganisms to uterine or abdominal wounds is discussed [55]. A randomised trial analysed the different outcomes of CS after cervical dilatation (CD) was performed with Hegar dilator or not. 400 women with a singleton pregnancy were included and planned for elective CS at term. All patients received vaginal disinfection preoperatively with povidone iodine. No difference was observed regarding wound infection or endometritis between the groups. In the cervical dilatation group, indicators of better healing of the scar were found: Significantly higher scar width and depth, thicker RMT, and fewer scar defects were found together with better blood supply to the scar. In comparison, women without cervical dilatation were at higher risk for subinvolution of the uterus [54].

In another recently published trial (DONDI-Trial, prospective, open-label, randomized controlled trial), 447 women randomly received cervical dilation or not during CS. Women with current antibiotic therapy, chorioamnionitis, onset of labour with dilatation of the cervix and gestational age below 24 weeks were excluded. Dilatation of the cervix had no effect on infectious morbidity (puerperal fever, endometritis, wound infection and urinary tract infection), blood loss or even operating time. The only benefit observed in the dilatation group was a lower prevalence of patients that had retained products in the uterus cavity compared to the no-dilation group (0 vs. 6.2%, p < 0.001) [56]. Although scar healing was not examined in this study, retention of products may potentially disturb wound healing.

A recently published review underlined the following findings, too: performing or not CD at elective CS at term either with double gloved index or Hegar dilator caused no differences regarding postpartum haemorrhage, postoperative fever, endometritis or subinvolution. Cervical dilatation led to a slightly higher mean blood loss, thicker endometrial cavity, less retained products of conception, less distortion of uterine incision and better healing ratio. Operating time, wound infection, urinary tract infection and integrity of scar (defined as scar thickness less than 2.3 mm) were not affected [57].

In conclusion, dilatation of the cervix has positive effects on scar integrity, wound healing and RMT due to less retention of products in utero. It is safe regarding infections; however, vaginal disinfection should be considered before CS.
