Sonographic imaging of cervical scars after Cesarean section

Uterine Scar Evaluation during the Postpartum: Pleading for Extradecidual Suturing during Cesarean Section

OBJECTIVE

 Our objective is to evaluate ultrasound differences in uterine scar between techniques using extramucosal suturing and full thickness suturing of the uterine incision.

STUDY DESIGN

 A retrospective observational study included cases of primary cesarean section. At 6-week postpartum, we evaluated by endovaginal ultrasound two elements in the sagittal view: the thickness of the uterine scar and the surface of defect (niche). Hysterotomy sites closed using a running full-thickness technique including the uterine mucosa (group 1) were compared to hysterotomies operated by the same surgeon but with extramucosal suturing (group 2). The operator switched from the running suture technique to extramucosal in 2013.

RESULTS

 The study included 241 patients (115 cases in group 1 that were compared to 126 cases in group 2). There were no significant differences in age or body mass index between the two groups. Cesarean scar and niche were detectable in the entire studied population. There was a significant difference in both uterine scar thickness (5.8 vs. 6.2 mm, p = 0.02) and the presence and size of the niche (49 vs. 40 mm2, p = 0.001) in transvaginal ultrasound performed at 6-week postpartum.

CONCLUSION

 Extramucosal suturing of the uterine scar seems to be associated with a better outcome on the postpartum ultrasound evaluation.

KEY POINTS

· The technique for suturing the hysterotomy can be the source of healing changes.. · An extramucosal suturing of the uterus seems to give a better aspect at the postpartum ultrasound.. · Decreasing the niche at cesarean scar may be beneficial for future pregnancies..

Prediction of spontaneous preterm birth in women with previous full dilatation cesarean delivery

BACKGROUND

A previous term (≥37 weeks' gestation), full-dilatation cesarean delivery is associated with an increased risk for a subsequent spontaneous preterm birth. The mechanism is unknown. We hypothesized that the cesarean delivery scar characteristics and scar position relative to the internal cervical os may compromise cervical function, thereby leading to shortening of the cervical length and spontaneous preterm birth.

OBJECTIVE

This study aimed to determine the relationship of cesarean delivery scar characteristics and position, assessed by transvaginal ultrasound, in pregnant women with previous full-dilatation cesarean delivery with the risk of shortening cervical length and spontaneous preterm birth.

STUDY DESIGN

This was a single-center, prospective cohort study of singleton pregnant women (14 to 24 weeks' gestation) with a previous term full-dilatation cesarean delivery who attended a high-risk preterm birth surveillance clinic (2017-2021). Women underwent transvaginal ultrasound assessment of cervical length, cesarean delivery scar distance relative to the internal cervical os, and scar niche parameters using a reproducible transvaginal ultrasound technique. Spontaneous preterm birth prophylactic interventions (vaginal cervical cerclage or vaginal progesterone) were offered for short cervical length (≤25 mm) and to women with a history of spontaneous preterm birth or late miscarriage after full-dilatation cesarean delivery. The primary outcome was spontaneous preterm birth; secondary outcomes included short cervical length and a need for prophylactic interventions. A multivariable logistic regression analysis was used to develop multiparameter models that combined cesarean delivery scar parameters, cervical length, history of full-dilatation cesarean delivery, and maternal characteristics. The predictive performance of models was examined using the area under the receiver operating characteristics curve and the detection rate at various fixed false positive rates. The optimal cutoff for cesarean delivery scar distance to best predict a short cervical length and spontaneous preterm birth was analyzed.

RESULTS

Cesarean delivery scars were visualized in 90.5% (220/243) of the included women. The spontaneous preterm birth rate was 4.1% (10/243), and 12.8% (31/243) of women developed a short cervical length. A history- (n=4) or ultrasound-indicated (n=19) cervical cerclage was performed in 23 of 243 (9.5%) women; among those, 2 (8.7%) spontaneously delivered prematurely. A multiparameter model based on absolute scar distance from the internal os best predicted spontaneous preterm birth (area under the receiver operating characteristics curve, 0.73; 95% confidence interval, 0.57-0.89; detection rate of 60% for a fixed 25% false positive rate). Models based on the relative anatomic position of the cesarean delivery scar to the internal os and the cesarean delivery scar position with niche parameters (length, depth, and width) best predicted the development of a short cervical length (area under the receiver operating characteristics curve, 0.79 [95% confidence interval, 0.71-0.87]; and 0.81 [95% confidence interval, 0.73-0.89], respectively; detection rate of 73% at a fixed 25% false positive rate). Spontaneous preterm birth was significantly more likely when the cesarean delivery scar was <5.0 mm above or below the internal os (adjusted odds ratio, 6.87; 95% confidence interval, 1.34-58; P =.035).

CONCLUSION

In pregnancies following a full-dilatation cesarean delivery, cesarean delivery scar characteristics and distance from the internal os identified women who were at risk for spontaneous preterm birth and developing short cervical length. Overall, the spontaneous preterm birth rate was low, but it was significantly increased among women with a scar located <5.0 mm above or below the internal cervical os. Shortening of cervical length was strongly associated with a low scar position. Our novel findings indicate that a low cesarean delivery scar can compromise the functional integrity of the internal cervical os, leading to cervical shortening and/or spontaneous preterm birth. Assessment of the cesarean delivery scar characteristics and position seem to have use in preterm birth clinical surveillance among women with a previous, full-dilatation cesarean delivery and could better identify women who would benefit from prophylactic interventions.

Incidence and risk factors for severe postpartum haemorrhage in women with anterior low-lying or praevia placenta and prior caesarean: Prospective population-based study

OBJECTIVE

To assess the incidence and risk factors for severe postpartum haemorrhage (PPH) in women with an anterior low-lying or praevia placenta, prior caesarean and no prenatal suspicion of placenta accreta spectrum (PAS).

DESIGN

Population-based study in 176 maternity units in France.

POPULATION

All women with anterior low-lying (0-19 mm from the cervical internal os) or praevia placenta, diagnosed prospectively before birth, prior caesarean and no prenatal suspicion of PAS.

METHODS

Multivariable logistic regression to identify risk factors for severe PPH in the main population and after exclusion of women with PAS diagnosed only at birth.

MAIN OUTCOME MEASURES

Severe PPH defined by a composite criterion either estimated blood loss of ≥1500 ml, transfusion of ≥4 or more units of packed red blood cells, embolisation or surgical treatment.

RESULTS

Of the 520 114 women constituting the source population, 230 (0.44/1000 women; 95% confidence interval [CI] 0.38-0.50) met the inclusion criteria. Severe PPH rate was 24.8% (95% CI 19.2-30.4) overall, 27.5% (95% CI 21.8-33.3) in women with placenta praevia and 15.4% (95% CI 10.7-20.0) in women with low-lying placenta. PAS was diagnosed at birth in 22 women (9.9%; 95% CI 5.8-13.4), although previously unsuspected. After their exclusion, severe PPH incidence was 17.3% (95% CI 12.4-22.2). In multivariate analysis, the only factor associated with a higher severe PPH risk was placenta previa (aOR, 3.65; 95%CI, 1.20-15.8).

CONCLUSION

Severe PPH is frequent among women with anterior low-lying or praevia placenta and prior caesarean, even after exclusion of women with PAS. The risk of severe PPH for those with praevia is nearly twice that with low-lying placenta.

The role of transvaginal ultrasound in the third-trimester evaluation of patients at high risk of placenta accreta spectrum at birth

BACKGROUND

Transvaginal ultrasound imaging has become an essential tool in the prenatal evaluation of the lower uterine segment and anatomy of the cervix, but there are only limited data on the role of transvaginal ultrasound in the management of patients at high risk of placenta accreta spectrum at birth.

OBJECTIVE

This study aimed to evaluate the role of transvaginal sonography in the third trimester of pregnancy in predicting outcomes in patients with a high probability of placenta accreta spectrum at birth.

STUDY DESIGN

This was a retrospective analysis of prospectively collected data of patients presenting with a singleton pregnancy and a history of at least 1 previous cesarean delivery and patients diagnosed prenatally with an anterior low-lying placenta or placenta previa delivered electively after 32 weeks of gestation. All patients had a least 1 detailed ultrasound examination, including transabdominal and transvaginal scans, within 2 weeks before delivery. Of note, 2 experienced operators, blinded to the clinical data, were asked to make a judgment on the likelihood of placenta accreta spectrum as a binary, low or high-probability of placenta accreta spectrum, and to predict the main surgical outcome (conservative vs peripartum hysterectomy). The diagnosis of accreta placentation was confirmed when one or more placental cotyledons could not be digitally separated from the uterine wall at delivery or during the gross examination of the hysterectomy or partial myometrial resection specimens.

RESULTS

A total of 111 patients were included in the study. Abnormal placental tissue attachment was found in 76 patients (68.5%) at birth, and histologic examination confirmed superficial villous attachment (creta) and deep villous attachment (increta) in 11 and 65 cases, respectively. Of note, 72 patients (64.9%) had a peripartum hysterectomy, including 13 cases with no evidence of placenta accreta spectrum at birth because of failure to reconstruct the lower uterine segment and/or excessive bleeding. There was a significant difference in the distribution of placental location (X2=12.66; P=.002) between transabdominal and transvaginal ultrasound examinations, but both ultrasound techniques had similar likelihood scores in identifying accreta placentation that was confirmed at birth. On transabdominal scan, only a high lacuna score was significantly associated (P=.02) with an increased chance of hysterectomy, whereas on transvaginal scan, significant associations were found between the need for hysterectomy and the thickness of the distal part of the lower uterine segment (P=.003), changes in the cervix structure (P=.01), cervix increased vascularity (P=.001), and the presence of placental lacunae (P=.005). The odds ratio for peripartum hysterectomy were 5.01 (95% confidence interval, 1.25-20.1) for a very thin (<1-mm) distal lower uterine segment and 5.62 (95% confidence interval, 1.41-22.5) for a lacuna score of 3+.

CONCLUSION

Transvaginal ultrasound examination contributes to both prenatal management and the prediction of surgical outcomes in patients with a history of previous cesarean delivery with and without ultrasound signs suggestive of placenta accreta spectrum. Transvaginal ultrasound examination of the lower uterine segment and cervix should be included in clinical protocols for the preoperative evaluation of patients at risk of complex cesarean delivery.

Intra-operative Guidelines for the Prevention of Uterine Niche Formation in Cesarean Sections: A Review

Formation of a uterine niche following a C-section can predispose the patient to future obstetric complications such as dehiscence, uterine rupture, ectopic pregnancy, and placenta accreta. The significant morbidity and mortality of these complications along with increasing C-section rates emphasizes the importance of prevention. However, there are no clear guidelines on intra-operative protocol to prevent postpartum niche formation. Besides surgical technique, the novel use of platelet-rich plasma (PRP) and mesenchymal stem cell (MSC) injections has demonstrated promising potential and may have applications in hysterotomy closures. The objective is to examine current research on optimal C-section procedures to prevent uterine niche formation and subsequent obstetric complications. A systematic review was conducted using PubMed and Google Scholar. Initial searches yielded 827 results. Inclusion criteria were human, animal, and in-vitro studies, peer-reviewed sources, and outcomes pertinent to the uterine niche. Exclusion criteria applied to articles with outcomes unrelated to myometrium and interventions outside of the intra-operative and immediate pre-/post-operative period. Based on the criteria, 41 articles were cited. Pathophysiology of uterine niche formation was associated with incisions through cervical tissue, adhesion formation, and poor approximation. Significant risk factors were low uterine incisions, advanced cervical dilatation, low station, non-closure of the peritoneum, and creation of a bladder flap. There was no consensus on uterine closure as it likely depends on surgical proficiency with the given technique, but a double-layered non-locking suture appears reliable to reduce niche severity. Recent trials indicate that intra-operative PRP/MSC injections may decrease niche incidence and severity, but more research is needed. If prevention or minimization of uterine niche is desired, the optimal C-section protocol should avoid low uterine incisions, choose uterine closure technique based on the surgeon's proficiency (double-layered non-locking is reliable), and close the peritoneum, and myometrial injection of PRP/MSC may be a useful adjunct intervention pending further clinical evidence.

Measurement of Lower Uterine Segment Thickness to Detect Uterine Scar Defect: Comparison of Transabdominal and Transvaginal Ultrasound

OBJECTIVES

Lower uterine segment (LUS) thickness measurement using transabdominal ultrasound (TA-US), transvaginal ultrasound (TV-US), or the combination of both methods can detect scar defect in women with prior cesarean. We aimed to compare the sensitivity of three approaches.

METHODS

Women with prior cesarean underwent LUS thickness measurement at 34-38 weeks' gestation. Among those who underwent repeat cesarean before labor, we compared the accuracy of TA-US, TV-US, and the thinner of the two measurements (the "combined measurement") for uterine scar dehiscence using the area under the curve (AUC) of receiver operating curves with their 95% confidence intervals (CI). We calculated the sensitivity and specificity of the three approaches using a cut-off of 2.3 mm based on prior literature.

RESULTS

We included 747 participants. The mean LUS thickness was greater with TA-US (3.8 ± 1.6 mm) compared with TV-US (3.5 ± 1.9 mm) or the combined measurement (3.2 ± 1.5 mm; P < .001). The AUC was 78% (95% CI: 69%-87%), 85% (95% CI: 79%-91%), and 88% (95% CI: 82%-93%), respectively (all with P < .001). The AUC difference between TA-US and the combined measurement was not significant (P = .057). A LUS below 2.3 mm would have predicted 9 (45%) of the 20 cases of uterine scar dehiscence using TA-US, 17 (85%) using TV-US, and 18 (90%) using the combined measurement (P < .01).

CONCLUSION

The choice of ultrasound approach influences the measurement of the LUS thickness. The combination of the TA-US and TV-US seems to be superior for the detection of uterine dehiscence.

Frequency and associated symptoms of isthmoceles in women 6 months after caesarean section: a prospective cohort study

PURPOSE

The purpose of this study was to determine the frequency of detection of isthmoceles by ultrasound 6 months after caesarean section (CS) and which symptoms associated with isthmocele formation occur after CS. Subsequently, it was determined how often the ultrasound finding "isthmocele" coincided with the presence of complaints.

METHODS

A prospective multicentre cohort study was conducted with 546 patients from four obstetric centres in Berlin, who gave birth by primary or secondary CS from October 2019 to June 2020. 461 participants were questioned on symptoms 3 months after CS; 329 participants were included in the final follow-up 6 months after CS. The presence of isthmoceles was determined by transvaginal sonography (TVS) 6 months after CS, while symptoms were identified by questionnaire.

RESULTS

Of the 329 women, 146 (44.4%) displayed an isthmocele in the TVS. There was no statistically significant difference in the manifestation of symptoms between the two groups of women with and without isthmocele; however, when expressed on a scale from 1 to 10 the intensity of both scar pain and lower abdominal pain was significantly higher in the set of women that had shown to have developed an isthmocele (p = 0.014 and p = 0.031, respectively).

CONCLUSION

The prevalence of isthmoceles 6 months after CS was 44.4%. Additionally, scar pain and lower abdominal pain were more pronounced when an isthmocele was also observed in the TVS.

TRIAL REGISTRATION

Trial registration number DRKS00024977. Date of registration 17.06.2021, retrospectively registered.

Reproducibility of assessment of full-dilatation Cesarean section scar in women undergoing second-trimester screening for preterm birth

OBJECTIVE

To assess the reproducibility of a standardized method of measuring the Cesarean section (CS) scar, CS scar niche and their position relative to the internal os of the uterine cervix by transvaginal ultrasound in pregnant women with a previous full-dilatation CS.

METHODS

This was a prospective, single-center reproducibility study on women with a singleton pregnancy and a previous full-dilatation CS who underwent transvaginal ultrasound assessment of cervical length and CS scar characteristics at 14-24 weeks' gestation. The CS scar was identified as a hypoechogenic linear discontinuity of the myometrium at the anterior wall of the lower uterine segment or cervix. The CS scar niche was identified as an indentation at the site of the scar with a depth of at least 2 mm. The CS scar position was evaluated by measuring the distance to the internal cervical os. CS scar niche parameters, including its length, depth, width, and residual and adjacent myometrial thickness, were assessed in the sagittal and transverse planes. Qualitative reproducibility was assessed by agreement regarding visibility of the CS scar and niche. Quantitative reproducibility of CS scar measurements was assessed using three sets of images: (1) real-time two-dimensional (2D) images (real-time acquisition and caliper placement on 2D images by two operators), (2) offline 2D still images (offline caliper placement by two operators on stored 2D images acquired by one operator) and (3) three-dimensional (3D) volume images (volume manipulation and caliper placement on 2D images extracted by two operators). Agreement on CS scar visibility and the presence of a niche was analyzed using kappa coefficients. Intraobserver and interobserver reproducibility of quantitative measurements was assessed using Bland-Altman plots.

RESULTS

To achieve the desired statistical power, 72 women were recruited. The CS scar was visualized in > 80% of images. Interobserver agreement for scar visualization and presence of a niche in real-time 2D images was excellent (kappa coefficients of 0.84 and 0.85, respectively). Overall, reproducibility was higher for real-time 2D and offline 2D still images than for 3D volume images. The 95% limits of agreement (LOA) for intraobserver reproducibility were between ± 1.1 and ± 3.6 mm for all sets of images; the 95% LOA for interobserver reproducibility were between ± 2.0 and ± 6.3 mm. Measurement of the distance from the CS scar to the internal cervical os was the most reproducible 2D measurement (intraobserver and interobserver 95% LOA within ± 1.6 and ± 2.7 mm, respectively). Overall, niche measurements were the least reproducible measurements (intraobserver 95% LOA between ± 1.6 and ± 3.6 mm; interobserver 95% LOA between ± 3.1 and ± 6.3 mm). There was no consistent difference between measurements obtained by reacquisition of 2D images (planes obtained twice and caliper placed), caliper placement on 2D stored images or volume manipulation (planes obtained twice and caliper placed).

CONCLUSIONS

The CS scar position and scar niche in pregnant women with a previous full-dilatation CS can be assessed in the second trimester of a subsequent pregnancy using either 2D or 3D volume ultrasound imaging with a high level of reproducibility. Overall, the most reproducible CS scar parameter is the distance from the CS scar to the internal cervical os. The method proposed in this study should enable clinicians to assess the CS scar reliably and may help predict pregnancy outcome. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prospective Evaluation of the Ultrasound Signs Proposed for the Description of Uterine Niche in Nonpregnant Women

OBJECTIVES

To evaluate the new ultrasound-based signs for the diagnosis of post-cesarean section uterine niche in nonpregnant women.

METHODS

We investigated prospectively a cohort of 160 consecutive women with one previous term cesarean delivery (CD) between December 2019 and 2020. All women were separated into two subgroups according to different stages of labor at the time of their CD: subgroup A (n = 109; 68.1%) for elective CD and CD performed in latent labor at a cervical dilatation (≤4 cm) and subgroup B (n = 51; 31.9%); for CD performed during the active stage of labor (>4 cm).

RESULTS

Overall, the incidence of a uterine niche was significantly (P < .001) higher in women who had an elective (20/45; 44.4%) compared with those who had an emergent (21/115; 18.3%) CD. Compared with subgroup B, subgroup A presented with a significantly (P = .012) higher incidence of uterine niche located above the vesicovaginal fold and with a significantly (P = .0002) lower proportion of cesarean scar positioned below the vesicovaginal fold. There was a significantly (P < .001) higher proportion of women with a residual myometrial thickness (RMT) > 3 mm in subgroup A than in subgroup B and a significant negative relationship was found between the RMT and the cervical dilatation at CD (r = -0.22; P = .008).

CONCLUSIONS

Sonographic cesarean section scar assessment indicates that the type of CD and the stage of labor at which the hysterotomy is performed have an impact on the location of the scar and the scarification process including the niche formation and RMT.

Fantastic niches and where to find them: the current diagnosis and management of uterine niche

Background

Caesarean section (CS) scar niche is a well recognised complication of caesarean delivery and is defined as an indentation at the site of the CS scar with a depth of at least 2mm.

Objectives

To review systematically the medical literature regarding the current diagnosis and management of uterine niche

Materials and methods

We carried out a systematic review using MeSH terms ‘niche’ OR ‘sacculation’ OR ‘caesarean scar defect’ OR ‘caesarean section scar’ OR ‘uterine defect’ OR ‘isthmocele.’ Articles included were peer-reviewed and in English language.

Main outcome measures

Prevalence, symptoms, diagnosis, pathophysiology and management of uterine niche.

Results

CS scar niche is common and, in a subgroup, produces a range of symptoms including post-menstrual bleeding, dyspareunia and subfertility. It may be linked to use of locked sutures during CS closure. Niche repair can be achieved laparoscopically or hysteroscopically and appears to improve symptoms, although solid conclusions regarding fertility outcomes cannot be drawn.

Conclusions

CS scar niche is associated with a range of symptoms. Repair may aid subfertile patients and those with post-menstrual spotting. The presence of a niche is probably irrelevant in the absence of symptoms.

What is new?

LNG-IUS and surgical repair appear to improve symptoms in those with a niche.

Duration of the second stage of labour and risk of subsequent spontaneous preterm birth

OBJECTIVES

To determine the risk of spontaneous preterm birth (sPTB) associated with the length of second stage of labour in the first term delivery.

DESIGN

Retrospective cohort study.

SETTING

University hospital.

POPULATION

Women with first two consecutive singleton births and the first birth at term. Those who did not reach the second stage of labour in the first delivery were excluded.

METHODS

Charts from 2007 to 2019 were reviewed.

MAIN OUTCOME MEASURES

Rate of sPTB (<37 weeks of gestation) in the second delivery.

RESULTS

Of 13 958 women who met study inclusion criteria, 1464 (10.5%) parturients had a prolonged second stage (≥180 min) in their first term delivery. The rate of sPTB in the second delivery was similar in those with and without a prolonged second stage in first delivery (2.8% versus 2.8%; adjusted odds ratio [aOR] 1.35, 95% CI 0.96-1.90). After adjustment for mode of delivery, prolonged second stage was also not associated with subsequent sPTB in those who delivered by spontaneous and operative vaginal delivery. Those delivered by second-stage caesarean section in the first delivery had a higher risk of sPTB in the second delivery (25/526, 4.8%; aOR 2.66, 95% CI 1.71-4.12; p < 0.001), with a more pronounced risk in those with second-stage caesarean following a prolonged second stage of labour (15/259, 5.8%; aOR 3.40, 95% CI 1.94-5.94; p < 0.001).

CONCLUSION

Second-stage duration in a first term vaginal delivery is not associated with subsequent sPTB. The risk of sPTB is increased following second-stage caesarean section, particularly if performed after a prolonged second stage.

Lower uterine segment scar assessment at 11-14 weeks' gestation to screen for placenta accreta spectrum in women with prior Cesarean delivery

OBJECTIVES

To validate prospectively transvaginal ultrasound assessment of the lower uterine segment (LUS) scar at the time of first-trimester screening in women with previous Cesarean section (CS) and to determine its feasibility and accuracy in stratifying women according to the risk for placenta accreta spectrum (PAS) disorder.

METHODS

Women with a history of CS were recruited between 11 + 0 and 13 + 6 weeks' gestation and underwent LUS scar assessment using transvaginal ultrasound. A standardized midsagittal plane, which included the cervicoisthmic canal (CIC), the uterine scar and the placental site, was obtained. The scar was described in terms of its size (narrow or dehiscent) and its location in relation to the CIC (within or above), with each LUS scar classified into one of four groups based on these features. Placental location was assessed and classified as high- or low-lying. Women were stratified according to the risk of PAS, based on the relationship between the scar location and placental site. Women were considered high risk when the scar was above the CIC and the placenta was low-lying (i.e. when the placenta was overlying an exposed scar) and low risk when the scar was within the CIC and/or the placenta was high. High-risk patients were followed up at 20 weeks and 28-30 weeks for the development of PAS. Maternal demographics, detailed obstetric history and obstetric outcome were collected.

RESULTS

First-trimester transvaginal ultrasound was offered to 535 women with prior CS during the study period. A LUS scar was visualized in 79.9% (401/502) of those who agreed to undergo the examination. At this scan, the LUS scar was above the CIC in 9.0% (36/401) of women, but only 5.7% (23/401) additionally had a low-lying placenta overlying the scar. Of these 23 high-risk women, two were found to have PAS on the mid-trimester screening scan and one was noted to have placental adherence during evacuation following mid-trimester termination of pregnancy. On the first-trimester scan, 94.3% (378/401) of women were at low risk of PAS. This screening protocol yielded a positive likelihood ratio of 21.33 (95% CI, 13.02-34.96), sensitivity of 100% (95% CI, 29.24-100%), specificity of 95.31% (95% CI, 92.39-97.35%), positive predictive value of 16.7% (95% CI, 5.8-39.2%) and negative predictive value of 100% (95% CI, 98.4-100%). On multivariable regression analysis performed to identify confounding variables associated with a LUS scar above the CIC, only maternal body mass index ≥ 30 kg/m² was significant (odds ratio (OR), 2.42 (95% CI, 1.04-5.39); P = 0.03). Although there was a trend towards an increased risk of a LUS scar above the CIC in women with prior elective prelabor CS (OR, 1.72 (95% CI, 0.80-3.68)), this association did not reach statistical significance.

CONCLUSIONS

Routine transvaginal ultrasound assessment of the location of the LUS scar and placenta at the time of first-trimester screening between 11 + 0 and 13 + 6 weeks' gestation in women with prior CS is a feasible and effective tool to identify those at risk of subsequent development of PAS disorder. A finding of placental implantation over an exposed LUS scar seems to be cardinal in predicting the risk of PAS disorder in women with prior CS, with an excellent negative predictive value. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Babu and Magon uterine closure technique during cesarean section: A randomized double-blind trial

AIM

We compared the effectiveness of the Babu and Magon uterine closure technique and unlocked double-layer uterine closure on the integrity and thickness of the uterine scar.

METHODS

A randomized double-blind trial was performed at Hazrat-e Rasoul -e-Akram Hospital, Tehran, Iran, from March 2018 to December 2019, in 72 pregnant women who were candidates for cesarean section for the first time. Women were randomly assigned to the Babu and Magon uterine closure technique (intervention group, n = 34) or double-layer closure of the uterine incision (control group, n = 38). The primary outcome of the study was the frequency of myometrial defects at the site of the scar (niche), and a large niche. Secondary outcomes, including the time taken for uterine closure and postpartum hemorrhage (early and late), were compared between groups.

RESULTS

Adjacent myometrium thickness (AMT) between the two groups was not statistically significant. A niche was reported in 23.5% (8/34) and 50% (19/38) of women in the intervention and controls, respectively (p = 0.02). A large niche was reported in 2.9% (1/34) and 23.7% (9/38) of women in the intervention and controls, respectively (p < 0.01). The duration of uterine closure was not statistically significant between the two groups. Hemoglobin levels did not differ significantly between groups during the first 24 h post-surgery.

CONCLUSION

The results of the study showed that the technique of uterine closure is one of the main potential determinants of myometrial healing. The Babu and Magon uterine closure technique seems to lead to tissue alignment during suturing and consequently cause better myometrial healing, although this issue calls for well-founded longer studies of appropriate design.

Position and integrity of uterine scar are determined by degree of cervical dilatation at time of Cesarean section

OBJECTIVE

Abnormal placental invasion is more common after an elective Cesarean delivery, suggesting that prelabor Cesarean section (CS) increases the likelihood of the CS scar being above the internal cervical os and predisposing to a scar pregnancy in the future. The aim of this study was to assess the location and integrity of the CS scar in postpartum women delivered by CS at different stages of labor.

METHODS

This was a prospective cohort study of women at term who underwent a CS for the first time. In all women, cervical dilatation was determined by digital examination at the time of the CS. All patients had a transvaginal ultrasound examination to assess the location of the CS scar in relation to the internal cervical os, as well as the presence of a scar niche.

RESULTS

A total of 407 pregnant women were recruited into the study: 103 with cervical dilatation ≤ 2 cm, 261 with cervical dilatation 3-7 cm and 43 with cervical dilatation ≥ 8 cm at the time of the CS. A statistically significant correlation was observed between cervical dilatation at the time of the CS and the position of the CS scar. The scar was positioned in the uterus above the internal cervical os in 97.1% (100/103) of women delivered at a cervical dilatation of 0-2 cm, whereas the scar was located at or below the internal cervical os in 97.7% (42/43) of cases delivered at a cervical dilatation of 8-10 cm (P < 0.001). A uterine-scar defect (niche) was observed in 38.1% (64/168) of women with the scar located above, compared with 18.0% (43/239) of those with the scar situated at or below, the internal cervical os (P < 0.001).

CONCLUSIONS

Prelabor and early-labor Cesarean delivery are associated with an increased prevalence of a scar in the uterine cavity as well as a scar niche. CS in late labor is associated with the uterine scar being situated in the endocervical canal and with a lower incidence of a niche. The position and integrity of the CS scar after prelabor and early-labor Cesarean delivery explain the predisposition to abnormal placental invasion in subsequent pregnancy. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Efficacy of transvaginal cervical cerclage in women at risk of preterm birth following previous emergency cesarean section

INTRODUCTION

Emergency cesarean sections (EMCS) are associated with subsequent preterm birth, particularly at full dilation (FDCS), which is a cause of both second trimester miscarriages and early, recurrent spontaneous preterm birth (sPTB). The optimal management for these women in subsequent pregnancies is currently unknown. This study aims to assess efficacy of transvaginal cervical cerclage (TVC) in prevention of preterm birth among women who have had an EMCS followed by a subsequent late miscarriage or sPTB.

MATERIAL AND METHODS

A historical cohort study was performed assessing outcomes of women attending the Preterm Surveillance Clinic at St Thomas' Hospital, London, who received TVC, with a history of EMCS (pregnancy A) followed by a sPTB/late miscarriage (pregnancy B) and a subsequent pregnancy (pregnancy C). A historical reference group managed in the same clinic was identified comprising women with any risk factor for sPTB, who required TVC. Incidence of delivery >24 to <30 weeks' gestation was compared with relative risk and 95% confidence intervals (CI). Subgroup analysis was carried out assessing women who had a previous FDCS.

RESULTS

209 women with a previous EMCS during labor (50 with FDCS), followed by sPTB/late miscarriage were identified. 178 progressed beyond 24 weeks; of these, 56 received TVC and formed the study group. 905 high-risk women were identified; of these, 154 received TVC and formed the reference group. Despite TVC treatment, 17/56 (30%) of the study group delivered <30 weeks' gestation compared with 5/154 (3%) of the reference group (RR 9.4, 95% CI 3.6-24.2, P < .001). In the subset of 17 women in the study group with a previous FDCS, followed by sPTB/late miscarriage, 6/17 (35%) delivered <30 weeks' gestation, significantly higher than the reference group (P < .001) but similar to EMCS at less than full dilation (35% vs 28%, P = .596). Overall, 33/72 (46%) women receiving cerclage with prior EMCS had either a mid-trimester loss or delivery <30 weeks.

CONCLUSIONS

Transvaginal cervical cerclage appears less effective in preventing preterm birth among pregnant women who have had an EMCS followed by a sPTB/late miscarriage compared with other high-risk women. The lack of efficacy in the subgroup with an FDCS was similar.

Prevention of preterm birth: Proactive and reactive clinical practice-are we on the right track?

Preterm birth remains the major cause of death and disability among children under the age of five. In developing countries antenatal preterm birth prevention clinics are set up to provide cervical length surveillance and/or treatment modalities such as cerclage or progesterone for those women with identified risk factors such as previous cervical treatment or preterm birth. However, 85% of women have no risk factors for PTB and currently there is no biomarker to screen women early in pregnancy. Women will present unexpectedly in threatened preterm labour and we have no choice but to adopt a re-active approach to their care by using predication and preparation strategies such as fetal fibronectin, tocolytic therapy and steroids. Despite these strategies approximately 15-20% of these women will give birth preterm before 34 weeks. There is a urgent need to re-design primary, secondary and tertiary prevention strategies for spontaneous preterm labour (sPTL) in singleton pregnancies aimed at identifying and addressing key gaps in clinical practice and research.

Development of placental abnormalities in location and anatomy

Low‐lying placentas, placenta previa and abnormally invasive placentas are the most frequently occurring placental abnormalities in location and anatomy. These conditions can have serious consequences for mother and fetus mainly due to excessive blood loss before, during or after delivery. The incidence of such abnormalities is increasing, but treatment options and preventive strategies are limited. Therefore, it is crucial to understand the etiology of placental abnormalities in location and anatomy. Placental formation already starts at implantation and therefore disorders during implantation may cause these abnormalities. Understanding of the normal placental structure and development is essential to comprehend the etiology of placental abnormalities in location and anatomy, to diagnose the affected women and to guide future research for treatment and preventive strategies. We reviewed the literature on the structure and development of the normal placenta and the placental development resulting in low‐lying placentas, placenta previa and abnormally invasive placentas.

Comparison of the lower uterine segment in pregnant women with and without previous cesarean section in 3 T MRI

BACKGROUND

Prenatal risk stratification of women with previous cesarean section (CS) by ultrasound thickness measurement of the lower uterine segment (LUS) is challenging. There is a wide range of proposed cutoff values and a valuable algorithm for selection before birth is not available. Using 3 T magnetic resonance imaging (MRI), we aimed to identify possible shortcomings of the current protocols used for birth selection after CS. Therefore, we evaluated anatomic and morphologic differences of the LUS and its thickness in patients with CS and those without. Possible impact factors on LUS thickness were studied.

METHODS

We retrospectively analyzed 3 T MRI scans of 164 pregnant women in their second or third trimester, with (patient group, n = 60) and without previous CS (control group, n = 104). Sagittal T2-weighted images were studied. Normal findings of the LUS in MRI, reliability of MRI measurements, as well as factors influencing LUS thickness were assessed. MRI findings were compared to intraoperative findings.

RESULTS

MRI provided good intra- (ICC 0.872) and fair inter-rater reliability (ICC 0.643). The relationship of the LUS and the cesarean scar to the surrounding anatomical structures and also its morphology varied strongly in patients and controls. Scar identification was possible in only 9/60 (15.0%) patients. The LUS was thinner in patients (1.9 ± 0.7 mm) than in controls (2.7 ± 1.3 mm). An LUS thinning up to 1 mm was observed in 23% of women without a previous CS and in 34% of women with normal intraoperative findings. Suspicion of a uterine dehiscence (LUS thickness < 1 mm) was only found in the patient group (5/59 (8.5%)) and was intraoperatively confirmed. In controls, LUS thickness was influenced by fetal weight, gestational age and amniotic fluid amounts.

CONCLUSION

Variability in anatomy, thickness and morphology seem to limit common prenatal LUS imaging diagnostics. Therefore, we consider that diagnostic protocols must be re-evaluated and imaging should be adjusted to the individual patient conditions. Due to its independency of ultrasound limitations, an additional MRI might be useful for altered anatomy and impaired ultrasound conditions. An LUS thinning up to 1 mm might be a normal finding and should be further investigated as reference value.

Hysterotomy level at Cesarean section and occurrence of large scar defects: a randomized single-blind trial

OBJECTIVE

To study the association between the level of Cesarean hysterotomy and the presence of large uterine scar defects 6-9 months after delivery.

METHODS

This was a two-center, randomized, single-blind trial of a surgical procedure with masked assessment of the principal outcome under study. Women without a history of Cesarean section (CS) who underwent emergency CS at cervical dilatation ≥ 5 cm were randomized to high or low incision. Hysterotomy was performed 2 cm above and 2 cm below the plica vesicouterina in the high and low incision groups, respectively. Women were examined using saline contrast sonohysterography to assess the appearance of the hysterotomy scar 6-9 months after delivery. The main outcome was presence of a large scar defect, defined as the remaining myometrial thickness over the defect being ≤ 2.5 mm. Secondary outcomes were perinatal outcome, operative complications within 8 weeks after delivery and long-term outcome in a subsequent pregnancy.

RESULTS

Of 122 patients enrolled in the trial, 114 were assessed by ultrasound examination, of whom 55 were randomized to high and 59 to low CS incision. Large scar defects were seen in four (7%) women in the high-incision group and in 24 (41%) in the low-incision group (P < 0.001; odds ratio, 8.7 (95% CI, 2.8-27.4)). There were no differences in operative complications and perinatal outcomes between the two groups. The median follow-up time was 4 years and 7 months, during which 56 (49%) women had a subsequent pregnancy. No significant differences were observed in the rate of complications in subsequent pregnancy and delivery between women who had low and those who had high incision at the index CS.

CONCLUSION

Low Cesarean hysterotomy level in women in advanced labor is associated with higher incidence of large scar defects detected by transvaginal ultrasound examination 6-9 months after delivery. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Isthmocele: From Risk Factors to Management

OBJECTIVE

 The aim of the present study was to perform a comprehensive review of the literature to provide a complete and clear picture of isthmocele-a hypoechoic area within the myometrium at the site of the uterine scar of a previous cesarean section-by exploring in depth every aspect of this condition.

METHODS

 A comprehensive review of the literature was performed to identify the most relevant studies about this topic.

RESULTS

 Every aspect of isthmocele has been studied and described: pathophysiology, clinical symptoms, classification, and diagnosis. Its treatment, both medical and surgical, has also been reported according to the actual literature data.

CONCLUSION

 Cesarean section is the most common surgical procedure performed worldwide, and one of the consequences of this technique is isthmocele. A single and systematic classification of isthmocele is needed to improve its diagnosis and management. Further studies should be performed to better understand its pathogenesis.

Why do niches develop in Caesarean uterine scars? Hypotheses on the aetiology of niche development

Caesarean section (CS) results in the occurrence of the phenomenon 'niche'. A 'niche' describes the presence of a hypoechoic area within the myometrium of the lower uterine segment, reflecting a discontinuation of the myometrium at the site of a previous CS. Using gel or saline instillation sonohysterography, a niche is identified in the scar in more than half of the women who had had a CS, most with the uterus closed in one single layer, without closure of the peritoneum. An incompletely healed scar is a long-term complication of the CS and is associated with more gynaecological symptoms than is commonly acknowledged. Approximately 30% of women with a niche report spotting at 6-12 months after their CS. Other reported symptoms in women with a niche are dysmenorrhoea, chronic pelvic pain and dyspareunia. Given the association between a niche and gynaecological symptoms, obstetric complications and potentially with subfertility, it is important to elucidate the aetiology of niche development after CS in order to develop preventive strategies. Based on current published data and our observations during sonographic, hysteroscopic and laparoscopic evaluations of niches we postulate some hypotheses on niche development. Possible factors that could play a role in niche development include a very low incision through cervical tissue, inadequate suturing technique during closure of the uterine scar, surgical interventions that increase adhesion formation or patient-related factors that impair wound healing or increase inflammation or adhesion formation.

Arterial hemorrhage from cesarean scar: a rare cause of recurring massive uterine bleeding and successful surgical management

Abnormal uterine bleeding and other gynecologic complications associated with a previous cesarean section scar are only recently being identified and described. Herein we report a rare case of a woman with recurring massive uterine bleeding after 2 cesarean sections. Curettage and hormone therapy were unsuccessfully used in an attempt to control the bleeding. After she was transferred to our hospital, she had another episode of vaginal bleeding that was successfully managed with oxytocin and hemostatic. Diagnostic hysteroscopy performed under anesthesia revealed an abnormal transected artery in the cesarean section scar with a thrombus visible. In the treatment at the beginning of laparoscopic management, we adopted temporary bilateral uterine artery occlusion with titanium clips to prevent massive hemorrhage. Secondly, with the aid of hysteroscopy, the bleeding site was opened, and then the cesarean scar was wedge resected and stitched interruptedly with 1-0 absorbable sutures. The postoperative recovery was uneventful. It would seem that the worldwide use of cesarean section delivery may contribute to the risk of gynecologic disturbances including some unrecognized and complex conditions as seen in this case.

Changes in Cesarean section scar dimensions during pregnancy: a prospective longitudinal study

OBJECTIVES

To describe changes in Cesarean section (CS) scars longitudinally throughout pregnancy, and to relate initial scar measurements, demographic variables and obstetric variables to subsequent changes in scar features and to final pregnancy outcome.

METHODS

In this prospective observational study we used transvaginal sonography (TVS) to examine the CS scar of 320 consecutive pregnant women at 11-13, 19-21 and 32-34 weeks' gestation. For scars visible on TVS, the hypoechoic part was measured in three dimensions and the residual myometrial thickness (RMT) was also measured. Analyses were carried out using one-way repeated measures ANOVA and mixed modeling. The incidence of subsequent scar rupture was recorded.

RESULTS

The CS scar was visible in 284/320 cases (89%). Concerning length and depth of the hypoechoic part of the scar and RMT, the larger the initial scar measurement, the larger the decrease observed during pregnancy. For the hypoechoic part of the scar, the width increased on average by 1.8 mm per trimester, while the depth and length decreased by 1.8 and 1.9 mm, respectively (false discovery rate P < 0.0001). Mean RMT in the first trimester was 5.2 mm and on average decreased by 1.1 mm per trimester. Two cases (0.62%) of uterine scar rupture were confirmed following a trial of vaginal delivery; these had a mean RMT of 0.5 mm at second scan and an average decrease of 2.6 mm over the course of pregnancy.

CONCLUSION

This study establishes reference data and confirms that the dimensions of CS scars change throughout pregnancy. Scar rupture was associated with a smaller RMT and greater decrease in RMT during pregnancy. There is the potential to test absolute values and observed changes in CS scar measurements as predictors of uterine scar rupture and outcome in trials of vaginal birth after Cesarean section.

Factors associated with lower uterine segment thickness near term in women with previous caesarean section

OBJECTIVE

To estimate the association between potential influencing factors and lower uterine segment (LUS) thickness at term in women with previous Caesarean section.

METHODS

We conducted a cohort study of women with previous low-transverse Caesarean section undergoing ultrasonographic measurement of LUS thickness between 35 and 38 weeks' gestation in a tertiary care centre between 2006 and 2009. Measurements of the full LUS thickness and the myometrial LUS thickness were performed both transabdominally and transvaginally. The thinnest measurements for both full and myometrial LUS thicknesses were considered dependent variables. Non-parametric analyses, multivariate linear regression analyses, and multivariate regression analyses were used to evaluate the relationships between LUS thickness and the potential influencing factors of maternal age, interdelivery interval, prior vaginal delivery, and several characteristics of the previous Caesarean section.

RESULTS

In 377 women who underwent measurement of LUS thickness, labour before previous Caesarean section was the only characteristic associated with a greater full LUS thickness (an additional 0.9 mm; 95% CI 0.5 to 1.2 mm) in multivariate linear regression analysis. Labour before previous Caesarean section (0.5 mm; 95% CI 0.2 to 0.7 mm) and the use of synthetic sutures (as opposed to catgut sutures) for the closure of the previous hysterotomy incision (0.3 mm; 95% CI 0.02 to 0.5 mm) were the only two variables significantly associated with a thicker myometrial LUS. In multivariate regression analysis, three factors were predictive of a full LUS thickness of > 2.3 mm: the presence of labour, a recurrent indication for Caesarean section, and the use of synthetic sutures for hysterotomy closure at previous Caesarean section (P < 0.05).

CONCLUSION

Labour at the time of previous Caesarean section is associated with a thicker LUS near term in the subsequent pregnancy. The use of synthetic sutures for hysterotomy closure is another factor potentially associated with a thicker LUS.

Sonographic assessment of post-cesarean section uterine scar in pregnant women

PURPOSE

To detect location of uterine cesarean scar in relation to cervix in pregnancies with previous cesarean section (CS) and to compare location between elective and emergent previous CS.

STUDY DESIGN

Prospective study, 91 pregnant women with previous low transverse CS. Two groups: previous elective [36 (39.6%)] and emergent CS [55 (60.4%)]. Transvaginal ultrasound was performed between 14 and 16 weeks. Cervical length (CL) and distance between external oss to hypoechogenic line (EO-HL distance), which describes location of cesarean scar, were measured. Surgical incision was considered cervical when EO-HL distance was smaller than CL.

RESULTS

Mean CL and EO-HL distance: 45.4 + 7. 0 and 39.0 + 9.4 mm, respectively for all patients. No significant differences were observed in CL (45.9 + 6.2 vs. 45.1 + 8.5 mm; p = not significant [NS]) and EO-HL distance (40.7 + 9.7 vs. 37.9 + 9.1 mm; p = NS) between both groups. Sixty-four cases (70.3%) had cervical scar, eight (8.8%) at the level of the internal oss and 19 (20.9) in the lower uterine segment. No significant difference was observed between both groups regarding location of scar (cervix -72 vs. 67% emergent vs. elective, respectively; p = NS).

CONCLUSION

CS incisions are mostly performed in cervix, in elective as well as in emergent operations.

Unforeseen consequences of the increasing rate of cesarean deliveries: early placenta accreta and cesarean scar pregnancy. A review

This review concentrates on 2 consequences of cesarean deliveries that may occur in a subsequent pregnancy. They are the pathologically adherent placenta and the cesarean scar pregnancy. We explored their clinical and diagnostic as well as therapeutic similarities. We reviewed the literature concerning the occurrence of early placenta accreta and cesarean section scar pregnancy. The review resulted in several conclusions: (1) the diagnosis of placenta accreta and cesarean scar pregnancy is difficult; (2) transvaginal ultrasound seems to be the best diagnostic tool to establish the diagnosis; (3) an early and correct diagnosis may prevent some of their complications; (4) curettage and systemic methotrexate therapy and embolization as single treatments should be avoided if possible; and (5) in the case of cesarean scar pregnancy, local methotrexate- and hysteroscopic-directed procedures had the lowest complication rates.

First-trimester uterine scar assessment by transvaginal ultrasound

OBJECTIVE

The objective of the study was to describe the assessment of lower segment uterine scar (LSCS) by transvaginal ultrasound (TVUS) during a first-trimester scan.

STUDY DESIGN

Patients with a history of LSCS were prospectively enrolled over a 6 month period. Four groups were defined: type 1A, thin scar within cervicoisthmic canal (CIC); type 1B, thin above the internal os (IO); type 2A, dehiscent within the CIC; type 2B, dehiscent above the IO. Accuracy of first-trimester TVUS was investigated by blind testing a panel of 14 operators over a web-based dataset.

RESULTS

The scar was visualized in 122 of 123 patients enrolled. Types 1A, 1B, 2A, and 2B occurred in 49.2%, 3.3%, 38.3%, and 9.2%, respectively. When blind tested, fetal medicine specialists achieved a median sensitivity of 82% and specificity of 100% for the detection of a scar. These were 83% and 87% for nonspecialists.

CONCLUSION

First-trimester uterine scar assessment may become a valuable tool in early recognition of patients at risk of subsequent perinatal complications.

Repercussões da cicatriz uterina resultante de cesariana prévia na dopplervelocimetria das artérias uterinas entre 26 e 32 semanas

OBJETIVO: Avaliar as repercussões da cicatriz uterina na dopplervelocimetria das artérias uterinas, entre 26 e 32 semanas, em gestantes primíparas com uma cesariana prévia, considerando quando esta foi realizada fora (cesárea eletiva) ou durante o trabalho de parto. MATERIAIS E MÉTODOS: Estudo prospectivo transversal em 45 gestantes, divididas em três grupos: 17 gestantes com cicatriz prévia resultante de cesariana eletiva (grupo A); 14 gestantes com uma cicatriz prévia oriunda de cesariana executada em trabalho de parto (grupo B); 14 gestantes cujo único parto anterior foi realizado por via vaginal (grupo C). A dopplervelocimetria das artérias uterinas foi realizada pela via abdominal. Foram calculados as médias, medianas e desvios-padrão (DP) para cada grupo em estudo. Em relação ao índice de pulsatilidade, a comparação dos grupos foi conduzida pelo teste não paramétrico de Kruskal-Wallis. RESULTADOS: Os valores médios do índice de pulsatilidade no grupo A variaram de 0,60 a 1,60 (média: 0,90; DP: 0,29), no grupo B, de 0,53 a 1,43 (média: 0,87; DP: 0,24), e no grupo C, de 0,65 a 1,65 (média: 1,01; DP: 0,37); p = 0,6329. CONCLUSÃO: Não houve repercussões da cicatriz de cesariana prévia na dopplervelocimetria das artérias uterinas avaliadas de 26 a 32 semanas de gestação.

High prevalence of defects in Cesarean section scars at transvaginal ultrasound examination

OBJECTIVES

To determine the ability to correctly identify Cesarean section scars, to estimate the prevalence of defective scars, and to determine the size and location of scar defects by transvaginal ultrasound imaging.

METHODS

Two hundred and eighty-seven women underwent transvaginal ultrasound examination 6-9 months after delivery: 108 had undergone one Cesarean section, 43 had had two Cesarean sections, 11 had undergone at least three Cesarean sections, and 125 were primiparae who had delivered vaginally. The ultrasound examiner was blinded to the obstetric history until all scans had been evaluated.

RESULTS

None of the 125 vaginally delivered women had a visible scar in the uterus, whereas all women who had undergone Cesarean section had at least one visible scar. Median myometrial thickness at the level of the isthmus was 11.6 mm in women who had only been delivered vaginally, and 8.3 mm, 6.7 mm and 4.7 mm in women who had undergone one, two and at least three Cesarean sections, respectively (P < 0.001). Scar defects were seen in 61% (66/108), 81% (35/43) and 100% (11/11) of the women who had undergone one, two and at least three Cesarean sections (P = 0.002); at least one defect was classified as large by the ultrasound examiner in 14% (15/108), 23% (10/43) and 45% (5/11) (P = 0.027), and at least one total defect was seen in 6% (7/108), 7% (3/43) and 18% (2/11) (P = 0.336). In women who had undergone one Cesarean section, the median distance between an intact scar and the internal cervical os was 4.6 (range, 0-19) mm, and that between a deficient scar and the internal cervical os was 0 (range, 0-26) mm (P < 0.001).

CONCLUSIONS

Cesarean section scars can be detected reliably by ultrasound imaging. Myometrial thickness at the level of the isthmus uteri decreases with the number of Cesarean sections and the frequency of large scar defects increases. Scars with defects are located lower in the uterus than intact scars.

Placenta accreta and cesarean scar pregnancy: overlooked costs of the rising cesarean section rate

An unintended consequence of the rising cesarean section rate is abnormal placentation in subsequent pregnancies, leading to the clinical complications of placenta accreta and cesarean scar pregnancies. Both of these clinical entities are associated with high rates of maternal morbidity and mortality. This article reviews the potential mechanisms by which uterine scarring may lead to abnormal trophoblast invasion, the association of cesarean section with placenta accreta and scar pregnancies, current management, and suggestions for future research to reduce the incidence of these potentially devastating complications of pregnancy.

Placenta Accreta: A Review of Current Advances in Prenatal Diagnosis

Placenta accreta is a life-threatening obstetrical condition requiring a multidisciplinary approach. Despite identified obstetrical risk factors, the diagnosis is often made at the time of delivery. Recent advances in biology could allow a prenatal screening of placenta accreta with the identification of biological markers in maternal blood including cell-free fetal DNA, placental mRNA, and DNA microarray. These promising technologies can detect the presence of anomalies and should play a future role in developing a better understanding of placental invasion. Ultrasound imaging is popular due to its low cost and accessibility and widely used for the screening of placenta location and potential abnormal development. This exam is associated with high sensitivity and specificity for diagnosis of placenta accreta when specific defined criteria are used for the diagnosis. A placental MRI provides a morphological description, as well as recently demonstrated topographical information that optimizes diagnosis and surgical management. The screening of placenta accreta should be improved with the use of a combination of these diagnostic techniques and benefit high-risk populations with a reduction in morbidity.

Vaginal Ultrasonographic and Hysterosonographic Evaluation of the Low Transverse Incision after Caesarean Section: Correlation with Gynaecological Symptoms

AIM

We investigated whether there is a correlation between morphological changes of the lower uterine segment after caesarean section (CS), visualized by means of either a transvaginal sonography (TVS) or a sonohysterography (SHG), and the frequency of abnormal uterine bleedings reported by the women.

METHODS

By means of a random selection of our population, anamnesis, medical records, and TVS and SHG images of the lower uterine segment were collected in 217 women (116 with previous CS and 101 with previous vaginal birth), and an observational case-control study was performed.

RESULTS

The uterine incision was identified in almost all women after CS (102/116) using TVS. It was observed that abnormal uterine bleeding was significantly more frequent in the CS group in comparison with the group of women who delivered vaginally. A correlation between the presence of abnormal uterine bleeding and the presence of significant sonographic findings in the lower uterine transverse incision in the women after CS was found. In the CS group, TVS findings were confirmed by those obtained by SHG, and, with this technique, a triangular anechoic area at the presumed site of incision (the niche) was identified in 69 of the 116 women (59.5%).

CONCLUSIONS

In this study, we found a correlation between abnormal uterine bleeding and sonographic findings in women after CS. This correlation appears to be more significant in women who had CS 5-10 years ago. A significant difference exists between the CS group and the group of women who delivered vaginally for both frequency of abnormal uterine bleeding and sonographic findings.

Laparoscopic and vaginal repair of uterine scar dehiscence following cesarean section as detected by ultrasound

INTRODUCTION AND OBJECTIVE

Cesarean section (CS) is the most common operation in obstetrics, with rising incidence in most countries. As a result of this operation late scar dehiscence may occur, which may lead to uterine rupture in a subsequent pregnancy. In this case series we have described sonographic detection of scar dehiscence after CS and feasibility of vaginal or combined laparoscopic and vaginal scar excision and uterine repair.

METHODS

Five consecutive patients underwent vaginal or laparoscopic assisted vaginal approach for repair of suspected scar dehiscence following CS, during a 5 year period. In all cases, transvaginal sonography detected suspicious features of scar dehiscence over the anterior uterine wall. Except of one, all patients had reported recurrent pelvic pain and/or irregular menstrual bleedings. Furthermore all patients planned for a further pregnancy.

RESULTS

Resection of the uterine defect and re-constitution of the uterine wall was successfully achieved in all five patients. There were no intra-operative complications and none of the patients required blood transfusion. The mean operation time was 117 min (27-192). Presence of scar tissue was confirmed on histology in all specimens. Four patients remained free of symptoms with no evidence of recurrent scar dehiscence on sonography over a median follow up of 30 months (3-46). One patient had an uneventful pregnancy 24 months after scar removal and was delivered by repeat CS at 39 weeks' gestation.

CONCLUSION

Patients with a history of CS should undergo transvaginal sonography of the scar region in order to detect latent scar dehiscence in combination with uterine wall thinning prior to planning further pregnancy. In suspected cases, a combined laparoscopic - vaginal or vaginal approach can be employed to repair the defect.

Recent advances in the management of placenta previa

PURPOSE OF REVIEW

Despite the widespread and routine use of ultrasound to make the diagnosis of placenta previa, evidence-based classification and management strategies have failed to evolve over the years. The purpose of this review is to present the current evidence supporting the screening, diagnosis and management of placenta previa.

RECENT FINDINGS

The prevalence of placenta previa is significantly overestimated due to the practice of routine mid-pregnancy scan, and many women currently undergo a repeat scan in late pregnancy for placental localization. Recent reports support limiting third-trimester scans to only those cases where the placental edge either reaches or overlaps the internal cervical os at 20-23 weeks of pregnancy. In some cases of mid-trimester placenta previa, the placental edge is more likely to "migrate" than others, and it appears that ultrasound may be useful to predict this process. At term, women with placental edge within 2 cm of the internal cervical os require a Caesarean section for delivery, whereas an attempt at vaginal birth is appropriate if this distance is more that 2 cm. Ultrasound also has a role in the diagnosis and management of both vasa previa and placenta accreta.

SUMMARY

This review addresses screening for placenta previa. A simple and pragmatic ultrasound classification of placenta previa and low-lying placenta is proposed. Caesarean section is recommended for delivery in cases of placenta previa. Women with a low-lying placenta have at least 60% chance of a vaginal birth, but should be monitored for post-partum haemorrhage. Vasa previa is a rare complication but antenatal diagnosis is possible. It should particularly be suspected in in-vitro fertilization conceptions, and where the placental edge covers the os in mid-pregnancy but recedes later on. Prenatal diagnosis of placenta accreta should be based on the placental lacunae signs rather than the absence of retro-placental clear space.