Fostering Excellence in Obstetrical Surgery

Figures & data

Table 1 Obstetrical Surgeries Benefit and Risk Considerations^1–8

Obstetrical Surgery	Benefit	Risk
Caesarean Delivery (CD) (primary; repeat)^Citation1,Citation2	Indication dependent: maternal or fetal benefit Robson CD category classification	Uterine hysterotomy/closure Surgical complications Post-partum hemorrhage
Vaginal Birth after CD (VBAC)^Citation3,Citation4	Successful vaginal delivery has range of 65–70% Selected maternal and/or neonatal factors impact potential successful VBAC: maternal co-morbidities previous neonatal birth weight previous fetal presentation (breech; occiput posterior) previous labor factors (maternal, placental, fetal, uterine, cervix)	Uterine rupture risk 1% with maternal and neonatal morbidity (mortality)
Operative Vaginal Delivery (OVD)^Citation5,Citation6	Assisted vaginal delivery by forceps or vacuum techniques with appropriate indications and fetal factors (presentation, position, descent)	Maternal cervical and/or vaginal trauma Neonatal cranial trauma Post=partum hemorrhage with uterine, cervical, and vaginal sources
Placenta Accreta Spectrum (PAS)^Citation7,Citation8	Antenatal recognition allows for counselling and planning. Optimal US/MRI imaging is necessary for optimal planning. Surgical team -based care has improved patient safety and outcomes.	Increased risk based on the number of uterine incisions Hysterotomy scar with blastocyst implantation Unrecognized PAS until delivery results in severe post-partum hemorrhage risk

Table 2 Robson Caesarean Delivery (CD) Classification: International Comparisons^9–12

Robson CD Classification^Citation9	Population Description/Group	Quebec CD %^Citation10	France CD %^Citation11	Greece CD %^Citation12
Baseline: global CD rate 21–23%		22.9	24.0	60.9
1	Nulliparous (NP) normal onset of labor	12.2	11.5	6.9
2a 2b	NP/induction NP/preterm labor	15.6 2.1	18.0 (total)	10.7 23.9
3	Multiparous (MP) normal onset of labor	2.2	4.1	0.2
4a 4b	MP/induction MP/preterm labor	2.2 1.4	10.8 (total)	0.4 0.6
5	Previous CD	35	28.8	30.6
6	NP/breech	10.6	6.7	5.3
7	MP/breech	6.5	3.8	2.0
8	Multiple fetal pregnancy	4.3	7.5	7.0
9	Fetal anomalies	2.2	1.1	0.8
10	Preterm labor < 37 weeks	5.7	7.7	11.7

Table 3 Uterine Closure Detail

Study Method [Reference]	Technique	Outcome
	Suture Type
Randomized Controlled Trial-2022^Citation13	Monofilament vs multifilament for uterine closure at the time of CD	In singleton pregnancies undergoing primary or secondary CD, the use of synthetic absorbable monofilament sutures after a CD was not associated with a reduction in uterine scar defect at 6 months after delivery compared to the use of ‘synthetic absorbable multifilament sutures.
Systematic Review /Meta-Analysis −2022/2021^Citation14–16	Considering the suture type for hysterotomy closure reported that the MA did not support a specific type of suture material for uterine closure at CD because of insufficient evidence.	A barbed suture was associated with decreased operative time, the use of conventional monofilament suture was associated with an increase in uterine scar thickness, but the clinical utility of these differences is not clear. The decreased operative time for the barbed suture was supported by two additional SR-MA publications.
	Uterine Closure Techniques
Systematic Review/Meta-Analysis-2014^Citation17	Compared single vs double layers and locking and unlocking sutures	Current RCT evidence does not support a specific type of uterine closure for optimal maternal outcomes and is insufficient to conclude about the risk of uterine rupture. Single-layer closure and locked first layer are possibly coupled with thinner residual myometrium thickness.
Enhanced Recovery After Surgery-Caesarean Delivery Review −2022^Citation18	Closure of hysterotomy in two layers maybe associated with a lower rate of uterine rupture.
Enhanced Recovery After Surgery-Caesarean Delivery- 2018^Citation19	Closure of hysterotomy in two layers maybe associated with a lower rate of uterine rupture.	Evidence level Low; Recommendation grade Weak
Systematic Review/Meta-Analysis −2021^Citation20	Single and double-layer CD closure on residual thickness and isthmocele	High quality evidence shows that double-layer closure results in a higher RMT compared to single-layer closure, despite no significant difference in an isthmocele formation.
Systematic Review/Meta-Analysis −2021^Citation21	Single and double-layer uterine closure techniques after CD in terms of ultrasound findings and rate of CD complications.	Favoured double-layered closure for RMT; dysmenorrhea while single-layer closure had a shorter OR time. Both techniques had similar results for uterine dehiscence or rupture risk (RR1.88); healing ratio; maternal infectious morbidity; hospital stay; re-admission rate.
Systematic Review/Meta-Analysis −2018^Citation22	Single and double-layer closure Locked and unlocked sutures Inclusion verses exclusion of decidual layer	Double-layered unlocked sutures are preferable to single locked sutures regarding RMT, healing ratio, and dysmenorrhea. Excluding decidua seemed to result in higher niche prevalence.
Systematic Review /Meta-Analysis-2017 Letter To Editor-2017^Citation23,Citation24	Risk of CD scar defect following single vs double-layer uterine closure SR /MA	Single and double-layer uterine closure after CD had similar incidence of scar defect, uterine dehiscence, uterine rupture in a subsequent pregnancy (Evidence GRADE quality was low) LTE: no correction for unlocked and locked sutures; method and timing of niche assessment; 4 small RCTs were excluded from the original SR /MA
Prospective cohort- 2022^Citation25	Impact of selected risk factors on the healing process after CD using single-layer continuous suture excluding decidua	Systemic disease during pregnancy and in the maternal history and colonization of the cervical canal have no impact on uterine scar healing
Other Closure Techniques
Randomized Controlled Trial- 2021 Randomized Controlled Trial −2021 Letter To Editor- 2021^Citation26–28	Babu and Magon uterine closure technique: far-far-near-near (FFNN) continuous unlocked double-layer method carried out in a single step	Kelm: providing protection from an isthmocele formation and ensuring a sufficient RMT. Tahermanesh: FFNN large niche 3% / control double-layer 24% RMT not significantly different Closure time not significantly different
Randomized Controlled Trial 3 arms −2022^Citation29	Group I: Classical double-layer closure of uterine incision was performed as follows: a holding Vicryl 1–0 was placed in the left corner to stabilise and define the demarcation of the suture line. A continuous unlocked stitch beginning at the right corner was used, closing the whole thickness of the uterine wall, including the decidual layer. The second unlocked stitch was performed by Vicryl 1–0 in a lateral–lateral (horizontal) position, adapting the first layer. Up to three additional single sutures were added for hemostasis if required. Group II: The Turan technique may be summarised as follows: beginning in one corner, the incision is closed using Vicryl 1–0 stitch. The first layer is transversely passed through the inner myometrium decidua line, and second layer is transversely passed through outer myometrium-visceral line continuously in the form of a purse-string closure. With this technique, the original string is returned to the starting point and tied with a knot. Following the double-layered purse-string closure, the aperture left in the middle of the uterine incision is closed with one separate figure of eight suture. Group III: New approach can be summarised as follows: the incision is closed using Vicryl 1–0 stitch starting from one corner. The first layer is transversely passed through the inner myometrium-decidua line, and second layer is transversely passed through outer myometrium-visceral line continuously by alternating continuous stitches through the upper (step up) and the lower (step down) uterine flaps. The original string is returned to the starting point and tied with a knot as in the Turan technique. Following the double-layered step up–step down closure, additional single sutures were added for hemostasis if required.	Compared to group II and Group III, residual myometrial thickness was significantly thinner in group I (p < 0.001). The number of patients with uterine niche was 10 (50% of all scar defects) in group I whereas it was 4 (20%) in group II and 6 (30%) in group III. Operative time was significantly longer in group II (p < 0.001). This led to our conclusion that Turan technique and our new approach are associated with thicker myometrial thickness and less frequency of uterine scar defect than classical double-layer uterine incision closure; however, our approach takes less operative time.
Prospective cohort- 2022^Citation30	402 CD patients Group 1: classical primary continuous suturing Group 2: novel technique as Z-suture on both corners and 8 sutures in the remaining middle part incision closure	Group 2:  ● less bleeding  ● less sutures were used  ● increased RMT (197 ± 50 mm/146 ±39mm)  ● thickened RMT showed negative correlation with incision length after closure, number of needle passes, and required uterine closure time. Group 1 and 2 were equal re isthmocele.

Table 4 Most Common Causes for Severe Maternal Morbidity (SMM): Opportunity to Alter Outcome Was Identified in 62% of Cases (Strong in 20% and Possible in 42%)^40,41

SMM Element % of Cases	Unpreventable %	Possibly %	Preventable %
Obstetrical hemorrhage 27%	29	45	26
Placental hemorrhage 18%	57	29	14
Infection 14%	32	50	18
Cardiovascular disease 11%	61	22	17
Hypertensive disorder 10%	40	40	20
Other medical-surgical disease 10%	20	60	20

Table 5 Potential Implementation Strategy Considerations

Implementation Process Choices	Process Studies	Positive Impact	Mixed or No Impact
Processes Used and Evaluated^Citation81
Multi-faceted intervention	88	Moderate	Moderate
Pre-identified barriers	59	Moderate	Moderate
Stakeholder engagement	42	Low	Low
Single intervention	30	Low	Low
Intervention tailored to pre-identified barriers	38	Low	Low
Theory or framework used	25	Very Low	Low
Five priorities for research on implementation strategies^Citation82
1. Enhance methods for designing and tailoring implementation strategies 2. Specify and test mechanisms of change 3. Conduct more effectiveness research on discrete, multi-faceted, and tailored implementation strategies 4. Increase economic evaluations of implementation strategies 5. Improve tracking and reporting of implementation strategies

Table 6 Barriers, Interventions, and Strategies in Guideline Implementation⁸³

Level of Interaction	Barriers	Interventions	Strategies
Personal	Physician knowledge attitudes	Traditional: Opinion leaders CME Review Audit and feedback Interactive discussion Academic society MD participation re guideline creation	Dissemination techniques Educational access Educational meetings/CME Opinion leaders Standing orders
Guideline	Lack of evidence Plausibility of recommendations Complexity Poor layout Access to guidelines Lack of applicability Information focused on a single disease Exclusion of complex disease Lack of clear intervention goals Trialability	Evidenced-based Medicine. Short and user-friendly versions Easy access Decision support systems Checklists Clear interventions goals Pilot projects	Use of methods of evidence-based medicine guideline development Communication strategies Marketing outreach visits (Computerized) decision support systems Reminders Pilot projects
External	Organizational Lack of resources Lack of collaboration Social and clinical norms	Standardization Protocols linked to QI Financial incentives Facilitation Collaboration Local consensus	Improvements in organisation of care Standing orders Local consensus Local adaption Incorporation into established structures

Table 7 Additional Evidenced-Based Quality Impact Areas

Obstetrical Surgery Procedure [Reference]	Summary for Fostering Excellence
VBAC/TOLAC^Citation84	Increasing TOLAC in Finland/Despite the rapidly increasing CD incidence globally, the rates of CD have remained low in Finland. According to the Finnish institute for health and welfare (THL), the overall proportion of CD during the last decades in Finland was approximately 16%. The incidence rates for elective CD, after the first CD, had a decreasing trend, decreasing from 45% in 1999, to 28% in 2018. The rates for VBAC remained relatively constant, ranging between 38 and 52%, but a slightly increasing trend at the end of the study period was seen. The main finding of the study was that despite the increasing annual total number of deliveries with CD in the first pregnancy, the absolute numbers for VBACs have increased towards the end of the study period in Finland. The epidemiology of TOLACs and VBACs should be better studied around the world, as with the rapidly increasing rate of CDs, these events are becoming a more common challenges in health care.
[4]	USA effective but low participatory numbers for VBAC/A repeated cross-sectional analysis was performed for singleton, cephalic, term deliveries in individuals with a history of one or two caesarean deliveries using the National Vital Statistics System from 2010 to 2020. Temporal trends in attempted and successful TOLAC, as well as VBAC, were characterized using join point regression. Overall, 4,277,800 deliveries were included. Attempted TOLAC increased from 15.3% in 2010 to 21.7% in 2020, with an annual percent increase (relative) of 4.25% (95% CI 2.9–5.6%). Successful TOLAC increased from 69.8% to 74.7%, with an annual percent change (relative) of 0.91% (95% CI 0.7–1.2%). The VBAC rate similarly increased such that, by 2020, it was 16.2%. This study provides US population-level trends on attempted and successful TOLAC.
[85]	Ecologic studies may be the better process/Individual-level observational studies of intended treatment effects have the potential for confounding by indication (disease severity) and may result in a treatment designed to prevent an adverse event, that may appear to cause it. Therefore, the advantage of an ecologic over individual-level observational study in the assessment of intended treatment effect will hold, even if variations in disease severity, socioeconomic status, and other unmeasured factors, are taken into account as the treatment utilization is influenced by practice style in the local medical community independently of disease severity. Ecologic studies can suggest the need for changes in practice, help resolve ethical issues, and indicate priorities for randomized trials.
CD Risk^Citation60	Canada and birth location impact/Hospital tier and adverse maternal and neonatal outcomes among patients with a previous caesarean delivery showed no clear pattern of decreasing SMMM and SNMM with increasing tiers of service and hospital volume. All hospitals, irrespective of tier or size, should continually review their rates of adverse maternal and neonatal outcomes.
OVD^Citation63	The conclusion reported that the rates of maternal and neonatal trauma following OVD are high in Canada compared with other countries with similar rates of OVD and are especially high in some provinces. These high rates call for a reassessment of the safety of OVD, not just in Canada, but in all settings where the rates of OVD and the opportunities for OVD training are changing.
[86]	A ‘trial’ of instrumental delivery, which accounts for between 2–5% of OVDs, is a concept that has developed whereby certain steps are taken if an attempt at OVD is deemed to have a higher likelihood of failure. These steps include the OVD being attempted in an operating theatre, allowing an expedited recourse to CD if required, as well as being performed by a more experienced operator.
[6]	Factors that were identified in a failed OVD were an older patient age, higher body mass index, obstructed labor, and neonatal birth weight more than 4000 g. During this period (2016–2020), physicians who attempted more operative vaginal deliveries were less likely to fail.
PAS^Citation7	The accuracy of ultrasound in this diagnosis of PAS, among women with low lying or placenta previa with previous caesarean section scars, is high and recommended for all suspected cases.
[69]	FIGO has consensually proposed a new classification and guidelines criteria for the pathologic diagnosis of PAS diseases, with seven major MRI features identified for use in diagnosis and management of PAS [Patel-Lippmann 2023].
[79]	Toronto PAS service pathway: Multidisciplinary team/formation of the core multidisciplinary team of MFM and surgical gynecology specialists. Regionalized referral of patients for assessment, management, and follow-up. Coordination of care by clinical nurse specialist. Programmatic creation of care plan, checklist, and standardized surgical and anesthetic approach. Preoperative optimization of hemoglobin. Creation of deidentified PAS database. Routine MRI/instituted for all patients with US suspected PAS disorder. IIA balloons vs IIA surgical ligation/the balloon procedure-specific complication rate was audited at 11% during the 2009–2016 period. As a result of these results alongside a literature review highlighting potential complications, balloon use was ceased and IIA surgical ligation was introduced in 2017. Team meetings/formal monthly PAS multidisciplinary team meetings of all clinical stakeholders who participate in pre- and postoperative case/imaging/pathology review, quality improvement discussion, research, and audit. Optimization of hemoglobin/routine antenatal measurement of levels of hemoglobin and ferritin, hemoglobinopathy screening, followed by oral and/or parenteral iron supplementation where indicated. Tranexamic acid/routine use of the antifibrinolytic tranexamic acid 1 g IV at commencement of caesarean hysterectomy. Cell salvage/implementation of cell salvage as a mainstay of PBM. Surgical briefing/formalized introduction of comprehensive surgical briefing immediately before caesarean hysterectomy to discuss individual clinical characteristics and considerations. In addition, formalized intraoperative discussion between surgical and anesthesia teams before allogenic blood transfusion. A team approach to PBM was adopted here focusing on reduction in nonessential allogenic pRBC transfusions. Fellows/trainees from formalized 2-year fellowship programs in surgical gynecology and MFM were streamlined as routine members of the surgical team present at all elective and emergent cases.

Abbreviations: IIA, internal iliac arteries; MRI, magnetic resonance imaging; PBM, patient blood management; pRBC, packed red blood cells.

Betran AP, Ye J, Moller A-B, et al. Trends and projections of caesarean section rates: global and regional estimates. BMJ Global Health. 2021;6(6):e005671. doi:10.1136/bmjgh-2021-005671

 PubMed Web of Science ®Google Scholar

Wu ML, Nichols PM, Cormick G, Betran AP, Gibbons L, Belizan JM. Global inequities in cesarean section deliveries and required resources persist. Eur J Obstet Gynecol. 2023;285:31–40. doi:10.1016/j.ejogrb.2023.03.036

 Web of Science ®Google Scholar

Turner MJ. Delivery after a previous cesarean section reviewed. Int J Gynecol Obstet. 2023:1–6. doi:10.1002/ijgo.14854

 Web of Science ®Google Scholar

Bruno AM, Allshouse AA, Metz TD. Trends in attempted and successful trial of labor after cesarean delivery in the United States From 2010 to 2020. Obstet Gynecol. 2023;141:173–175. doi:10.1097/AOG.0000000000004998

 PubMed Web of Science ®Google Scholar

Operative vaginal birth. ACOG practice bulletin No. 219. American College of Obstetricians and Gynecologists. Obstet Gynecol. 2020;135:e149–59. doi:10.1097/AOG.0000000000003764

 PubMed Web of Science ®Google Scholar

Panelli DM, Leonard SA, Joudi N, et al. Clinical and physician factors associated with failed operative vaginal delivery. Obstet Gynecol. 2023;141:1181–1189. doi:10.1097/AOG.0000000000005181

 PubMed Web of Science ®Google Scholar

Maged AM, El-Mazny A, Kamal N, et al. Diagnostic accuracy of ultrasound in the diagnosis of placenta accreta spectrum: systematic review and meta-analysis. BMC Pregnancy Childbirth. 2023;23:354. doi:10.1186/s12884-023-05675-6

 PubMed Web of Science ®Google Scholar

Abdel Wahab M, Cackovic M. Placenta accreta spectrum and postpartum hemorrhage. Clin Obstet Gynecol. 2023. doi:10.1097/GRF.0000000000000783

 Web of Science ®Google Scholar

Campos MG, Franco-Sena AB, Rebelo F. Direct standardization method according to Robson classification for comparison of cesarean rates. BMC Pregnancy Childbirth. 2023;23:117. doi:10.1186/s12884-023-05416-9

 PubMed Web of Science ®Google Scholar

Roberge S, Dubé E, Blouin S, Chaillet N. Reporting caesarean delivery in Quebec using the Robson classification system. J Obstet Gynaecol Can. 2017;39(3):152e156. doi:10.1016/j.jogc.2016.10.0102017

 Google Scholar

Quibel T, Rozenberg P, Bouyer C, Bouyer J. Variation between hospital caesarean delivery rates when Robson’s classification is considered: an observational study from a French perinatal network. PLoS One. 2021;16(8):e0251141. doi:10.1371/journal.pone.0251141

 PubMed Web of Science ®Google Scholar

Glaxi P, Gourounti K, Vivilaki V, et al. Implementation of the Robson classification in Greece: a retrospective cross-sectional study. Healthcare. 2023;11:908. doi:10.3390/healthcare11060908

 Web of Science ®Google Scholar

Saccone G, Angelis MC, Zizolfi B, et al. Monofilament vs multifilament suture for uterine closure at the time of cesarean delivery: a randomized clinical trial. Am J Obstet Gynecol. 2022;4:1005592. doi:10.1016/j.ajogmf.2022.100592

 Google Scholar

Roberge S, Demers S, Berghella V, Chaillet N, Moore L, Bujold E. Impact of single- vs double-layer closure on adverse outcomes and uterine scar defect: a systematic review and meta-analysis. Am J Obstet Gynecol. 2014;211:453–460. doi:10.1016/j.ajog.2014.06.014

 PubMed Web of Science ®Google Scholar

Fay E, Sultan P, Bollag L. Cesarean delivery. In: Nelson G, Ramirez PT, Dowdy SC, Wilson RD, Scott MJ, editors. The ERAS Society Handbook for Obstetrics and Gynecology. Academic Press; 2022. ISBN 978-0-323-91208-2; Surgical Techniques. 261.

 Google Scholar

Caughey AB, Stephen L, Wood SL, et al. Guidelines for intraoperative care in caesarean delivery: enhanced recovery after surgery society recommendations (Part 2). Amer J Obstet Gynecol. 2018. doi:10.1016/j.ajog.2018.08.006

 Web of Science ®Google Scholar

Marchand GJ, Masoud A, Ruther S, et al. Effect of single- and double-layer cesarean section closure on residual myometrial thickness and isthmocele- A systematic review and meta-analysis. Turk J Obstet Gynecol. 2021;18:322–332. doi:10.4246/tjog.galenos.2021.71173

 PubMed Web of Science ®Google Scholar

Qayam K, Kar I, Sofi J, Panneerselvam H. Single-verses double-layer uterine closure after cesarean section delivery: a systematic review and meta-analysis. Cureus. 2021;13(9):e18405. doi:10.7759/cureus.18405

 PubMed Web of Science ®Google Scholar

Stegwee HB, Jordans IPM, van der Voet LF, et al. Uterine caesarean closure techniques affect ultrasound findings and maternal outcomes: a systematic review and meta-analysis. BJOG. 2018;125:1097–1108. doi:10.1111/1471-0528.15048

 PubMed Web of Science ®Google Scholar

Di Spiezo Sardo A, Saccone G, McCurdy R, Bujold E, Bifulco G, Bergella V. Risk of Cesarean scar defect following single- vs double-layer uterine closure: systematic review and meta-analysis of randomized controlled trials. Ultrasound Obstet Gynecol. 2017;30:578–583. doi:10.1002/uog.17401

 Google Scholar

Huire JAF, Stegwee SI, van der Voet LF, de Groot CJM, Hehenkamp WJK, Brolmann HAM. Risk of Cesarean scar defect following single- vs double-layer uterine closure. Ultrasound Obstet Gynecol. 2017;50:662–668. doi:10.1002/uog.18893

 PubMedGoogle Scholar

Bubny-Winska J, Zimmer-Stelmach A, Pomorski M. Impact of selected risk factors on uterine healing after cesarean section in women with single-layer uterine closure: a prospective study using two- and three-dimensional transvaginal ultrasonography. Adv Clin Exp Med. 2022;31(1):41–48. doi:10.17219/acem/142519

 PubMed Web of Science ®Google Scholar

Elkhouly NI, Abdelaal NK, Solyman AE, Elkelani OA, Elbasueny BF, Elhalaby AF. A new technique for uterine incision closure at the time of caesarean section: does it make a difference? J Obstet Gynaecol. 2022;42(3):416–423. doi:10.1080/01443615.2021.1910636

 PubMedGoogle Scholar

Erkayiran U, Arslanca T. Comparative analysis of classical primary continuous and novel technique uterine suturing methods on uterine scar formation after caesarean section: a prospective clinical study. Gynekologia Polska. 2022;93(7):552–557. doi:10.5603/GP.a2022.002

 Web of Science ®Google Scholar

Grechukkina O, Lipkind HS, Lundsberg LS, et al. Severe maternal morbidity review and preventability assessment in a large academic center. Obstet Gynecol. 2023;141(4):875–880. doi:10.1097/AOG.0000000000005116

 PubMed Web of Science ®Google Scholar

Kilpatrick SK, Ecker JL, Callaghan WM. Severe maternal morbidity screening and review. Obstetric care consensus No. 5. American College of Obstetricians and Gynecologists. Obstet Gynecol. 2016;128:e54–60.

 PubMed Web of Science ®Google Scholar

Peters S, Sukumar K, Blanchard S, et al. Trends in guideline implementation: an updated scoping review. Implement Sci. 2022;17:50. doi:10.1186/s13012-022-01223-6

 PubMed Web of Science ®Google Scholar

Powell BJ, Fernandez ME, Williams NJ, et al. Enhancing the impact of implementation strategies in healthcare: a research agenda. Front Public Health. 2019;7(3). doi:10.3389/fpubh.2019.0000

 Google Scholar

Vaajala M, Liukkonen R, Ponkilainen V, Kekki M, Mattila VM, Kuitunen I. The rates of vaginal births after cesarean section have increased during the last decades: a nationwide register-based cohort study in Finland. Arch Gynecol Obstet. 2023;308:157–162. doi:10.1007/s00404-023-07010-y]

 PubMed Web of Science ®Google Scholar

Wen SW, Kramer MS. Uses of ecologic studies in the assessment of intended treatment effects. J Clin Epidemiol. 1999;52(1):7–12. doi:10.1016/s0895-4356(98)00136-x

 PubMed Web of Science ®Google Scholar

Joseph KS, Young CB, Muraca GM, et al. Hospital factors associated with maternal and neonatal outcomes of deliveries to patients with a previous caesarean delivery: an ecological study. CMAJ. 2023;195:E178–86. doi:10.1503/cmaj.220928

 PubMed Web of Science ®Google Scholar

Muraca GM, Boutin A, Razaz N, et al. Maternal and neonatal trauma following operative vaginal delivery. CMAJ. 2022;194:E1–12. doi:10.1503/cmaj.210841

 PubMed Web of Science ®Google Scholar

Kane D, Wall E, Malone E, et al. A retrospective cohort study of the characteristics of unsuccessful operative vaginal deliveries. Eur J Obstet Gynecol Reprod Biol. 2023;26(285):159–163. doi:10.1016/j.ejogrb.2023.04.02

 Google Scholar

Patel-Lippmann KK, Planz VB, Phillips CH, Ohlendorf JM, Zuckerwise LC, Moshiri M. Placenta accreta spectrum disorders: updates and pictorial review of the SAR-ESUR Joint Consensus Statement for MRI. Radiographics. 2023;43(5):e220090. doi:10.1148/rg.220090

 PubMed Web of Science ®Google Scholar

Hobson SR, Kingdom JCP, Windrim RC, et al. Safer outcomes for placenta accreta spectrum disorders: a decade of quality improvement. Int J Gynecol Obstet. 2022;157:130–139. doi:10.1002/ijgo.13717

 PubMed Web of Science ®Google Scholar