Impact of a Bladder Flap on Cesarean Scar Niche Development

Overview

The goal of this trial is to examine if the completion or omission of a bladder flap impacts the location and formation of cesarean scar niche in women undergoing primary cesarean section. The main question it aims to answer is if omission of a bladder flap changes the prevalence of cesarean scar niche on a 6-8 week postpartum ultrasound. Researchers will compare participants that have a bladder flap made to those that have a bladder flap omitted at time of their primary cesarean delivery. Participants will have routine postpartum care and be asked to return for a 6-8 week postpartum transvaginal ultrasound.

Detailed description

As the rate of cesarean deliveries increases globally, the importance of a cesarean scar niche (CSN) has evolved into a significant clinical concern with long term obstetric and gynecologic implications including increasing risk for placenta accreta spectrum (PAS) in future pregnancies and abnormal uterine bleeding. In fact, the main cause of PAS is placentation into uterine scars secondary to cesarean deliveries

Bladder flap formation is a standard step in cesarean deliveries and involves dissecting the bladder off the uterus to push it inferiorly to allow better access to the lower uterine segment for hysterotomy and decrease risk of bladder injury. The lower uterine segment is targeted for hysterotomy as it has been shown that the proportion of muscle tissue and the thickness of the wall of the uterus increases as one travels from the cervix to the fundus. Therefore, by making an incision in the lower uterine segment, the surgeon has less tissue to go through to deliver the fetus and disrupts less muscle to preserve uterine myometrial integrity. While studies have suggested bladder flap omission in primary cesarean deliveries does not increase intraoperative complications and reduces operating time. CSN assessment was not an outcome evaluated in these studies and the decision to omit or perform a bladder flap is at the discretion of the surgeon.

Previous studies have looked at different surgical techniques and different cervical dilations at time of cesarean delivery and the impact on niche formation and location. There has been no consensus on hysterotomy or other surgical techniques to decrease risk of CSN formation. To our knowledge, there have not been studies that have assessed postoperative CSN in relation to completion or omission of a bladder flap prior to hysterotomy. As such, the investigator team hypothesizes that omission of a bladder flap lends itself to a more cephalad hysterotomy and potentially more clinically significant CSNs.

Interventions

• Procedure Bladder flap formation
  Participants in this arm will have a bladder flap completed at the time of their cesarean delivery.

Primary outcome measures

• Presence of cesarean scar niche [Time frame: From enrollment to transvaginal ultrasound, completed approximately 6-8 weeks postpartum]

Secondary outcome measures (7)

• Distance of cesarean scar niche from internal os [Time frame: From enrollment to time of transvaginal ultrasound, completed approximately 6-8 weeks postpartum]
• Size of cesarean scar niche [Time frame: From enrollment to time of transvaginal ultrasound, completed approximately 6-8 weeks postpartum]
• Measurement of residual myometrium [Time frame: From enrollment to time of transvaginal ultrasound, completed approximately 6-8 weeks postpartum]
• Size of cesarean scar defect in subsequent pregnancy [Time frame: From time of enrollment to time of subsequent pregnancy, up to 5 years following baseline pregnancy]
• Cases of abnormal placentation in subsequent pregnancies [Time frame: From time of enrollment to time of subsequent pregnancy, up to 5 years following baseline pregnancy]
• Uterine Position/Flexion [Time frame: From enrollment to time of transvaginal ultrasound, completed approximately 6-8 weeks postpartum]
• Number/percentage of Operative and Postoperative Complications [Time frame: From enrollment to time of transvaginal ultrasound, completed approximately 6-8 weeks postpartum]

Eligibility criteria

Inclusion criteria

• Age 18 years or older
• Primary low transverse cesarean section performed at Montefiore Weiler or Wakefield Hospitals
• Able to provide informed consent in English or Spanish
• Plan for postpartum care at Montefiore Medical Center

Exclusion criteria

• History of a prior uterine surgery
• Known congenital uterine anomalies
• Inability to safely access lower uterine segment at time of delivery
• Hysterotomy is extended past/outside the lower uterine segment at time of surgery
• Hysterectomy is indicated prior to postpartum follow-up

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Prevention

Study locations

United States · 2 centers

• Jack D. Weiler Hospital - Einstein Campus — The Bronx
• Montefiore Einstein Hospital - Wakefield Campus — The Bronx

Publications

• Kamel R, Thilaganathan B. Time to reconsider elective Cesarean birth. Ultrasound Obstet Gynecol. 2021 Mar;57(3):363-365. doi: 10.1002/uog.22158. No abstract available. PMID 33220003
• Kamara M, Henderson JJ, Doherty DA, Dickinson JE, Pennell CE. The risk of placenta accreta following primary elective caesarean delivery: a case-control study. BJOG. 2013 Jun;120(7):879-86. doi: 10.1111/1471-0528.12148. Epub 2013 Feb 28. PMID 23448347
• Shi XM, Wang Y, Zhang Y, Wei Y, Chen L, Zhao YY. Effect of Primary Elective Cesarean Delivery on Placenta Accreta: A Case-Control Study. Chin Med J (Engl). 2018 Mar 20;131(6):672-676. doi: 10.4103/0366-6999.226902. PMID 29521289
• O'Neill HA, Egan G, Walsh CA, Cotter AM, Walsh SR. Omission of the bladder flap at caesarean section reduces delivery time without increased morbidity: a meta-analysis of randomised controlled trials. Eur J Obstet Gynecol Reprod Biol. 2014 Mar;174:20-6. doi: 10.1016/j.ejogrb.2013.12.020. Epub 2013 Dec 22. PMID 24411951
• Tuuli MG, Odibo AO, Fogertey P, Roehl K, Stamilio D, Macones GA. Utility of the bladder flap at cesarean delivery: a randomized controlled trial. Obstet Gynecol. 2012 Apr;119(4):815-21. doi: 10.1097/AOG.0b013e31824c0e12. PMID 22395144
• Fukuda M, Fukuda K, Shimizu T, Bujold E. Ultrasound Assessment of Lower Uterine Segment Thickness During Pregnancy, Labour, and the Postpartum Period. J Obstet Gynaecol Can. 2016 Feb;38(2):134-40. doi: 10.1016/j.jogc.2015.12.009. Epub 2016 Mar 2. PMID 27032737
• Rorie DK, Newton M. Histologic and chemical studies of the smooth muscle in the human cervix and uterus. Am J Obstet Gynecol. 1967 Oct 15;99(4):466-9. doi: 10.1016/0002-9378(67)90292-x. PMID 4167498
• Kamel R, Eissa T, Sharaf M, Negm S, Thilaganathan B. Position and integrity of uterine scar are determined by degree of cervical dilatation at time of Cesarean section. Ultrasound Obstet Gynecol. 2021 Mar;57(3):466-470. doi: 10.1002/uog.22053. PMID 32330331

Identifiers

NCT: NCT07634679 · 2025-17472

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗