OBJECTIVE: The aim of this study was to explore the risk of levator ani muscle (LAM) avulsion and enlargement of the levator hiatus following vaginal birth after Cesarean section (VBAC) in comparison with vaginal delivery in primiparous women. METHODS: In this two-center observational case-control study, we identified all women who had a term VBAC for their second delivery at the Departments of Obstetrics and Gynecology at the Faculty of Medicine in Pilsen and the 1st Faculty of Medicine in Prague, Charles University, Czech Republic, between 2012 and 2016. Women with a repeat VBAC, preterm birth or stillbirth were excluded from the study. As a control group, we enrolled a cohort of primiparous women who delivered vaginally during the study period. To increase our control sample, we also invited all primiparous women who delivered vaginally in both participating units between May and June 2019 to participate. All participants were invited for a four-dimensional pelvic floor ultrasound scan to assess LAM trauma. LAM avulsion and the area of the levator hiatus were assessed offline from the stored pelvic floor volumes obtained at rest, during maximum contraction and during Valsalva maneuver. The laterality of the avulsion was also noted. The cohorts were then compared using the χ2 test and Wilcoxon's two-sample test according to the normality of the distribution. P < 0.05 was considered statistically significant. Multivariate regression analysis, controlling for age and body mass index (BMI), was also performed. RESULTS: A total of 356 women had a VBAC for their second delivery during the study period. Of these, 152 (42.7%) attended the ultrasound examination and full data were available for statistical analysis for 141 women. The control group comprised 113 primiparous women. A significant difference was observed between the VBAC group and the control group in age (32.7 vs 30.1 years; P < 0.05), BMI (28.4 vs 27.4 kg/m2 ; P < 0.05) and duration of the first and second stages of labor (293.1 vs 345.9 min; P < 0.05 and 27.6 vs 35.3 min; P < 0.05, respectively) at the time of the index birth. The LAM avulsion rate was significantly higher in the VBAC compared with the control group (32.6% vs 18.6%; P = 0.01). The difference between the groups was observed predominantly in the rate of unilateral avulsion and remained significant after controlling for age and BMI (adjusted odds ratio 2.061 (95% CI, 1.103-3.852)). There was no statistically significant difference in the area of the levator hiatus at rest (12.0 vs 12.6 cm2 ; P = 0.28) or on maximum Valsalva maneuver (18.6 vs 18.7 cm2 ; P = 0.55) between the VBAC and control groups. The incidence of levator hiatal ballooning was comparable between the groups (17.7% and 18.6%; P = 0.86). CONCLUSIONS: VBAC is associated with a significantly higher rate of LAM avulsion than is vaginal birth in nulliparous women. The difference was significant even after controlling for age and BMI. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Biomedical Center Faculty of Medicine in Plzen Charles University Plzen Czech Republic

Department of Obstetrics and Gynecology 1st Faculty of Medicine Charles University Prague Czech Republic

Department of Obstetrics and Gynecology Faculty of Medicine in Plzen Charles University Plzen Czech Republic

Zobrazit více v PubMed

Knight H, Gurol-Urganci I, Meulen J, Mahmood T, Richmond D, Dougall A, Cromwell D. Vaginal birth after caesarean section: a cohort study investigating factors associated with its uptake and success. BJOG 2014; 121: 183-192.

Zhang J, Troendle J, Reddy UM, Laughon SK, Branch DW, Burkman R, Landy HJ, Hibbard JU, Haberman S, Ramirez MM, Bailit JL, Hoffman MK, Gregory KD, Gonzalez-Quintero VH, Kominiarek M, Learman LA, Hatjis CG, van Veldhuisen P; Consortium on Safe Labor. Contemporary cesarean delivery practice in the United States. Am Obstet Gynecol 2010; 203: 326.e1-326.e10.

Gardner K, Henry A, Thou S, Davis G, Miller T. Improving VBAC rates: the combined impact of two management strategies. Aust N Z J Obstet Gynaecol 2014; 54: 327-332.

Guise JM, Eden K, Emeis C, Denman MA, Marshall N, Fu RR, Janik R, Nygren P, Walker M, McDonagh M. Vaginal birth after cesarean: new insights. Evid Rep Technol Assess (Full Rep) 2010; 191: 1-397.

Declercq E, Cabral H, Ecker J. The plateauing of cesarean rates in industrialized countries. Am J Obstet Gynecol 2017; 216: 322-323.

Dietz HP, Campbell S. Toward normal birth - but at what cost? Am J Obstet Gynecol 2016; 215: 439-444.

Hehir MP, Mackie A, Robson MS. Simplified and standardized intrapartum management can yield high rates of successful VBAC in spontaneous labor. J Matern Fetal Neonatal Med 2017; 30: 1504-1508.

Hehir MP, Fitzpatrick M, Cassidy M, Murphy M, O'Herlihy C. Are women having a vaginal birth after a previous caesarean delivery at increased risk of anal sphincter injury? BJOG 2014; 121: 1515-1520.

Lowder JL, Burrows LJ, Krohn MA, Weber AM. Risk factors for primary and subsequent anal sphincter lacerations: a comparison of cohorts by parity and prior mode of delivery. Am J Obstet Gynecol 2007; 196: 344.e1-5.

Räisänen S, Vehviläinen-Julkunen K, Cartwright R, Gissler M, Heinonen S. A prior cesarean section and incidence of obstetric anal sphincter injury. Int Urogynecol J 2013; 24: 1331-1339.

Rusavy Z, Francova E, Paymova L, Ismail KM, Kalis V. Timing of cesarean and its impact on labor duration and genital tract trauma at the first subsequent vaginal birth: a retrospective cohort study. BMC Pregnancy Childbirth 2019; 19: 207.

Jardine JE, Knight HE, Carroll FE, Gurol-Urganci I. Risk of obstetric anal sphincter injury in women having a vaginal birth after a previous caesarean section: a population-based cohort study. Eur J Obstet Gyn Rep Biol 2019; 236: 7-13.

Friedman T, Eslick GD, Dietz HP. Delivery mode and the risk of levator muscle avulsion: a meta-analysis. Int Urogynecol J 2019; 30: 901-907.

Schwertner-Tiepelmann N, Thakar R, Sultan A, Tunn R. Obstetric levator ani muscle injuries: current status. Ultrasound Obstet Gynecol 2012; 39: 372-383.

Dietz HP, Shek KL, Chantarasorn V, Langer SE. Do women notice the effect of childbirth-related pelvic floor trauma? Aust N Z J Obstet Gynaecol 2012; 52: 277-281.

Manzini C, Friedman T, Turel F, Dietz H. Vaginal laxity: which measure of levator ani distensibility is most predictive? Ultrasound Obstet Gynecol 2020; 55: 683-687.

Dietz HP, Franco AV, Shek KL, Kirby A. Avulsion injury and levator hiatal ballooning: two independent risk factors for prolapse? An observational study. Acta Obstet Gynecol Scand 2012; 91: 211-214.

Dietz H. Quantification of major morphological abnormalities of the levator ani. Ultrasound Obstet Gynecol 2007; 29: 329-334.

Thibault-Gagnon S, Yusuf S, Langer S, Wong V, Shek KL, Martin A, Dietz HP. Do women notice the impact of childbirth-related levator trauma on pelvic floor and sexual function? Results of an observational ultrasound study. Int Urogynecol J 2014; 25: 1389-1398.

Horak TA, Guzman-Rojas RA, Shek K, Dietz HP. Pelvic floor trauma: does the second baby matter? Ultrasound Obstet Gynecol 2014; 44: 90-94.

Dietz H, Abbu A, Shek K. The levator-urethra gap measurement: a more objective means of determining levator avulsion? Ultrasound Obstet Gynecol 2008; 32: 941-945.

Dietz HP, Bernardo MJ, Kirby A, Shek KL. Minimal criteria for the diagnosis of avulsion of the puborectalis muscle by tomographic ultrasound. Int Urogynecol J 2011; 22: 699-704.

Dietz H, Shek C, Clarke B. Biometry of the pubovisceral muscle and levator hiatus by three-dimensional pelvic floor ultrasound. Ultrasound Obstet Gynecol 2005; 25: 580-585.

Dietz HP, Shek C, De Leon J, Steensma A. Ballooning of the levator hiatus. Ultrasound Obstet Gynecol 2008; 31: 676-680.

Guzmán Rojas R, Shek K, Langer S, Dietz H. Prevalence of anal sphincter injury in primiparous women. Ultrasound Obstet Gynecol 2013; 42: 461-466.

Handa VL, Blomquist JL, Carroll M, Roem J, Muñoz A. Longitudinal Changes in the Genital Hiatus Preceding the Development of Pelvic Organ Prolapse. Am J Epidemiol 2019; 188: 2196-2201.

Nandikanti L, Sammarco AG, Kobernik EK, DeLancey JOL. Levator ani defect severity and its association with enlarged hiatus size, levator bowl depth, and prolapse size. Am J Obstet Gynecol 2018; 218: 537-539.

Kearney R, Miller JM, Ashton-Miller JA, DeLancey JO. Obstetric factors associated with levator ani muscle injury after vaginal birth. Obstet Gynecol 2006; 107: 144-149.

Valsky DV, Lipschuetz M, Bord A, Eldar I, Messing B, Hochner-Celnikier D, Lavy Y, Cohen SM, Yagel S. Fetal head circumference and length of second stage of labor are risk factors for levator ani muscle injury, diagnosed by 3-dimensional transperineal ultrasound in primiparous women. Am J Obstet Gynecol 2009; 201: 91.e1-7.

Urbankova I, Grohregin K, Hanacek J, Krcmar M, Feyereisl J, Deprest J, Krofta L. The effect of the first vaginal birth on pelvic floor anatomy and dysfunction. Int Urogynecol J 2019; 30: 1689-1696.

Shek K, Green K, Hall J, Guzman-Rojas R, Dietz HP. Perineal and vaginal tears are clinical markers for occult levator ani trauma: a retrospective observational study. Ultrasound Obstet Gynecol 2016; 47: 224-227.

Kimmich N, Birri J, Zimmermann R, Kreft M. Prediction of levator ani muscle avulsion by genital tears after vaginal birth - a prospective observational cohort study. Int Urogynecol J 2020; 31: 2361-2366.

Rusavy Z, Paymova L, Kozerovsky M, Veverkova A, Kalis V, Kamel R, Ismail K. Levator ani Avulsion Systematic Evidence Review (LASER). BJOG (in press).

Caudwell-Hall J, Kamisan Atan I, Brown C, Guzman Rojas R, Langer S, Shek KL, Dietz HP. Can pelvic floor trauma be predicted antenatally? Acta Obstet Gynecol Scand 2018; 97: 751-757.

Volløyhaug I, Mørkved S, Salvesen Ø, Salvesen K. Forceps delivery is associated with increased risk of pelvic organ prolapse and muscle trauma: a cross-sectional study 16-24 years after first delivery. Ultrasound Obstet Gynecol 2015; 46: 487-495.