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Prior non-lower segment uterine scar: when to plan cesarean delivery

Women with a prior non-lower uterine segment scar (including classical cesarean scar and myomectomy are at higher risk of uterine rupture in subsequent pregnancies, and late-preterm to early term delivery by repeat cesarean delivery should be planned.

The objective of this SMFM Consult article is to delineate the appropriate timing of delivery for women with a prior classical cesarean scar, prior myomectomy, multiple previous cesarean deliveries, and prior uterine rupture.

Definition: A prior non-lower uterine segment scar includes a classical cesarean scar, which is made by performing a vertical hysterotomy incision in the mid-portion of the uterus. Recommendations for the management of women with prior T or J uterine incisions with involvement of the upper uterine segment are the same as those for the management of women with a prior classical cesarean incision. 

Risks: The main concern in pregnancies after a non-lower uterine segment scar is the risk of uterine rupture.  

The risk for uterine rupture varies based on clinical scenario:

  • Risk is 4% to 9% for women with a prior classical cesarean who labor, with the overall range in the literature reported as 0.9% to 12%. 
  • Risk for uterine rupture after myomectomy may be somewhat lower but is difficult to quantitate given small numbers of cases reported in the literature.  
  • Risks of adverse outcomes do not appear to be elevated for women with multiple prior low-transverse cesarean scars.o Risk for women with a prior uterine rupture is hard to quantify, but may be as high as 9-10%  

Cesarean delivery timing to optimize maternal and neonatal outcomes:

  • Prior classical cesarean delivery, 36 - 37 weeks gestation 
  • Prior myomectomy, 37 - 38 weeks gestation
  • Multiple prior cesarean deliveries: 39 weeks
  • Prior uterine rupture: 36 – 37 weeks gestation