The following statements are related to rupture uterus except:
Rupture Uterus
Disruption in the continuity of the all uterine layers (endometrium, myometrium and serosa) any time beyond 28 weeks of pregnancy is called rupture of the uterus.
The causes of rupture of the uterus are broadly divided into:

Spontaneous
Scar rupture
Iatrogenic

SPONTANEOUS
During pregnancy: It is rare for an apparently uninjured uterus to give way during pregnancy.
The causes are: 
(1) Previous damage to the uterine walls following dilatation and curettage operation or manual removal of placenta
(2) Grand multiparae ( due to weak uterine walls)
(3) Congenital malformation of the uterus (bicornuate variety)
(4) In Couvelaire uterus.
Spontaneous rupture during pregnancy is usually complete, involves the upper segment and usually occurs in later months of pregnancy.
During labor: Spontaneous rupture which occurs predominantly in an otherwise intact uterus during labor. It is due to:

Obstructive rupture—This is the end result of an obstructed labor. The rupture involves the lower segment and usually extends through one lateral side of the uterus to the upper segment.
Non-obstructive rupture—Grand multiparae are usually affected and rupture usually occurs in early labor. The rupture usually involves the fundal area and is complete.

SCAR RUPTURE: The incidence of lower segment scar rupture is about 1–2%, while that following classical one is 5–10 times higher. Uterine scar, following operation on the nonpregnant uterus such as myomectomy or metroplasty hardly rupture. Uterine scar following hysterotomy behaves like that of a classical scar. During pregnancy: Classical cesarean or hysterotomy scar is likely to give way during later months of pregnancy. Lower segment scar rarely ruptures during pregnancy.
Lower segment scar rarely ruptures during pregnancy
In incomplete rupture the peritoneal coat remains intact
Classical caesarean scar often rupture during late pregnancy
Risk of lower segment scar rupture is high compared to classical scar rupture