Those who have a caesarean section typically have more blood loss than a vaginal birth; so 1000 mL is commonly used to determine excessive blood loss. It is easy to underestimate maternal blood loss because the primary method of assessment is visual observation. Evaluation and diagnosis
Identifying risk factors early in the pregnancy is essential in managing uterine atony and PPH. This allows for planning and organizing the necessary resources including staff, medicines, assistive devices, and the proper blood products. The delivery plan should also be cognizant of the ability of the hospital or facility to provide an appropriate level of care if any complications occur.Most diagnosis of uterine atony are made during the physical exam directly upon completion of the delivery. Diffuse uterine atony is typically diagnosed by patient observation rather than blood loss. The uterus can be directly palpated or observed indirectly using a bimanual examination post delivery. An atonic uterus can feel soft, "boggy" and/or enlarged. Bleeding from the cervical os is also common. If the atony is localized to one area of the uterus, the upper, fundal region may be still be squeezing while the lower uterine segment is non functional. This can be difficult to see with a cursory abdominal examination and easily overlooked. Therefore, a comprehensive vaginal, abdominal, and rectal examination should be performed. The physical examination may include  ultrasound imaging for rapid visualization of the uterus and other causes of bleeding.
The overall rate of severe PPH (>1000 ml) was much lower at an overall rate of 2.8%, again with the highest rate in Africa (5.1%). References
External links

WHO recommendations for the prevention and treatment of postpartum haemorrhage. Geneva: World Health Organization. 2012. ISBN 9789241548502. Postpartum hemorrhage and the B-Lynch technique