Postpartum hemorrhage | Reproductive system physiology | NCLEX-RN | Khan Academy

Postpartum hemorrhage | Reproductive system physiology | NCLEX-RN | Khan Academy


– [Voiceover] Postpartum hemorrhage, it’s as scary as the name sounds, and it is always an emergency. Unfortunately, it’s not an uncommon one because postpartum hemorrhage is one of the top three causes
of maternal mortality, and it is the absolute most common reason that postpartum women
are admitted to ICUs, or Intensive Care Units. You guys probably want a definition of postpartum hemorrhage. I wish I could give you a
simple, clear cut definition, but people have been struggling with coming up with one
for a really long time. There’s what I think
is the best definition, that postpartum hemorrhage
is any significant amount of blood loss that
occurs after delivery that makes the woman symptomatic. So an amount of blood loss that makes the woman feel fatigued, or light-headed, or confused and sweaty, or perhaps makes her look pale, or a significant amount of blood loss that results in signs
of low blood volumes. So signs such as low blood pressure, or rapid heart rate, or perhaps decreased urine production. So that’s what I think is the best sort of definition of
postpartum hemorrhage, any significant amount of blood loss that either results in symptoms or in signs of low blood volume. Then there’s the most common definition, that postpartum hemorrhage is a blood loss of more than 500 milliliters, so more than 500 milliliters, after a vaginal delivery, 500 milliliters after a vaginal delivery, and more than 1,000 milliliters with a C section. But this isn’t the best way really to define things since practitioners tend to underestimate
the amount of blood loss. Actual studies have shown that. Then finally, there’s a definition that postpartum hemorrhage is anything that results in more than a 10% fall in hemoglobin concentration. Hemoglobin is a lab measure of the amount of red blood cells that
you have in the body. This definition is even more problematic because it takes time for the blood loss to be reflected in lab values, and that time could delay treatment. All right, so hopefully that convinces you that this whole area of defining what postpartum hemorrhage is needs some work. Well let’s step away from that and let’s talk about what causes postpartum hemorrhage. So first, remember that after the delivery of the baby, the placenta separates from the uterus. That leaves these vessels that supplied the placenta broken and ruptured, but the myometrium, so the muscular layer of the uterine wall,
contracts and constricts these blood vessels to stop the bleeding. The reason why that works is because of the way that the muscle fibers of the uterus are arranged in kind of a crisscross pattern
around the blood vessels. So if these are the muscle
fibers of the uterus there, they’re arranged as kind of a lattice around the blood vessels so that when the muscle fibers contract, they actually clamp
down on the blood vessel to stop the bleeding. After that happens, the
coagulation pathways activate and they form a clot at the site at which the placenta was initially attached. Okay, so if you understand
all of that, hopefully, you’ll understand that any disturbance in any one of those events will lead to a postpartum hemorrhage, or an excessive bleeding
after the delivery of the baby. So for example, you could have a problem with the uterus not
contracting well enough, which is called uterine atony. So uterine atony, where the a stands for lack of. So lack of tone in the uterus. And you’ll actually feel a floppy, sort of limp uterus in that case. There are a few different things that can cause uterine atony to occur. So if the uterus is
over-distended for some reason, either from having
multiple fetuses inside it, so if a woman is having twins, or triplets, or quadruplets, or if the uterus has one baby, but that one baby is larger than normal, or perhaps if there’s
too much amniotic fluid inside the uterus, so any
cause of over-distension of the uterus can lead to atony. Or the atony could result from using uterine relaxing agents, or even from uterine fatigue from having really prolonged labor. So atony is one cause of
postpartum hemorrhage, and actually it’s the most common cause of postpartum hemorrhage. Now if you feel the uterus
and the uterus feels really firm and well contracted, then we have to consider another cause. So what are some of the other causes of postpartum hemorrhage? Well postpartum hemorrhage could also be the result of a coagulopathy. So it could be the
result of a coagulopathy, which is a term that we use to describe any sort of problem with
the clotting cascade. And you can have problems with the clotting cascade as a result of acquired or even inherited clotting factor deficiencies. So you could have too few clotting factors circulating in the blood. There are even certain
drugs that can affect coagulation, that can impair coagulation. Now if none of those causes are present, so if there’s no uterine atony and there’s no coagulopathy, it’s really important to consider trauma, or perhaps even lacerations that occurred during the delivery. So you need to do a
vaginal exam at that point to see if any of those causes are present. Now as far as treatment goes, postpartum hemorrhage isn’t treated much differently from
other causes of hemorrhage. If uterine atony is the
cause of the hemorrhage, we usually try first a uterine massage, and we’ll usually add
on a uterotonic agent, so an agent that helps
the uterus contract, to help the myometrium contract, and clamp down, and stop the bleeding. If coagulation defects are to blame, that’s treated with usually a transfusion of blood products containing the factors that are deficient in the patient’s blood. Traumatic bleeding lesions are usually treated surgically. But again, with all of
these different causes, you can’t forget how
you first and foremost treat a hemorrhage, and that is with repletion of blood volume. So that’s always very important. All right, so that is
postpartum hemorrhage in a nutshell.

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