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Obstetrics and Gynecology > antepartum hemorrhage > Flashcards

antepartum hemorrhage Flashcards

1
Q

what are the 3 main causes of first trimester bleeding

A

ectopic

SA

normal pregnancies

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2
Q

what are the major causes of antepartum hemorrhage

A

placenta previa (20%)

placental abruption (30%)

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3
Q

define placental previa

A

abnormal implantation of the placenta over the internal cervical os

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4
Q

define complete previa

A

placenta completely covers the internal os

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5
Q

define partial previa

A

occurs when the placenta covers a portion of the internal os

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6
Q

define marginal previa

A

edge of placenta reaches margin of the os

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7
Q

define low lying placenta

A

implanted in the lower uterine segment in close proximity but not extending to the internal os

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8
Q

define vasa previa

A

fetal vessel lying over the cervix

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9
Q

define placental migration

A

with the progression of pregnancy, more than 90% of low lying placentas will appear to move away from the cervix and out of the lower uterine segment

the placenta does not actually move itself, but instead the lower uterine segment stretches and elongates

also the placenta may grow preferentially towards a better vascularized fundus (trophotropism) whereas the placenta overlying the less well vascularized lower uterine segment atrophies

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10
Q

define succenturiate lobe

A

is cases where atrophy of the placenta in the lower uterine segment is incomplete and leaves a placental lobe discrete from the rest of the placenta

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11
Q

why do placenta previas bleed

A

results from small disruptions in the placental attachment during normal development and thinning of the lower uterine segment during the third trimester

bleeding may stimulate further uterine contractions which in turn stimulates further placental separation and bleeding

initial bleeds are rarely a problem–> however in labour as the cervix dilates and effaces, there is usually placental separation and unavoidable bleeding –> profuse hemorrhage and shock can occur

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12
Q

what is the rate of maternal mortality due to placenta previa in the US

A

0.03%–> 10x higher than general pop

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13
Q

list fetal complications associated with placenta previa

A

preterm delivery and its complications

preterm premature rupture of membranes

intrauterine growth restriction

malpresentation

vasa previa

congenital abnormalities

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14
Q

define placenta accreta

A

superficial attachment of the placenta to the uterine myometrium

may complicate placenta previa

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15
Q

define placenta increta

A

invades the myometrium

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16
Q

define placenta percreta

A

placenta invades the myometrium to the uterine serosa

this may lead to invasions of other organs like the bladder or rectum

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17
Q

why do we care about placenta accreta

A

causes an inabillity of the placenta to properly separate from the uterine wall after the delivery of the fetus

can result in profuse hemorrhage and shock with substantial maternal morbidity and mortality (need for hysterectomy, surgical injury to ureters, bladder, other viscera, adults respiratory distress syndrome, renal failure, coagulopathy, death)

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18
Q

what is the average blood loss at delivery in women with placenta accreta

A

3000-5000 mL

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19
Q

what % of women with both placenta previa and accreta require a hysterectomy at the time of delivery

A

“peripartum hysterectomy”

2/3 require this if have both conditions

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20
Q

list placental causes of antepartum bleeding

A

placenta previa
placental abruption
vasa previa

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21
Q

list maternal causes of antepartum bleeding

A

uterine rupture

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22
Q

list fetal causes of antepartum bleeding

A

fetal vessel rupture

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23
Q

list cervical causes of antepartum bleeding

A

severe cervicitis
polyps
cervical dysplasia/cancer

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24
Q

list vaginal/vulvar causes of antepartum bleeding

A

lacerations
varices
cancer

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25
Q

list other causes of antepartum bleeding

A

hemorrhoids
congential bleeding disorder
abdo or pelvic trauma
hematuria

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26
Q

what % of women with previous C/S get placenta previa

A

1-4%

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27
Q

what % of women with placenta previa also have placenta accreta

A

5%—> risk of placenta accreta is increased in women with placenta previa in the setting of prior C/S–> gtes much higher the more C/S the woman has had

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28
Q

why do you get abnormalities in placentation

A

result of events that prevent normal migration of the placenta during normal progressive development of the lower uterine segment during pregnancy

previous placental implantations and prior uterine scars are thought to contribute (i.e previous myomectomies, uterine anomalies, smoking, previous placenta previa)

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29
Q

how do women with placenta previa usually present

A

sudden and profuse painless vaginal bleeding

the first/”sentinel” bleedin usually occurs after 28 weeks of gestation

during this time, the lower uterine segment develops and thins, disrupting the placental attachment and resulting in bleeding

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30
Q

how does placenta accreta/incrata usually present

A

usualyl asymptomatic

on rare occasions, patient with percreta into the bladder or rectum may present with a hematuria or rectal bleeding

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31
Q

how do you examine a woman with placenta previa

A

vaginal examination is contraindicated as the digital exam can cause further separation of the placenta and trigger catastrophic hemorrhage

if it is undiagnosed prior to exam, and an exam is performed, cervical exam may reveal soft, spongy tissue just inside the cervix

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32
Q

define circumvallate placenta

A

occurs when the membranes double back over the edge of the placenta, forming a dense ring around the periphery of the placenta–> often considered a variant of placental abruption–> major cause of second trimester hemorrhage

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33
Q

define velamentous placenta

A

blood vessels insert between the amnion and chorion, away from the margin of the placenta, leaving the vessels largely unprotected and vulnerable to compression or injury

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34
Q

define succenturiate placenta

A

extra lobe of the placenta that is implanted at some distance away from the rest of the placenta–> fetal vessels may course between the two lobes, possibly over the cervix, leaving these vessels unprotected and at risk for rupture

35
Q

how do you diagnose placenta previa

A

U/S–> sensitivity over 95%

follow up U/S in third trimester if dx made in second trimester to determine if has resolved

TRANSVAGINAL U/S is better (transabdominal causes more false positives)

36
Q

how do you diagnose placenta accreta

A

U/S or MRI

37
Q

in which women should you suspect placenta accreta

A

women who have both placenta previa and a hx of C/S or other uterine surgery

38
Q

how is placenta previa managed

A

strict pelvic rest (no intercourse and no excessive activity) and modified bed rest

some clinicians wait until sentinel bleed has happened before instructing strict pelvic rest

some clinicians hospitalize patients after sentinel bleed

39
Q

what are indications for immediate C/S in setting of placenta previa

A

unstoppable labour
fetal distress
life threatening hemorrhage

regardless of gestational age

patients with complete or partial previa require C/S

40
Q

can patients with low lying placenta or marginal placenta previa (more than 2 cm from internal os) delivery vaginally

A

yes as long as there is no evidence of fetal distress or excessive hemorrhage

41
Q

what % of women with placenta previa require delivery before week 36 due to recurring bleed episodes

A

70%

of those that make it to 36 weeks, advise C/S between 36-37 weeks depending on fetal lung maturity

42
Q

describe a course of action plan in the case of a woman with vaginal bleeding and suspected placenta previa and/or placenta accreta

A
  1. stabilize the patient–> every patient with vag bleeding and known or suspected previa should be hospitalized
  2. place on continuous fetal monitoring
  3. have IV access established –> if large bleed, two large bore IV catheters
  4. lab evaluation–> hematocrit, group and screen, PTT, d dimer, fibrinogen
  5. if Rh -, should do KB test to determine extent of any fetomaternal transfusion –> rhogam if necessary
  6. if not yet a catastrophic hemorrhage, can do expectant management–> hospitalization, bed rest, hematocrit monitoring, consideration of limiting oral intake–> 1 or 2 units of typed/matched blood should be made available
  7. transfuse to maintain a hematocrit of 25% or greater
  8. if woman is between 24-34 weeks when admitted for bleed, give steroids to promote fetal lung maturity
  9. detailed U/S to exclude accreta
  10. if before 32 weeks–> manage moderate to severe bleed aggressively with transfusions, rather than moving towards delivery–> cautious use of tocolytics in women with previa who appear to be having contractions can help prolong pregnancy up to 34 weeks
43
Q

define placental abruption

A

premature separation of the normally implanted placenta from the uterine wall, resulting in hemorrhage between the uterine wall and the placenta

44
Q

when do 50% if placental abruptions occur

A

before labour and after 30 weeks

45
Q

what % of placental abruptions occur during labour

A

15%

46
Q

what % of placental abruptions are found only on placental inspection after delivery

A

30%

47
Q

what are the risks associated with placental abruption

A

premature delivery
uterine tetany
DIC
hypovolemic shock

48
Q

what is the primary cause of placental abruption and what are associated predisposing and precipitating factors

A

primary cause unknown –could be due to abnormal placental vasculature, thrombosis, reduced placental perfusion

49
Q

what are associated predisposing and precipitating factors for placenta abruption

A

predisposing–

HTN 
previous abruption
advanced maternal age
multiparity
uterine distension 
multiple pregnancy
polyhydramnios
vascular deficiency
DM
collagen vascular disease
cocaine use
meth use
cigarette smoking
alcohol use
circumvallate placenta
short umbilical cord

precipitating factors–

trauma
external/internal version
MVA
abdo trauma 
sudden uterine volume loss
delivery of first twin
rupture of membranes with polyhydramnios
PPROM
50
Q

describe the process of placental abruption

A

at initial point of separation, non clotted blood courses from the injury site–> enlarging collection of blood may cause further separation from the placenta

51
Q

in what % if apruptions is bleeding confined within the uterine cavity

A

20%–> concealed hemorrhage

52
Q

why can concealed hemorrhages actually cause greater fetal demise

A

because form retroplacental clots that are asymtomatic to the mom but can cause fetal demise

53
Q

what is the cause of death in women with placental abruption

A

hemorrhage
cardiac failure
renal failure

54
Q

what is the rate of fetal mortality in placental abruption

A

35% of all clinically relevant antepartum placental abruptions (can be as high as 50-80% if severe)

cause of fetal demise is usually hypoxia from decreased placental surface area and maternal hemorrhage

55
Q

what % of third trimester bleeding is due to placental abruption

A

30%

56
Q

what % of perinatal mortality is due to placental abruption

A

15%

57
Q

why is there such high mortality associated with abruption

A

due to strong association with preterm birth –> more than 50% of excess perinatal deaths in pregnancies with abruption are accounted for by premature delivery

58
Q

what is the most common factor associated with increased incidence of abruption

A

HTN (whether due to chronic, preeclampsia, cocaine or meth)

in cases that are severe enough to cause fetal death, 50% are due to HTN (25% chronic HTN and 25% preeclampsia)

59
Q

what is the further risk of abruption after one abruption

A

10%

25% risk after 2 prior

60
Q

what is the classic presentation of placental abruption

A

third trimester vaginal bleeding associated with severe abdo pain and/or frequent, strong contraction

30% of abruptions are small with few or no symptoms and are only ID-ed after birth

classically taught that painless uterine bleeding is more likely previa and painful bleeding is more likely abruption (however labour accompanying previa may look like abruption)

61
Q

placental abruption on exam

A

vaginal bleeding with firm, tender uterus

on tocometer, small, fequent contractions are usually seen along with tetanic contractions

non reassuring NSTs are often seen secondary to hypoxia

62
Q

what is the classic sign of abruption seen at C/S delivery

A

Couvelaire uterus–> life threatening condition and occurs when there is enough blood from the abruption that markedly infiltrates into the myometrium to reach the serosa, especially at the cornua, that is gives the myometrium a bluish/purple tone that can be seen on the surface of the uterus

63
Q

how is apruption diagnosed

A

mostly clinical

only 2-25% of abruptions are dx through U/S (retroplacental clot)

however, U/S is often done when presenting with abruption to tule out previa with vaginal bleeding

negative findings on U/S CANNOT exclude placental abruption and dx should be confirmed with inspection of placenta at delivery

presence of retroplacental clot with overlying placental destruction confirms the diagnosis

64
Q

what lab test may indicate a severe abruption

A

a consumptive coagulopathy (low fibrinogen, high d dimer) due to activation of intravascular coagulation with varying degrees of defibrination

65
Q

do you have to deliver right away in placental abruption

A

in some cases due to risk of rapid deterioration but most are small and non catastrophic and thus do not need immediate delivery

66
Q

describe an action plan for management of a patient presenting with abruption

A
  1. if abruption is known or suspected, hospitalize patient and place on continuous fetal monitoring with IV access
  2. lab eval should include CBC, group and screen, PTT, fibrinogen, d dimer
  3. rho gam for Rh - women
  4. notify anesthesia in case C/S is needed urgently
  5. start infusion of ringers lactate and prepare cross matched blood in case of hemorrhage (help prevent hypovolemia and DIC due to consumptive coagulopathy)
  6. in preterm pregnancies, can give betamethasone to promote fetal lung maturity; can possibly use tocolytics to prolong pregnancy to week 34 if otherwise stable
  7. if bleeding is life threatening or fetal testing is non reassuring, should deliver baby regardless of GA or steroid admin status –> vaginal delivery is preferred as long as bleeding is controlled and there are no signs of fetal distress
67
Q

when do most complete uterine ruptures occur

A

during the course of labour–> more than 90% of all uterine ruptures are associated with a prior uterine scar either from C/S or other uterine surgery

68
Q

other than prior uterine scar, what can cause a uterine rupture

A

abdominal trauma–> MVA, version procedures

associated with labour and delivery–> improper oxytocin use or excessive fundal pressure

spontaneous–> placenta percreta, muliple gestation, grand multiparity, invasive mole, choriocarcinoma

69
Q

what are the primary maternal complications from a uterine rupture

A

hemorrhage and hypovolemic shock

70
Q

what is the overall maternal mortality for uterine rupture

A

less than 1%

but if rupture occurs in antepartum patient at home, it is higher

71
Q

what is the risk of uterine rupture in women with low transverse C/S scars? vertical scars?

A

transverse–0.5-0.1%

vertical–6-12%

72
Q

list risk factors for uterine rupture

A

prior uterine surgery/scar

injudicious use of oxytocin

grand multiparity

marked uterine distension

abnormal fetal lie

large fetus

external version

trauma

73
Q

how does uterine rupture present

A

highly variable

typically characterized by sudden onset of intense abdominal pain

bleeding may not be present, or may vary from spotting to lots of bleeding

can also have non reassuring NST, abnormal abdo contour, cessation of uterine contractions, disappearance of fetal heart tones, regression of the presenting part

74
Q

how do you treat uterine rupture

A

immediate laparotomy and delivery of the fetus

if feasible, rupture site should be repaired and hemostasis obtained–> in cases of large rupture, may need hysterectomy

patients discouraged to attempt further pregnancies due to risk of rupture –> trial of labour should be avoided if they do have another pregnancy

75
Q

what is the most common reason for fetal vessel rupture?

A

most due to velamentous cord insertion –> blood vessels insert between amnion and chorion away from placenta instead of directly into chorionic plate

may also occur with a succenturiate lobe of the placenta

76
Q

what is the pathogenesis behind fetal vessel rupture due to velamentous cord insertion?

A

because vessels course unprotected through the membranes before inserting onto the placental margin, they are vulnerable to rupture, shearing or laceration

also may cross over the internal os (vasa previa) making them vulnerable to compression by the presenting fetal part or may be torn during the rupture of membranes

77
Q

what is the perinatal mortality associated with vasa previa

A

40-60%

increases if membranes are also ruptured

78
Q

list risk factors for rupture of fetal vessels

A

abnormal palcentation leading to succenturiate lobe

multiple gestation that increases risk of velamentous insertion

79
Q

how does vasa previa present

A

if known–> fetal vessels are palpated and recognized through the dilated cervix

most commonly–> presentation of a fetal vessel rupture is vaginal bleeding associated with sinusoidal variation of the FHR indicative of fetal anemia

whenever bleeding accompanies rupture of membranes in labour, especially is there are associated decels/brady/sinusoidal heart tracing, OB should have high index of suspicion for ruptured vasa previa

80
Q

what fetal heart tracing is associated with fetal vessel rupture/fetal anemia

A

sinusoidal

81
Q

what test can be done at the time of vaginal bleeding to test for vasa previa

A

Apt test

diluting the blood with water, collecting the supernatant and combining it with 1% NaOH–> if mixture is pink, indicates fetal blood//if yellow-brown it is maternal blood

82
Q

how do you manage vasa previa/rupture of fetal vessels

A

high risk of fetal exsanguination and death –> need emergent cesaerean

immediate transfusions may be lifesaving

83
Q

how do non obstetric causes of antepartum hemorrhage usually present

A

spotting rather than frank bleeding

no uterine contractions or abdo pain

dx usually by speculum exam

pap tests, cultures or colposcopy as indicated

Obstetrics and Gynecology (21 decks)

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