Maternal-Fetal Disorders B&B

Question 1

A woman in her 1st trimester of pregnancy presents to the ED with vaginal bleeding and abdominal pain, which she believes is appendicitis. Serum hCG level is measured, which are lower than expected. What is most likely going on, and how can you pharmacologically treat her?

Answer 1

ectopic pregnancy - almost all occur in fallopian tube (usually ampulla)

this causes placental tissue to develop abnormally, leading to an abnormally slow rise in hCG

dx w/ ultrasound
rx: methotrexate: folate antagonist (only used if ectopic pregnancy is small, larger require surgery)

Question 2

explain why the following are risk factors for ectopic pregnancy:
a. tubal disorders
b. Chlamydia or Neisseria infection
c. Kartagener syndrome

Answer 2

a. tubal disorders - almost all ectopic pregnancies occur in fallopian tubes

b. Chlamydia or Neisseria infection - may cause pelvic inflammatory disease, which damages fallopian tubes

c. Kartagener syndrome (aka primary ciliary dyskinesia) - fallopian tubes have ciliated epithelium to move fertilized egg along

Question 3

spontaneous abortion vs stillbirth

Answer 3

spontaneous abortion/miscarriage is pregnancy loss before 20 weeks, often requires D&C surgery to remove all fetal tissue

stillbirth/fetal demise is pregnancy loss after 20 weeks

Question 4

what is the usual cause of spontaneous abortion? what are some maternal risk factors?

Answer 4

50% due to fetal chromosomal abnormalities

risk factors: maternal smoking/alcohol/cocaine, maternal TORCH infections, hyper-coagulable state, Lupus/antiphospholipid syndrome

Question 5

what fetal system is usually defective in oligohydramnios vs polyhydramnios?

Answer 5

amniotic fluid comes from fetal urine + lung secretions, and major source for removal is fetal swallowing

therefore, it makes sense that oligohydramnios is often caused by fetal kidney problem (bilateral renal agenesis, posterior urethral valves in males) —> Potter’s sequence

… while polyhydramnios is often caused by fetal swallowing/GI problem (esophageal/duodenal atresia, anencephaly)

Question 6

will each of the following fetal abnormalities cause oligo- or poly-hydramnios? explain
a. bilateral renal agenesis
b. esophageal/duodenal atresia
c. posterior urethral valves (males)
d. anencephaly
e. fetal anemia

Answer 6

amniotic fluid comes from fetal urine/ removed via swallowing - oligohydramnios is often caused by fetal kidney problem, while polyhydramnios is often caused by fetal swallowing/GI problem

a. bilateral renal agenesis - kidneys can’t produce enough urine —> oligo-
b. esophageal/duodenal atresia - do not have fully formed GI tract —> poly-
c. posterior urethral valves (males) - tissue obstructs urine flow —> oligo-
d. anencephaly - may not have neurological function to swallow —> poly-
e. fetal anemia - high fetal CO increases urine production —> poly-

Question 7

Explain how fetal anemia can cause polyhydramnios. What infection is this associated with?

Answer 7

fetal anemia causes an increase in fetal cardiac output —> increased urine production —> polyhydramnios

can occur in parvovirus infection

Question 8

for each of the following maternal issues, state whether they cause oligo- or poly-hydramnios of the fetus:
a. preeclampsia
b. maternal diabetes
c. maternal vascular disease

Answer 8

a. preeclampsia - insufficient blood flow to placenta —> oligo-
b. maternal diabetes - fetal hyperglycemia causes polyuria —> poly-
c. maternal vascular disease - insufficient blood flow to placenta —> oligo-

Question 9

what is considered a low birth weight?

Answer 9

less than 2,500 grams or 5.5lbs

Question 10

what is the cause and consequence of a premature baby exhibiting persistent fetal circulation?

Answer 10

persistently high PVR (pulmonary vascular resistance) causes persistent R —> L shunt and hypoxemia

due to inadequate surfactant production, small vessels with thickened walls, excessive vasoconstriction

Question 11

what is the major risk factor for babies to develop necrotizing enterocolitis?

Answer 11

prematurity / low birth weight

intestinal necrosis/obstruction, usually in terminal ileum or colon - can lead to perforation

Question 12

what type of cerebral hemorrhage are low birth weight babies especially at risk for?

Answer 12

intraventricular hemorrhage into the lateral ventricle

due to underdevelopment/ poor auto-regulation of the germinal matrix (highly vascular area near ventricles)

—> hypotonia, loss of spontaneous movement, seizures, coma

Question 13

Pt is a newborn taken to the ED by their parents due to concerns of hypotonia and loss of spontaneous movements. Upon arrival, the baby begins to seize. The baby was born 4.7lbs prematurely. What is your most immediate concern?

Answer 13

intraventricular hemorrhage into the lateral ventricle

low birth weight babies are especially at risk due to underdevelopment/ poor auto-regulation of the germinal matrix (highly vascular area near ventricles)

Question 14

What causes placental abruption?

Answer 14

placental detachment prior to delivery of the baby due to blood loss from maternal vessels

rupture of maternal vessels in the decidua basalis —> blood gets between decidua basalis and uterus, and separates them —> loss of gas in nutrient exchange, life-threatening to mother and fetus

Question 15

A woman in her 3rd trimester of pregnancy presents to the ED with abrupt onset of painful vaginal bleeding, abdominal pain, and uterine contractions. What is your biggest concern, and what will be done?

Answer 15

placental abruption due to rupture of maternal vessels in decidua basalis

life-threatening (may lead to DIC) and diagnosed clinically because ultrasound is not reliable - treatment is to deliver the baby immediately

Question 16

How does placental abruption present?

Answer 16

occurs in 3rd trimester with abrupt onset of painful vaginal bleeding, abdominal/back pain, and uterine contractions

due to rupture of maternal blood vessels in decidua basalis

life threatening - may lead to disseminated intravascular coagulation (DIC) or renal cortical necrosis

Question 17

A woman in her 3rd trimester of pregnancy presents to the ED with abrupt onset of painful vaginal bleeding, uterine contractions, flank pain, and gross hematuria. What is most likely going on?

Answer 17

renal cortical necrosis secondary to placental abruption

placental abruption - due to rupture of maternal blood vessels in decidua basalis

cortical necrosis - due to ischemic necrosis, rare cause of acute renal failure but often associated with placental abruption

Question 18

why does it make sense that preeclampsia is a risk factor for placental abruption?

Answer 18

both are caused by issues with the spiral arteries of the uterus

Preeclampsia due to abnormal transformation of the trophoblasts into spiral arteries, while placental abruption is due to rupture of the spiral arteries

Question 19

what occurs in placenta previa?

Answer 19

placenta “previous” (placenta before baby) - placenta is attached to lower uterus, over/close to cervical os, blocking the baby’s way out

may cause painless bleeding, often requires C-section for safe delivery

Question 20

what is defective about a velamentous umbilical cord? what is the risk of this?

Answer 20

normal umbilical cords insert directly into the central placenta

velamentous umbilical cords insert into fetal membranes, then travel to the placenta - in this portion they are exposed and unprotected from Wharton’s jelly —> risk of rupture

Question 21

what occurs in fetal vasa previa?

Answer 21

vasa previa = vessels first

fetal blood vessels are near cervical os, in the way of the baby’s exit

associated with velamentous umbilical cords - insert into fetal membranes, then travel to the placenta - in this portion they are exposed and unprotected from Wharton’s jelly

C-section performed as soon as baby is ready to be born to prevent rupture

Question 22

placenta accreta vs placenta increta vs placenta percreta

Answer 22

all forms of abnormal placental attachment, caused by defective uterine decidualization (decidua basalis doesn’t growth properly or is blocked by scar tissue)

placenta accreta: placenta attaches to myometrium (most common) - Accreta is Attached

placenta increta: placenta grows into myometrium - Increta is Inside

placenta percreta: placenta penetrates myometrium and invades uterine serosa, may attach to bladder/rectum (most dangerous) - Percreta is Penetrating

Question 23

what is the most dangerous form of abnormal attachment of the placenta?

Answer 23

all forms due to defective uterine decidualization (decidua basalis doesn’t growth properly or is blocked by scar tissue)

most dangerous form is placenta percreta: placenta penetrates myometrium and invades uterine serosa, may attach to bladder/rectum

Question 24

what is the most important risk factor for abnormal placental attachment?

Answer 24

due to defective uterine decidualization

most important risk factor: prior C-section due to scar tissue blocking growth of decidua basalis

prior C-section + placenta previa = almost always abnormal attachment !

Question 25

what occurs if abnormal placental attachment goes undetected until birth?

Answer 25

placenta attaches to/ penetrates myometrium due to defective growth of the decidua basalis if undetected, placenta fails to detach after birth - parts are left behind and break into pieces, causing massive bleeding —> maternal hemorrhage, shock, DIC, ARDS fortunately, usually detected by ultrasound before and C-section is performed… however, hysterectomy is often still required due to inability to remove all the placental pieces

Question 26

what is the most common cause of postpartum hemorrhage and how is it treated?

Answer 26

*urine atony*: failure of spiral arteries to vasoconstrict after delivery treated with uterine massage or *oxytocin*

Question 27

how does amniotic fluid embolism occur?

Answer 27

during labor or shortly after, amniotic fluid/fetal cells/fetal debris enter maternal circulation and cause diffuse inflammatory reaction that is often fatal

Question 28

what are the 2 clinical phases of amniotic fluid embolism?

Answer 28

embolism of amniotic fluid/fetal cells/fetal debris that enters maternal circulation during/shortly after labor Phase I (respiratory/shock): respiratory distress, low O2, hypotension Phase II (hemorrhagic): massive hemorrhage, DIC, bleeding *seizures or coma may also occur, often fatal*

Question 29

how can you differentiate a female patient with seizures due to eclampsia vs seizures due to amniotic fluid embolism?

Answer 29

eclampsia will cause seizures on top of features of preeclampsia - HTN, proteinuria, end-organ damage that were throughout 3rd trimester amniotic fluid embolism will cause seizures in a patient who has usually had an otherwise healthy/normal pregnancy

Question 30

A women goes into labor after an uneventful pregnancy. Shortly after delivery, she goes into respiratory distress. She is hypotensive and bleeding heavily. She then begins to seize. What is your biggest concern?

Answer 30

amniotic fluid embolism - often fatal Phase I (respiratory/shock): respiratory distress, low O2, hypotension Phase II (hemorrhagic): massive hemorrhage, DIC, bleeding