Chapter 58: Amniotic Fluid and Fetal Membranes

what is the role of the amniotic fluid?

allows fetus to move freely within the amniotic cavity, maintains intrauterine temperature, and protects the developing fetus from injury

developing something from a source or origin

derivation

amniotic fluid is produced by…

umbilical cord, membranes, lungs, skin, and kidneys

the amount of amniotic fluid reflects the balance between ___ and ___.

production and removal

fetal portion of implantation

chorion frondosum

in the 2nd or 3rd trimester, what is primarily responsible for production of fluid?

kidneys

as the fetus and placenta mature, amniotic fluid production and consumption change. changes in amniotic fluid includes…

movement of fluid across chorion frondosum and fetal skin, fetal urine output and swallowing, GI absorption

the further functions of the amniotic fluid include…

acts as cushion to protect fetus, allows embryonic and fetal movements, prevents adherence of amnion to embryo, allows symmetric growth, maintains constant temperature, acts as a reservoir to fetal metabolites before excretion by maternal system

___ development is highly dependent on amniotic fluid.

lung

the amount of amniotic fluid is regulated by…

production of fluid, removal of fluid by swallowing, fluid exchange within lungs, membrane and cord

amniotic fluid ____ during first trimester.

increases rapidly

AF volume increases rapidly during the first trimester and as the fetus grows, and peaks in the ___.

third trimester

when the fetus swallows the fluid, it is either ___ or ___.

reabsorbed by the GI tract or recirculates through the kidneys

there is increased AF production in which trimester?

1st

fluid should be ___.

anechoic

in cases of a funneling cervix or incompetent cervix, the baby is at risk for ___.

preterm delivery

if particulate matter is seen at the internal os of the cervix, it is likely due to ___.

hemorrhage

what type of assessment performed as sonographer initially scans “through” entire uterus to determine a visual of fluid present, lie of fetus, and the position of the placenta?

subjective

when measuring fluid, the probe should be ___.

perpendicular to the floor

an MVP of ___ is considered oligo.

< 2 cm

an MVP of __ is considered poly.

>8 cm

an AFI of ___ is considered oligo.

<5 cm

an AFI of ___ is considered poly.

>24 cm

the largest pocket of AF is typically found in the ___.

lower lateral quadrants

a 2×2 cm pocket of fluid for the MVP is ___.

normal

if there is a separating membrane in a twin pregnancy, how should fluid be measured?

MVP in each sac

why would color doppler be used when doing an AFI?

to confidently show no cord is in the measurement

polyhydramnios is associated with ____.

increased perinatal mortality and morbidity and maternal complications

a patient with poly will present with clinical finding of __.

uterus that measures greater than dates

in cases of poly, sonography is order to rule out…

multiple gestation, molar pregnancy, or fetal size greater than dates

acute onset of polyhydramnios may…

be painful, compress other organs or vascular structures, cause hydronephrosis, produce SOB

polyhydramnios is often associated with ___ disorders and/or ____ problems.

CNS, GI

CNS disorders cause ___.

depressed swallowing

GI abnormalities result in _____ that are often caused by a blockage of the esophagus, stomach, duodenum, small bowel.

inneffective swallowing

GI abnormalities result in ineffective swallowing that are often caused by a ____.

blockage (atresia)

GI abnormalities result in ineffective swallowing that are often caused by a blockage (atresia) of the…

esophagus, stomach, duodenum, small bowel

if there is duodenal atresia, there will be a ___ sign.

double bubble

fluid around baby in places that it shouldn’t be

fetal hydrops

maternal conditions associated with polyhydramnios include…

diabetes mellitus, obesity, Rh incompatibility, anemia, congestive cardiac failure

what are the sonographic findings of polyhydramnios?

freely floating fetus within swollen amniotic cavity, accentuated fetal anatomy, AFI greater than 24 cm

baby moving too much is a subjective finding of ___.

polyhydramnios

no fluid

anhydramnios

overall reduction in the amount of AF results in…

fetal crowding and decreased fetal movement

development of oligohydramnios may be attributed to…

congenital anomalies, IUGR, post-term pregnancies, rupture of membranes, iatrogenesisun

unintentional illness/problem caused by medical intervention

iatrogenesis

second trimester oligo often has a ___ prognosis.

poor

second trimester oligohydramnios often has a poor prognosis, especially if ____.

MSAFP is also elevated

maternal conditions associated with oligo include…

HTN, preeclampsia, chronic cardiac or renal disease, connective tissue disorders (lupus), patients receiving indomethacin

____ may produce growth restriction and oligohydramnios.

fetal hypoxemia

there is a ___ increased risk of growth delay when oligo is present.

four-fold

what does doppler evaluation of a growth restricted fetus show?

abnormal umbilical flow (extremely elevated, AEDF, reversal)

___ may cause IUGR associated with oligohydramnios.

placental insufficiency

in cases of fetal hypoxia, redistribution of fetal blood away from ___ and toward ___.

kidneys, brai

if oligo is present, think the ___ aren’t functioning properly first, then think the ___.

kidneys, placenta

post-term pregnancy is defined as gestational age of ___.

40 weeks or more

__ is a common complication of postdate pregnancies.

oligohydramnios

what are iatrogenic causes of oligohydramnios?

medication, insensible fluid loss, maternal intravascular fluid depletion (anemic), prior procedures such as CVS or amnio

fetal anomalous conditions that cause oligo

infantile polycystic kidney disease, renal agenesis, posterior urethral valve syndrome, dysplastic kidneys, chromosomal abnormalities

integrity and makeup of cells aid in the determination of ___.

strength of membrane

under normal conditions, chorioamniotic membranes rupture due to…

normal cell death activation of enzymes and mechanical forces

when do membranes normally rupture?

after onset of labor

____ describe conditions in which membranes rupture (“water breaks”) abnormally, resulting in loss of AF and/or oligo

premature, preterm, and spontaneous rupture of membranes

how do patients that are suspected to have ROM present clinically?

sudden gush or leaking of fluid

___ and ___ used as screening test to determine presence of AF in vaginal secretions.

nitrazine paper and fern test

patient is checked for ___ and ____ with coughing or fundal pressure.

cervical dilation and for leaking of fluid

the prognosis of fetus affected by abnormal ruptured membranes depends on…

fetal GA, fetal status (BPP), and ability to control uterine contractions

abnormal ROM is associated with…

preterm delivery, fetal and neonatal death, neonatal respiratory distress, prolapsed umbilical cord, chorioamnionitis, placental abruption

pt has infection in amniotic fluid, will have fever, tremors, and a poor BPP

chorioamnionitis

role of sonography is used to document integrity of..

placenta, fetal size, AF volume, fetal well-being, perform fetal Doppler studies

amniotic band syndrome is associated with ___.

abnormality in fetal membranes

___ is a common, non-recurrent cause of various fetal malformations involving limbs, craniofacial region, trunk

amniotic band syndrome

synonyms used to describe disruption of fetal tissue due to the presence of amniotic bands

ADAM complex, (amniotic deformities, adhesion, mutilation), amniotic band sequence, abberant band sequence, congenital constricting bands

rupture of amnion during early pregnancy development leads to subsequent entanglement of various embryonic or fetal parts by fibrous mesodermic bands, which emanate from the chorionic side of the amnion

amniotic band syndrome

entrapment of fetal parts by bands may cause…

lymphedema, amputations, slash defects in nonembryologic distributions

what are common findings found in amniotic band syndrome?

facial clefts, asymmetric encephaloceles, constriction or amputation defects of the extremities, clubfoot deformities

amniotic sheets are identified as…

echogenic, nonfloating bands crossing through the amniotic cavity

amniotic sheets are ____ than bands associated with amniotic band syndrome.

thicker

amniotic sheets do/do not cause fetal malformations.

do not

amniotic sheets most likely signify ___.

uterine synechiae

visualization of amniotic sheets are believed to be caused by…

uterine scars from previous instrumentation used in uterus, C-section, episodes of endometritis

patients with a history of …… are at risk for developing uterine scars.

endometrial D&C, intrauterine infections, endometritis, removal of fibroids or endometrial polyps, or prior C-section

synechiae is associated with ___ and ___.

infertility and miscarriages

what are the sonographic findings of amniotic sheets?

may show fine echo-dense line in uterine cavity separated from uterine wall by echo-lucent space, may either completely surround fetus or be freely mobile in amniotic cavity

disparity between amounts of serous fluid being produced and sborbed

hydrops

hydrops leads to accumulation of fluid, or edema, within the fetus that can be represented by…

pleural effusions, ascites, cardiac effusion, skin edema, anasarca

___ can be seen as anechoic fluid surrounding abdominal, pelvic organs, and umbilical organs.

ascites

normal physiologic fluid around the heart should measure ___.

2 mm

skin edema can be seen as increased skin thickening around the ___, ____, ___, or ___.

skull, neck, extremities, or abdomen

when skin edema is massive, encasing the majority of the body, the term ___ is used.

anasarca

maternal ___ is associated with skin thickening on the forehead due to edema.

diabetes

___ is seen as excess anechoic fluid in pericardial cavity.

pericardial effusion

pericardial effusion is noted when fluid surrounding the apex measures ___.

greater than 2 mm

pericardial effusion is typically seen on the ___ portion.

anterior

placental edema can be identified as a thickened placenta measuring ___.

greater than 4 cm

if there is an increased AFP and unexplained hydrops, check the ____.

placenta

immune and nonimmune hydrops correspond to ___.

Rh sensitivity

immune hydrops is associated with ___ or ____.

alloimmune hemolytic disease (erythroblastosis fetalis) or rhesus (Rh) isoimmunization

isoimmunization to the antibody K or D, causes ___.

hydrops

what does the MCA doppler tell us?

tells us if baby has or has the potential to have anemia and checks for brain sparing effect

presence of abnormal accumulations of fluid in fetal body and/or skin and is associated with numerous conditions and causes

nonimmune hydrops fetalis (NHF)