OB- Maternal / Fetal Physiology

What is an increase in saliva production secondary to a placental hormone?

*tx: mints, gum, small frequent meals & sips of water, Nexium

Ptyalism

What condition is characterized by severe/refractory N/V that can lead to dehydration, hypovolemia, electrolyte imbalances, ketosis, weight loss & erosion of enamel?

Hyperemesis Gravidarum

What is the treatment for mild-moderate Hyperemesis Gravidarum (HG)?

PO fluids w/ elytes, ginger, unisom/B6, magnesium (PO/TD), antiemetics - zofran, reglan, promethazine rectal suppository

Which antiemetic should be avoided in the first trimester due to potential cardiac effects to the fetus?

Ondansetron (Zofran)

What antiemetic has a BBW of tardive dyskinesia with prolonged use?

Reglan

What antiemetic is a good option if a pregnant patient can’t tolerate PO & provides quick relief (rectal absorption), but can be habit forming & can increase risk of NRDS if used late in pregnancy?

Promethazine rectal suppository

What is the treatment for moderate-severe HG?

Reglan, promethazine, IV zofran pump & IVFs at home (w/ home nurse)

Hospitalization & IV fluid transfusion if refractory

Low dose prednisolone if severe & not responding to antiemetics

What risk is associated with low dose prednisolone started prior to 10 weeks gestation?

Orofacial clefting

What is the pathophysiology of gallbladder dysfunction associated with pregnancy?

Inc estrogen → inc cholesterol & lecithin → cholesterol supersat & crystallization → Cholelithiasis

Progesteron & relaxin → relaxes SM → less GB contraction → Cholestasis

*both inc risk of cholecystitis & choledocholithiasis

What condition?

• occurs in the third trimester due to increased estrogen & other hormones that reduces bile transport through the liver

• lack of bile salts → dec fat digestion & absorption of fat soluble vitamins

• bile back up in blood → hyperbilirubinemia & maternal & fetal comps

Intrahepatic cholestasis

What sx are associated with intrahepatic cholestasis of pregnancy?

Generalize pruritus worst on palms/soles & at night, secondary insomnia, RUQ pain, N, dec appetite, steatorrhea, encepahlopathy (severe)

What is the dx for intrahepatic cholestasis of pregnancy?

CMP: elevated LFTs, ALP, total & direct bili

Bile acids: increased

PTT: prolonged d/t poor vit K absorption

GGT: normal

What is the treatment for intrahepatic cholestasis of pregnancy?

Ursodeoxycholic acid until delivery; resolves w/ delivery of child

Why do pregnant women experience physiologic or dilutional anemia?

RBC count increases, but not as much as blood volume

What causes hypercoagulability in pregnancy?

Inc in estrogen, factor VII, fibrinogen, thrombin

Dec in protein S (an anticoagulant)

*inc risk of VT: 2x during pregnancy, 5.5x puerperium

What causes the increased risk for pulmonary edema during pregnancy?

Extra plasma → delusional effect → dec colloid osmotic pressure

What is permpartum cardiomyopathy?

Specific type of dilated cardiomyopathy when other causes outside of pregnancy can’t be found; MC in mothers > 30 y/o

What are RF for peripartum cardiomyopathy?

Pre existing cardiac disorders, obesity, smoking. alcoholism, poor nutrition, multiples, preeclampsia

What may be an issue for asthmatics during pregnancy?

Mucosal hyperemia secondary to inc blood volume & overall vasodilation → congestion & inc secretions

How is renal function affected in pregnancy?

Inc renal plasma flow, inc GFR, inc plasma renin activity, inc angiotensin, inc CrCl → dec in serum cr, uric acid, & BUN

What does increased GFR in pregnancy cause?

Inc load of glucose in renal tubules → inc glucose excretion

What effect does progesterone have on the bladder during pregnancy?

Dec bladder tone → inc residual volume → dilation of collecting system → increased risk of urinary stasis → increased risk of UTI & pyelonephritis in pts w/ asx bacteriuria

What does the increased amount estrogen and glucose in the urine during pregnancy increase the risk of?

Bacteria overgrowth & UTIs

How does the enlarging uterus during pregnancy affect the bladder?

Dec bladder capacity → urgency, frequency, & retention → urinary stasis → inc risk infx

How does the increased estrogen affect the skin in pregnancy?

Dark discoloration / hyperpigmentation, spider telangiectasias/angiomas, palmar erythema

What can increased MSH d/t increased estrogen in pregnancy cause?

Chloasma / melasma (“mask of pregnancy”) & lines nigra (abd vertical line)

What causes pregnancy nose?

Inc estrogen → vasodilation of nasal vessels → congestion & physical increase in size and widening

What is the treatment for varicosities of the LE in pregnancy?

Support stockings & rest periods

What causes hemorrhoids during pregnancy?

Mechanical compression of enlarging uterus, increased intraabdominal pressure, and/or constpation → varicosities of rectal veins

What can create a sharp side pain in pregnancy, especially with sudden movements?

Stretching of round ligament that holds down the fungus of the uterus as pregnancy progresses

What can cause symphysis pubis dysfunction in pregnancy?

Relaxin & progesterone causing ligament laxity which causes pubic symphysis to separate at 28-30wks

Does pregnancy cause a true decrease in total serum calcium?

No- it’s d/t hemodilution

In what trimester are headaches common and often due to caffeine withdrawal?

First trimester

Headaches starting in which semester can be a sign of pre-eclampsia?

Second trimester

Why can carpal tunnel syndrome occur in pregnancy?

Median nerve compression d/t water retention & swelling

What causes leukorrhea in pregnancy?

Hormonal stimulation → increased vaginal transudation (fluid seeps from vessels into walls) → more profuse vaginal dc

How does the uterus change during pregnancy?

Goes from 70 g & 10 mL → 1110 g & 5 L

What is Chadwicks sign?

Blue discoloration of vulva, vagina, and/o vaginal portion of cervix

What is goodell’s sign?

Softening of cervix secondary to increased vascularity

What is Hegar’s sign?

Softening of lower uterine segment just above cervix (cervical isthmus)

What is Ladin’s sign?

Small area of uterine softening in anterior midline along cervicouterine junction

What is Von Fernwald’s sign?

Irregular softening of the fungus which develops over the site of implantation

What pregnancy hormones contribute to physiologic insulin resistance allowing for adequate fetal growth?

Resisting, human placental lactose, cortisol, estrogen

How is blood sugar affected in pregnancy?

Fetus has own insulin production but gets glucose from mother via facilitated diffusion → contain drain on maternal glucose, therefore lower fasting glucose levels → exaggerated response w/ hypoglycemia & hypoinsulinemia

What is the net effect of thyroid changes in pregnancy?

Euthyroid (estrogen inc TBG , total T4 & T3, unchanged free T3 & T4)

What other endocrine changes are seen in pregnancy?

Estrogen inc plasma corticosteroid binding globulin → inc plasma cortisol

Inc plasma free cortisol & deoxycorticosterone (precursor to aldosterone)

What carries oxygenated blood from the placenta to the fetus?

Umbilical vein

What carries deoxygenated blood from the fetus to the placenta?

Umbilical artery

What forms amniotic fluid?

Fetal kidneys forming “urine” (hypotonic solution)

When does the fetal liver finish development?

2 years after birth (bilirubin eliminated through placenta during pregnancy)

Is the fetal thyroid gland development influenced by the mother?

No; TSH does not cross placenta (only small amounts of T3/T4)

If fetal testes are present, what hormones are inhibited the development of female external genitalia?

Testosterone & mullieran inhibitory factor (MIF)

Which genital organs are dependent upon chromosomal makeup, not the presence/absence of specific hormones?

Ovaries & testes

What Bishop score indicates that induction is less likely to be initiated successfully?

< 5

What Bishop score suggests that labor will occur spontaneously & alternatively, that induction will likely be successful?

≥ 9

What score assesses cervical favorability. looking at position, consistency, effacement, dilation & station to assess readiness for labor & induction?

Bishop score

What is effacement?

Shortening of the cervix expressed as a percentage (normally 3cm long, shortens during labor)

How is dilation determined?

Placement of 1-2 fingers in the cervix & assessing diameter of the opening; from “closed” or 0cm to 10 cm

What is station?

Distance in cm between the lowest bony portion of the fetus and the maternal ischial spines

*”engagement” is synonymous w/ zero station

What is position?

Orientation of the presenting part with respect to maternal pelvis (should be the head)

*can be difficult to determine if < 5 cm dilated

What is the progressive cervical dilation in the presence of regular contractions?

Labor

What stage of labor begins with cervical effacement & dilation and ends with complete dilation?

First stage

What phase of the first stage of labor begins with cervical changes in the presence of regular contractions?

Latent phase

What phase of the first stage of labor begins with increasing rate of cervical dilation?

Active phase

What stage of labor begins with complete dilation and ends with birth of the baby; consists of pushing?

Second stage

What stage of labor begins after birth of the baby and ends with the delivery of the placenta?

Third stage

In a woman’s first labor, what is considered prolonged second stage?

> 2 hrs (>3 hrs w/ epidural)

In a woman’s second labor, what is considered a prolonged second stage?

> 1 hr

What is cephalic presentation?

Fetus is in a longitudinal lie & head enters pelvis first

What is the MC cephalic presentation?

Vertex presentation → head is flexed (chin tucked), and occiput is leading

What are the classifications of vertex presentations (according to position of occiput)?

L or R occipito-anterior, occipito-posterior, & occipito-transverse

What position is ideal for birth?

Left occiput anterior (LOA)

What is occiput anterior?

Head down facing spine, baby’s chin is tucked onto chest & smallest part of head will be applied to the cervix first

What are the 6 cardinal movements in labor for a vertex fetus?

Engagement

Descent

Flexion

Internal rotation

Extension

External rotation (restitution)

Expulsion

Which mechanism of labor occurs when the biparietal diameter passes through pelvic inlet (0 station)?

Engagement

Which mechanism of labor occurs after the head is engaged and moves below the level of ischial spines?

Descent

Which mechanism of labor occurs as the head moves down, the chin tucks toward the chest to present smallest aspect of head to birth canal?

Flexion

Which mechanism of labor occurs as the occiput of head moves from transverse position toward symphysis?

Internal rotation

Which mechanism of labor occurs as the top of the head reaches the perineum, occiput extends so that it follows the curve of the pelvis?

Extension

Which mechanism of labor occurs as the head rotates back to its original orientation to the L or R (and to line up with the spine)?

External rotation (Restitution)

Which mechanism of labor is the delivery of the shoulders and body?

Expulsion

When can narcotics be given for pain relief in labor?

Normal latent phase (can cause resp distress in neonate if given too close to delivery, prolong labor & interfere w/ fetal monitoring)

What is the most commonly used narcotic in labor (textbook answer)?

*real world its fentanyl

Stadol

What are complications of epidurals?

Hypotension, pruritus, wet tap w/ leakage of CSF, respiratory compromise & hematoma

What method of pain relief during labor is very effective with fewer SEs, & consists of a small catheter placed into the lumbar epidural space & left in space?

Epidural

When are epidurals given?

Started once 3-4cm dilated, not given once fully dilated

What local anesthesia is for labor & is injected at 3 and 9 o’clock into the cervix?

Paracervical block

What local anesthesia is for delivery & is injected just beneath the ischial spine through the sacrospinous ligament?

Pudendal block

What local anesthesia is used for the repair of any lacerations in the absence of regional anesthesia?

Local infiltration in the perineum

What kind of local anesthesia is used mainly to prep for C section & is inserted into the intrathecal space / subarachnoid?

*not routinely used for labor analgesia

Spinal block

What is baseline FHR?

Mean FHR rounded to nearest 5 bpm for 10 minutes, must occur for no less than 2 min, does not have to be contiguous

What does baseline FHR exclude?

Periodic / episodic changes, periods of marked variability, segments of baseline that vary by > 25 bpm

What is baseline variability FHR?

Fluctuations in FHR tracing that are irregular in amplitude and frequency over 10 minutes; described as a range in bpm bt peak & trough

*excludes accelerations & decelerations

What is acceleration in FHR?

Visually evident abrupt increase in FHR from baseline, peaks in less than 30s and lasts less then 2 minutes → normal, due to movement

*greater than 15pm from baseline if ≥32w; 10 bpm if < 32w

What is prolonged acceleration?

2 to < 10 minutes (if ≥10 minutes, its baseline change)

What is fetal bradycardia?

< 110 bpm baseline

What is fetal tachycardia?

> 160 bpm baseline

What are FHR decelerations?

Depth of decelerations determined in BPM from onset to nadir (lowest point); recurrent if occurs with ≥50% of contractions or intermittent if less often

What are early decelerations?

Nadir of deceleration occurs at same time as peak of contraction

What are late decelerations?

Nadir of deceleration occurs after peak of contraction