OB- Genetics & Operative Obstetrics

What is a teratogen?

Anything that disturbs fetal development (highly dependent on time of exposure)

What period during a pregnancy is the most vulnerable to the effects of teratogens?

1st trimester (organogenesis)

What is the minimum theoretical radiation threshold for fetal injury?

50 mSv

At what radiation level is fetal neurological injury thought to begin, if exposure occurs between 8-15 weeks?

200 mSv

What is the radiation dose associated with dental xrays?

0.06 mSv

What is the radiation dose associated with CXRs?

0.1 mSv

What is the radiation dose associated with head CTs?

1.5 mSv

What is the radiation dose associated with abdominal CTs?

5.3 mSv

What is the radiation dose associated with chest CTs?

5.8 mSv

What imagining modalities have no known or suspected radiation risks?

US & MRI

Is safety in pregnancy the same as safety in lactation?

No

Known teratogens chart

know the known teratogens column (especially accurate / retinol cream), dont worry about generally safe column

What are known chemical teratogenic risks?

Heavy metals such as mercury & lead (assoc w/ intellectual disability), pesticides (treating lice), organ solvents such as esters & alcohol

What is aneuploidy?

Extra or missing entire chromosome → typically d/t problems during meiotic nondisjunction, chromosomes fail to pair or separate

What is translocation?

Portion of chromosome is rearranged

What is deletion?

Portion of chromosome is missing

What chromosomal abnormality generally result in serious or lethal damage?

Autosomal abnormality → duplication or absence of large portions of the 22 autosome pairs

Which chromosomal anomaly tends to be less deleterious?

Sex chromosome errors

What is mosaicism?

2 different cell lines present d/t error in mitosis

The incidence of congenital anomalies ______ with maternal age

Rises

The is the MC trisomy, that is also commonly seen with older maternal patients?

Trisomy 21

What is trisomy 21 (3 copies of chromosome 21 / long arm)?

Down syndrome

Which trisomy has the following appearance?

• Small head, upslanting palpebral tissues w/ epicanthic folds, low set / folded / dysplastic ears, flat nasal bridge

• Open mouth, thick protruding tongue, & loose skin at nape of neck

• Single palmar crease (Simian Crease), short broad hands, hypermonile joints, gap bt 1st & 2nd toe (sandal gap)

• Tendency for subluxation of C spine → risk of paralysis, especially w/ intubation

Trisomy 21

What other conditions can be seen in trisomy 21?

Heart defects (AV septal defects MC), GI malformation, childhood leukemia, thyroid disease, & significant intellectual disability

What is trisomy 18?

Edwards syndrome

Which trisomy is 4x MC in females, presents with a profound intellectual disability, and less than 10% survive to age 1?

*hospice is an option for those born alive

Trisomy 18

What is trisomy 13?

Patau syndrome

What trisomy presents most commonly presents with cardiac defects, most have missing portions of the brain, & less than 10% survive to age 1?

Trisomy 13

What is the MCC of aneuploidy in miscarriages (98% abort in first trimester)?

*those that survive to live birth often only have minor problems

Turner’s syndrome

What condition is an X chromosome abnormality of females with an absent or nonfunctional x sec chromosome → 45 X or 45 X0?

*can be mosaicism (only in come cells) or absence in all (gonadal dysgenesis)

Turner’s syndrome

The following findings are commonly seen with what condition?

• cystic hygroma, fetal hydrops

• hypogonadism → delayed puberty (absence of breasts), infertility, primary amenorrhea (MC) or secondary w/ premature ovarian failure

• CoA is common**; MVP, bicuspid AV, aortic dissection, HTN

• horshoe kidney, hydronephrosis

• hypothyroidism, osteoporosis, DM, DLD

• telangiectasias of GI tract

Turner’s syndrome

The following physical presentation is seen with what condition?

• short stature

• low posterior hairline, webbed neck, low set/prominent ears, high arched palate

• broad chest w/ wide set nipples, lack of breast developemnt

• short 4th metacarpals, nail abnormalities

• intellectual impairments

Turner’s syndrome

What condition has the following presentation?

• phenotypic male

• normal intelligence

  • intellectual disabilities and physical abnormalities if > 2 Y chormosomes

• tall

• emotional difficulties

• learning disability

Jacob’s syndrome / XYY syndrome

What condition occurs in phenotypic males due to failure of separation of sex chromosomes or translocation, & is the MC chromosomal abnormality with hypogonadism?

Klinefelter’s syndrome / 47 XXY

The following presentation is seen with what condition?

• normal appearance before puberty

• tall stature → long limbs & thin

• normal intelligence, occasional mild developmental delay & expressive language disorders

• small testes, scant pubic hair, reduced fertility

• inc risk for GCT & breast CA

• minority have breast development sufficient to warrant surgery

• ice risk obesity in adulthood

Klinefelter’s syndrome / 47 XXY

The is the absence/dullness of sensibility to pain or the relief of pain without loss of consciousness?

Analgesia

What is the total loss of sensory perception & may include loss of consciousness?

Anesthesia

What is regional anesthesia/analgesia?

Region of body anesthetized w/o making person unconscious

What is the MC used local anesthetic?

Bupivacaine

What is added to local anesthetics to prolong duration & confines to the area affected by medication?

Vasoconstrictors (Epinephrine)

What may be a dded to the local anesthetic used in spinal epidurals to provide prolonged pain relief, block transmission of nerve signals & sensory signals, & limits motor?

Opioids

What kind of regional anesthesia?

• pt loses sensation in legs & lower abdomen

• used for labor pains, vaginal delivery & episiotomy

• injected into epidural space → bolus or continuous infusion of bupivacaine via catheter

Lumbar epidural

What is a walking epidural?

Low dose CSE that generally preserves motor function

What is a combined spinal epidural (CSE)?

Narcatics (fentanyl) added to lumbar epidural

What are complications of lumbar epidurals?

Failure to anesthetize, venous pooling, HA, infx, misapplication of catheter placement, slower labor, drop in FHR

What kind of regional anesthesia?

• loss of sensation of lower body & motor function

• better for surgical management - C sections

• anesthetic injected into spinal fluid (subarachnoid space) w/ fine needle & catheter (3.5 in)

  • may use 7 in long spinal needle for extremely obese pts

Spinal block

What kind of regional anesthesia?

• quick pain relief to perineum, vulva & vagina

  • does NOT help abdominal labor pains

• given in 2nd stage of labor just before delivery or for episiotomy

• anesthetic is injected into pudendal canal near pudendal nerve

Pudendal block

Where are surgical incisions made in a cesarean section?

Through mother’s abdomen (laparotomy) and uterus (hysterectomy)

What are fetal indications for c-section?

Mal presentation, cephalo-pelvic disproportion (CPD), extreme prematurity, fetal intolerance to labor (non reassuring FHR), predicted macrosomia, multiple gestations, maternal active genital infx

If a patient wants a tubal ligation during the c-section, how far in advance might a patient on public assistance need special government papers signed?

30 days

What should you do before surgical prep for a c section if it is for a CPD and the head is engaged?

Gently push up on presenting part to dislodge it slightly

Who should you call to the OR during a c-section if the fetal is in distress?

Peds

What abdominal incision allows quicker access to the uterus & entry is commonly enhanced by diastases of the rectus muscles?

Midline infraumbilical incision (vertical)

Which c-section abdominal incision?

• MC; preferred cosmetically

• takes slightly longer to enter peritoneal cavity

• less painful, less blood loss, shorter post op pain and lower analgesic requirement

• smaller risk of developing incisional hernia

Transverse incision through lower abdomen

*MC pfannenstiel (bikini-low) or Maryland or Joel Cohen (high)

What are the 7 layers of c-section closure in order?

Uterus 1st layer - has to be placed

Uterus 2nd layer - leaves uterus stronger for VBAC attempts

Visceral peritoneum (not commonly used)

Parietal peritoneum (optional)

Fascia - necessary

SC tissue - reduces wound comps if incision > 2cm

Skin - closed w/ staples or dissolving sutures / steristrips

What complications are seen with c-sections?

Blood loss requiring blood transfusion, inc risk endometritis (give props cephalosporin at time of cord clamping), DVT, damage to adjacent organs, maternal death

When should a patient urinate after removal of a foley?

Within 4 hours (replace foley for another 12 hrs if not)

What are potential causes of a fever post op from a c section?

Wind: atelectasis, PNA (24 hrs)

Water: UTI (POD 2-3)

Wound: incisional infx, endomyometritis, septic shock (POD 3-5)

Walking: DVT< PE, pelvic thromboembolism (POD 5-7)

Wonder: meds

When can dressing be removed after c-section?

24-48 hrs (attending specific)

*may become soaked w/ serosanguinous fluid in first 12-24 hrs → replace

What is wound dehiscence?

Separation of a wound, usually during staple removal 1-2 wks post op

What is the management for c-section wound dehiscence?

Explore entire wound to determine depth, open if needed, props abx (keflex, bactrim, clindamycin), close FU & wound exploration

if thru rectus fascia → back to OR

if SC layer → deride daily w/ sterile saline/H2O2 & pack w/ gauze

What pharmacology postpartum counseling is given to the patient after a c-section?

Continue prenatals, colace, Motrin, Percocet for breakthrough, & OCPs can be started 4-6 wks post partum (progesterone only if breastfeeding), IUD can be inserted 6 wks after vaginal delivery or 8wks after c section

What are the activity restrictions for patients after a c-section?

No lifting objects over baby’s weight, continue ambulation, no strenuous activity, NOTHING by vagina for 6 wks (sex, tampons, douches, bathtubs, hot tubs)