| System | Pregnancy change | Number / detail | Test pearl |
|---|---|---|---|
| CNS/MAC | MAC decreases | ↓ 40% at term | Due to ↑ progesterone and ↑ β-endorphins. |
| Local anesthetic sensitivity | Enhanced sensitivity | ↓ epidural/LA dosing about 30% | Due to epidural venous engorgement + ↓ CSF → ↑ cephalad spread. |
| Respiratory | ↑ minute ventilation, TV, O₂ consumption, RR, PaO₂ | MV +50%, TV +40%, O₂ consumption +20%, RR +10%, PaO₂ +10% | Rapid desaturation = ↑ O₂ consumption + ↓ FRC. |
| Respiratory | ↓ airway resistance, FRC, PaCO₂, HCO₃ | Airway resistance -35%, FRC -20%, PaCO₂ 28–32, HCO₃ -15% | Pregnancy baseline PaCO₂ is low; do not call 30 “hyperventilation pathology.” |
| Cardiovascular | ↑ plasma volume, CO, blood volume, SV, HR | Plasma +50%, CO +40%, blood volume +30%, SV +30%, HR +20% | Plasma > RBC/blood volume → dilutional anemia. |
| Cardiovascular | ↓ pulmonary resistance, peripheral resistance, DBP, SBP | PR -30%, PVR/SVR -15%, DBP -15%, SBP -5% | Widened pulse pressure pattern. |
| EBV | EBV increases | 65 → 90 mL/kg; blood volume +1000–1500 mL at term | Can tolerate blood loss before symptoms, but hemorrhage still huge morbidity risk. |
| CO position | CO decreases supine after ~20 weeks | IVC compression | Treat with left uterine displacement >15° or wedge under right hip. |
| P50 | Right shift | 26.7 → 30 | ↑ CO + ↑ P50 = ↑ O₂ delivery. |
| Renal | ↑ GFR, ↓ tubular threshold for glucose/amino acids | Mild glycosuria 1–10 g/day; mild proteinuria <300 mg/day | Creatinine may look lower than expected. |
| GI | ↑ GERD/esophagitis, ↓ gastric motility, ↓ LES tone | Full stomach/aspiration risk | GETA risk: aspiration/difficult airway. |
| Hepatic/hematologic | ↓ colloid oncotic pressure, ↓ PchE, hypercoagulable | PchE ↓ ~25%; majority clotting factors ↑ except factor XI | ↓ PchE → ↑ succinylcholine DOA. Factor XI exception is a favorite. |
| Metabolic/MSK | Diabetogenic + ligament laxity | hPL + progesterone → insulin resistance; relaxin → laxity | ↑ serum glucose availability to fetus; positioning/back injury risk. |
| Topic | High-yield item | Professor-style trap |
|---|---|---|
| Consent | Must include risk, benefit, alternative. | Patient CAN consent despite pain; CAN consent with nitrous oxide. Minors = state/facility specific. |
| Evaluation | Maternal Hx, pregnancy complications, heart/lungs/back/airway, meds/herbs, labs as indicated. | OB = airway + aspiration + coags + fetal status. |
| Scoliosis | Increased wet tap and patchy block risk. | Do not fully trust labor epidural for C-section conversion. |
| Spinal instrumentation | Biggest concern: infection/hardware requiring removal; also unintentional dural puncture and inadequate coverage. | Instrumentation does not automatically make neuraxial impossible, but coverage may be unreliable. |
| Dermal/skin findings | Acne lesions OK, tattoos OK, dermal piercings hard to prep. | Do not over-call tattoo as contraindication. |
| Stage/phase | Definition | Pain | Nerve/dermatome | Trap |
|---|---|---|---|---|
| Stage 1 | Onset of labor → full cervical dilation | Visceral pain from uterus/cervix | T10–L1 via A-delta/C fibers | Early epidural should cover T10–L1, but labor epidural goal often T10–S4. |
| Latent phase | 0–4 cm | Early Stage 1 | T10–L1 | May ask order. |
| Active phase | 4–7 cm | Stage 1 | T10–L1 | Watch labor progress. |
| Transition phase | 7–10 cm | Stage 1 intense | T10–L1 | Often confused with Stage 2. |
| Stage 2 | Delivery of infant | Somatic/localized perineal pain | S2–S4 via pudendal nerve | Pudendal = Stage 2/perineal. |
| Stage 3 | Delivery of placenta | After infant | Variable | Do not call Stage 3 “delivery of infant.” |
| Concept | High-yield fact | Why it matters |
|---|---|---|
| FHR baseline | Common test range: 110–160 bpm | Use with variability/decels, not alone. |
| Variability | BEST indicator of fetal well-being | Reflects adequate O₂, intact CNS, cardiac function. |
| Moderate variability | 6–25 bpm | Normal/reassuring. |
| ↓ variability | Can be caused by opioids (~30 min), magnesium, CNS depressants/autonomic agents. | Do not assume fetal acidosis if meds explain it. |
| Maternal autotransfusion | Contraction increases central volume; maternal HR can decrease with contraction. | Maternal tracing can be mistaken for fetal tracing. |
| Pattern | Look | Cause | Action/meaning |
|---|---|---|---|
| Variable deceleration | Variable depth/onset/duration; unrelated to uterine contractions; most common. | Cord compression | Reposition, relieve cord compression; watch severity. |
| Early deceleration | Uniform, mirror image of contraction. | Head compression → vagal response | Usually benign. |
| Acceleration | Increase in FHR. | OK/reassuring | Good sign. |
| Late deceleration | Begins after contraction, repetitive/varying depth. | Uteroplacental insufficiency | Correct maternal hypotension and hypoxemia; concerning. |
| Condition | Presentation | Risk/complication | Treatment/pearl |
|---|---|---|---|
| Occiput posterior (OP) | “Sunny side up”; failure to rotate anteriorly. | ↑ labor duration and ↑ pain; back/butt pain. | Epidural can assist due to pelvic relaxation; manual/forceps/vacuum rotation often needed. |
| Shoulder dystocia | Shoulder impacted against pubic symphysis. | True emergency; major birth injury risk; fetal macrosomia = greatest risk factor. | Birth injuries include torticollis/Erb’s palsy/brachial plexus injury. |
| Breech | Breech fetus. | 3–4% deliveries; increased maternal/fetal morbidity/mortality; 10-fold ↑ cord prolapse. | Most OBs deliver breech by C-section. |
| External cephalic version | Manual manipulation to vertex. | May be attempted >34 weeks before labor; risks: abruption, cord compression. | Epidural may be requested for comfort; emergency C-section may be needed. |
| Umbilical cord prolapse | Sudden fetal bradycardia → physical exam. | Cord compression → fetal asphyxia. Risk factors: long cord, malpresentation, LBW, grand parity, multiples, AROM. | Steep Trendelenburg/knee-chest, manual elevation/manipulate cord back into pelvis, immediate C-section. May need GA if no working epidural and cannot position for spinal. |
| Topic | Definition/key facts | Test trap |
|---|---|---|
| Preeclampsia | SBP >140 or DBP >90 after 20 weeks + proteinuria >300 mg/dL. | PIH and preeclampsia are not automatically identical; seizure = eclampsia. |
| Thromboxane/prostacyclin | Thromboxane > prostacyclin; notes say ~7:1 in preE vs 1:1 normal. | Vasoconstricted state. |
| Systemic complications | Neuro: headache/seizure/stroke/hemorrhage/edema. Pulm: airway edema/pulm edema. Cardiac: hypovolemia/HTN/HF. Hepatic: ↑LFTs/rupture. Renal: proteinuria/↓GFR/failure. Heme: coagulopathy/↓plt/plt dysfunction. | Airway, platelets, pulmonary edema, and renal function all matter for anesthesia. |
| HELLP | Hemolysis, Elevated Liver enzymes, Low Platelets. | Platelets/trend determine neuraxial risk. |
| Treatment | Antihypertensives such as hydralazine/labetalol; magnesium sulfate for hyperreflexia/seizure prevention. | Mg goal 4–6 mg/dL. |
| Mg anesthesia | Potentiates nondepolarizing neuromuscular blockers. | Decrease NDMR dose; IV calcium for Mg toxicity. |
| HTN C-section | Caution with uterotonic methergine. | Methergine worsens HTN. |
| Level | Clinical effect |
|---|---|
| 4–6 mg/dL | Therapeutic goal. |
| 10–12 mg/dL | Loss of patellar reflex. |
| >12 mg/dL | Respiratory depression. |
| >18 mg/dL | Apnea. |
| >25 mg/dL | Cardiac arrest. |
| Condition | Presentation | Risks/notes | Trap |
|---|---|---|---|
| Placenta previa | Placenta covers cervix; painless vaginal bleeding. | Risk factors: prior C-section, uterine myomectomy, advanced maternal age, large placenta. Usually C-section. | Painless = previa. |
| Placental abruption | Placenta separates from uterus; painful vaginal bleeding. | Hidden blood loss and fetal distress possible. | PainFULL = abruption is FULL of blood. |
| Uterine rupture | Continuous abdominal pain with fetal distress; may break through epidural. | Risk factors: scar dehiscence from previous uterine surgery, intrauterine manipulation, spontaneous, short interval between pregnancies. | Continuous pain + fetal distress = rupture until proven otherwise. |
| Condition | High-yield definition | Exam clue |
|---|---|---|
| Uterine atony | Leading cause of postpartum hemorrhage. | Give uterotonics; uterus “boggy.” |
| Accreta | Placenta attaches on/to myometrium; most common in spectrum. | High hemorrhage risk. |
| Increta | Placenta invades into myometrium. | “Increta into.” |
| Percreta | Placenta penetrates through myometrium. | “Percreta perforates.” |
| Topic | High-yield | Treatment/targets |
|---|---|---|
| Amniotic fluid embolism | Entry of amniotic fluid into maternal circulation; very high mortality; sudden cardiovascular/respiratory collapse followed by DIC/hemorrhage. | Supportive care FIRST, MTP/DIC, deliver fetus, vasopressors such as levophed. |
| A-OK regimen | Adjunct to supportive care. | Atropine 1 mg IV, Ondansetron 8 mg IV, Ketorolac 30 mg IV. |
| DIC labs | ↓ fibrinogen and platelets; ↑ PT/INR, PTT, fibrin degradation products/D-dimer. | Eliminate cause, replace clotting factors, support circulation; TEG/ROTEM helps. |
| MTP target/action | INR >1.5 | 2 units FFP; goal INR <1.5. |
| MTP target/action | Platelets <100,000 | 1 apheresis unit; goal >50k. |
| MTP target/action | Fibrinogen <200 | 10 units cryo; goal >300. |
| TXA | 1 g over 10–20 min; may repeat after 30 min. | Give separate line from blood products; caution with active DIC. |
| Uterine relaxation | For retained placenta/uterine inversion. | Nitro 50–200 mcg IV or 400 mcg SL; if ineffective, volatile 1–3 MAC under GETA. |
| Option/drug | High-yield point | Trap |
|---|---|---|
| Psychoprophylaxis | Natural childbirth/Lamaze. | “PSYCHO” clue in notes. |
| TENS | Gate theory; may enhance endorphins; T10–L1 placement may help early labor. | Stage 1 dermatome tie-in. |
| Etonox | 50:50 N₂O/O₂ mixture; dizziness, N/V, dysphoria, lack of cooperation. | No scavenging/availability may be issue; appears no hepatic/renal/cardiac/pulm effect. |
| IV analgesia | Nearly all parenteral opioids/sedatives cross placenta and can impact fetus. | Used if neuraxial unavailable, refused, or contraindicated. |
| Demerol/meperidine | Assists labor shivering. | Normeperidine remains in neonate for days → neonatal depression/behavior score issues; avoid. |
| Fentanyl | High potency, short duration; common early labor choice. | Maternal respiratory depression outlasts analgesia. |
| Morphine | Long duration. | Rarely used due to maternal sedation and fetal depression. |
| Remifentanil | PCA, rapid metabolism. | Less satisfaction than epidural. |
| Butorphanol/Nalbuphine | Agonist-antagonists, ceiling effect, decreased N/V; Nubain 10 mg ≈ morphine 10 mg. | Avoid in opioid-dependent patients. |
| NSAIDs before delivery | No. | Suppress uterine contractions and promote closure of fetal ductus arteriosus. |
| Paracervical plexus block | 1st stage labor pain. | No longer used commonly due to high fetal bradycardia rate; injection close to uterine artery. |
| Pudendal nerve block | Perineal anesthesia for 2nd stage. | Risks: IV injection, hematoma, abscess. |
| Neuraxial | Best method of labor pain relief; catheter in place for emergency. | Risks: hypotension, pruritus, N/V, failed/inadequate block, PDPH, high block, LAST, abscess, nerve injury, hematoma, death. |
| Category | Items | Trap |
|---|---|---|
| Required equipment | Ambu bag, suction, emergency drugs/supplies, crash cart, difficult airway equipment, Intralipid 20%. | LAST preparedness is expected. |
| Absolute contraindications | Patient refusal, severe hypovolemia, uncorrected coagulopathy, elevated ICP, infection at insertion site, untreated bacteremia, severe stenotic valvular lesions, documented LA allergy. | Acne/tattoos are not automatic contraindications. |
| Relative contraindications | Preexisting CNS disease, chronic severe headaches/back pain, poorly controlled HTN, prior major back surgery, platelets <100k, previous VBAC? | Fear of masking uterine rupture with VBAC is unjustified; prefer early epidural in some VBAC contexts. |
| Labor options | Epidural, CSE, DPE, single-shot spinal, continuous spinal. | Continuous spinal must be labeled/dosed/monitored carefully; many avoid due to high-risk dosing mistakes. |
| Placement | L3/L4 or L4/L5; T10–S4 blockade goal. | Stage coverage matters. |
| CSE concerns | Fetal intolerance, hypertonic contractions, hypotension. | Can look like fetal distress after rapid analgesia/onset. |
| Opioids with LA | Synergistic; opioids decrease total LA dose requirement. | Useful because less LA can mean less motor block. |
| Item | High-yield detail | Treatment/pearl |
|---|---|---|
| Hypotension | Most common adverse effect; defined as 20% decrease from baseline or SBP <100. | Goal: maintain maternal BP to prevent fetal distress. |
| Prevention | Left uterine displacement 15°, crystalloid co-loading 500–1000 mL. | LUD is always a good answer in supine/aortocaval compression. |
| Ondansetron | Consider 4 mg IV at time of spinal for C-section. | Linked to Bezold-Jarisch reflex/serotonin antagonism to prevent reflex hypotension/bradycardia. |
| Phenylephrine | 50–100 mcg boluses. | Can cause maternal bradycardia. |
| Ephedrine | 5–10 mg boluses. | Can cause fetal tachycardia. |
| Aortocaval compression | Supine position; gravid uterus compresses IVC. | Treat with LUD/manual displacement; in arrest, manually displace uterus. |
| Topic | Need-to-know | Treatment/pearl |
|---|---|---|
| PDPH | Postural, fronto-occipital. | Conservative: hydration, analgesics, caffeine. Moderate: transnasal sphenopalatine block for smaller punctures. Aggressive: epidural blood patch. |
| Epidural blood patch | Gold standard for PDPH. | Perform >24 hr post-puncture; same interspace; 15–20 mL. |
| Total spinal | Dyspnea, difficult phonation, hypotension; can cause respiratory demise. | Supportive, may need GETA. |
| Test dose | 3 mL 1.5% lidocaine with epi 1:200k; aspirate before injecting; assess 3–5 min. | Watch circumoral numbness, lightheadedness, auditory changes, HR increase, impending doom. |
| LA IV injection/LAST | Early: tongue numbness, lightheadedness, visual/auditory disturbance, twitching. Late: seizure, coma, respiratory arrest, cardiac arrest. | Airway/O₂, seizure control; lipid emulsion 20% for CV collapse. |
| Lipid dosing | <70 kg: 1.5 mL/kg bolus then 0.25 mL/kg/min. >70 kg: 100 mL bolus then 200 mL over 20 min. | Repeat bolus 1–2x if persistent; upper limit 12 mL/kg. |
| Epidural disconnect | Replace. | Do not reconnect questionable catheter. |
| No emergency epidural | Do not place an emergency epidural. | If patient/spouse faints: spouse sits/RN helps; if patient faints, withdraw needle and assist. |
| Concept | High-yield | Trap |
|---|---|---|
| Ion trapping | Fetal pH < maternal pH → fetal ion trapping. | Acidemic fetus traps more weak-base drug. |
| Infected tissue | LA becomes more ionized in acidic/infected tissue. | Poorer block. |
| Carbonation | Increases onset and intensity. | CO₂ effect. |
| Sodium bicarb | Increases speed of onset. | Alkalinization increases nonionized fraction. |
| Lipid solubility | Potency. | More lipid soluble = more potent. |
| Protein binding | Duration of action. | More binding = longer DOA. |
| pKa | Speed of onset; closer to physiologic pH = faster. | Chloroprocaine 3% has pKa 8.7 but is fast due to high concentration. |
| Bupivacaine | Sensory > motor; cardiotoxic/cardiac arrest risk. | More dangerous in LAST. |
| Ropivacaine | Less motor, less cardiotoxic. | Often useful for labor. |
| Lidocaine | Rapid onset, good for C-section. | High dose risk: cauda equina/transient neuro symptoms. |
| Chloroprocaine | Ester; PABA/allergy risk; rapid onset, brief DOA; low toxicity due to cholinesterase metabolism; minimal fetal transfer. | pKa exception due to concentration. |
| Drug/topic | Use | High-yield effects/contraindications |
|---|---|---|
| Oxytocin | Labor induction/strengthen contractions; after placenta delivery for uterine tone. | Side effects: hypotension, HR changes, N/V. Half-life 4–17 min. |
| Magnesium sulfate | PreE seizure prevention; also uterine relaxation by altering calcium transport. | Therapeutic 4–6; toxicity levels table above; potentiates NMBs. |
| Methergine/methylergonovine | Uterotonic. | CAUTION/avoid HTN and preeclampsia. |
| Carboprost/Hemabate | Uterotonic. | Avoid asthma/wheezing. If wheezing, think ketamine/no hemabate. |
| Misoprostol | Uterotonic adjunct. | Common OB hemorrhage option. |
| Terbutaline | Tocolytic β2 agonist. | Uterine relaxation; fetal tachycardia/maternal hypokalemia possible. |
| Nitroglycerin | Emergency uterine relaxation for inversion/retained placenta. | 50–200 mcg IV or 400 mcg SL. |
| Volatile anesthetic | Uterine relaxation if nitro ineffective. | GETA with 1–3 MAC. |
| Precedex | Safe adjunct per notes. | Epidural 25 mcg, intrathecal 5 mcg. DOA: fentanyl < dex < duramorph. |
| Breastfeeding meds | Review caution vs avoid categories. | Likely pharm-test tie-in. |
| Drugs crossing placenta | Most parenteral sedatives/opioids cross. | Fetal effects depend on drug, dose, timing. |
| RSI/incision timing | C-section GETA risk. | Difficult airway and aspiration risk loom large. |
| APGAR | Know scoring basics if included in pharm lecture. | Often matching/recognition. |
| TOLAC/VBAC | TOLAC = trial of labor after cesarean; VBAC = vaginal birth after cesarean. | Neuraxial is not contraindicated solely due to VBAC. |