Free RDMS OB/GYN Exam Flashcards

Most accurate for dating between 7 weeks 0 days and 13 weeks 6 days. Measured in a true sagittal plane with neutral fetal position; includes head and rump but excludes limbs.

Seen transvaginally at ~5 weeks; should contain a yolk sac by ~5.5 weeks and fetal pole with cardiac activity by ~6 weeks. Absence of expected structures raises concern for failed pregnancy.

First sonographic evidence of intrauterine pregnancy. Abnormally large or irregular yolk sac correlates with increased risk of pregnancy loss. Should not be used alone for dating after CRL is measurable.

Measures fluid behind fetal neck at 11w0d–13w6d. Increased NT suggests aneuploidy and structural anomalies. Requires certified NT sonographers and calibrated equipment per FMF/AIUM standards.

Adnexal mass separate from ovary, empty uterus, pseudogestational sac, or free fluid. Live ectopic with cardiac activity outside the uterus is diagnostic. Correlation with β-hCG and clinical findings is essential.

CRL ≥7 mm with no cardiac activity, or absence of cardiac activity ≥2 weeks after a gestational sac with yolk sac, or ≥11 days after a gestational sac without yolk sac—per accepted first-trimester guidelines.

Measured at the level of the thalami and cavum septi pellucidi, perpendicular to the falx. Used for biometry in the second and third trimesters; affected by head shape and breech presentation.

Measured around the outer skull table at the same thalamic plane as BPD. Combined with BPD, AC, and FL for composite gestational age and growth assessment.

Measured at the skin line around the liver and umbilical vein at the portal sinus. Most sensitive single biometric for asymmetric fetal growth restriction.

Measured from the greater trochanter to the distal metaphysis, excluding epiphyses. Short FL may suggest skeletal dysplasia, chromosomal abnormality, or asymmetric growth restriction.

Derived from composite biometry formulas (e.g., Hadlock). <10th percentile suggests fetal growth restriction; >90th percentile suggests macrosomia. Single measurements are less reliable than composite EFW.

Standard screening plane showing both atria, both ventricles, atrioventricular valves, and interventricular septum. Sits within the mid-trimester anatomic survey—major cardiac defects may be suspected here.

Lateral ventricle atrium width ≥10 mm. Mild (10–12 mm) warrants follow-up; >15 mm suggests severe hydrocephalus. Measure at the glomus of the choroid plexus in the transthalamic plane.

Lemon sign: frontal bone scalloping on axial cranium. Banana sign: cerebellum wrapped around brainstem in Chiari II malformation. Both are indirect markers of open neural tube defect.

Previa: placenta covers the internal cervical os. Low-lying: edge within 2 cm of os but not covering. Transvaginal sonography is the gold standard for cervical length and placental edge assessment.

Abnormal trophoblast invasion into myometrium (accreta), into muscle (increta), or through serosa (percreta). Risk rises with prior cesarean and placenta previa. Look for loss of retroplacental clear space and bladder wall interruption.

Normal SDP 2–8 cm. <2 cm oligohydramnios; >8 cm may indicate polyhydramnios in a single-pocket assessment. Used when AFI is impractical (e.g., twins).

Sum of four quadrant vertical pockets. Normal ~8–24 cm (institution-specific). <5 cm oligohydramnios; >24 cm polyhydramnios. Assesses fetal urine production and membrane integrity.

Five items (2 points each): fetal breathing, gross body movement, fetal tone, amniotic fluid volume, and NST (non-stress test). Score 8–10 is reassuring; ≤4 suggests delivery evaluation.

Single shared placenta risks twin-to-twin transfusion syndrome (TTTS), selective FGR, and twin anemia-polycythemia sequence (TAPS). Requires frequent surveillance with MCA Doppler and serial fluid assessment.

Two placentas (or lambda/twin peak sign if fused), thick dividing membrane, and gender discordance confirms dichorionicity. Lower complication risk than monochorionic pairs.

Elevated systolic/diastolic ratio and absent/reversed end-diastolic flow indicate increased placental resistance and fetal compromise. Used in growth restriction surveillance.

Brain-sparing reflex shows decreased MCA pulsatility index in fetal anemia or hypoxia. Peak systolic velocity >1.5 MoM suggests moderate–severe fetal anemia (e.g., alloimmunization).

Notching and elevated PI after 24 weeks correlate with increased risk of preeclampsia and placental insufficiency. Often assessed during second-trimester aneuploidy/anatomy protocols.

Thin echogenic line 1–4 mm during days 1–5 as the functionalis layer sloughs. Thick hyperechoic endometrium suggests secretory phase; trilaminar pattern indicates late proliferative/pre-ovulatory phase.

Well-defined hypoechoic or heterogeneous masses within or distorting the myometrium. Submucosal fibroids may impair fertility; calcified fibroids cast posterior acoustic shadowing.

Globular uterine enlargement, heterogeneous myometrium, myometrial cysts, and indistinct endometrial–myometrial junction. Often causes dysmenorrhea and menorrhagia.

Unilocular, anechoic, thin smooth wall, no solid components or internal vascularity. <3 cm in premenopausal women is usually physiologic; postmenopausal simple cysts need size/follow-up criteria per IOTA.

≥20 follicles per ovary (2–9 mm) and/or ovarian volume >10 mL on adequate-frequency transducer. Requires clinical or biochemical hyperandrogenism for PCOS diagnosis—morphology alone is insufficient.

Enlarged ovary, peripheral follicles (string-of-pearls), decreased or absent arterial/venous flow on Doppler. Clinical pain and adnexal tenderness are key—Doppler cannot exclude torsion.

Endometrium ≤4 mm without bleeding has low malignancy risk; >4 mm or heterogeneous lining warrants further evaluation (biopsy/SIS). Hormone therapy alters thresholds.

Mesosalpinx, mesovarium, and mesometrium suspend the uterus, tubes, and ovaries. The uterine artery travels within the broad ligament—relevant for surgical and Doppler anatomy.

TV offers superior resolution for early pregnancy, endometrium, and adnexa. TA requires full bladder for acoustic window and is preferred for large masses or late second-trimester overview.

As Low As Reasonably Achievable—use lowest output settings and shortest scan time to obtain diagnostic information. Justify every scan and document medical indication.

TI estimates temperature rise potential; TIS for soft tissue, TIB for bone near focus. MI estimates cavitation risk. Keep indices as low as possible while maintaining diagnostic quality.

Permanent images of all abnormal findings, biometry measurements, and survey structures. Reports must include indication, technique, comparison to prior, and impression with recommendations.

Typically 18–22 weeks. Systematic evaluation of fetal brain, spine, heart, abdomen, extremities, face, and placenta/cord. Incomplete views should be documented with follow-up plan.

Lie: long axis relative to maternal spine (longitudinal/oblique/transverse). Presentation: presenting part (cephalic/breech). Position: relationship of fetal back to maternal left or right.

Color maps mean velocity and direction in a region. Spectral (pulsed-wave) displays velocity over time at a sample gate—required for PI, RI, and S/D calculations in fetal vessels.

Endovaginal: empty bladder for best resolution. Transabdominal obstetric: moderately full bladder for early second trimester. Communicate prep instructions before the appointment.

Dark area distal to strongly attenuating structures (bone, calcification, gas). Helps identify stones, ribs, and calcified fibroids but can obscure posterior anatomy.

Repeated bright parallel lines caused by sound bouncing between strong reflectors (e.g., needle, prosthetic valve). Can mimic extra structures if unrecognized.

Axial (along beam): improved by higher frequency and shorter pulse length. Lateral (across beam): improved by focused beam width and line density. Trade-off: higher frequency penetrates less.

Velocity measurements are accurate when the beam is ≤60° to flow direction (cosine correction). Angles >60° produce large error—align the sample volume parallel to vessel flow when possible.

Uses returned harmonic frequencies to reduce near-field clutter and improve contrast resolution in difficult body habitus or late-gestation imaging.

Grade 0 (smooth) to III (calcifications and basal indentations). Grading alone is a poor indicator of fetal maturity; clinical decisions rely more on biometry, fluid, and Doppler.

Umbilical vessels traverse membranes before reaching the placenta. Vasa previa risk if vessels cross the internal os—can rupture with membrane rupture causing fetal exsanguination.

Sensitized pregnancies need serial MCA-PSV and possible cordocentesis. Rising MCA peak systolic velocity predicts fetal anemia before hydrops develops.

Benign features: unilocular, solid components <7 mm, smooth multilocular <10 cm. Malignant features: solid irregular mass, ascites, papillary projections with flow. Guides referral to gynecologic oncology.

170 questions in 3 hours at Pearson VUE. Passing scaled score 555 (~70%) on a 300–700 scale. Requires prior SPI credential and eligible clinical/education pathway. 60-day wait between retakes.