USMLE Step 2 2023 Obstetrics Exam Solved 100% Correct

Define Gravidity - ANSWER-The number of times a woman has been pregnant Define Parity - ANSWER-The number of times a pregnancy has led to a birth beyond 20 weeks gestation, or infant >500g Define developmental age - ANSWER-Time since fertilization, in weeks and days. Usually unknown Define gestational age - ANSWER-Time since LMP What are the four things that can be used to determine gestational age? - ANSWER-Fundal height (*umbilicus at 20 wks. 2-3cm/week thereafter*) Fetal heart tones (Doppler) Quickening (17-18 weeks at earliest) USS What features of USS can help you identify the gestational age? - ANSWER-Fetal crown-rump length (done at 6-12 wks - most reliable) Biparietal diametre Femur length Abdominal circumference (all done from 13 weeks) What produces bHCG and when does it peak? - ANSWER-Placenta Peaks around week 10 How is bHCG used to diagnose ectopic pregnancy? - ANSWER-bHCG doubles around every 48 hours in early pregnancy. If this is abnormal, you may suspect ectopic. Also, if it is low, chances of ectopic are around 4x higher When is the uterine sac visible on USS? - ANSWER-*5 weeks GA*, or b-HCG between 1000 and 1500 How does renal function change during pregnancy? - ANSWER-GFR rises by around 50% in 1st trimester, then plateaus Renal flow rises by 25-50% in 1st trimester, by then returns to normal over the 3rd trimester What is the average increase in body weight during pregnancy? - ANSWER-*11kg.* Range for healthy mother - 11.5-16kg How many more daily kilojoules should a pregnant woman have? - ANSWER-100 calories in 1st Trim 400 calories in 2nd/3rd Trim 500 when breastfeeding What 3 nutrients need to be supplemented in pregnancy, and why? - ANSWER-Folate/Folic acid - NTD Calcium - infant bones Iodine - Metabolism Also, for specific pts (e.g. vegetarians): Iron - Anaemia Vit D - infant bones B12 - Anaemia How much folic acid should pregnant women receive? - ANSWER-0.4 mg/day. 4mg/day if Hx of NTD (all women of childbearing age should receive this, as it is required in early Trim One to work properly) How much calcium supplementation should pregnant women receive? - ANSWER-*1000mg/day* if >19yrs. 1300 if < 19 How much Vitamin D and B12 should vegetarian pregnant women receive? - ANSWER-D - *10 micrograms*/day B12 - *2 micrograms*/day (10 + B2 = B12) How much exercise should pregnant women perform per day? - ANSWER-30 mins Describe the changes to the CVS witnessed in pregnancy - ANSWER-Heart rate and SV gradually increase (SV plateaus at 19 weeks) CO rises rapidly by 20%, and another 10% by week 28 *BP decreases* as pregnancy progresses, *until week 34*, where it returns to normal Venous distension increases to term, while TPR decreases to term Describe the changes experienced by the pulmonary system during pregnancy - ANSWER-Tidal volume and respiratory minute volume up 30-40% Expiratory reserve gradually declines Describe the changes seen in the haematological system during pregnancy - ANSWER-50% *increase in volume* (and *fibrinogen*) by 2nd trim Hematocrit decreases slightly How does the GIT change during pregnancy? - ANSWER-Decrease *sphincter tone* Increased *gastric emptying* time Which type of immunoglobulin can cross the placenta? - ANSWER-IgG List the infective organisms which can cross the placenta and ruin a baby - ANSWER-Modified version TORCHES: Toxoplasmosis Other: Parvovirus B19, Listeria monocytogenes Rubella CMV HIV Enteroviruses Syphilis (Trepanoma pallidum) How often does a pregnant woman require a prenatal visit to GP/Obs+Gyn? - ANSWER-Every 4 weeks to week 28 Every 2 weeks to 34 Every week to delivery What haematological tests need to be run in the first prenatal visit? - ANSWER-CBC Blood type +/- HbA1c or Sickle Cell Anaemia (if indicated) Which tests, screening for infectious diseases, need to be run in the initial prenatal visit? - ANSWER-UA and culture Pap smear + culture (STIs) + Chlamydia Rubella antigen titre HBsAg RPR/VDRL HIV +/- HCV, PPD and Varicella Other than infectious disease screening and CBC + typing, what do you need to do in the initial antenatal visit? - ANSWER-Genetic screening discussion - Tay-sachs, CF What investigations need to be run in the 11th week of pregnancy? - ANSWER-USS - *nuchal translucency* (11-13) +/- CVS (11-12) Pregnancy Associated Plasma Protein A(*PAPP-A*; week 9-14) Free *b-HCG* What investigations need to be run between weeks 15 and 22? - ANSWER-Quad screen - AFP, estriol, b-HCG, inhibin A +/- Amniocentesis USS morphology scan - week 18-20 When do you need to test for gestational diabetes? - ANSWER-24-28 weeks. Do OGTT If the woman is Rh(-), what test needs to be run between weeks 28-30? - ANSWER-Antibody screen (also admin RHOgam if needed) What two tests must be run at week 35, and what tests must be considered? - ANSWER-GBS + repeat FBC Cervical chlamydia, gonorrhoea cultures, HIV and RPR need to be also run in high risk pts What are the four elements of quad-screening? - ANSWER-MSAFP (maternal serum alfa-fetoprotein) Inhibin A Estriol b-HCG Why is accurate gestational dating important when assessing MSAFP? - ANSWER-AFP produced by the fetus and measured as multiples of the median (MoM). Median is based on age Elevated MSAFP (>2.5 MoM) could be indicative of what conditions? - ANSWER-Neural tube defect (*NTD*) Abdominal wall defect *Multiple gestation* Fetal *death* Placental abnormality (also, don't forget, incorrect gestational aging) A reduced MSAFP (<0.5 MoM) could be indicative of what two conditions? - ANSWER-Trisomy 21 or 18 Fetal demise (again, don't forget gestational aging) What is PAPP-A? - ANSWER-Pregnancy associated plasma protein A. Should be measured between weeks 9 and 14 What can PAPP-A be used to detect? - ANSWER-Trisomy 21 and 18 (earlier and safer than CVS) But only in conjunction with Nuchal Translucency + b-HCG How do quad screening tests change in Trisomy 21? - ANSWER-MSAFP - Down Estriol - Down Inhibin A - Up b-HCG - Up BIN (up) PEA (down) How do quad screening tests change in Trisomy 18? - ANSWER-MSAFP - Down Estriol - Down Inhibin A - Down b-HCG - Down Distinguish between how Chorionic Villi Sampling and Amniocentesis are performed - ANSWER-CVS - Transcervical OR transabdominal; aspiration of placental tissue. 10-12 weeks Amniocentesis - Only transabdominal aspiration of amniotic fluid. 15-20 weeks Distinguish between risks associated with CVS and Amniocentesis - ANSWER-CVS - 1% loss of foetus Amniocentesis - Membrane rupture, chorioamnionitis, fetal-maternal haemorrhage When is Amniocentesis indicated? - ANSWER-*Abnormal quad screen* or Nuchal translucency *>2.2-2.8mm* *Rh-sensitized pregnancy* to obtain foetal blood type, or detect foetal hemolysis To evaluate foetal lung maturity Some maternal infections that could be passed to foetus How does amniocentesis evaluate foetal lung maturity? - ANSWER-Provides *lethicin-sphingomyelin ratio* (>2.5) Detects phosphatidylglycerol What are the most common sequelae of maternal-fetal infection? - ANSWER-Premature delivery CNS abnormality Anaemia Jaundice Hepatosplenomegaly Growth retardation What is a spontaneous abortion? - ANSWER-Loss of products of conception (POC) prior to the 20th week of pregnancy. 80% in Trim 1 What are the four main risk factors for spontaneous abortion? - ANSWER-Chromosomal Abnormality Maternal factors Environmental factors - tobacco, alcohol, caffiene, toxins/drugs, radiation Anatomical malformations What maternal factors can be risk factors for fetal damage/spontaneous abortion? - ANSWER-Inherited *thrombophilias* - Factor V Leiden, prothrombin, antithrombin, Protein C/S *Immunologic issues* *Anatomic issues* - uterine abnormality, incompetent cervix (conization, injury, anatomical abnormality), DES exposure *Endocrinology* issues - GDM, hypothyroid, progesterone deficiency Other - maternal *trauma, age, infection, dietary deficency* Low hCG and USS are used to diagnose spontaneous abortion. What three features on USS are suggestive of spontaneous abortion between weeks 5 and 7? - ANSWER-Gestational sac abnormalities (wk 5-6) Fetal pole abnormalities (6) Cardiac inactivity (6-7) How is Toxoplasmosis avoided in pregnancy? - ANSWER-Toxoplasmosis is caught transplacentally through undercooked meat, gardening or cat faeces. Avoid these factors Spiramycin prophylaxis may be appropriate in 3rd trim What neonate symptoms may be exhibited due to toxoplasmosis infection in utero? - ANSWER-Hydrocephalus Intracranial calcification Chorioretinitis Ring-enhancing lesion on MRI How is toxoplasmosis treated in utero? - ANSWER-Pyrimethamine + Sulfadiazine What four foetal infections are identified using serologic testing? - ANSWER-Toxoplasmosis Rubella HSV CMV What are the sequellae of rubella in a foetus/neonate? - ANSWER-Purpuric "blueberry muffin" rash Cataracts Mental retardation Hearing loss Patent ductus arteriosus What are the symptoms of congenital CMV? - ANSWER-Petechial rash Periventricular calcifications Hepatosplenomegaly How is CMV diagnosed in a foetus? - ANSWER-Urine culture PCR of amniotic fluid How is CMV treated? - ANSWER-Post-partum Ganciclovir How does a person catch congenital HSV? - ANSWER-Intrapartum transmission from active lesions How does HSV present in a neonate? - ANSWER-Skin, eye and mouth infection CNS or systemic infection (life-threatening) How do you prevent HSV infection in neonates? - ANSWER-Do a C-section if active lesions are present on the mother at delivery How is HIV spread to neonate? - ANSWER-In utero, at delivery or via breast milk How is neonatal HIV prevented? - ANSWER-C Section if viral load > 1000 Zidovidine or nevirapine in pregnant women Infants receive prophylactic Zidovidine What are the symptoms of syphilis infection in neonate? - ANSWER-Maculopapular rash Lymphadenopathy Hepatomegaly 'Snuffles" - mucopurulent rhinitis Osteitis If late congenital syphilis - Saber shins, saddle nose, CNS involvement, *Hutchinson's triad: peg shaped central incisors, deafness, interstitial keratitis* What tests are used to diagnose syphilis? - ANSWER-Dark-field microscopy VDRL/RPR FTA-ABS List the 8 types of Spontaneous Abortion - ANSWER-Complete Incomplete Threatened Inevitable Missed Septic Intrauterine fetal demise Recurrent Distinguish between the diagnosis of a Complete and Incomplete spontaneous abortion - ANSWER-Complete - POC expelled; closed os. Empty uterus on USS Incomplete - Some POC expelled +/- bleeding/cramping; open os. Some remaining tissue on USS. Incomplete may require manual uterine aspiration, dilation and curettage, or medical therapy. Complete requires no treatment (except emotional) What might a threatened miscarriage present like? - ANSWER-No POC expelled. Uterine bleeding +/- abdo pain Closed os + intact membranes + heart movements on USS How is a threatened miscarriage treated? - ANSWER-Pelvic rest for 24-48 hours + follow-up USS to assess viability How will an inevitable miscarriage differ from a threatened miscarriage? - ANSWER-Open os +/- RoM. MUA, D&C, or misoprostol/methotrexate will likely be required What is a missed miscarriage? - ANSWER-Miscarried, but remains in the uterus. No POC expelled and no uterine bleeding, however, brownish discharge, no fetal heart motion or cardiac activity. Os closed. Fetal tissue on USS. Same Tx as inevitable/incomplete miscarriage Endometritis leading to septicaemia is associated with septic miscarriage. What is the maternal mortality rate? - ANSWER-10-15% What are the symptoms and treatment for septic miscarriage? - ANSWER-Hypotension Hypothermia WCC elevated D&C, MUA and IV antibiotics urgently What is intrauterine fetal demise? - ANSWER-Absence of fetal cardiac activity - the fetus has died. What are the signs of fetal demise? - ANSWER-Small uterus given GA No heart tones or movement on USS What treatment must be administered in fetal demise and why? - ANSWER-Induce labor D&C if earlier than 16 weeks to prevent DIC Distinguish between the main causes of recurrent spontaneous abortion (>2 consecutive) in different stages of pregnancy - ANSWER-early - *chromosomal* abnormality mid - *cervical* abnormality (18-32, so early to late) late - *hypercoaguable states* What medical options are available for elective abortion in 1st trimester? - ANSWER-Oral mifepristone (low dose) + oral/vaginal misoprostol (up to 9 wks) IM/oral methotrexate + oral/vaginal misoprostol High dose misoprostol (can be done up to 59 days, as oppose to 49) What surgical options are available for elective abortion? - ANSWER-Manual aspiration D&C with vacuum aspiration Done *up to 13 weeks* What surgical elective abortion option is available up until 24 weeks? - ANSWER-Dilation and evacuation (*D&E*) During delivery, what needs to be inspected during cervical examination? - ANSWER-*Dilation, effacement*, cervical *position*, cervical *consistency* Determine *fetal position* (using fontanelles and fetal sutures) Determine *station* (based on fetal head relative to line through ischial spines; (-) station is when head is superior to this line. Seen in image) What tool must you use to help determine fetal position if there is rupture of membranes? - ANSWER-Sterile Speculum Describe the two components to the first stage of labour - ANSWER-Latent - <3-4cm dilation. 6-11 hrs prim; 4-8 multi. Active - 4cm - 10cm. 4-6hrs prim; 2-3 hours multi. What can prolong the first stage of labour? - ANSWER-Excessive *sedation* (latent stage) *Cephalopelvic disproportion* (active stage) Describe the second stage of labour - ANSWER-From complete dilation to delivery. Takes 0.5-3 hours prim, or 5-30 minutes multi. Describe the third stage of labour - ANSWER-Delivery of placenta, after baby is delivered. Happens up to 30 minutes afterwards (prim or multi) What are the two options for monitoring fetal heartrate? - ANSWER-*Electrode* to the scalp (more accurate) *Doppler* USS (less invasive) When is continuous electronic fetal heart rate monitoring beneficial? - ANSWER-In patients who are moderate-to-high risk. Low risk patients only need intermittent heart rate monitoring How regularly should the fetal heart rate be measured in low-risk patients without complications? - ANSWER-Stage 1 - every 30 mins Stage 2 - every 15 mins How regularly should FHR be measured in low-risk patients with complications? - ANSWER-Stage 1 - every 15 mins Stage 2 - every 5 mins What is the normal fetal heart rate? - ANSWER-110-160 What are the two main causes of fetal bradycardia? - ANSWER-Congenital heart malformation Severe hypoxia What are the three main causes of fetal tachycardia? - ANSWER-Hypoxia Maternal fever Fetal anaemia What level of variability would you expect in fetal heart rate? - ANSWER-6-25bpm What does low variability in fetal heart rate indicate? - ANSWER-If undetectable - *severe fetal distress* If detectable (<6) - Fetal *hypoxia, opioids, magnesium, sleep cycle* What does high variability of fetal heart rate indicate? - ANSWER-Fetal hypoxia - can occur before a drop in variability What specific pattern of fetal heart rate variability indicates serious fetal anaemia? - ANSWER-Sinusoidal pattern Why are <30sec transient accelerations of FHR reassuring? - ANSWER-They indicate the foetus has the ability to appropriately respond to the environment What is an Early Fetal Deceleration, and are they normal? - ANSWER-Reduction in fetal heart rate in synchrony with uterine contraction. Caused by head compression - totally normal What is a Late Fetal Deceleration? - ANSWER-Drop in fetal heart rate, beginning around the peak of contraction - caused by Uteroplacental insufficiency and fetal hypoxemia Umbilical cord compression will cause what kind of Fetal Deceleration? - ANSWER-*Variable* type - abrupt, visually apparent drop in FHR, lasting less than 2 mins (but >15 seconds, w/ 30 seconds to peak)