USMLE Obstetrics I

• is a glycoprotein produced by the trophoblast.
• During the first trimester, PAPP-A can be measured with beta - hCG and ultrasound nuchal translucency with a detection rate of -85% for Down syndrome.
• Fetuses with Down syndrome produce less PAPP-A.
• The marker is less accurate with increasing gestational age and is therefore not used in the second trimester

• Indications
• • Maternal age >35
• • Abnormal maternal serum screening test
• • Sonographic findings associated with fetal aneuploidy
• • Previous pregnancy with fetal aneuploidy
• • Parental-balanced Robertsonian translocation
• Applications
• • Screening for trisomy 21 , 18, 13 & sex- chromosome aneuploidies
• • Fetal sex detennination

• During the second and third trimesters of pregnancy, the placenta secretes hormones that increase maternal insulin resistance to promote fetal growth and metabolism.
• Women with inadequate pancreatic function to overcome insulin resistance are at risk of developing gestational diabetes mellitus (GDM).
• Risk factors for GDM include obesity, excessive weight gain during pregnancy, family history of DM, and a previous macrosomic infant.
• Uncontrolled hyperglycemia is dangerous to both the mother and fetus, with complications such as miscarriage, birth defects, fetal macrosomia, and preeclampsia.
• Women who are at risk for undiagnosed type 2 DM should undergo screening during their initial prenatal visit with a hemoglobin A 1 c or glucose tolerance test.
• All other patients should undergo an oral glucose challenge test (GCT) at the end of the second trimester (24-28 weeks).
• The most common approach consists of screening with a 1-hour 50-g GCT, followed by confirmation with a 3-hour 100-g glucose tolerance test

• Prior delivery complicated by neonatal GBS infection
• • GBS bacteriuria or GBS urinary tract infection during the current pregnancy (regardless of treatment)
• • GBS-positive rectovaginal culture
• • Unknown GBS status PLUS any of the following:
• <37 weeksgestation
• Intrapartum fever
• Rupture of amniotic membranes for >18 hours
•  Screening Done by Rectovaginal culture at 35-37 weeks gestation
• Universal screening occurs at 35-37 weeks gestation as the result is most accurate within 5 weeks of the anticipated delivery date.
• Exceptions include a history of GBS bacteriuria, urinary tract infection, or an infant with early-onset GBS disease; these patients should receive antibiotic prophylaxis without testing

• All pregnant women should be screened for GDM at 24-28 weeks gestation.
• Patients with risk factors (eg, obesity, previous GDM, previous macrosomic infant) should be screened early in pregnancy and then rescreened at 24-28 weeks gestation if the initial screen is negative.

• Target blood
• • Fasting <95 mg/dl (5.3 mmoi/L) glucose levels
• • 1-hour postprandial <1 40 mg/dl (7.8 mmoi/L)
• • 2-hour postprandial <120 mg/dl (6.7 mmoi/L)
• Treatment
• • 1st-line: Dietary modifications
• • 2nd-line: Insulin, metformin, glyburide

• defined as the inability to deliver fetal shoulders with routine gentle traction, is an obstetric emergency that can lead to both infant and maternal complications.
• Infant risks include brachial plexus injuries, clavicular or humeral fractures, and hypoxic encephalopathy.
• Maternal risks include fourth-degree (eg, rectal mucosa) perineal lacerations and postpartum hemorrhage.

• is caused by impaction of the anterior shoulder behind the pubic symphysis.
• Maneuvers help dislodge the anterior shoulder or reorient the infant to deliver through the widest diameter of the bony pelvis.
• The initial steps in relieving a shoulder dystocia are the McRoberts maneuver (eg, flexing the hips back against the abdomen) and applying suprapubic pressure.
• The McRoberts maneuver flattens the sacral promontory and decreases obstruction through the bony pelvis.
• Suprapubic pressure may dislodge the anterior shoulder and allow passage of the infant through the widest diameter of the maternal pelvis.
• The combination of these maneuvers relieves almost half of shoulder dystocias without further intervention.

• B Breathe, do not push; lower head of the bed
• E Elevate legs into McRoberts position -sharp hip flexion while in supine position
• C Call for help - nurses, anesthesiologists, pediatricians, another physician
• A Apply suprapubic pressure - downward & lateral to release anterior shoulder
• L Enlarge vaginal opening with episiotomy to facilitate extra maneuvers
• M Maneuvers
• • Delivery of posterior arm
• • Pressure against baby's posterior shoulder either anteriorly or posteriorly & anterior rotation (Woods corkscrew or Rubin maneuver)
• • Mother on hands & knees- "all fours" (Gaskin maneuver)
• • Replacement of baby's head to vagina followed by cesarean delivery (Zavanelli maneuver)

• • Multilocular
• Presentation
• • Bilateral
• • 10-15 em ovaries
• Pathogenesis
• Ovarian hyperstimulation due to:
• o Gestational trophoblastic disease
• o Multifetal gestation
• o Infertility treatment
• Clinical course
• • Resolve with decreasing P-hCG levels

• results from abnormal fertilization of an empty ovum by either 2 sperm or by 1 that subsequently duplicates its genome.
• The resultant gestation is composed of proliferative trophoblastic tissue that secretes high levels of P-hCG.
• The markedly elevated j3-hCG level causes hyperstimulation of the ovaries and formation of theca lutein cysts, which are large, bilateral, multilocular ovarian cysts.
• Theca lutein cysts are expectantly managed as they resolve after treatment of the HM by suction curettage or hysterectomy when the P-hCG level decreases.

• If the patient is known to have lupus before pregnancy, the appearance of proteinuria during pregnancy may represent lupus nephritis, preeclampsia or both.
• Signs that favor lupus as the origin of the proteinuria include a rapid aggravation of the proteinuria, associated clinical signs of active SLE, and the presence of RBC casts in the urinalysis which indicates true nephritis rather than simple protein loss.
• If the proteinuria persists after delivery, renal biopsy is then indicated and will most likely be diagnostic of lupus nephritis.
• SLE, however, rarely presents for the first time during pregnancy.

• Preterm premature rupture of membranes (PPROM) refers to rupture of membranes at <37 weeks gestation prior to the onset of labor.
• Some patients with membrane rupture have a gush of vaginal fluid.
• Others experience intermittent leakage (as with this patient) or vaginal wetness, symptoms also seen with urinary incontinence.
• Although this patient has experienced stress urinary incontinence for the past 6 weeks, her increased leakage frequency, nitrazine-positive vaginal fluid, and decreased amniotic fluid index are consistent with PPROM.
• Patients with PPROM at or more than 34 weeks gestation should be delivered as the morbidity and mortality associated with premature delivery decrease after 34 weeks and delivery decreases the incidence of chorioamnionitis.
• Patients with PPROM at <34 weeks with signs of infection (eg, maternal fever, fetal tachycardia) or fetal compromise should also be delivered.
• To prevent neonatal group B Streptococcus (GBS) infection, intrapartum intravenous penicillin should be administered to patients with PPROM who are delivered and have either an unknown or positive GBS status.
• Tocolytics are contraindicated.
• This patient has PPROM at 35 weeks gestation and her GBS status is unknown.
• She should be delivered and receive intrapartum penicillin.

Amnioinfusion involves instillation of saline into the uterine cavity for treatment of recurrent variable decelerations due to umbilical cord compression during labor.

• (Hemolysis, Elevated Liver enzymes, Low Platelet count).
• HELLP syndrome may be a variation of severe preeclampsia and affects 10%-20% of women with preeclampsia.
• Serious liver problems include centrilobular necrosis, hematoma formation, and thrombi in the portal capillary system.
• These processes can cause liver swelling with distension of the hepatic (Glisson's) capsule, resulting in right upper quadrant or epigastric pain.

• is characterized by nausea, vomiting, abdominal pain, and significant elevations of liver markers in the third trimester.
• Many features of AFLP overlap with those of HELLP syndrome, but patients with AFLP are more likely to have additional extrahepatic complications such as leukocytosis, hypoglycemia, and acute kidney injury.
• Severe hypertension is less likely in AFLP than in HELLP syndrome.

• sudden-onset dyspnea, hypoxia, and crackles are most likely due to acute pulmonary edema, a rare and life-threatening complication of severe preeclampsia.
• Preeclamptic patients have generalized arterial vasospasm leading to increased systemic vascular resistance and high cardiac afterload.
• The heart becomes hyperdynamic to try to overcome the systemic hypertension.
• Additional factors that may contribute to pulmonary edema include decreased renal function, decreased serum albumin, and endothelial damage leading to increased capillary permeability.
• Management includes supplemental oxygen, fluid restriction, and diuresis in severe cases.
• Fluid restriction and diuresis must be used with caution as plasma volume is effectively decreased through third-spacing and placental perfusion can be compromised.

• Risk factors
• • Hydatidiform mole
• • Multifetal gestation
• • History of hyperemesis gravidarum
• Clinical features
• • Severe, persistent vomiting
• • >5% loss of prepregnancy weight
• • Dehydration
• • Orthostatic hypotension
• Laboratory abnormalities
• • Ketonuria
• • Hypochloremic metabolic alkalosis
• • Hypokalemia
• • Hypoglycemia elevated serum aminotransferases
• • Hemoconcentration
• Treatment
• • Admission to hospital
• • Antiemetics & intravenous fluids

• Associated conditions
• • Chronic alcoholism (most common)
• • Malnutrition (eg, anorexia nervosa)
• • Hyperemesis gravidarum
• Pathophysiology
• • Thiamine deficiency
• Clinical features
• • Encephalopathy
• • Oculomotor dysfunction (eg, horizontal nystagmus & bilateral abducens palsy)
• • Postural & gait ataxia
• Treatment
• • Intravenous thiamine followed by glucose infusion

manifests years after an initial syphilitic infection and is characterized by tabes dorsalis (eg, sensory ataxia, lancinating pain) and Argyll Robertson pupils (eg, normal pupillary constriction with accommodation but not light).

• presents with dementia and a subacute combined degeneration due to demyelination of spinocerebellar tracts (eg, gait ataxia), lateral corticospinal tracts (eg, spastic paresis), and dorsal columns (eg, loss of position and vibration sense).
• However, the clinical course of vitamin B 12 deficiency is indolent rather than acute.
• Patients also have a macrocytic anemia (mean corpuscular volume >100 fl).

• Oxytocin is a hormone secreted by the posterior pituitary that stimulates uterine contractions. Oxytocin is similar in structure to antidiuretic hormone.
• Consequently, prolonged administration of high doses of oxytocin can cause water retention and hyponatremia.
• Hyponatremia can present with headaches, abdominal pain, nausea, vomiting, lethargy, and tonic-clonic seizures.
• Management of hyponatremia involves gradual administration of hypertonic saline (eg, 3% saline) to normalize sodium levels.

• • Induction or augmentation of labor
• • Prevention & management of postpartum hemorrhage

• • Hyponatremia
• • Hypotension
• • Tachysystole

• typically presents with hyporeflexia, lethargy, headache, respiratory failure, and ultimately cardiac arrest, not with seizures.
• This patient's magnesium level is in the therapeutic range for preeclampsia management (approximately 5-8 mg/dl).
• Magnesium becomes toxic at concentrations >8 mg/dl.

• Sheehan syndrome is a complication of massive obstetrical hemorrhage. Ischemic pituitary necrosis may result in amenorrhea, lactational failure, and persistent hypotension.
• Pathogenesis
• • Heavy peripartum blood loss complicated by hypotension &/or blood transfusion
• • Postpartum pituitary infarction
• Clinical features
• • Symptoms of hypopituitarism (l prolactin, ACTH, TSH, FSH, LH, &/or growth hormone):
• o Lactation failure
• o Amenorrhea
• o Loss of sexual hair
• o Anorexia/weight loss
• o Lethargy
• o Hyponatremia

• refers to fetal death at or more than 20 weeks gestation and before the onset of labor.
• Although IUFD most commonly occurs in uncomplicated pregnancies, risk factors include fetal growth restriction, abnormal fetal karyotype, and tobacco use.
• Other Risk factors for IUFD include nulliparity, obesity, hypertension, and diabetes mellitus.
• Patients typically present with decreased or absent fetal movement.
• Inability to find the fetal heart rate by Doppler sonography is not diagnostic and can be due to fetal malpresentation or maternal obesity. The diagnosis of IUFD must be confirmed by absence of fetal cardiac activity on ultrasound.
• Once the diagnosis is confirmed, it is critical to inform the parents as empathically as possible.
• The timing and route of an IUFD delivery are dependent on gestational age and patient preference. The diagnosis can be overwhelming for prospective parents, and some patients are unable to make decisions at the time of diagnosis.
• If the fetus is at 20-23 weeks, Dilation & evacuation or Vaginal delivery is preferred.
• Patients should be informed that vaginal delivery is the preferred delivery route at or more than 24 weeks gestation, regardless of fetal presentation (eg, vertex, breech).
• Although most patients prefer to begin an induction immediately, it can generally be delayed until the patient is ready.
• However, retention of the fetus for several weeks can lead to coagulopathy.
• Therefore, waiting for spontaneous labor, which usually occurs 2-3 weeks after the diagnosis, is not recommended.

• Fetal
• • Autopsy
• • Gross & microscopic examination of placenta, membranes & cord
• • Karyotype/genetic studies
• Maternal
• • Kleihauer-Betke test for fetomaternal hemorrhage
• • Antiphospholipid antibodies
• • Coagulation studies

• False labor is mild, Irregular contractions that cause no cervical change (eg, Braxton Hicks contractions) .
• Latent labor is regular contractions with increasing frequency and intensity that cause gradual cervical change .
• Labor is regular, painful uterine contractions that cause cervical change (eg, dilation, effacement).

• Penicillin is administered during labor in patients with culture-proven group B Streptococcus colonization at any gestational age or in laboring patients at <37 weeks with unknown status to prevent vertical transmission.
• Penicillin administration prior to labor is not beneficial due to rapid bacterial regrowth necessitating treatment in labor.

• Tocolysis is not indicated after 34 weeks gestation as risks of the therapies exceed those of preterm delivery.
• Indomethacin, a common tocolytic, is contraindicated after 32 weeks gestation due to potential closure of the ductus arteriosus.
• Magnesium sulfate is administered for fetal neuroprotection before 32 weeks gestation.

• occurs when there is no fetal descent after pushing for more than 3 hours in nulliparous patients or more than 2 hours in multiparous patients.
• The most common cause of a prolonged or arrested second stage is fetal malposition.
• The fetal position is the relationship of the fetal presenting part to the maternal pelvis.
• The optimal fetal position is occiput anterior as it facilitates the cardinal movements of labor.
• Deviations from this position (eg, occiput transverse, occiput posterior) can cause cephalopelvic disproportion and arrest of the second stage.

• refers to the lowest part of the fetus in the maternal pelvis.
• The most common presentation (seen in this patient) is vertex, in which the fetal occiput is the lowest presenting part.
• Malpresentation refers to any nonvertex presentation (eg, face, breech) and can cause labor protraction.

Inadequate contractions (eg, <3 contractions in 10 minutes, soft to palpation) are the most common cause of a protracted first stage of labor.

• Low back pain is a very common complaint in the third trimester of pregnancy.
• It is believed to be caused by the increase in lumbar lordosis and the relaxation of the ligaments supporting the joints of the pelvic girdle

• Risk factors
• • Adolescent pregnancy
• • Late/noncompliant prenatal care
• • Inadequate pregnancy weight gain
• Obstetric complications
• • Spontaneous abortion
• • Preterm birth
• • Preeclampsia
• • Abruptio placentae
• • Fetal growth restriction
• • Intrauterine fetal demise
• all patients should be screened for illicit drug use at the initial prenatal visit. Patients with positive screening should be followed with serial urine drug tests and counseled regarding options for managing cessation.

• Nonstress test plus ultrasound assessmentof the following:
• • Amniotic fluid volume
• • Fetal breathing movement
• • Fetal movement
• • Fetal tone
• 2 points per category if normal & 0 points if abnormal (maximum 10 points )
• Normal: 8-10 points
• • Equivocal: 6 points
• • Abnormal: 0, 2,4 points or oligohydramnios

• A score of 0/1 o to 4/10 indicates fetal hypoxia due to placental dysfunction (placental insufficiency).
• Risk factors for placental insufficiency include advanced maternal age, tobacco· use, hypertension, and diabetes. The patient requires prompt delivery due to the high likelihood of fetal demise.

is defined as a temperature ~38 C (100.4 F) after the first 24 hours post delivery

• Early puerperium is characterized by several physiologic processes that can be mistaken for signs of pathology.
• Immediately after placental delivery, shivering occurs commonly and is theorized to be due to thermal imbalance.
• The uterus contracts and becomes firm and globular with the fundus typically 1-2 em above or below the umbilicus.
• During the first few days after delivery, lochia rubra occurs, which is a red or reddish-brown vaginal discharge (the normal shedding of the uterine decidua and blood), as seen in this patient.
• After 3-4 days, the discharge becomes thin and pink or brown colored (lochia serosa). After 2-3 weeks, the discharge becomes white or yellow (lochia alba).

• routine postpartum care in Pueperium.
• This includes perineal care, pain management, a voiding trial, and lactation support.
• Fundal and perineal pad checks should be performed to screen for signs of postpartum hemorrhage (eg, "boggy" uterus. heavy vaginal bleeding, unstable vital signs).