Disorders of labor Notes


Osmosis High-Yield Notes

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Placenta accreta

Placenta previa

Placental abruption

Preterm labor

NOTES NOTES DISORDERS OF LABOR PLACENTA ACCRETA osms.it/placenta-accreta PATHOLOGY & CAUSES SIGNS & SYMPTOMS ▪ A type of abnormally developed, invasive placenta ▫ Normally a spontaneous, complete placenta separation from uterine wall (myometrium) ▫ Maternal placenta side (decidua) separates from myometrium at stratum basalis layer ▪ Absent/underdeveloped decidua occurs in placenta accreta → adherence of fetal chorionic villi directly to myometrium → placenta fails to fully separate after fetus is delivered ▫ Partial separation → profuse hemorrhage → hemorrhagic shock and coagulopathy ▫ If no separation → hemorrhage is induced when manual separation is attempted ▪ Placenta fails to spontaneously deliver after fetus’s birth ▫ Manual separation attempts unsuccessful, provoke increased bleeding ▪ Severe hemorrhage ▪ Boggy (soft, spongy) uterus unresponsive to uterotonics/uterine massage TYPES DIAGNOSTIC IMAGING ▪ Placenta accreta; placenta increta; placenta percreta (based on invasiveness) ▪ Placenta accreta also increases risk of preterm bleeding ▫ Association between placenta accreta, concurrent placenta previa RISK FACTORS ▪ Previous uterine surgery ▫ Cesarean section (most common), myomectomy, curettage ▫ Scar tissue prevents normal placental implantation ▪ Previous placenta previa 732 OSMOSIS.ORG DIAGNOSIS ▪ Based on clinical presentation of hemorrhage post-delivery; severe hemorrhage after attempted manual placenta delivery ▪ Prenatal diagnosis allows planned management (e.g. cesarean birth, cesarean hysterectomy) Ultrasound, color Doppler ▪ Evaluate alterations in intraplacental blood flow, status of placental-myometrial interface LAB RESULTS ▪ Laboratory tests may show ↑ maternal serum alpha fetoprotein
Chapter 123 Disorders of Labor TREATMENT MEDICATIONS ▪ Circulatory support ▫ Fluids, blood products SURGERY ▪ Hysterectomy may be needed to control postpartum hemorrhage ▫ Most common life-saving intervention ▪ Cesarean hysterectomy (fetus delivery followed by uterus + placenta removal as one unit) may be planned preoperatively with invasive placenta evidence Figure 123.1 A uterus removed following cesarian section demonstrating complate invasion through the uterine wall by the placenta, known as placenta percreta. PLACENTA PREVIA osms.it/placenta-previa PATHOLOGY & CAUSES ▪ Placenta implants in lower uterine segment (placenta previa = placenta first) ▪ Implantation is in lower uterine segment, close to/covering uterine opening (cervical os) → as pregnancy progresses, uterine segment grows → disruption of uterine blood vessels → bleeding (usually after 20 weeks of gestation) ▪ Classified by placenta’s closeness to cervical os ▫ Complete: placenta completely covers cervical os ▫ Partial: placenta partially covers cervical os ▫ Marginal: placenta edge extends to within 2cm/0.79in of cervical os CAUSES RISK FACTORS ▪ Multiple placentas or placenta with a larger than normal surface area (e.g. multiple gestation) ▪ Previous cesarean section/any uterine surgery ▪ Multiparity ▪ Intrauterine fibroids ▪ Spontaneous/induced abortion ▪ Placenta accreta ▪ Maternal age ≥ 35 years old ▪ Smoking COMPLICATIONS ▪ Maternal: hemorrhage ▫ Severity depends on placenta location ▫ Disseminated intravascular coagulation (DIC) if bleeding severe/prolonged ▪ Fetal: hypoxia, preterm birth ▪ Placenta implants lower in uterus when upper uterine endometrium is not well vascularized due to endometrial damage OSMOSIS.ORG 733
SIGNS & SYMPTOMS ▪ Bleeding ▫ Painless ▫ Bright red ▫ Intermittent/continuous ▫ Often increases during labor from uterine contractions, cervical dilation ▪ Uterine hyperactivity ▪ Electronic fetal monitoring tracings may show fetal heart rate deceleration, indicating hypoxia DIAGNOSIS DIAGNOSTIC IMAGING Prenatal ultrasound ▪ During routine prenatal ultrasound Transabdominal ultrasound ▪ When bleeding occurs during labor, determines placental location TREATMENT MEDICATIONS ▪ Corticosteroids as indicated to enhance fetal lung maturity SURGERY ▪ Emergent cesarean delivery if placenta obstructs delivery or hemorrhage is severe 734 OSMOSIS.ORG Figure 123.2 An MRI scan of the abdomen of a pregnant female demonstrating major placenta praevia. The internal cervical os is completely covered by the placenta. ▪ After delivery, measures to control bleeding include ▫ Hysterectomy/interventional radiology (e.g. uterine artery embolization) OTHER INTERVENTIONS ▪ Manage maternal bleeding; support mother, fetus hemodynamic stability ▫ Transfusion of blood products ▫ IV fluids ▪ Continuous fetal heart rate monitoring
Chapter 123 Disorders of Labor PLACENTAL ABRUPTION osms.it/placental-abruption PATHOLOGY & CAUSES ▪ Premature separation of all/section of otherwise normally implanted placenta from uterine wall after 20 weeks of gestation wall resulting in hemorrhage TYPES ▪ Partial/complete: depending on separation degree ▪ Concealed: central separation may cause a pocket of blood to form, concealing bleeding between decidua basalis and uterine wall → hematoma promotes separation ▪ Apparent: bleeding is visualized CAUSES ▪ Uterine artery degeneration in decidua basalis → diseased vessels rupture → hemorrhage → placenta separation RISK FACTORS Previous placental abruption Chronic hypertension Preeclampsia/chronic hypertension Multiparity Rapid uterine decompression (e.g. as with polyhydramnios/multiple gestation) ▪ Trauma (e.g. car crash, fall, domestic violence) ▪ Smoking ▪ Drugs: cocaine, methamphetamine ▪ ▪ ▪ ▪ ▪ SIGNS & SYMPTOMS ▪ Uterus ▫ Pain in abruption area ▫ Abdominal/back pain ▫ Irritability, tachysystole, tetany ▫ Mild to severe vaginal bleeding (evidence of consumptive coagulopathy if severe bleeding) ▪ Fetal hypoxia, bradycardia DIAGNOSIS ▪ Ultrasound may show retroplacental blood collection ▪ Blood-stained amniotic fluid in vagina ▪ Abruption signs evidenced by fetal heart rate, uterine activity DIAGNOSTIC IMAGING Electronic fetal monitoring ▪ Decelerations may indicate fetal hypoxia, bradycardia COMPLICATIONS ▪ Maternal: hypovolemic shock, disseminated intravascular coagulation (DIC), end organ damage (e.g. renal failure, Sheehan syndrome (pituitary necrosis related to hypovolemia)) ▪ Fetal: hypoxia; asphyxia; premature birth, related sequelae; death Figure 123.3 An ultrasound scan in pregnancy demonstrating a placental abruption. There is a crescent of avascular hypoechoic fluid between the placenta and the uterine wall. OSMOSIS.ORG 735
TREATMENT MEDICATIONS ▪ Corticosteroids as indicated to enhance fetal lung maturity SURGERY ▪ Emergent delivery ▫ Vaginal/cesarean, as indicated OTHER INTERVENTIONS ▪ Expectant management for small abruptions ▪ For significant bleeding: support hemodynamic stability of mother, fetus ▪ Blood product transfusion ▪ IV fluids ▪ Continuous fetal heart rate monitoring POSTPARTUM HEMORRHAGE osms.it/postpartum-hemorrhage PATHOLOGY & CAUSES ▪ Postpartum (post = after; partum = birth) hemorrhage (PPH) is excessive blood loss after giving birth ▪ Defined by estimated blood loss (EBL), mode of birth ▫ > 500mL after vaginal delivery ▫ > 1000mL after cesarean delivery TYPES ▪ Primary/early: within 24 hours after delivery ▪ Secondary/late: after 24 hours, before six weeks postpartum CAUSES Four Ts ▪ Tone: soft, boggy uterus (uterine atony) and ineffective uterine contractions that normally cause uterine involution (return of uterus to its pre-pregnancy state) and provide tourniquet-like action on major blood vessels → hemorrhage from placental attachment site ▫ Associated with uterine overdistension: multiple gestation or polyhydramnios (excessive myometrium stretching); uterine fatigue from prolonged labor; full bladder (interferes with contractions); medications (anesthetics, especially halothane)/preterm labor 736 OSMOSIS.ORG drugs (magnesium sulfate, nifedipine, terbutaline) ▪ Trauma: damage to reproductive/genital structures (e.g. uterus, cervix, vagina, perineum) → hemorrhage ▫ Surgical incision: cesarean delivery or episiotomy ▫ Large fetus/fetal malpresentation/ shoulder dystocia (baby’s shoulder impacted against maternal pubic symphysis) → soft tissue damage during descent through vaginal canal ▫ Soft tissue laceration from instruments used in delivery (e.g. use of forceps, vacuum extraction), uterine rupture (lacerations may result in hematoma formation → hidden bleeding → interference with uterine involution → uterine atony → hemorrhage) ▪ Tissue: retained placental fragments, placenta accreta, excessive traction on umbilical cord → interferes with uterine contractions → uterine atony → hemorrhage from placental attachment site ▪ Thrombin: impaired clotting → hemorrhage ▫ Associated with clotting disorders (e.g. von Willebrand disease) ▫ Coagulopathy (e.g. disseminated intravascular coagulation) related to an obstetrical complication (e.g. eclampsia, placenta previa)
Chapter 123 Disorders of Labor SIGNS & SYMPTOMS ▪ Excessive bleeding visualization ▪ Maternal physiological response to decreased circulating volume ▫ ↑ heart rate ▫ ↓ blood pressure ▫ ↓ pulse pressure ▫ ↓ oxygen saturation ▫ ↓ hematocrit ▫ Delayed capillary refill ▫ Shock signs usually appear when hemorrhage is advanced due to normally ↑ pregnancy blood volume ▪ Soft, “boggy” uterus ▪ Clinical presentation suggesting hematoma DIAGNOSIS OTHER DIAGNOSTICS ▪ Based on clinical signs, symptoms ▪ Estimated blood loss TREATMENT MEDICATIONS ▪ Uterotonics: stimulate uterine contractions ▫ Oxytocin ▫ Methylergonovine: ergot derivative ▫ Prostaglandins SURGERY ▪ Laparoscopic arterial ligation ▪ Hysterectomy OTHER INTERVENTIONS ▪ Maintain adequate circulating volume; clotting factors, as needed ▫ IV fluids ▫ Blood products ▪ Intrauterine packing/balloon tamponade ▪ Interventional radiology ▫ Uterine artery embolization ▪ Address underlying cause (e.g. repair lacerations, remove retained placental fragments, assess for hematoma; repair ruptured uterus) ▪ Fundal massage ▫ Massaging fundus (upper portion of uterus) often causes entire uterus to contract OSMOSIS.ORG 737
PRETERM BIRTH osms.it/preterm-birth PATHOLOGY & CAUSES ▪ Birth is considered preterm when between 20–37 gestation weeks ▫ Moderate to late preterm: 32–37 weeks ▫ Very preterm: 28–32 weeks ▫ Extremely preterm: < 28 weeks ▪ Worldwide: approximately 15 million babies are born prematurely each year ▫ In the U.S., about 1 in 10 babies are born prematurely ▪ Maternal-fetal unit responds to one or more pathologic risk factors + gene-environment interaction influence → preterm labor, birth ▪ Pathologic processes activate major pathway components to labor, birth ▫ Cervical changes (ripening) include softening, thinning, shortening ▫ Enhanced uterine contractility (myometrial gap-junction formation → synchronized uterine contraction; ↑ oxytocin receptors) ▫ Fetal membrane-maternal decidua interface disruption → preterm premature rupture of membranes (PPROM) RISK FACTORS Maternal ▪ Obstetric history: previous preterm birth, short interval between pregnancies, conception through assisted reproductive technology (ART)(e.g. in vitro fertilization), previous pregnancy termination, history of stillbirth ▪ Family history of preterm birth: associated genes include FSHR (follicle-stimulating hormone receptor), IGF1R (insulin-like growth factor 1 receptor) 738 OSMOSIS.ORG ▪ Obstetric disorders: preeclampsia, placenta previa, placental abruption, uterine or cervical anomalies (e.g. cervical insufficiency—cervix unable to sustain the pregnancy) ▪ Distended uterus: multiple gestation, polyhydramnios ▪ Infections: bacterial vaginosis, sexuallytransmitted infections, urinary tract infections, periodontal disease ▪ Concurrent medical diagnoses: diabetes, pulmonary disease, heart disease, anemia (hemoglobin < 10g/dL) ▪ Socioeconomic/personal factors: low income, lack of prenatal care, ethnic minority, maternal age < 18 or > 40; stressful working conditions, intimate partner violence ▪ Behavioral factors: smoking, substance abuse, poor nutrition, inadequate weight gain, BMI < 19.6 or > 30 Fetal ▪ Intrauterine growth restriction, genetic anomalies, multiple gestation, twin-to-twin transfusion COMPLICATIONS Maternal ▪ Increased risk of hemorrhage, infection; complications from cesarean section Fetal ▪ Increased fetal/neonatal morbidity, mortality; low birth weight (less than 2.5kg/5.5lbs), lung immaturity, hypoxicischemic encephalopathy, cerebral palsy
Chapter 123 Disorders of Labor SIGNS & SYMPTOMS ▪ Vaginal discharge before completed gestation ▫ Fluid or blood leak (bloody show) ▫ Ruptured membranes may present as a sudden gush of water ▪ Lower abdominal or pelvic pressure ▪ Low, dull back pain ▪ Onset of contractions every 10 minutes or less ▪ Electronic fetal monitoring may show fetal tachycardia/decelerations (drops in heart rate during contractions) DIAGNOSIS ▪ Pelvic exam shows cervical changes ▫ Cervical shortening, softening, effacement (thinning) ▫ Opening of cervical os DIAGNOSTIC IMAGING Transvaginal ultrasound ▪ Shows shortened cervix length LAB RESULTS ▪ Fetal fibronectin (fFN) test ▫ Glycoprotein that acts like a “glue” between maternal decidua and fetal membrane ▫ Presence of fFN in cervicovaginal secretions indicates preterm labor, birth ▪ Cervical culture for Group B streptococcus if status unknown ▪ Bacterial infection that increases neonatal sepsis, pneumonia, meningitis risks TREATMENT MEDICATIONS ▪ Tocolytic medications (drugs that interfere with myometrial contractions) may delay birth for up to 48 hours. Allows time for corticosteroids to affect fetal lung development, for transport to a higher level of care if needed ▫ Nifedipine: calcium channel blocker ▫ Indomethacin: prostaglandin inhibitor ▫ Terbutaline: beta 2-adrenergic ▫ Magnesium sulfate: reduces calcium influx into muscle cell, relaxing myometrium; may have fetal neuroprotective benefit (e.g. reducing cerebral palsy risk) ▪ Antibiotics ▫ If bacterial infection suspected/ confirmed ▪ Corticosteroids ▫ To enhance fetal lung maturity, other organ development ▫ Helpful if given between 24–34 gestation weeks SURGERY ▪ Vaginal/cesarean birth as indicated OTHER INTERVENTIONS ▪ Cervical cerclage ▫ Stitch application to keep cervix closed, if indicated ▪ Adequate hydration ▫ Dehydration may induce uterine irritability ▪ Lecithin/sphingomyelin (L/S) ratio in amniotic fluid: indication of fetal lung maturity; directes neonate treatment ▪ Continuous ante- and intrapartum surveillance of maternal and fetal status OSMOSIS.ORG 739

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Disorders of labor essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Disorders of labor by visiting the associated Learn Page.