Disorders of labor Notes

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