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OB14 Obstetrics
Obstetrical Hemorrhage Toronto Notes 2019 Placenta Previa
Definition
• placentaimplantedinthelowersegmentoftheuterus,presentingaheadoftheleadingpoleofthefetus • placentalpositionisdescribedinrelationtotheinternalosas“mmaway”or“mmofoverlap”
Clinical Features
• PAINLESSbrightredvaginalbleeding(recurrent),maybeminimizedandceasespontaneouslybutcan become catastrophic
• meanonsetofbleedingis30wkGA,butonsetdependsondegreeofprevia
• physicalexam
■ do not perform pelvic exam until ruling out placenta previa ■ uterus soft and non-tender
■ presenting fetal part high or displaced
■ FHR usually normal
■ shock/anemia correspond to degree of apparent blood loss
• complications
■ fetal
◆ perinatal mortality low but still higher than with a normal pregnancy ◆ prematurity (bleeding often dictates early C/S)
◆ intrauterine hypoxia (acute or IUGR)
◆ fetal malpresentation
◆ PPROM
◆ risk of fetal blood loss from placenta, especially if incised during C/S
■ maternal
◆ <1% maternal mortality
◆ hemorrhage and hypovolemic shock, anemia, acute renal failure, pituitary necrosis (Sheehan
syndrome)
◆ placenta accreta – especially if previous uterine surgery, anterior placenta previa
◆ hysterectomy
Investigations
• transvaginalU/SismoreaccuratethantransabdominalU/Satdiagnosingplacentapreviaatany gestational age
• Spontaneouslyresolutionislikelywithincreasinguterinedistentioniftheplacentaobscurestheinternal os by less than 20mm at 20 wk GA.
• Transvaginal U/S should be repeated in the third trimester as continued change in the placental location is likely
Management
• goal:keeppregnancyintrauterineuntiltheriskofcontinuingpregnancyoutweighstheriskofpreterm delivery
• stabilizeandmonitor
■ maternal stabilization: large bore IV with hydration, O2 for hypotensive patients
■ maternal monitoring: vitals, urine output, blood loss, blood work (hematocrit, CBC, INR/PTT,
platelets, fibrinogen, FDP, type and cross match)
■ electronic fetal monitoring
■ U/S assessment: when fetal and maternal conditions permit, determine fetal viability, GA, and
placental position
• Rhogam®ifmotherisRhnegative
• Kleihauer-BetkeTesttodetermineextentoffetomaternaltransfusionandadministerRhogam®at
adequate dose
• GA<37wkandminimalbleeding:expectantmanagement
■ admit to hospital
■ limited physical activity, no douches, enemas, or sexual intercourse
■ consider corticosteroids for fetal lung maturity
■ delivery when fetus is mature or hemorrhage dictates due to maternal or fetal compromise
• GA≥37wk,profusebleeding,orL/Sratiois>2:1–deliverbyC/S
Do NOT perform a vaginal exam until placenta previa has been ruled out by U/S