DIFFERENTIAL DIAGNOSIS OF LATE PREGNANCY BLEEDING
Definition. Vaginal bleeding occurring after 20 weeks’ gestation. Prevalence is <5%, but whenit does occur, prematurity and perinatal mortality quadruple.
Etiology
• Cervical causes include erosion, polyps, and, rarely, carcinoma.
• Vaginal causes include varicosities and lacerations.
• Placental causes include abruptio placenta, placenta previa, and vasa previa.
Initial Evaluation. What are patient’s vital signs? Are fetal heart tones present? What is fetalstatus? What is the nature and duration of the bleeding? Is there pain or contractions? What is the location of placental implantation?
Initial Investigation. Complete blood count, disseminated intravascular coagulation (DIC)workup (platelets, prothrombin time, partial thromboplastin time, fibrinogen, D-dimer), type and cross-match, and sonogram for placental location. Never perform a digital or speculum examination until ultrasound study rules out placenta previa.
Initial Management. Start an IV line with a large-bore needle; if maternal vital signs areunstable, run isotonic fluids without dextrose wide open and place a urinary catheter to moni-tor urine output. If fetal jeopardy is present or gestational age is ±36 weeks, the goal is delivery.
ABRUPTIO PLACENTA
A 32-year-old multigravida at 31 weeks’ gestation is admitted to the birthing unit after a motor-vehicle accident. She complains of sudden onset of moderate vaginal bleeding for the past hour. She has intense, constant uterine pain and frequent contractions. Fetal heart tones are regular at 145 beats/min. On inspection her perineum is grossly bloody.
Etiology/Pathophysiology
• A normally implanted placenta (not in the lower uterine segment) separates from the uterine wall before delivery of the fetus. Separation can be partial or complete.
• Most commonly bleeding is overt and external. In this situation blood dissects between placental membranes exiting out the vagina.
• Less commonly, if bleeding remains concealed or internal, the retroplacental hema-toma remains within the uterus, resulting in an increase in fundal height over time.
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OB Triad
Abruptio Placenta
• Late trimester painful bleeding
• Normal placental implantation
• Disseminated intravascular coagulopathy (DIC)
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Diagnosis. This is based on the presence of painful late-trimester vaginal bleeding with a normalfundal or lateral uterine wall placental implantation not over the lower uterine segment.
Clinical Presentation. Abruptio placenta is the most common cause of late-trimester bleeding,occurring in 1% of pregnancies at term. It is the most common cause of painful late-trimester bleeding.
Classification
• With mild abruption, vaginal bleeding is minimal with no fetal monitor abnormality.
Localized uterine pain and tenderness is noted, with incomplete relaxation between contractions.
• With moderate abruption, symptoms of uterine pain and moderate vaginal bleeding can be gradual or abrupt in onset. From 25 to 50% of placental surface is separated. Fetal monitoring may show tachycardia, decreased variability, or mild late decelerations.
• With severe abruption, symptoms are usually abrupt with a continuous knifelike uterine pain. Greater than 50% of placental separation occurs. Fetal monitor shows severe late decelerations, bradycardia, or even fetal death. Severe disseminated intra-vascular coagulation (DIC) may occur.
• Ultrasound visualization of a retroplacental hematoma may be seen.
| Partial separation | Marginal separation | Complete separation | |
| with concealed | |||
| hemorrhage |
A
B 
C
Figure 6-1. Abruptio Placenta
Risk Factors. Abruptio placenta is seen more commonly with previous abruption, hyperten-sion, and maternal blunt trauma. Other risk factors are smoking, maternal cocaine abuse andpremature membrane rupture.
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Chapter 6 l Late Pregnancy Bleeding
Management. Management is variable:
• Emergency cesarean delivery—This is performed if maternal or fetal jeopardy is pres-ent as soon as the mother is stabilized.
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• Vaginal delivery—This is performed if bleeding is heavy but controlled or pregnancyis >36 weeks. Perform amniotomy and induce labor. Place external monitors to assess fetal heart rate pattern and contractions. Avoid cesarean delivery if the fetus is dead.
• Conservative in-hospital observation—This is performed if mother and fetus arestable and remote from term, bleeding is minimal or decreasing, and contractions are subsiding. Confirm normal placental implantation with sonogram and replace blood loss with crystalloid and blood products as needed.
Complications. Severe abruption can result in hemorrhagic shock with acute tubular necrosis from profound hypotension, and DIC from release of tissue thromboplastin into the gen-eral circulation from the disrupted placenta. Couvelaire uterus refers to blood extravasating between the myometrial fibers, appearing like bruises on the serosal surface.
PLACENTA PREVIA
A 34-year-old multigravida at 31 weeks’ gestation comes to the birthing unit stating she woke up in the middle of the night in a pool of blood. She denies pain or uterine contractions. Examination of the uterus shows the fetus to be in transverse lie. Fetal heart tones are regular at 145 beats/min. On inspection her perineum is grossly bloody.
Etiology/Pathophysiology
• Placenta previa is present when the placenta is implanted in the lower uterine seg-ment. This is common early in the pregnancy, but is most often not associated withbleeding.
• Usually the lower implanted placenta atrophies and the upper placenta hypertrophies, resulting in migration of the placenta. At term placenta previa is found in only 0.5% of pregnancies.
• Symptomatic placenta previa occurs when painless vaginal bleeding develops through avulsion of the anchoring villi of an abnormally implanted placenta as lower uterine segment stretching occurs in the latter part of pregnancy.
Diagnosis. This is based on the presence of painless late-trimester vaginal bleeding with anobstetric ultrasound showing placental implantation over the lower uterine segment.
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Classification
• Total, complete, or central previa is found when the placenta completely covers theinternal cervical os. This is the most dangerous location because of its potential for hemorrhage.
• Partial previa exists when the placenta partially covers the internal os.
• Marginal or low-lying previa exists when the placental edge is near but not over theinternal os.
OB Triad
Placenta Previa
• Late trimester bleeding
• Lower segment placental implantation
• No pain
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| Normal placenta | Low-lying placenta | |
| previa | ||
| Partial placenta | Total placenta previa | |
| previa | ||
Figure I-6-2. Placenta Previa
Clinical Presentation. The classic picture is painless late-pregnancy bleeding, which can occurduring rest or activity, suddenly and without warning. It may be preceded by trauma, coitus, or pelvic examination. The uterus is nontender and nonirritable.
Risk Factors. Placenta previa is seen more commonly with previous placenta previa and mul-tiple gestation. Other risk factors are multiparity and advanced maternal age.
Management. Management is variable:
• Emergency cesarean delivery—This is performed if maternal or fetal jeopardy is pres-ent after stabilization of the mother.
• Conservative in-hospital observation—Conservative management of bed rest is per-formed in preterm gestations if mother and fetus are stable and remote from term. The initial bleed is rarely severe. Confirm abnormal placental implantation with sono-gram and replace blood loss with crystalloid and blood products as needed.
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• Vaginal delivery—This may be attempted if the lower placental edge is >2 cm fromthe internal cervical os.
• Scheduled cesarean delivery—This is performed if the mother has been stable afterfetal lung maturity has been confirmed by amniocentesis, usually at 36 weeks’ gestation.
Complications. If placenta previa occurs over a previous uterine scar, the villi may invade intothe deeper layers of the decidua basalis and myometrium. This can result in intractable bleeding requiring cesarean hysterectomy. Profound hypotension can cause anterior pituitary necrosis (Sheehan syndrome) or acute tubular necrosis.
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