Abruptio Placenta

V. Yogeeta

Introduction

Abruptio placentae is defined as the premature separation of the placenta from the uterus.

Anatomy Of A Normal Placenta

Risk factors

High Birth Order Maternal age: pregnant women who are younger

than 20 or older than 35 are at greater risk Maternal trauma, such as

motor vehicle accidents, assaults, falls, or nosocomial

Hypertension Malnutrition,Low Socio economic status Cocaine (powder or crack) abuse Previous abruption: Women who have had an

abruption in previous pregnancies are at greater risk.

Hypertension

The most predisposing risk factor. Pre-eclampsia,gestational hypertension and

essential hypertension, all are associated with placental abruption.

The association varies from 10-50 percent. Mechanism- spasm of the vessels in the

utero placental bed->anoxic endothelial damage->rupture of vessels or extravasation(retroplacental hematoma).

Cigarette Smoking

Cigarette smoking increases a patient's overall risk of placental abruption.

Smoking is known to affect blood circulation through the placenta, which could theoretically effect the early separation of the placenta.

In addition to the increased risk of abruption caused by tobacco abuse, the perinatal mortality rate of infants born to women who smoke and have an abruption is increased.

Cocaine Abuse

The hypertension and increased levels of catecholamines caused by cocaine abuse are thought to be responsible for a vasospasm in the uterine blood vessels that causes placental separation and abruption. However, this hypothesis has not been definitively proven.

The rate of abruption in patients who abuse cocaine has been reported to be approximately 13-35% and may be dose-dependent.

Trauma

Abdominal trauma is a major risk factor for placental abruption.

Motor vehicle accidents often cause abdominal trauma. The lower seat belt should extend across the pelvis, not across the mid abdomen, where the fetus is located.

Trauma may also be due to domestic abuse or assault, both of which are underreported.

Risk factors

Short umbilical cord Retroplacental fibromyoma Sudden uterine Decompression Torsion of uterus Elevated second trimester maternal serum

alpha-fetoprotein Thrombophilia Chorioamnionitis Prolonged rupture of membranes (24 h or

longer)

Types

1. Area of Detachment (Abruption)2. Placenta3. Baby4. Uterine Wall

Pathophysiology

Depending upon the etiological factors, premature placental seperation is initiated by hemorrhage into the decidua basalis. The collected blood(Decidual hematoma) may be small and self limited and its evident only after the expulsion of the placenta(retroplacental hematoma).

The features of retroplacental hematoma are a) depression on the maternal surface of

placenta. b) areas of infarction.

Rupture of the basal artery may occur communicating the hematoma with the intervillous space.

If, a major spiral artery ruptures, a big hematoma is formed.

As the uterus remains distended by the conceptus, it fails to contract and compress the torn bleeding points.

The blood, so accumulated finds its way in the following directions:

Complete accumulation behind the placenta. Blood may dissect downwards in between the

membranes and the uterine wall and express as vaginal bleeding.

The blood may gain access to the amniotic cavity after rupturing through the membranes(rare).

Grade 0: Asymptomatic and only diagnosed through post partum examination of the placenta.

Grade 1:External bleeding is slight with mild uterine tenderness or tetany.FHS is good.

Grade 2: The mother is symptomatic but not in shock. There is some evidence of fetal distress can be found with fetal heart rate monitoring.Grade 3: Severe bleeding (which may be occult) leads to maternal shock and fetal death. There may be maternal disseminated intravascular coagulation.

Clinical Classification

Couvelaire Uterus

Utero-Placental Apoplexy. Associated with severe form of placental

seperation with widespread extravasation of blood into the uterine musculature and below the serous coat of the uterus.

May lead to uterine tetany, shock and death of the fetus.

Complications : Clotting defects, renal failure.

Changes In Other Organs

In the liver, apart from changes found in pre-eclampsia, fibrin knots are found in the hepatic sinusoids.

Kidneys may show acute cortical necrosis or tubular necrosis.

Shock proteinuria is due to renal anoxia which disappears after delivery, whereas proteinuria due to preeclampsia tends to last longer.

Clinical Features

Vaginal Bleeding, Uterine contractions, Foetal distress Rapidly increased fundal height due to intra

uterine haemorrhage.

Bleeding

Vaginal bleeding is present in 80% of patients diagnosed with placental abruptions.

Bleeding may be profuse and come in "waves" as the patient's uterus contracts.

A fluid the color of port wine may be observed when the membranes are ruptured.

Bleeding may be significant enough to jeopardize both fetal and maternal health in a relatively short period.

Uterine Contractions/ Tenderness

Contractions and uterine hypertonus are part of the classic triad observed with placental abruption.

Uterine activity is a sensitive marker of abruption and, in the absence of vaginal bleeding, should suggest the possibility of an abruption, especially after some form of trauma or in a patient with multiple risk factors.

Uterine contractions / Tenderness

Contractions progress as the abruption expands, and uterine hypertonus may be noted.

Contractions are painful and palpable. Uterine hyperstimulation may occur with little

or no break in uterine activity between contractions

Foetal Distress

Decreased fetal movement This may be the presenting complaint. Decreased fetal movement may be due to

fetal jeopardy or death. Absence of fetal heart sounds: This occurs

when the abruption progresses to the point that the fetus dies.

Fundal Height

This may increase rapidly because of an expanding intrauterine hematoma.

Shock

Shock is often due to blood loss and hypovolaemia or due to coagulopathy.

It is usually associated with severe haemorrhage(loss>40%).

Placental abruption seen after delivery

Complications

Infection Uncontrollable Haemorrhage Disseminated intravascular coagulation (DIC) Need for Premature Delivery

Refrences

Mudaliar and Menon’s Clinical Obstetrics Text book of Obstetrics D.C.Dutta www.wikipedia.com www.eMedicine.com www.medilineplus.com