Nicola Fratelli U.O. Ostetricia e Ginecologia 1-2

Spedali Civili di Brescia

nicola.fratelli@asst-spedalicivili.it

Placente ad impianto anomalo:

stratificazione del rischio emorragico,

modalità e sede del parto

• The factors that determine the site of nidation of the human

blastocyst are not fully understood

• The human blastocyst implants normally in the upper

portion of the uterus

• Abnormal implantation may lead to placenta previa

Placental implantation

Benirschke K, 2006

Placenta previa The placenta either totally or partially lies within the lower uterine segment

Complete

placenta previa The placenta completely

covers the internal os

Partial

placenta previa The placenta partially

covers the internal os

Marginal

placenta previa The placenta reaches

the internal os, but does

not cover it

Low-lying

placenta The placenta extends

into the lower

uterine segment but

does not reach the

internal os Schacher, 1709

Placenta con il margine inferiore distante

<20 mm dall’OUI

Epoca gestazionale > 26 settimane

Diagnosi

Risks

Oyelese Y, 2006

Incidence

• from 3 to 5 per 1000 births

• severe bleeding and preterm birth

• need for cesarean delivery

• maternal mortality 3 per 10.000 births

Oyelese Y, 2006

Diagnosis

• Bleeding in the late second trimester or early third

trimester

• Routine US in asymptomatic women, usually

during the second trimester

Women who present with bleeding in the second

half of pregnancy should have a sonographic examination for placental

location prior to any attempt to perform a digital examination

Smith RS, 1997

TVS is superior to TA sonography for the

diagnosis of placenta previa

• FPR and FNR using TA sonography range from 2% to 25%

• In 26% of the cases of suspected placenta previa, the initial

diagnosis may change after TVS

Leerentveld RA, 1990

For an individual patient, it is not

possible to predict whether a bleed

will occur, nor the gestational age

Ghourab S, 2001 Ghi T, 2010 Stafford IA, 2010

• placenta completely covering the os

• placenta with a thick edge (>1 cm)

• cervical length ≤3 cm

The positive predictive

value for previa at delivery increases the later

in gestation that previa is detected

sonographically

Dashe J, 2002

940 ultrasound examinations

714 pregnancies

• At each interval, complete previa is more likely to persist than incomplete previa

• Prior cesarean delivery is an independent risk factor

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15-19w 20-23w 24-27w 28-31w 32-35w

Placenta previa: Gestational age of diagnosis

Placental migration may occur progressively

throughout the third trimester

Oppenheimer L, 2001

There is a place for TVS prior to an otherwise planned

caesarean section

Placenta-cervix distance Migration Rate CS for placenta previa

> 20 mm 100% 0%

Between –20 mm and +20 88% 12%

Overlap >20 mm

0% 100%

rate of migration: 5 mm/week

Management based on likelihood of APH

and need for CS

Vergani P, 2009

Treatment decisions should be based

on the placenta-cervix distance measured by TVS

Oppenheimer L, 2009

Timing of Delivery

Committee Opinion No. 560. American College of Obstetricians and Gynecologists. Obstet Gynecol 2013;121:908–10

Migration of a low-lying

placenta

Benirschke K, 2006

• Placenta grows preferentially toward a better vascularized fundus, whereas the

placenta overlying the less well vascularized cervix may undergo atrophy

• In some cases, this atrophy leaves vessels running through the membranes,

unsupported by placental tissue or cord (vasa previa)

• In cases where the atrophy is incomplete, a succenturiate lobe may develop

• Development of the lower uterine segment

Resolution of a low-lying placenta can be

associated with vasa previa

Low-lying placenta is associated with

increased risk of PPH

Previa or Low-lying placenta has an increased risk of PPH

Fan D, 2017

Abnormally invasive placenta

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Benirschke K, 2006

Le donne col più alto rischio di placenta accreta sono quelle con pregresso taglio cesareo e placenta previa impiantata

sopra la cicatrice uterina Wortman C, 2013

• massive obstetric hemorrhage

• need for emergency hysterectomy

• damage to adjacent organs

• blood transfusion

• postoperative complications

• maternal death (7%)

placenta accreta (AIP) becomes problematic

during delivery when the placenta does not

completely separate from the uterus

La diagnosi antepartum riduce la morbilità emorragica e

le complicanze legate all’ isterectomia d’ emergenza

Centri di eccellenza per placenta

Accreta

In caso di placenta previa che ricopre

l’orificio uterino interno (OUI) (previa maior)

o in presenza di placenta anteriore con il

margine inferiore distante <20 mm dall’OUI

(previa minor) in paziente già cesarizzata

va riferita a Centro nascita adeguato alla

gestione della patologia

Take home message

info@sparkseventi.com

Grazie