Obstetrics Simplified - Diaa
Bleeding in Late Pregnancy (Antepartum
It is bleeding from the genital tract after the 28th week of pregnancy
and before the end of the second stage of labour.
- Placental site bleeding: (62%)
- Placenta praevia (22%): Bleeding from separation of a placenta
wholly or partially implanted in the lower uterine segment.
- Abruptio placentae (30%): Premature separation of a normally
- Marginal separation(10%)ý: Bleeding from the edge of a normally
- Non-placental site bleeding: (28%)
- Vasa praevia: Bleeding from ruptured foetal vessels.
- Rupture uterus.
- Bloody show.
- Cervical ectopy, polyp or cancer.
- Vaginal varicosity.
The placenta is partially or totally attached to the lower uterine segment.
0.5% of pregnancies . It is more common in multiparas and in twin pregnancy
due to the large size of the placenta.
Not well known but may be due to:
- Low implantation of the blastocyst.
- Development of the chorionic villi in the decidua capsularis leading
to attachment to the lower uterine segment.
- Large placenta as in twin pregnancy.
- First degree (Type I = P.P. lateralis = low-lying placenta):-
- The lower edge of the placenta reaches the lower uterine segment
but not the internal os.
- Second degree (Type II= P.P. marginalis):
- The lower edge of the placenta reaches the margin of the internal
os but does not cover it.
- Third - degree (Type III= P.P. incomplete centralis):
- The placenta covers the internal os when it is closed or partially
dilated but not when it is fully dilated.
- Fourth - degree (Type IV = P.P. complete centralis):
- The placenta covers the internal os completely whether the cervix
is partially or fully dilated.
N.B. Placenta praevia marginalis posterior is of bad prognosis than marginalis
- It encroaches on the true conjugate diameter delaying engagement
of the head.
- Engagement of the head will compress the placenta against the sacrum,
causing foetal asphyxia.
Mechanism of bleeding
Progressive stretching of the lower uterine segment normally occurs during
the 3rd trimester and labour, but the inelastic placenta cannot stretch
with it. This leads to inevitable separation of a part of the placenta with
unavoidable bleeding. The closer to term, the greater is the amount of bleeding.
- Causeless, painless and recurrent bright-red vaginal bleeding;
- It is causeless, but may follow sexual intercourse or vaginal
- It is painless, but may be associated with labour pains .
- It is recurrent, but may occur once in slight placenta praevia
lateralis. Fortunately, the first attack usually not severe.
- General examination:
- The general condition of the patient depends upon the amount
of blood loss. Shock develops if there is acute severe blood
loss and anaemia develops if there is recurrent slight blood
- Abdominal examination:
- The uterus is corresponding to the period of amenorrhoea,
relaxed and not tender.
- The foetal parts and heart sound (FHS) can be easily detected.
- Malpresentations, particularly transverse and oblique lie
and breech presentation are more common as well as non-engagement
of the head. This is because the lower uterine segment is occupied
by the placenta.
- Vaginal examination
- Speculum examination to exclude local lesions is only permissible
when placenta praevia has been excluded by ultrasound.
- P/V is indicated only if active treatment is initiated.
This may provoke a severe attack of bleeding so it should be
done with the following precautions:
- In the operating room,
- under general anaesthesia,
- cross- matched blood is in hand,
- operating theatre is ready for immediate caesarean section.
- If the index finger is introduced gently through the dilated
cervix, the placenta can be felt as a tough fibrous mass.
Other causes of antepartum haemorrhage.
- It is the most simple, precise and safe method for placental
localization. A partially full bladder is necessary to identify
the lower edge of the placenta. If it is less than 3 cm from the
margin of the internal os, it is diagnosed as placenta praevia.
- The posterior placenta praevia is difficult to be identified
due to shadowing from the presenting part of the foetus. This can
be overcome by head-down tilt of the patient or displacing, the
presenting part manually. If difficulty still present, the distance
between the presenting part and the promontory of the sacrum is
measured. If this exceeds 1.5 cm it means that placenta lies
- In mid - pregnancy the placenta reaches the internal os in up
to 20% of pregnancies. With increasing gestational age and the formation
of the lower uterine segment, a gap develops between the placental
edge and the internal os " placental migration". So it is recommended
to repeat scan when placenta praevia is diagnosed in mid - pregnancy.
- Soft tissue placentography, isotopes and thermography:
- are old methods for placental localization that are obsolete
- Arrange for immediate transfer to the hospital.
- No vaginal examination and no vaginal pack, only a sterile vulval
pad is applied.
- No oral intake as anaesthesia may be required.
- Antishock measures as pethidine IM, fluids and blood transfusion
may be given in the way to the hospital if bleeding is severe.
- Assessment of the patient's condition, general and abdominal examination
and resuscitation if needed.
- At least 2 unites of cross matched blood should be available.
- Ultrasonography for:
- differentiation between abruptio placentae (retroplacental haematoma
in a normally implanted placenta), marginal bleeding (separation
of the margin of a normally implanted placenta) and placenta praevia
(in the lower uterine segment),
- assessment of foetal viability age, position and presentation.
Then management is carried out as following:
- If the patient is not in labour:
- Look to the amount of bleeding;
- If the bleeding is severe, continue antishock measures and
do immediate caesarean section .
- If the bleeding is slight, look to the gestational age;
- If completed 37 weeks (36 weeks by some authors) or
more, pregnancy is terminated by induction of labour or
caesarean section (see later). At this time, the foetus
is mature and the mother will be in a risk of severe haemorrhage
as term approaches.
- If less than 37 weeks (36 weeks by others), conservative
treatment is indicated till the end of 37 (or 36) weeks
but not more.
- Conservative treatment:
- The patient is kept hospitalized with bed rest and observation
- Anaemia should be corrected if present.
- Observation of foetal wellbeing.
- Anti-D immunoglobulin is given for the Rh-negative mother.
- If the patient is in labour:
- Vaginal examination is done under the previously mentioned precautions.
According to the findings, the patient will be delivered either
vaginally by amniotomy + oxytocin or by caesarean section.
- Vaginal delivery is allowed if the following findings are fulfilled:
- Placenta praevia is lateralis or marginalis anterior,
- bleeding is slight,
- vertex presentation,
- adequate pelvis with no soft tissue obstruction.
- partially dilated cervix to allow amniotomy. Amniotomy has
- Allows descent of head so it compresses the placental
site preventing further bleeding.
- It abolishes the shearing movement of the placenta during
uterine contractions. As the bulging of fore bag of water
during contractions with intact membranes will drag the
edge of the placenta evoking more bleeding.
Caesarean section is indicated in:
- Placenta praevia centralis whether complete or incomplete even if
the foetus is dead.
- Placenta praevia marginalis posterior.
- Severe bleeding.
- Presentation other than vertex.
- Other obstetric indications as contracted pelvis, cord prolapse
and elderly primigravida.
- Vasa praevia.
N.B. Although upper segment C.S. is sometimes advocated to be away from
the placenta, lower segment C.S. is preferable because:
- It allows better control of bleeding from the placental site.
- It leaves a stronger scar can withstand subsequent vaginal delivery.
If placenta praevia was anteriorly implanted it is gently displaced laterally
to reach the foetal head otherwise cut through it (not preferred).
Complications of Placenta Praevia
- Maternal mortality rate is 0.2%.
- During pregnancy:
- Preterm labour.
- Antepartum haemorrhage.
- Malpresentation and non-engagement.
- During labour:
- Premature rupture of membranes.
- Cord prolapse.
- Obstructed labour.
- Postpartum haemorrhage.
- Retained placenta.
- Placenta accreta due to deficient decidual reaction
in the lower segment allows deep penetration of chorionic villi.
This may necessitate hysterectomy.
- Lacerations of lower uterine segment due to increased
vascularity and friability.
- Air embolism due to low placental site.
- Foetal mortality rate is 20 %.
- Malformations (2%).
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Edited by Aldo Campana,