Antepartum haemorrhage Separation of the Placenta by benbenzhou


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									  9               Antepartum haemorrhage

                                          Haemorrhage from the vagina after the 24th week of
SYNOPSIS                                  gestation is classified as antepartum haemorrhage. The
Uteroplacental haemorrhage    121         factors that cause antepartum haemorrhage may be
  Placenta praevia 121                    present before 24 weeks, but the original distinction
  Abruptio placentae 124
                                          between a threatened miscarriage and an antepartum
Other causes of antepartum haemorrhage    haemorrhage was based on the potential viability of the
 127                                      fetus.
 Unexplained antepartum haemorrhage 127
 Vaginal infections 127                      Vaginal bleeding may be due to:
 Cervical lesions 127
                                          • Haemorrhage from the placental site and uterine
Essential information   128                 cavity
                                          • Lesions of the vagina or cervix
                                          • Fetal bleeding from vasa praevia.

                                           UTEROPLACENTAL HAEMORRHAGE
                                          The major causes of uterine bleeding are:
                                          •   Placenta praevia
                                          •   Abruptio placentae or accidental haemorrhage
                                          •   Uterine rupture
                                          •   Unknown aetiology.

                                          Placenta praevia
                                          The placenta is said to be praevia when all or part of the
                                          placenta implants in the lower uterine segment and
                                          therefore lies in front of the presenting part (Fig. 9.1)

                                          Approximately 1% of all pregnancies are complicated
                                          by clinical evidence of a placenta praevia. Unlike the
                                          incidence of placental abruption, which varies ac-
                                          cording to social and nutritional factors, the incidence
                                          of placenta praevia is remarkably constant.
                                            Placenta praevia occurs more commonly in multi-
                                          parous women, in the presence of multiple pregnancy
                                          and where there has been a previous caesarean section.

                                          Placenta praevia is due to delay in implantation of the
                                          blastocyst so that this occurs in the lower part of the


                                                Marginal                     Central

                                           Fig. 9.1 Classification of placenta praevia.

      uterus. It is commoner in high parity and in conditions       women who have a marginal placenta are now delivered
      where the placental area is large, such as multiple           by caesarean section, there is probably little point in
      pregnancy or placenta membranacea.                            differentiating between grades II and III unless the
                                                                    mother is in labour when the diagnosis is made.
                                                                       Bleeding results from separation of the placenta as
                                                                    the formation of the lower segment occurs and the
      From the point of view of management, there are three         cervix effaces. This blood loss occurs from the venous
      degrees of severity of placenta praevia (Fig. 9.1):           sinuses in the lower segment. Occasionally, fetal blood
                                                                    loss may occur, particularly where one of the placental
      • Lateral: The placenta encroaches on the lower               vessels lies across the cervical os – a condition known as
        uterine segment but does not reach the internal             vasa praevia.
        cervical os
      • Marginal: The placenta encroaches on or covers the
        internal cervical os before cervical dilatation occurs      Symptoms and signs
      • Central: The placenta completely covers the os even
                                                                    The main symptom of placenta praevia is painless
        with cervical dilatation.
                                                                    vaginal bleeding. There may sometimes be lower abdo-
      Classification is important in relation to management         minal discomfort where there are minor degrees of
      because spontaneous delivery is extremely rare where          associated placental abruption.
      there is central placenta praevia but normal labour             The signs of placenta praevia are:
      and delivery may occur with lateral or marginal
                                                                    • Vaginal bleeding
                                                                    • Malpresentation of the fetus
         An alternative classification is based on grades, with
                                                                    • Uterine hypotonus.
      grade 1 being defined by the placenta encroaching on
      the lower segment but not on the internal cervical os,        Development of the lower uterine segment begins at 28
      grade II when the placenta reaches the internal os, grade     weeks gestation and thus bleeding is likely to occur
      III with the placenta eccentrically covering the os and       from 28 weeks onwards. Bleeding is unpredictable and
      grade IV as central placenta praevia. Grades II and III are   may vary from minor shows to massive and life-
      equivalent to marginal placenta praevia and, as most          endangering haemorrhage.

                                                                                ANTEPARTUM HAEMORRHAGE                    9

                                                              is posterior, the head is pushed forward over the
          Case study                                          pelvic brim and is easily palpable. When the placenta
          Placenta praevia                                    is anterior, the presenting part is difficult to feel.
                                                              Lateral placement of the placenta results in
   Janet Y was admitted to hospital at 28 weeks               contralateral displacement of the presenting part.
   gestation with a substantial painless vaginal              Where there is a central placenta praevia, the fetal
   haemorrhage in her first pregnancy. The                    head is held away from the pelvic brim and the lie
   presenting part was high but central and the               may be transverse or oblique. If the head does not
   uterine tone was soft. A diagnosis of placenta             approach the pelvic brim when the placenta is
   praevia was made and she was advised to stay               anterior, the presenting part is difficult to palpate.
   in hospital under observation until delivery. There      • Flaccidity of the uterus: Uterine muscle tone is
   was no further bleeding and, at 32 weeks                   usually low and the fetal parts are easy to palpate.
   gestation, she asked to go home to marry her
   partner. As this necessitated a 1 hour flight, she       Diagnostic procedures
   was strongly advised against this action so her          • Ultrasound scanning: This is predominantly used to
   partner flew to Janet instead and the wedding              localize the placenta and has largely replaced other
   was arranged in a church close to the hospital.            techniques. Errors in diagnosis are most likely to
   At the wedding, Janet had a further substantial            occur in posteriorly situated placentae because of
   bleed as she walked down the aisle and was                 difficulties in identifying the lower segment.
   rushed back into hospital. The bleeding again              Anteriorly, the bladder provides an important
   subsided but, at 35 weeks gestation, Janet had a           landmark for the lower segment and diagnosis is
   massive haemorrhage in the ward to the extent              more accurate. Localization of the placental site in
   that blood soaked her bed linen and flowed over            early pregnancy may result in inaccurate diagnosis,
   the side of the bed. The resident staff inserted           as fundal development may lead to an apparent
   two intravenous lines and she was rushed to                upward displacement of the placenta.
   theatre. She was shocked and hypotensive and it          • Magnetic resonance imaging: This is the most
                                                              accurate method of placental localization because
   was extremely difficult to maintain her blood
                                                              the internal cervical os can be clearly visualized.
   pressure. A ‘crash section’ was performed and
                                                              However, it is not as yet widely available or used and
   the diagnosis of central placenta praevia was
                                                              would only be relevant if the ultrasound image was
   confirmed. A healthy male infant was delivered.
   Had Janet been at home, it is very unlikely that
   she would have survived.
                                                            When antepartum haemorrhage of any type occurs, the
Diagnosis                                                   diagnosis of placenta praevia should be suspected and
                                                            hospital admission advised. The diagnosis should be
Clinical findings                                           established by ultrasound imaging. Vaginal examina-
                                                            tion should be performed only in an operating theatre
Painless bleeding occurs suddenly and tends to be
                                                            prepared for caesarean section, with blood cross-
recurrent. When labour starts and the cervix dilates,
                                                            matched. There are only two indications for performing
profuse haemorrhage may occur, although sometimes
                                                            a vaginal examination:
in a lateral placenta praevia the presenting part
compresses the placental site and bleeding is controlled.   • When there is serious doubt about the diagnosis
                                                            • When bleeding occurs in established labour.
Abdominal examination
                                                            It is, in fact, often difficult to establish a diagnosis of
• Displacement of the presenting part: The presence         placentae praevia by vaginal examination where the
  of the placenta in the lower segment tends to             placenta is lateral, and there is a serious risk of preci-
  displace the presenting part and, when the placenta       pitating massive haemorrhage if the placenta is central.


      If the placenta is lateral, then it may be possible to         Out of 7.5 million pregnancies in the USA, the inci-
      rupture the membranes and allow spontaneous vaginal         dence of placental abruption has been recorded as
      delivery.                                                   6.5/1000 births with a perinatal mortality of 119/1000
         Conservative management of placenta praevia in-          births.
      volves keeping the mother in hospital with blood cross-        The incidence of placental abruption is increased in
      matched until fetal maturity is adequate, and then          the presence of pre-eclampsia or essential hypertension.
      delivering the child by caesarean section. Providing        It must be remembered that hypertension and protein-
      there is no active bleeding, there is no need to keep the   uria may develop as a result of abruption.
      mother in bed and she should remain ambulant, as she           Whatever factors predispose to placental abruption,
      is as likely to bleed lying supine. Blood loss should be    they are well-established before the abruption occurs.
      treated by transfusion where necessary so that an           The fetus is more likely to be male and the birthweight
      adequate haemoglobin concentration is maintained.           is often low, indicating pre-existing growth retardation.
         Postpartum haemorrhage is also a hazard of the low-      A history of a placental abruption in a previous preg-
      lying placenta, as contraction of the lower segment is      nancy is a predictor for a further abruption. The prog-
      less effective than contraction of the upper segment.       nosis for fetal survival is significantly worse in those
         There is an increased risk of placenta accreta where     women who smoke cigarettes during pregnancy. Trauma
      placental implantation occurs over the site of a previous   is a relatively uncommon cause of abruption and in the
      uterine scar.

                                                                            Case study
             Placenta praevia accreta is one of the most lethal             Abruptio placentae
             conditions in obstetrics. It commonly occurs
             where the placenta is implanted over a previous
             section scar. The trophoblast grows into the scar       Mandy, a 23-year-old primigravida, was
             tissue, making it almost impossible to separate         admitted to hospital at 35 weeks gestation with a
             the placenta from the uterine wall and, as a
                                                                     complaint that she had developed severe
             consequence, massive bleeding may occur. The
        !    only way this bleeding can be controlled is by
             hysterectomy. The condition carries a high
                                                                     abdominal pain followed by substantial vaginal
                                                                     bleeding. On examination, she was restless and
             mortality rate. The important management issue          in obvious pain. Her blood pressure was
             is to be prepared. Caesarean section associated         150/90 and the uterus was rigid and tender.
             with anterior implantation of a placenta praevia
                                                                     Her pulse rate was 100 bpm and she looked
             and a previous section scar should be performed
             by an experienced obstetric surgeon with ample          pale and tense. The uterine fundus was palpable
             supplies of blood on standby.                           at the level of the xiphisternum. The fetal lie was
                                                                     longitudinal, with the head presenting. The fetal
                                                                     heart beat could not be detected. An intravenous
                                                                     line was established and blood cross-matched as
      Abruptio placentae
                                                                     a matter of urgency. Mandy was given pain
      Abruptio placentae or accidental haemorrhage is de-            relief and her blood picture and clotting profile
      fined as haemorrhage resulting from premature separa-          were examined. Vaginal examination showed
      tion of the placenta. The term ‘accidental’ implies            that the cervix was effaced and 3 cm dilated and
      separation as the result of trauma, but most cases do not      the membranes were bulging through the os. A
      involve trauma and occur spontaneously.                        forewater rupture was performed and blood-
                                                                     stained amniotic fluid was released. Labour
                                                                     ensued and Mandy was delivered 3 hours later
                                                                     of a stillborn male infant. A large amount of clot
      Placental abruption tends to occur more frequently             was delivered with the placenta, and some 50%
      under conditions of social deprivation in association          of the placenta appeared to have been avulsed
      with dietary deficiencies. Folic acid deficiency, in           from the uterine wall.
      particular, has been implicated.

                                                                                     ANTEPARTUM HAEMORRHAGE                     9

majority of cases no specific predisposing factor can be     confinement. Uterine tonus is increased and pain and
identified for a particular episode.                         shock are common features. The uterus may become
                                                             rigid and tender.
Clinical types and presentation
Three types of abruption have been described (Fig. 9.2):               It is important to realize that initially, even in the
                                                                       presence of substantial intra-uterine
• Revealed                                                             haemorrhage where the blood loss is concealed,
• Concealed                                                            the blood pressure may be raised and the pulse
• Mixed, or concealed and revealed.
Unlike placenta praevia, placental abruption presents
                                                                   !   rate slowed but eventually the patient becomes
                                                                       shocked with the development of tachycardia,
                                                                       hypotension and oliguria. The peripheral
with pain, vaginal bleeding and increased uterine                      circulation becomes vasoconstricted and there
                                                                       may be physical signs of vasoconstriction even
                                                                       before hypotension develops.

Revealed haemorrhage
The major haemorrhage is apparent externally, as               In some severe cases, haemorrhage penetrates through
haemorrhage occurs from the lower part of the placenta       the uterine wall and the uterus appears bruised. This is
and blood escapes through the cervical os. Under these       described as a Couvelaire uterus. On clinical examination
circumstances the clinical features are less severe.         the uterus will be tense and hard and the uterine fundus
   Abruption tends to occur after 36 weeks gestation,        will be higher than is normal for the gestational age.
with the fetal lie longitudinal and the presenting part      The patient will often be in labour and in approxi-
sitting well into the pelvic brim. In revealed placental     mately 30% of cases the fetal heart sounds will be
abruption, uterine activity may be increased, but this       absent and the fetus will be stillborn. The prognosis for
finding is not consistent.                                   the fetus is dependent on the extent of placental
                                                             separation and is inversely proportional to the interval
Concealed haemorrhage                                        between onset and delivery.

In this case the haemorrhage occurs between the pla-
                                                             Mixed, or concealed and revealed haemorrhage
centa and the uterine wall. The uterine content increases
in volume and the fundal size appears larger than            In most cases the haemorrhage is both concealed and
would be consistent with the estimated date of               revealed. Haemorrhage occurs close to the placental

                 Revealed                              Concealed                             Concealed and revealed

                                       Fig. 9.2 Types of placental abruption.


      edge and, after an interval when the haemorrhage is
                                                                                              History and examination
      concealed, blood loss soon appears vaginally.

      Differential diagnosis                                                              Vaginal bleeding after 24 weeks

      The diagnosis is made on the history of vaginal
      bleeding, abdominal pain, increased uterine tonus,
      proteinuria and the presence of a longitudinal lie. This               Placental abruption                  Placenta praevia
      must be distinguished from placenta praevia, where the                         Pain                         Painless bleeding
      haemorrhage is painless, the lie unstable and the uterus                  Haemorrhage                         ‘Soft’ uterus
                                                                                 ‘Hard’ uterus                     Malpresentation
      hypotonic. Occasionally, some manifestations of
                                                                                Longitudinal lie                      High p/p
      placental abruption may arise where there is a low-lying
      placenta. In other words, placental abruption can arise                                                      Hb/haematocrit
      where there is low placental implantation and, on these                                                          IV line
                                                                               CVP and IV line
      occasions, the diagnosis can only really be clarified by                                                    Transfuse Hb low
                                                                                Clotting profile
      ultrasound location of the placenta.                                   Transfuse as needed
         The diagnosis should also be differentiated from                                                        Check fetal condition
      other acute emergencies such as acute hydramnios,                                                             Usually good
                                                                             Check fetal condition
      where the uterus is enlarged, tender and tense but there                Often poor or SB
      is no haemorrhage. Other acute abdominal emergencies                                                    Conservative management
                                                                                                                  Deliver 38 weeks
      such as perforated ulcer, volvulus of the bowel and                                                           usually by CS
                                                                                Induce labour
      strangulated inguinal hernia may simulate concealed                   Section if fetal distress         Before if severe/persistent
      placental abruption, but these problems are rare during                                                             loss
                                                                               Monitor PP loss                     Monitor PP loss

                                                                       Fig. 9.3 Differential diagnosis and management of
      The patient must be admitted to hospital and the                 antepartum haemorrhage.
      diagnosis established on the basis of the history and
      examination findings (Fig. 9.3). Mild cases may be               should be effected by caesarean section. Pain relief is
      treated conservatively and the placental site localized to       achieved by the use of opiates. Epidural anaesthesia
      confirm the diagnosis. If the haemorrhage is severe,             should not be used until a clotting screen is available.
      resuscitation is the first prerequisite.
         It is often difficult to assess the amount of blood loss
      accurately and intravenous infusion should be started
      with normal saline, Hartmann’s solution or blood sub-            The complications of placental abruption are summa-
      stitutes until blood is cross-matched and transfusion            rized in Figure 9.4.
      can be commenced. Fluid replacement should be moni-
      tored by the use of a central venous pressure line.
      Unlike placenta praevia, any significant abruption
      should be treated by delivering the fetus as soon as             In afibrinogenaemia, severe placental abruption results
      possible.                                                        in significant placental damage and the release of
         If the fetus is alive and there are no clinical signs of      thromboplastin into the maternal circulation. This in
      fetal distress, or if the fetus is dead, surgical induction of   turn may lead to intravascular coagulation and to
      labour is performed as soon as possible and, where               defibrination, with the development of hypo- and
      necessary, uterine activity is stimulated with a dilute          afibrinogenaemia. The condition may be treated by the
      Syntocinon infusion. If the fetus is alive, it should be         infusion of fresh frozen plasma, platelet transfusion
      monitored and caesarean section should be performed              and fibrinogen transfusion but can only be reversed by
      if signs of fetal distress develop. If induction is not          delivering the fetus. It may lead to abnormal bleeding if
      possible because the cervix is closed, then delivery             operative delivery is attempted or may result in

                                                                                     ANTEPARTUM HAEMORRHAGE               9

                                         Monitor fluid
                                         with CVP


                                                               Umbilical cord
 uterus                                  Hypovolaemia
                                         from blood loss              Vasa praevia                       Carcinoma
  PPH                                                                                                    of cervix
                                                                        cervical polyp
                                         Renal tubular or                                                Vaginitis
                                         cortical necrosis

                                                             Fig. 9.5 Non-placental causes of antepartum

                                                                These cases involve a significant increase in perinatal
Fig. 9.4 Complications of placental abruption. CVP,
                                                             mortality and it is therefore important to monitor
central venous pressure; PPH, postpartum
                                                             placental function and fetal growth. The pregnancy
                                                             should not be allowed to proceed beyond term.
                                                                Rarely, the bleeding may be fetal in origin and arises
uncontrollable postpartum haemorrhage unless the             from the rupture of an aberrant placental vessel known
clotting defect has been corrected.                          as a vasa praevia. The only way that this can be diag-
                                                             nosed is by detecting the presence of fetal haemoglobin
Renal tubular or cortical necrosis                           in the vaginal blood loss.
This is a complication that must always be considered as
a possibility and it is essential to keep careful fluid      Vaginal infections
balance charts and to take particular note of urinary
output. This complication may, on occasion, necessitate      Vaginal moniliasis or trichomoniasis may cause blood-
haemodialysis or peritoneal dialysis, but it is becoming     stained discharge and, once the diagnosis is established,
increasingly rare.                                           should be treated with the appropriate therapy.

 OTHER CAUSES OF ANTEPARTUM                                  Cervical lesions
                                                             Benign lesions of the cervix such as cervical polyps are
These are summarized in Figure 9.5.                          treated by removal of the polyp. Cervical erosions are
                                                             best left untreated.
Unexplained antepartum                                          Carcinoma of the cervix is occasionally found in
haemorrhage                                                  pregnancy. If the pregnancy is early, termination is
                                                             indicated. If the diagnosis is made late in pregnancy, the
In many cases, it is not possible to make a definite         diagnosis should be established by biopsy and the
diagnosis of abruption or placenta praevia.                  lesion treated according to the staging.


      • Vaginal bleeding after 24 weeks.                          Placental abruption
                                                                  •   Incidence 0.5–1.0%
      Placenta praevia
                                                                  •   Diagnosis – uterus hypertonic
      •   Lower segment implantation                              •   Normal fetal lie
      •   Incidence 1%                                            •   Commonly associated with maternal hypertension
      •   Classification – marginal, central and lateral.         •   Management – replace blood loss
      •   Diagnosis – painless loss, unstable lie, soft uterus.   •   Check for DIC
      •   Diagnosis confirmed by ultrasound or MRI                •   Deliver the infant if abruption severe
      •   Management – conservative until 37 weeks                •   Prognosis for fetus poor
      •   Hospital admission for all major degrees                •   Maternal complications
      •   Blood held – cross-matched                              •   Afibrinogenaemia
      •   Caesarean section unless marginal                       •   Renal tubular necrosis
      •   Prognosis for the fetus – good.                         •   Scar dehiscence and uterine rupture

                                                                  Unexplained causes
                                                                  • Cervical and vaginal lesions
                                                                  • Vasa praevia


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