In the last trimester of pregnancy the isthmus of the uterus unfolds to form the lower segment. Normally, the placenta does not overlie it, so there is no bleeding. If however the placenta does overlie the lower segment, it may shear off over a small area and bleed.
Most patients with placenta praevia bleed before labour starts. They bleed painlessly and pass bright red blood. The first bleed may be slight, and subsequent ones increasingly severe, as the area of placental separation increases. You are unlikely to have ultrasound, or any other test to confirm the position of a patient's placenta, so you will have to find out where it is by examining her in the theatre, when you are fully prepared for an elective or emergency delivery. The correct timing of this is vital. You can do it early, soon after she presents. Or, if she is not bleeding severely, you can postpone it, and manage her non-operatively in hospital until she reaches 36 weeks, by which time her baby's chances of survival are almost as good as they would be at term. Most of your patients with placenta praevia will present before the 36th week, so non-operative treatment will improve your perinatal mortality[md]but it is only justified if Caesarean section is instantly available 24 hours a day, 7 days a week!
Unfortunately, the worst type of placenta praevia (Type Four) often does not bleed until labour starts. Even so, a high presenting part, or a persistent transverse lie, should lead a smart midwife to suspect it in the antenatal clinic.
There are several ways in which you can deliver a patient with placenta praevia:
(1) Caesarean section is the safest method in 95 per cent of cases. Its various risks and difficulties are described in Sections 18.8 and 18.10.
(2) You can deliver her vaginally. This may be necessary in health centres, if she cannot be referred, so it is described in Primary Mother Care. There are two ways of doing this. (a) The baby's head can be brought down on to the placental site, if necessary with Willet's forceps or a vulsellum, and a weight attached to his scalp. (b) A leg can be brought down and his buttocks used to compress the placental site. These methods almost always kill him, so it is desirable that he be already dead, or so small as to be unlikely to survive. They are both ancient methods, and are no longer done when Caesarean section is available, unless he is dead, and her cervix well dilated ([mt]5 cm) and not too thick.
The main risks of vaginal delivery are that, in trying to bring down the head or a leg, you separate more of the placenta and increase bleeding. If you fail, and the task is not easy, you worsen her prognosis. You may also be tempted to force delivery before adequate dilatation, and so tear her cervix.
Placenta praevia increases the risk of puerperal sepsis, and of postpartum haemorrhage, because the lower segment, to which the placenta was attached, contracts less well after delivery.
MRS X died in hospital during labour. The doctor who treated her certified her death as being due to [f10]placenta praevia. [f09]The specialist obstetrician said that haemorrhage might not have been fatal, if she had not been anaemic due to parasitic infection and malnutrition. There was also concern because she had only been given 500 ml of blood, and because she died on the table while being sectioned by a trainee. The hospital administrator noted that she had not arrived at the hospital until 4 hours after the onset of severe bleeding, and that she had bled several times during the previous month, for which she did not seek treatment. A sociologist observed that she was 39 years old, with seven previous pregnancies and 5 living children. She had never used contraceptives, and her last pregnancy was unwanted. She was also poor, illiterate, and lived in a rural area. LESSONS Here we are concerned with the technology of treatment, but the critical factors are often the social ones.
PLACENTA PRAEVIA This is the patient with a probable placenta praevia diagnosed in the last section.
If she continues to bleed, and the the presentation is cephalic do an EIT (examination in theatre). If it is not cephalic, section her.
If she is no longer bleeding, her baby is alive and she is not in labour, admit her to the labour ward for observation and non-operative treatment. If she has not bled for 6 hours transfer to the antenatal ward and ask her to do a kick count (M 28.3). Keep her in bed in the antenatal ward for 5 days. If she does not bleed during this time, she can get up to go to the toilet. Abandon non-operative treatment at any time if she goes into labour, or she bleeds seriously, or her baby dies. If none of these things happen, allow her to continue to 36 weeks, or if you don't know her dates, until her baby has reached a reasonable size.
CAUTION ! This non-operative management is only indicated if: (1) Her baby is alive. (2) She is not in labour. (3) She is in hospital. (4) You have plenty of blood to transfuse her, if necessary. (5) You can section her at any moment.
If her baby is dead, don't section her unless her placenta praevia requires it. Encourage her to go into labour. See Section 16.4 on the ''dead baby'.
AN EXAMINATION IN THE THEATRE [s7](''EIT') FOR PLACENTA PRAEVIA The purpose of a vaginal examination at this stage is to find whether she has a placenta praevia or not, and what type it is. If it is Type One or Two, she should be able to deliver vaginally, unless she has other problems. For Types Three or Four she needs Caesarean section.
INDICATIONS. A patient with suspected placenta praevia and a cephalic presentation who has (1) reached 36 weeks, or (2) bled heavily before reaching 36 weeks.
PREPARATION. Take her to the theatre and have everything absolutely ready for a Caesarean section, with the trolley laid, the trolley nurse scrubbed up, and your assistant also scrubbed up ready for a Caesar. Have two units of blood cross-matched for her ready in the theatre.
ANAESTHESIA. If she is very likely to have a placenta praevia, give her a general anaesthetic and intubate her. There may not be time for a local one. If she is unlikely to have placenta praevia, and your anaesthetist is good have everything ready to give her a general anaesthetic, if necessary, but don't actually start to give it. If there is time, starve her.
CAUTION ! If your anaesthetist is unskilled, anaesthetize all patients having an EIT. She may bleed suddenly, and an unskilled anaesthetist may panic.
Don't pass a stomach tube, because gagging may precipitate bleeding. Set up a drip. Catheterize her bladder.
VAGINAL EXAMINATION. Start by doing a vaginal examination with one or two Sims' specula to confirm that blood is actually coming from her cervix. Occasionally, you find that it is coming from a varicosity on her vulva or in her vagina.
Then ask an assistant to press the baby's head into the brim of her pelvis. Explore her vaginal fornices with your finger.
Can you feel any abnormal thickness in her lower uterine segment between your finger and the presenting part? Is the thickening all round her os, or only related to part of it? You should be able to get a fairly good idea of what type of placenta praevia she has: One, Two, Three, or Four (Fig. 16-9). If necessary, put your whole hand into her vagina.
If you can feel an abnormal thickening, she probably does have a placenta praevia. The type pf placenta she has is all important. Feel very carefully where the thickening is in relation to her os. If there is abnormal thickening all round it (probably Type Four), don't put your finger through her os. Section her.
If: (1) you cannot feel any abnormal thickening, or (2) the thickening you can feel does not suggest a Type Four placenta praevia, put your index finger very gently through her os, and explore all round it. Sweep it in gently widening circles, until you have examined all round as far as you can reach with your finger. Stop, as soon as you feel any placenta! Remove your finger from time to time to see if she has started to bleed. If you feel placenta over her os, or if she bleeds, section her.
If you cannot feel the placenta anywhere, when you put your finger through her os, and she does not bleed much, she is probably a case of abruption, or Type One placenta praevia. Rupture her membranes. Avoid oxytocin to begin with, because its use in a case of abruption can cause nasty cervical tears, rupture of the uterus, and occasionally amniotic fluid embolus. If, however, she does not go quickly into labour, set up an oxytocin drip (2.5 units in 500 ml of dextrose 5%). If you are giving her oxytocin, watch the fetal heart carefully. If fetal distress develops in the first stage, section her.
If she bleeds so severely that it cannot be controlled by rupturing her membranes, and pressing his head into her pelvis, section her.
PLACENTA PRAEVIA [s7]DURING LABOUR IF SHE IS IN LABOUR AND IS BLEEDING SEVERELY, she is usually an emergency admission. Take her to the theatre, give her a general anaesthetic, and do an EIT as above. Section her, unless her cervix is fully dilated or almost so, and her membranes are presenting at the os.
If you can feel the vertex is presenting through the membranes, rupture them, so as to bring her baby's head down on to her placenta. This is possible for a Type One and an anteriorly placed Type Two placenta, and usually stops bleeding in a multip when it begins during labour.
If bleeding continues, section her, unless you expect her to deliver soon.
If the placenta is fully detached or nearly so, and is sitting on top of the baby's head (rare), remove it and deliver him.
If any other part is presenting, management depends on where the placenta is.
If the breech is presenting, the placenta does not cover her internal os, and her cervix is sufficiently dilated, consider bringing down a leg and delivering her vaginally (M 12.2). This is always satisfactory for a dead fetus; but only consider it for a live one, if her cervix is more than 5 cm dilated and the baby is very small. Improvise a string of gauze swabs, tie this to his leg, tie a weight of 500 g to the other end, and hang this over the end of her bed.
CAUTION ! Don't pull the baby through an inadequately dilated cervix (it need not necessarily be fully dilated, depending on the size of the baby).
If the placenta covers her internal os and she bleeds, section her and transfuse her if necessary.
OTHER TREATMENT Finally, don't hurry labour, take careful aseptic precautions, and restore her blood volume. Monitor the fetal heart carefully. If there are signs of fetal distress, consider Caesarean section.
Give her ergometrine with oxytocin at the completion of the second stage. Watch carefully for further bleeding for at least 24 hours.