Bleeding during pregnancy can be quite alarming for the mother. Bleeding can be divided into more minor causes and more serious causes, as shown in the table below.
Minor causes include cervical polyps and ectropion. If a cervical problem is suspected, then a speculum examination must be carried out, since the incidence of cervical cancer is greater in pregnancy. More often, however, bleeding from the cervix can be attributed to cervicitis or, if from the vagina, vaginitis. If the infectious agent can be identified (i.e. Chlamydia trachomatis) then appropriate antibiotic therapy should be prescribed.
A "show" before labour is very common and is a result of dilatation and effacement of the cervix. The mucus plug is dislodged and some blood may be seen due to tearing of small vessels. Vaginal varicosities, which are varicose veins of the vagina, may similarly tear and cause some bleeding.
Although coagulopathies can cause quite prolonged and serious bleeding, this is not a direct result of pregnancy and may be considered as a "usual" response to trauma in these women. Women with known coagulopathies such as Factor VIII deficiency, for example, should be managed with blood products containing the missing factor as required.
Bleeding before 24 weeks gestation is likely to indicate a spontaneous abortion. To read more about spontaneous abortion click here.
Ectopic pregnancymay also present with bleeding. This is usually described as a short, dark bleed, although this may not occur in all patients. Ectopic pregnancy is an obstetric emergency which must be managed immediately.
Gestational trophoblastic disease includes the premalignant hydatidform moles and the malignant invasive mole and choriocarcinoma.
A hydatidform mole can also present with bleeding in the first trimester. A hydatidform mole is a benign tumour of the trophoblast. It may be a complete mole, where an ovum with no maternal chromosomes is fertilised by two sperm or one sperm which duplicates its chormosomes, or a partial mole, where two sperm fertilise a normal ovum. Women will usually present with bleeding and due to the extremely elevated levels of hCG, symptoms such as nausea and vomiting will be exaggerated. The uterus will also expand to a size greater than expected for the particular time of gestation. Ultrasound is used to identify the hydatidform mole; a complete mole characteristically appears as a "snowstorm". Treatment is with dilatation and evacuation of the uterus and women are followed up with serial blood and urine hCG tests, which should decrease if the mole has been fully removed. If hCG continues to rise or remains elevated, it is likely that an invasive mole is present, so chemotherapy with methotrexate is instituted.
Choriocarcinomas may also cause bleeding. These are malignant tumours which have the ability to metastasise. They present similarly to hydatidiform moles, but usually occur following a normal pregnancy or termination.
Bleeding beyond the second trimester can indicate a number of pathologies. Placenta praevia occurs when a low-lying placenta covers part of the cervical os. It can be divided into four grades:
Risk factors for placenta praevia include increased maternal age, twin or higher multiple pregnancy, prior placenta praevia, prior caesarean section, cigarette smoking and high levels of maternal serum alpha-foetoprotein.
Placenta praevia is usually seen at the 16-20 week ultrasound anomaly scan. These patients will be monitored closely and managed expectantly, as most placentas will rise away from the cervix before labour. Symptomatic placenta praevia is characterised by painless bleeding. The abdomen is soft and non-tender. Vaginal examination should not be attempted as this may preciptate bleeding. Caesarean section is recommended.
Maternal and perinatal mortality has decreased over the years. Death in the foetus is usually due to preterm delivery.
Placental abruption is a life threatening cause of antepartum haemorrhage. The placental attachment to the uterine wall is disrupted by haemorrhage and blood escapes through the cervix. Occasionally the blood is concealed, which may delay diagnosis. It may be caused by abdominal trauma, but in most cases the cause is unknown. Women may be at increased risk if they suffer, for example, from thrombophilia, have hypertension or smoke.
Placental abruption presents with bleeding and pain. The patient appears unwell, the abdomen is tender and the uterus has a "woody" consistency. Cardiotocography may indicate signs of foetal hypoxia such as tachycardia and late decelerations (placental abruption is therefore a recognised cause of cerebral palsy).
The patient must be treated immediately. Blood loss should be corrected, blood crossmatched and Caesarean section carried out. If the baby has died, then vaginal delivery will be attempted. Maternal death may be caused by hypovolaemic shock, postpartum haemorrhage, renal failure or disseminated intravascular coagulation. Maternal and perinatal death has reduced over the years, but it remains a significant cause of mortality.
A rare cause of antepartum haemorrhage is vasa praevia. This is when the foetal vessels cross the cervical os. This is most often due to velamentous insertion of the umbilical cord (when the umbilical cord inserts into the foetal membranes rather than the centre of the placenta). It usually presents with vaginal bleeding when the foetal membranes rupture. It may be detected by looking for foetal haemoglobin in vaginal blood. Emergency Caesarean section is carried out, but the foetus will be stillborn. However, if vasa praevia is detected by ultrasound before labour begins, survival is greatly increased by elective Caesarean section.
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