Obstetrics Quiz

The correct way to calculate the EDD is to add 9 months and 1 week onto the first day of the last normal menstrual period. This method may not be reliable if a woman is unsure about when her last menstrual period was. As a result ultrasound is used to more accurately date pregnancies.

Syntocinon is a synthetic form of oxytocin. Oxytocin causes uterine contractions and cervical dilatation. Misoprostol is a prostaglandin which causes thinning of the cervix and uterine contraction.

If the placenta is not supplying adequate blood to the fetus the body directs prioritises brain development at the expense of the body. As a result the abdominal circumference decreases whilst the head circumference remains normal.

Induction of labour increases the risk of a number of complications. The uterus can become over stimulated causing prolonged contractions which can starve the baby of oxygen. It can also cause contractions to be so powerful they cause rupture of the uterus. Finally if a women is induced to early it can result in prolonged labour.

IUGR can occur for a large number of reasons . Smoking accounts for around 30-40% of IUGR cases.

Misoprostol is inserted vaginally and causes effacement of the cervix in addition to uterine contraction.

A midwife usually performs an internal examination on the mother and uses their finger to separate the amniotic membranes from the walls of the cervix. This causes release of prostaglandins which can kickstart the labour process.

The most common cause of PPH is uterine atony, however retained placenta and vaginal lacerations also account for a significant proportion of PPH. Uterine atony describes a state in which the uterus can no longer effectively contract. Because the uterus cannot contract the blood vessels which were supplying the placenta are not compressed and can therefore bleed profusely. A uterus can become atonic for a number of reasons such as prolonged labour, large baby, multiple pregnancy and retained placenta.

The second trimester begins at 13 weeks and ends at 28 weeks.

Linea nigra can be seen on this image. This occurs in around 3/4 of pregnancies. It's described as a vertical line of increased pigmentation running down the centre of the pregnant abdomen. The increased pigmentation occurs over the linea alba which is stretched during pregnancy to accommodate the developing foetus.

The first trimester refers to the first 12 weeks of pregnancy.

Hyperemesis gravidarum is a severe form of morning sickness in which women suffer with excessive nausea and vomiting which prevents them taking in adequate amounts of food and water. It is thought to be caused by high levels of circulating HCG. This is supported by the fact that it's more common in multiple pregnancies and also tends to only affect women during the first 12 weeks of pregnancy.

Symmetrical IUGR usually suggests a baby has a chromosomal disorder. This is because in a healthy baby the head circumference should remain normal, even if there is significant placental insufficiency, as the body makes sure the brain receives the necessary fuel at the expense of the rest of the body. That's why in placental insufficiency the abdominal circumference is reduced but the head circumference is normal (asymmetrical IUGR).

Most women will become aware of foetal movements around 18-20 weeks. However if a women has had previous pregnancies they often notice movements earlier (around 15-18 weeks).

Pre-eclampsia is defined as the presence of both hypertension and proteinuria during pregnancy.

The third trimester starts at 29 weeks and ends at 40 weeks.

All of the above are potential causes of PPH with uterine atony been the most common. Coagulopathy is a rare cause, accounting around 1% of PPH.

Primary postpartum haemorrhage is defined as a loss of blood >500ml from the vagina within 24 hours of delivery. If the blood loss is between 500-1000ml it is defined as a minor PPH. If the blood loss is more than 1000ml it is defined as a major PPH.