Obstetrics - All

At what gestation does the uterus usually extend to the umbilicus?

~Week 20

Cord prolapse - management?

EMERGENCY

Presenting part of foetus may be pushed back into the uterus to avoid compression

Minimal handling of cord, keep warm and moist to avoid vasospasm

All fours position, left lateral if not possible

Immediate C-Section

Tocolytics to reduce uterine contractions

Retrofilling the bladder with 500-700ml of saline may be helpful as it gently elevates the presenting part

Name three gestational trophoblastic disorders

Complete hydatidiform mole

Partial hydatidiform mole

Choriocarcinoma

Describe the genetics/pathophysiology of a complete hydatidiform mole

Benign tumour of trophoblastic material

Occurs when an empty egg is fertilised by a single sperm that then duplicates its own DNA - hence all 46 chromosomes are of paternal origin

Describe the genetics/pathophysiology of a partial hydatidiform mole

A normal haploid egg may be fertilised by two sperms/one sperm with duplication of the paternal chromosomes. DNA is both maternal and paternal in origin, usually triploid (eg. 69 XXX or 69 XXY). Foetal parts may be seen

Features of molar pregnancy?

Bleeding in first or early second trimester

Exaggerated symptoms of pregnancy eg. hyperemesis

Uterus large for dates

Very high levels of hCG

Hypertension and hyperthyroidism (hCG can mimic TSH)

Around 2-3% go on to develop choriocarcinoma

Management of molar pregnancy?

Urgent referral to specialist centre for evacuation of the uterus

Effective contraception is recommended to avoid pregnancy in the next 12 months

Describe the changes in volume of amniotic fluid throughout a normal pregnancy

Steadily increases until 33 weeks, then plateau’s, then decreases from 38 weeks to around 500ml at term

What is the main risk of amniocentesis?

Miscarriage, 0.5%, higher risk in multiple pregnancy

When can amniocentesis be performed?

From week 15 onwards

What does amniocentesis look at in the fluid?

Foetal cells

Describe the amniocentesis procedure.

Local anaesthetic, then under ultrasound guidance, a needle is passed through the mother’s abdominal wall and into the amniotic sac. The needle should not pass through the placenta unless absolutely necessary.

A small amount of amniotic fluid is taken, and fetal cells are sent for karyotyping and/or PCR.

Note: Rhesus-negative women will need Anti-D immunoglobulin after the test.

What is the most common indication for amniocentesis?

A “high risk” result from a first trimester screening test, or a previous pregnancy affected by a genetic condition.

What does amniocentesis look for?

Down’s syndrome, Edward’s syndrome and/or Patau’s syndrome

When can CVS be performed?

10 - 13+6 gestation

Which complication is most associated with an amnioreduction?

Placental abruption - Rapid loss of amniotic fluid can cause the placenta to come away from the wall of the uterus, causing placental abruption.

How is polyhydramnios defined?

An amniotic fluid index above the 95th centile for gestational age

What are the most common aetiologies of polyhydramnios?

Idiopathic (50-60%)

Any condition that prevents foetus from swallowing - oesophageal atresta, CNS abnormalities, muscular dystrophies, congenital diaphragmatic hernia obstructing the oesophagus

Duodenal atresia (double bubble sign on US)

Anaemia (alloimmune disorders, viral infections)

Fetal hydrops

Twin-to-twin transfusion syndrome

Increased lung secretions – cystic adenomatoid malformation of lung

Genetic or chromosomal abnormalities

Maternal diabetes – especially if poorly controlled

Maternal ingestion of lithium – leads to fetal diabetes insipidus

Macrosomia – larger babies produce more urine.

How is polyhydramnios diagnosed?

US - using either Amniotic Fluid Index or Maximum Pool Depth

What tests need to be done once polyhydramnios is seen on US?

Maternal glucose tolerance test – for maternal diabetes

Karyotyping (if appropriate) – especially if other structural abnormalities are detected, or if the fetus is small.

Some viral infections can cause polyhydramnios. Therefore, a TORCH (Toxoplasmosis, Other (Parvovirus), Rubella, Cytomegalovirus, Hepatitis) screen should be undertaken. Maternal red cell antibodies should also be checked; in the UK this is performed routinely at 28 weeks for all pregnancies.

What are possible treatment options for polyhydramnios (other than treating the root cause)?

Amnioreduction, indomethacin (to enhance water retention, reduces fetal urine output. Associated with premature closure of the ductus arteriosus and therefore should not be used beyond 32 weeks.)

In idiopathic polyhydramnios, what needs to be checked after delivery?

Paediatrician rv of baby before first feed, NGT should be passed to ensure there is not a tracheoesophageal fistula or oesophageal atresia.

Why is severe and persistently unexplained polyhydramnios associated with increased perinatal mortality?

1 - likely presence of an underlying abnormality or congenital malformation

2 - increased incidence of preterm labour (due to over-distension of the uterus)

3 - malpresentation is more likely as foetus has more room to move within the uterine cavity

4 - care must be taken at rupture of membranes, as there is a higher risk of cord prolapse.

5 - After delivery, there is a higher incidence of postpartum haemorrhage, as the uterus has to contract further to achieve haemostasis.

What is the prognosis for polyhydramnios?

Good - Only 1% of structurally normal fetuses on ultrasound have an associated congenital abnormality.

What classes as major/minor PPH?

Minor - 500/1000ml in 24hrs

Major - >1000ml in 24hrs

What are the causes of primary PPH?

Tone (uterine atony, most common)

Tissue (retained, 2nd most common cause)

Trauma (CS, instrumental delivery, episiotomy)

Thrombin (Vascular – Placental abruption, hypertension, pre-eclampsia. Coagulopathies – von Willebrand’s disease, haemophilia A/B, ITP or acquired coagulopathy i.e. DIC, HELLP)

Main risk factors for uterine atony?

• Maternal profile: Age >40, BMI > 35, Asian ethnicity.

• Uterine over-distension – multiple pregnancy, polyhydramnios, fetal macrosomia.

• Labour – induction, prolonged (>12 hours).

• Placental problems – placenta praevia, placental abruption, previous PPH

Treatment of retained tissue causing primary PPH?

IV oxytocin, manunal removal of placenta with regional or general anaesthetic, prophylactic ABx in theatre. Start IV oxytocin infusion after removal

Treatment of uterine atony causing primary PPH?

Bimanual compression to stimulate uterine contraction

Pharmacological measures

Surgical measures (intrauterine balloon tamponade, haemostatic suture around uterus, BL uterine/internal iliac artery ligation, hysterectomy (as a last resort)

Sintocinon - MoA, side effects, contraindications

Synthetic oxytocin, act on oxytocin receptors in the myometrium

Nausea, vomiting, headache, rapid infusion a hypotension

Hypertonic uterus, severe CVS disease

Ergometrine - MoA, side effects, contraindications

Multiple receptor sites action

Hypertension, nausea, bradycardia

Hypertension, eclampsia, vascular disease

Carboprost - MoA, side effects, contraindications

Prostaglandin analogue

Bronchospasm, pulmonary oedema, HTN, cardiovascular collapse

Cardiac disease, pulmonary disease i.e. asthma, untreated PID

Misoprostol - MoA, side effects

Prostaglandin analogue

Diarrhoea

Prevention on PPH risk?

Active management of 3rd stage of labour routinely reduces PPH risk by 60%:

• Women delivering vaginally should be administered 5-10 units of IM Oxytocin prophylactically

• Women delivering via C-section should be administered 5 units of IV Oxytocin

How often is induction of labour required?

1 in 5 pregnancies

Indications for Induction of Labour?

Prolonged gestation (past 40w) to avoid risks of fetal compromise and stillbirth (thought to be secondary to placental aging)

PROM >37w (or expectant 24hrs)

Maternal health problems (HTN, pre-eclampsia, diabetes, obstetric cholestasis)

Fetal growth restriction

Intrauterine foetal death

Management of PROM?

>37w offer IOL, or expectant management for maximum of 24hrs (84% will spontaneously go into labour in 24hrs).

Management of PPROM?

<34w delay IOL except if obstetric factors indicate otherwise (eg. foetal distress)

>34w is risks vs benefits discussion, increased risk of infection etc

Absolute contraindications to IOL?

Cephalopelvic disproportion

Major placenta praevia

Vasa praevia

Cord prolapse

Transverse lie

Active primary genital herpes

Previous classical Caesarean section

Relative contraindications to IOL?

Breech presentation

Triplet or higher order pregnancy

Two or more previous low transverse caesarean sections

What are the three main methods of induction?

Vaginal prostaglandins (ripen the cervix + help contract smooth muscle of uterus, 1 dose/24hrs)

Amniotomy (once cervix is ripe, usually alongside syntocinon infusion, titrating upwards)

Membrane sweep

When is membrane sweep indicated?

40 and 41 weeks’ gestation to nulliparous women

41 weeks to multiparous women

What scoring system is used to measure cervical ripeness?

Bishop score

When does foetal cardiac activity start (and can be seen on transvaginal US)?

5.5-6 weeks gestation

How is gestation estimated on US?

Foetal Crown-Rump Length

When do patients require anti-D prophylaxis for treatment of miscarriage?

If the patient is Rhesus -ve and >12 weeks gestation. If having surgical management, then any gestation requires prophylaxis