Paediatrics: Basic obstetrics

2021-04-15 11:16 AM

The aim of obstetrics is to monitor and promote foetal and maternal well-being during pregnancy and labour and to identify and manage high-risk pregnancies or complications.

Basic obstetrics

The aim of obstetrics is to monitor and promote foetal and maternal well-being during pregnancy and labour and to identify and manage high-risk pregnancies or complications. In the UK most women choose to deliver in a hospital, although planned home deliveries are on the increase. Depending on local provision women may also choose to deliver in a birthing centre, community midwifery unit, or midwife-led unit attached to an obstetric centre.

All ‘high-risk’ deliveries should be in a consultant-led obstetric unit, and clear protocols should be in place for the transfer of women from outlying centres if problems arise during labour.

Routine antenatal care of the low-risk pregnancy

In the UK, care is usually shared among GP, community midwife, and obstetrician.

  • The first antenatal (‘booking’) visit usually occurs at 10–12wks gestation when significant risk factors should be identified.
  • The foetal US is usually performed to determine gestational age.

Women are assessed every few weeks to monitor:

  • general health;
  • haemoglobin (Hb);
  • BP, urine glucose and albumin;
  • foetal growth, movements, HR, and lie (liquor volume).

Routine prenatal screening

Maternal testing is offered for:

  • Blood group and antibodies (iso-immune haemolytic disease);
  • Serology for syphilis, rubella, hepatitis B, and human immunodeficiency virus (HIV);
  • Urine for protein, glucose, and bacteria.

Blood tests are also offered at 17–18wks to screen for chromosomal disorders and structural anomalies. Controversy exists as to what is most cost-effective and they may include:

  • α-fetoprotein (AFP);
  • Human chorionic gonadotrophin (hCG);
  • Oestriol (combined with above 2 tests = ‘triple test’);
  • Triple test plus inhibin (‘quadruple test’);
  • Quadruple test plus pregnancy-associated protein-A (PrAP-A) ± US nuchal thickness.

A detailed foetal US looking for abnormalities is usually done at 718wks.

Chorionic villus biopsy (>10wks gestation) or amniocentesis (usually at 15–16wks) is offered for chromosomal, enzymatic, or gene probe analysis, if screening tests show a high risk of serious problems (also if maternal age >35yrs, previously abnormal baby, +ve family history). Both diagnostic tests carry a risk of miscarriage (71%, slightly higher with the cardiovascular system (CVS)).

Induction of labour

Indicated when delivery is safer for either mother or baby than to remain in utero. Method: use prostaglandin (PO or vaginally, per vagina (PV)) or amniotomy.

Normal labour

Occurs >37wks and should result in delivery within 24hr of starting.

  • 1st stage: from the onset of labour to full cervical dilatation. Oncecervix is 3cm dilated should then be at least 1cm/hr.
  • 2nd stage: time from the fully dilated cervix to birth. Normal duration is45–120min in a primiparous woman; 15–45min if multiparous. Active pushing during the second stage should not usually exceed 60–90min.
  • 3rd stage: time from birth to placental delivery.

Intrapartum foetal assessment

Intrapartum foetal heart monitoring detects signs of foetal compromise:

  • In established low-risk labour intermittent auscultation (by Doppler USS, or Pinard stethoscope) should be undertaken for 1min after contractions, at least every 15min in the first stage and every 5min in the second stage.
  • Continuous electronic foetal monitoring (cardiotocograph) should be undertaken in high-risk pregnancies and when:
  • abnormal foetal HR detected;
  • meconium staining of liquor or bleeding in labour;
  • maternal pyrexia;
  • oxytocin use;
  • maternal request.
  • Foetal blood sampling is indicated if foetal distress suspected.

Mode of delivery

The majority of term infants are delivered by normal vaginal delivery. Indications for caesarean section (CS) include:

  • maternal ill-health;
  • acute foetal distress;
  • antepartum haemorrhage (APH);
  • placenta praevia;
  • umbilical cord prolapsed;
  • failure to progress;
  • failed induction;
  • previous CS;
  • foetal malpresentation (including breach);
  • multiple pregnancies;
  • pregnancy-induced hypertension;
  • maternal HIV or HSV;
  • evidence of ongoing foetal compromise, e.g. severe IUGR.

Instrumental delivery (forceps or vacuum extraction) may be indicated when there is:

  • prolonged 2nd stage;
  • malpresentation, e.g. breech delivery or occipital-posterior;
  • foetal distress.