B4. Fetal lie. Assessing fetal lie

From greek.doctor

Foetal lie refers to how the foetus lies in the uterine cavity, specifically how the foetus’ long axis is compared to the mother’s long axis. Foetal lie may be:

  • Longitudinal – foetus’ long axis is parallel with the mother’s
    • Can be either cephalic (physiological) or breech presentation
  • Transversal – foetus’ long axis is perpendicular to the mother’s
  • Oblique – foetus’ long axis is oblique compared to the mother’s

Transverse lie and breech presentation are covered in topic B28.

Assessing foetal lie and Leopold’s manoeuvres

During routine prenatal care, the provider (GP or midwife) should assess the foetal lie and presentation. This can be performed most accurately with ultrasound (if available), alternatively with physical examination with the Leopold’s manoeuvres.

Leopold’s manoeuvres are a set of palpation techniques which can be used to tell whether the foetal lie and presentation is normal (longitudinal and cephalic). There are four manoeuvres, which are a bit difficult to explain with words (look up images). These manoeuvres are only performed in the later weeks (35 onwards), as in the earlier weeks the foetal lie may change regularly, and so identifying the lie has no use.

  • First manoeuvre
    • Palpate the woman’s upper abdomen (uterine fundus) with both hands to identify the uppermost lying structure and the lie
  • Second manoeuvre
    • Palpate the woman’s abdomen in general to locate the foetal back
    • Back should be facing mother’s left or right side
  • Third manoeuvre
    • Palpate the lower abdomen just above the pubic symphysis to identify the lowermost lying structure
    • If the entire head is palpable, the foetus is unengaged (not yet entered the bony pelvis)
  • Fourth manoeuvre
    • Palpate the lateral sides of the uterus to locate the foetal forehead (brow) and the degree of head flexion

The foetal head is hard and round and moves independently of the trunk. The foetal buttocks are soft and symmetric and move with the trunk.

The sensitivity of Leopold’s manoeuvres at weeks 35 – 37 is approximately 70%.