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Pregnant Abdomen Exam

Edit this Article | Original article by Tom Leach | Last updated on 2/6/2014 | View Revisions
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Introduction

  • Introduce yourself to the patient and explain the procedure. Use a chaperone.
  • Ask the patient to expose her abdomen. You need to expose her down to the hairline to be able to fell properly later on.
  • Wash your hands
 
The format of the exam follows the usual pattern:
  • Inspection
  • Palpation
  • Percussion
  • Auscultation
 

Inspection

Look for:
  • Scars – e.g. caesarean scar (Pfannenestiel scar)
  • Linea Nigra – a dark coloured line on the skin running downwards from the umbilicus. It is present in about 75% of all pregnancies, and usually about 1cm wide. It usually appears in the second trimester, and will regress after birth, although it may never disappear completely. It may recur after sun exposure.  It is thought to be the result of excess melanin production (hyperpigmentation) as a result of the high oestrogen levels in pregnancy.
  • Striae Gravidarum – stretch marks
  • Fetal movements – are any visible?
  • Comment on the size / shape / appearance of the abdomen – e.g. this is a uniformly distended abdomen, consistent with pregnancy
 

Palpation

Ask if the woman is in any pain first! You may also want to ask if she has urinated recently, as you are going to be pressing around this area and it may be uncomfortable. As usual, watch the mother’s face as you palpate to see if she is any pain.

Fundal height

The fundal height can be used to estimate the gestation of the pregnancy. After 20 weeks gestation, the fundal height (in cm)roughly corresponds to weeks gestation (26-36wks [± 2cms], 36+wks [±3cms])
  • Palpate the fundus. It is usually relatively easy to feel. There are several ways of feeling; some like to use a’ chopping’ action – using the lateral aspect of the little finger, but it is probably more accurate just to have a good feel with the palms, using both your hands.
  • Now find the upper board of the pubic symphysis, and measure the distance between this and the top of the fundus. It is best practice to measure ‘blind’ – with the scale on the blank side of the tape so you do not inadvertently bias your reading.
  • The uterus cannot normally be palpated until 12 weeks. At 16 weeks it lies roughly ½ way between the pubis symphysis and the umbilicus. At 36 weeks, the fundus may be under the ribs, particularly in primigravida. After 36 weeks, the fundal height may be slightly lower, as the head may have descended into the pelvis. 

Assessing the fetus

For a pregnancy of >32 weeks gestation you should asses the lie and presentation, and feel the head.
Lie – this is the position of the long axis of the fetus in relation to the mother. Palpating the abdomen try to feel the baby’s back and limbs. The back will feel like smooth curve, whilst the limbs will feel irregular and usually indistinct.

  • Longitudinal lie – the spine of the fetus is perpendicular to (or in line with)  the mothers
  • Transverse - the spine isat 90’ to the mothers. Usually it is inferior and the limbs superior. Associated with breech presentation, and will usually need to be delivered by caesarean.
  • Oblique – describes a lie where the spine is not perpendicular not at 90’ to the mothers.

Presentation

This is determined by the fetal lie and the presenting part

  • Cephalic – the lie is usually normal (although could be
  • Breech –refers to when the buttocks / feet present first
  • Other presentations
  • Shoulder presentation – common in transverse lie
  • Face presentation
  • Brow presentation
  • Breech presentation is still described as longitudinal lie (e.g. – see image). Breech occurs in 3-4% of all pregnancies.

Position

This describes the position of the fetal head in relation to the pelvis, e.g.:

  • Left occipito-Anterior (LOA) – i.e. the fetal occiput is on the mother’s left/anterior
  • Right occipito anterior (ROA)
  • Occipito anterior (OT)
  • Left occipito transverse (LOT) – the fetal occiput is on the mother left
  • Right occipituo transverse (ROT)
  • Direct Occipito Posterior (OP) – the fetal occiput is at the mothers back
  • Left Occipito Posterior (LOP) – the fetal occiput is pointing diagonally backwards to the left
  • Right Occipito Posterior (ROP)
  • Breech positions - Right sacrum posterior (RSP) – the fetal sacrum is pointing diagonally backwards to the mother’s right
 

Engagement

In a normal lie and presentation, this asseses how far the head has descended into the pelvis. We describe it by noting how may ‘fifths’ of the head are palpable, e.g.:
  • The whole head is palpable – “the head is 5/5ths palpable”
  • The jaw only is palpable – 1/5th palpable
  • In primigravida, the head normally engages by the 37th week. In subsequent pregnancies, it usually does not engage until labour.
  • The head is ‘engaged’ when the widest part has passed through the pelvic brim – thus roughly equal to 2 or 3/5thspalpable.
 

Percussion

There isn’t really much to do for percussion. Some may recommend percussing to determine a rough idea of the amniotic fluid volume. Place the palm of one hand flat on the left side of the abdomen. With the other hand, flick the right side of the abdomen, and feel the vibrations with the palm of your left hand. This is known as the fluid thrill. The normal amniotic fluid volume is 500ml – 1L
  • Oligohydramnios – low volume of amniotic fluid. A normal fetus will drink amniotic fluid, and urinate back into the fluid, keeping the volume stable. Reduced volume could be the result of a fetal kidney problem.
  • Polyhydramnios – high volume of amniotic fluid. Associated with maternal diabetes (of any type: e.g. type I, type II, gestational).
 

Auscultation

You should listen for the fetal heart beat. By now, you should have identified the lie of the baby, and thus can determine where the shoulder is.
Pinard stethoscope – place the bell over the area you determined to be the child’s shoulder. Put your ear to the ear piece, and then let go of the stethoscope (don’t hold it with your hand whilst listening, just use your ear to keep it in place). You should be able to hear the fetal heartbeat (12-160bpm is normal). It might be difficult to count the rate, but comment on:
  • Is the rate normal?
  • Is it regular?
  • Pinard stethoscopes only enable you to hear the fetal heartbeat from 24 weeks.

Doppler fetal monitor (aka Sonicaid) – more commonly used in clinical practice than the Pinard, as it allows the mother to hear the hearbeat as well. Can come up in the OSCE so make sure you know how it use it. Basically, just put some of the gel over the shoulder area of the fetus, then put the probe on the gel, and turn it on.

  • Despite what the midwives might tell you – there is no relationship between fetal heart rate and fetal gender!
  • Enables you to hear heart sounds from 10-12 weeks
 

Finishing off

You could:
 

Presenting

Describe:
  • Inspection – was there anything visible?
  • Lie (e.g. longitudinal)
  • Presentation (e.g. cephalic or breech)
  • Position (e.g. LOP)
  • Fetal heart rate – e.g. was heard – roughly xxxbpm, and regular