Artificial rupture of membranes
Artificial rupture of membranes (ARM) is one of the most commonly performed midwifery procedures. The argument often given in favour of ARM is that of ‘speeding up labour’. The suggestion is that labour may be shortened by 1 hour. However, this procedure is often associated with an increase in intervention due to fetal heart rate abnormalities and changes in the mother’s ability to cope. In line with Nursing Midwifery Council (NMC) guidance this procedure should only be undertaken following the fully informed consent of the mother.
Obstetricians may choose to undertake a controlled ARM in the presence of polyhydramnios (increased amniotic fluid) or a high presenting part. This is when the presenting part (most commonly the fetal head) is above the ischial spines (a landmark on the maternal pelvis). The risk of cord prolapse is increased in these situations.
As an advocate for the woman, the midwife should ensure that this is undertaken in the safest environment, that is access to an obstetric theatre or in an obstetric theatre in the event of cord prolapse and the procedure carried out by the most experienced clinician. In the event that a more junior obstetrician is undertaking the procedure the midwife should ensure they are supported/ overseen by senior colleagues.
The amnihook is an instrument that resembles a long crochet hook. However, the end has a sharp hook and as such can cause tissue damage so care must be taken to protect the mother from injury during the procedure (Figure 56.1).
- Discuss with the mother the indication for wishing to undertake the procedure allowing enough time for her to ask questions.
- Gain her informed consent.
- Wash hands.
- Undertake an abdominal examination and auscultation of the fetal heart.
- If any deviations from normal are detected the midwife must not carry out the ARM but refer to the obstetrician.
- Gather all necessary equipment (Figure 56.1).
- Ensure the mother has had opportunity to empty her bladder prior to procedure.
- As the mother will need to adopt a semirecumbent position with legs apart and ankles together you must ensure dignity, comfort and privacy is maintained throughout.
- Wash hands and maintaining an aseptic non-touch technique (ANTT) open pack and set out equipment and put on sterile gloves.
- Ensure mother is ready for you to commence procedure.
- Undertake vaginal examination and locate cervix to ensure conditions are suitable for ARM, i.e. no high presenting part, no suspected cord presentation, favourable Bishop’s score (5 or more) (Table 56.1).
- Maintaining sterility of the amnihook – hold with the non-examining hand and slide between index and middle finger of examining hand and the anterior vaginal wall ‘hook down’ – the aim is to protect the woman from injury.
- Guide the hook into position against the membranes with the non-examining hand (Figure 56.2).
- Press the hook against the membranes and rotate it with the non-examining hand so that the point then tears the membranes (Figure 56.3).
- Success is marked by obvious drainage of amniotic fluid.
- Leaving the examining hand in situ, remove the amnihook, again taking care not to injure the mother.
- The examining hand may then locate the tear and if needed digitally enlarge the hole.
- It is vital that the midwife ensures that she reassess the cervix, position and station of presenting part before removing her fingers and excludes cord presentation and cord prolapse.
- Remove hand.
- Auscultate fetal heart with Pinard’s stethoscope or hand-held sonicaid.
- Ensure that the mother is clean and dry, offer fresh sanitary towel.
- Discuss findings with the mother. Ensure she knows what is normal and what she needs to alert you to, i.e. blood/meconium-stained amniotic fluid.
- Correctly dispose of all equipment.
- Wash your hands.
- Document discussions, indications, procedure and findings in line with NMC 2015 and Trust guidelines.
- Inform midwife in charge and obstetrician if appropriate, and ensure plan of care in place.
- Monitor the maternal and fetal wellbeing in line with your national/local guidelines.