Artificial rupture of membranes (amniotomy)

• Artificial rupture of membranes (ARM) is the process in which the foetal amniotic sac is ruptured to facilitate labour
• It is usually done once the active stage of labour begins
• The membranes are ruptured using Kocher’s forceps
• The liquor should be examined for meconium staining
  • Meconium staining of liquor indicates foetal distress
• Once ARM is done, foetal heart rate should be checked
  • Transient changes may occur due to pressure on the cord by the foetal parts that change position once the liquor is drained
  • Prolonged changes in foetal heart rate indicates foetal distress
  • When associated with bleeding, it can be due to abruptio placenta or vasa previa

Advantages of ARM:

1. Accentuates labour by release of endogenous prostaglandins
2. Meconium staining of liquor can be diagnosed
3. Application of foetal scalp electrodes is possible

Disadvantages of ARM:

1. Chance of spread of infection, especially if many per vaginal examinations are conducted
2. Risk of abruption in case of polyhydramnios
3. If ARM is done before presenting part is fixed, cord prolapse can occur