Prelabour rupture of membranes or also known as premature rupture of membranes is when a patient who is beyond 37 weeks has ruptured her membranes (‘water bag breaks’) without having any contractions. This occurs in about 8% of term pregnancies. 1 Most women with prelabour rupture of membranes with spontaneous go into labour and deliver within 24, 48 and 72 hours of rupture of membranes in 70, 80 and 95% of women respectively. 2
Whereas, preterm premature rupture of membranes (PPROM) refers to rupture of membranes prior to 37 weeks. This occurs in about 3% of all pregnancies and is associated with 30-40% of preterm deliveries. Spontaneous rupture of membranes (SROM) is rupture of membranes after or with the onset of labour.
What is the cause of prelabour rupture of membranes?
This is usually due to the normal physiological process of natural breakdown of cell and structure over time. As term approaches, uterine activity and Braxton-Hicks contractions increase. This repetitive process will lead to stretching and weakening of the membranes at the neck of the womb causing some part of the membranes to prolapse downwards and rupture leading to prelabour rupture of membranes.
How is the diagnosis of prelabour rupture of membranes is made?
Based on your symptoms which is suggestive includes sudden ‘gush of fluid’ coming out of your vagina or excessive watery vaginal discharge, your doctor will do an internal examination no you. He/ she will insert a speculum inside your vagina.
A diagnosis of prelabour rupture of membranes could be made if there is obvious fluid pooling inside your vagina during the examination. However, sometimes this pooling of amniotic fluid is not obvious and your doctor may need to do other bed side test such as using Nitrazine paper. Unfortunately, blood in your vagina could contaminate your nitrazine paper and give a false positive result.
Is there a specific vaginal swab test that my doctor could do to confirm the diagnosis of prelabour rupture of membranes?
Occasionally, there is no obvious pooling of amniotic fluid in your vagina. In order to confirm whether you have prelabour rupture of membranes or not, your doctor could do a specialized vaginal swab tests called Amnisure or Actin PROM. Ask your doctor about it.
How are the possible complications of prelabour rupture of membranes?
- Increase risk of infection which for both you and your baby.
- Your baby may be distressed.
How is prelabour rupture of membranes is managed? Could I wait for my natural labour to occur or should I proceed with induction of labour?
There are basically two options to manage prelabour rupture of membranes i.e expectant manage where your will wait for labour to spontaneously occur or induction of labour. This should be discussed with your doctor taking into consideration your overall clinical picture. However, there is clear evidence to show that women known to be carrier of Group B Streptococcus should be immediately induced with oxytocin as expectant management was associated with three to four-fold increased risk of infection to the baby.1
Is there any scientific evidence for management of prelabour rupture of membranes?
Prior to the 1980s, women with prelabour rupture of membranes had induction of labour immediately due to the belief of associated increased risk of infection to the mother and baby. Subsequently, a more conservative approach of expectant management i.e wait for the labour to spontaneously was adopted as observational studies at that time have showed low rate of infection in the expectant group and increased risk of caesarean section in the group of patients where induction of labour were done.3,4
However, following this several propective randomized trials have refuted the above stating that induction of labour for PROM at term with even unfavourable cervix is not associated with higher rate of caesarean section and is associated with reduce risk of maternal infection. 2,5,6
1.Jones G. Pre-Labour Rupture of the Membranes. Obstetrics and Gynaecology. An evidence-based text for MRCOG. Ed. Luesley and Baker. Arnold Publisher, London 2004. Chapter 22: 297-302.
2.Hannah ME, Ohlsson A et al. Induction of Labour compared to expectant management for prelabour rupture of membranes at term TERMPROM Study Group. N Eng J Med 1996 April 18; 334(16): 1005 – 1010.
3.Duff P, Huff RW et al. Management of premature rupture of membranes and unfavourable cervix in term pregnancies. Obstet Gynecol 1984 May; 63(5):697-702.
4.Morales WJ, Lazar AJ. Expectant management of rupture of membranes at term. South Med J 1986 Aug; 79(8):955-8.
5. Wagner MV, Chin VP, Peters CJ et al. A comparison of early and delayed induction of labour with spontaneous rupture of membranes at term. Obstet Gynecol 1989 Jul; 74(1): 93-7.
6.Dare M, Middleton P. Planned early Birth vs expectant management (waiting) for prelabour rupture of membranes at term. Cochrane Database Syst Rev. 2006 Jan 25;(1): CD005302.