**9. Lactate in AF, a new diagnostic tool when handling a suspect PROM**

Lac-test, a good, reliable and useful clinical test for PROM with both a high sensitivity and a high specificity has been presented in several publications. The test is easy to use in the clinical situation with an answer immediately available at the bedside. A vaginal fluid lactate concentration of >4.5 mmol/l in women having a history of suspect PROM is shown

Lactate Level in Amniotic Fluid, a New Diagnostic Tool 237

24 hours and in 95% within 72 hours. However, it is crucial to diagnose ruptured membranes. 10% of pregnant women at term attend hospitals with suspected PROM, and to have the possibility to predict those who will start labor spontaneously would clearly simplify management (Wiberg-Itzel et al. 2006). A good prediction is also appreciated by the

The time to onset of labor was in this work essentially similar among women with lactate concentration of >4.5mmol/l in vaginal fluid. In contrast, women with lactate concentrations <4.5 mmol/l appeared to have longer time to spontaneous onset of labor (median time 54 hours) from the time of examination. These findings lend support to the view that it is the rupture of the membranes (ROM) which is crucial to diagnose, when

In clinical practice there is a lack of any adequate predictor to identify women with spontaneous onset of labor within a certain time limit. Transvaginal ultrasonographic measurement of cervical length is one method which is used in clinical practice. However, this method is mainly used in cases with a risk of pre-term labor. No clear, rational and

diagnose,

In this study 54 % of all the women included were in labor within 24 hours. Among those with a lactate concentration > 4.5 mmol/l, 88% had spontaneous onset of labor < 24 hours, compared with 21%among those with lower lactate value. However, in the group where amniotic fluid was not visible and the lactate level was low (<4.5 mmol/l), only 15% had started labor within 24 hours. By using lactate concentration > 4.5 mmol/l as cut-off, a total number of 83%would be correctly classified as to whether they were going to be in labor

Summarising suggests that cases with suspected PROM (not water streaming down the woman's legs) should primarily be correctly diagnosed with the `Lac-test´, to avoid false positive tests at inspection and unnecessary intervention, and to obtain a good prediction of

Preterm prelabor rupture of membrane (PPROM) is defined as 'rupture of the fetal membranes prior to onset of labor in a patient who has a gestational age of less than 37 weeks'. PPROM occurs in approximately 3–5% of all pregnancies and accounts for one-third of all preterm births. PPROM is associated with risks of preterm delivery and with

An accurate diagnosis of PPROM is critical to both long- and short-term health and survival for the baby. The absence of a 'gold standard' for the diagnosis of PPROM has stimulated us to search for a clinically applicable marker of PPROM and a marker to predict onset of

We have previously shown that a positive 'LAC test', that is a lactate concentration >4.5 mmol/l in vaginal fluid, is a reliable test for rupture of the membranes in pregnancies of 34 weeks of gestation or more. We have also found a significant association between a positive

substantially increased risks of perinatal morbidity and mortality.

preterm labor (Wiberg-Itzel et.al 2009).

estimating the probability of spontaneous onset of labor within one or two days.

evaluated strategy for daily practical use has emerged.

parturient.

within 24 hours or not.

onset of labor.

**9.2 PPROM** 

to be the best cut-off value to discriminate between visible/non visible AF at speculum examination.

300 Women attending the delivery ward in South General Hospital, Stockholm, with a suspected PROM were included in this prospective study (Wiberg-Itzel E et.al 2005). All women had a singleton pregnancy, a suspected history of PROM (scanty leakage of fluid from the vagina) after 34 weeks gestation and without uterine contractions. Cases with suspected PROM but with obvious pouring water were excluded. A speculum examination was performed, and the clinical management was based on whether AF was visible or not at examination. If AF was observed, induction of labor was planned after two days if labor had not started spontaneously. If AF was not seen and the pregnancy was otherwise uneventful, the woman was sent home with no further follow-up planned. Visible AF at speculum examination was regarded as `true´ ruptured membranes. The lactate concentration in vaginal secretions was analysed and registered by an independent nurse, and the value was concealed from the clinician in charge of the delivery ward.

In most cases, the diagnosis of PROM is obvious. The woman describes having experienced a history of limited water-like secretions from the vagina, and water is seen streaming down the legs or in pads. However, there still remain cases in which the history is strongly suggestive of ruptured membranes but at physical examination no AF can be seen. In these situations a speculum examination is recommended to confirm or exclude ruptured membranes. Studies have shown a false negative diagnosis with visual inspection of speculum examination to be 12% (Ladfors et al 1996). No increased morbidity (i.e. infection) is found in this group. In presented studies where only speculum examination was used, no comments were made on the assumed false positive group i.e. those where AF was thought to be seen but the membranes were obviously not broken. However, 3.1% of the women were reported to have signs of intact membranes at induction of labor, and could represent cases with false positive diagnosis as inspection was used.

When a speculum examination is performed, experience suggests that all ´water seen´ is not always ruptured membranes. Consequently, no visible AF can be a false negative observation, and visible AF can be a false positive one. If the woman has not started labor spontaneously within 48 hours after a diagnosed PROM, she will normally be exposed to induction of labor. 44% intervention rate (instrumental or emergency caesarean delivery) was shown in the induction group in this study. A particularly high frequency of intervention occurred in the group of women with visible AF but low lactate concentration (<=4.5mmol/l). This is an important finding, as reliable diagnosis might prevent unnecessary intervention, the `Lac-test´ is shown to be such a reliable test, which also is simple and handy in the clinical management.

To summarise the `Lac-test´ was found to be a reliable test with both a high sensitivity and a high specificity. Its ease of application makes it attractive in clinical practice.

#### **9.1 Prediction of onset of labor**

At term pregnancy PROM is often a part of normal parturition and most of the women with PROM will have a spontaneous onset of labor within a limited period of time. PROM occurs in 5-19% of all patients at term and is followed by spontaneous onset of labor in 60% within

to be the best cut-off value to discriminate between visible/non visible AF at speculum

300 Women attending the delivery ward in South General Hospital, Stockholm, with a suspected PROM were included in this prospective study (Wiberg-Itzel E et.al 2005). All women had a singleton pregnancy, a suspected history of PROM (scanty leakage of fluid from the vagina) after 34 weeks gestation and without uterine contractions. Cases with suspected PROM but with obvious pouring water were excluded. A speculum examination was performed, and the clinical management was based on whether AF was visible or not at examination. If AF was observed, induction of labor was planned after two days if labor had not started spontaneously. If AF was not seen and the pregnancy was otherwise uneventful, the woman was sent home with no further follow-up planned. Visible AF at speculum examination was regarded as `true´ ruptured membranes. The lactate concentration in vaginal secretions was analysed and registered by an independent nurse, and the value was

In most cases, the diagnosis of PROM is obvious. The woman describes having experienced a history of limited water-like secretions from the vagina, and water is seen streaming down the legs or in pads. However, there still remain cases in which the history is strongly suggestive of ruptured membranes but at physical examination no AF can be seen. In these situations a speculum examination is recommended to confirm or exclude ruptured membranes. Studies have shown a false negative diagnosis with visual inspection of speculum examination to be 12% (Ladfors et al 1996). No increased morbidity (i.e. infection) is found in this group. In presented studies where only speculum examination was used, no comments were made on the assumed false positive group i.e. those where AF was thought to be seen but the membranes were obviously not broken. However, 3.1% of the women were reported to have signs of intact membranes at induction of labor, and could represent

When a speculum examination is performed, experience suggests that all ´water seen´ is not always ruptured membranes. Consequently, no visible AF can be a false negative observation, and visible AF can be a false positive one. If the woman has not started labor spontaneously within 48 hours after a diagnosed PROM, she will normally be exposed to induction of labor. 44% intervention rate (instrumental or emergency caesarean delivery) was shown in the induction group in this study. A particularly high frequency of intervention occurred in the group of women with visible AF but low lactate concentration (<=4.5mmol/l). This is an important finding, as reliable diagnosis might prevent unnecessary intervention, the `Lac-test´ is shown to be such a reliable test, which also is

To summarise the `Lac-test´ was found to be a reliable test with both a high sensitivity and a

At term pregnancy PROM is often a part of normal parturition and most of the women with PROM will have a spontaneous onset of labor within a limited period of time. PROM occurs in 5-19% of all patients at term and is followed by spontaneous onset of labor in 60% within

high specificity. Its ease of application makes it attractive in clinical practice.

concealed from the clinician in charge of the delivery ward.

cases with false positive diagnosis as inspection was used.

simple and handy in the clinical management.

**9.1 Prediction of onset of labor** 

examination.

24 hours and in 95% within 72 hours. However, it is crucial to diagnose ruptured membranes. 10% of pregnant women at term attend hospitals with suspected PROM, and to have the possibility to predict those who will start labor spontaneously would clearly simplify management (Wiberg-Itzel et al. 2006). A good prediction is also appreciated by the parturient.

The time to onset of labor was in this work essentially similar among women with lactate concentration of >4.5mmol/l in vaginal fluid. In contrast, women with lactate concentrations <4.5 mmol/l appeared to have longer time to spontaneous onset of labor (median time 54 hours) from the time of examination. These findings lend support to the view that it is the rupture of the membranes (ROM) which is crucial to diagnose, when estimating the probability of spontaneous onset of labor within one or two days. will two

In clinical practice there is a lack of any adequate predictor to identify women with spontaneous onset of labor within a certain time limit. Transvaginal ultrasonographic measurement of cervical length is one method which is used in clinical practice. However, this method is mainly used in cases with a risk of pre-term labor. No clear, rational and evaluated strategy for daily practical use has emerged.

In this study 54 % of all the women included were in labor within 24 hours. Among those with a lactate concentration > 4.5 mmol/l, 88% had spontaneous onset of labor < 24 hours, compared with 21%among those with lower lactate value. However, in the group where amniotic fluid was not visible and the lactate level was low (<4.5 mmol/l), only 15% had started labor within 24 hours. By using lactate concentration > 4.5 mmol/l as cut-off, a total number of 83%would be correctly classified as to whether they were going to be in labor within 24 hours or not.

Summarising suggests that cases with suspected PROM (not water streaming down the woman's legs) should primarily be correctly diagnosed with the `Lac-test´, to avoid false positive tests at inspection and unnecessary intervention, and to obtain a good prediction of onset of labor.
