Assessment of labor progress via digital exams is considered the standard of care in most delivery rooms. However, this method can be stressful, painful and imprecise and multiple exams increase the risk for chorioamnionitis. Trans-perineal ultrasound (TPUS) was found to be an objective noninvasive way to monitor labor progress. The study aim is to investigate whether, in nulliparous women, the use of TPUS during labor can reduce the number of vaginal exams and the incidence of chorioamnionitis.

The prevalence of chorioamnionitis in term deliveries is 1-5% and in preterm deliveries the numbers can be as high as 25%. Most infections are a result of an ascending infection of the normal vaginal flora. Among risk factors are nulliparity, rupture of membranes, an extended duration of labor, multiple vaginal examinations and GBS colonization.

The digital vaginal examination remains to this day the standard method for evaluating the patient's cervical status. However, this method is both highly subjective as well as painful and stressogenic for the patients.

In recent years there has been great progress in the field of translabial/transperineal sonography. There have been several studies which showed that this technique could be as useful as digital examinations in helping clinicians predict the course of labor. Recent studies demonstrate that using transperineal sonography can reduce the perception of pain compared with routine digital vaginal examinations. Even so, there has been little evidence as to whether using perineal ultrasound may also reduce peripartum and puerperal infections and if using sonography and refraining from digital examinations affects the course and duration of labor.

Our objective is to evaluate whether the incidence of chorioamnionitis or fever can be decreased. This goal would hopefully be achieved by assessing the progression of labor using mostly transperineal ultrasound, thus avoiding digital vaginal examination as much as possible.

The study would focus on primigravid women as they are known to be in a higher risk for infection and also other potential risk factors such as GBS carriers and PROM.

Inclusion Criteria:

• Primigravida
• Gestational age ≥ 37 weeks (according to 1st trimester sonography)
• Single fetus •Cephalic presentation

Exclusion Criteria:

o Other known active infection (such as URTI, UTI)

• Women who are taking immunosuppressive therapy
• Women who arrived in active labor and delivered before being assessed by a physician.
• Women with contra-indications for vaginal birth