Modifying Cervical Bishop Scoring System
Condition: Failed Induction of Labor
Study type: Observational

Summary: 
      To have an early more precise way to predict failed induction in patients undergoing elective
      termination of pregnancy & those more likely to undergo caesarian section,this will Spare
      patients with decreased chances of favorable induction a long and exhausting trial of labour
      with increased probability of complications and an emergency caesarian
    

Detailed description: 
      After approval of the ethical & scientific committees of the OBGYN department of Kasr El Aini
      hospital, 80 primigravidas undergoing induction of labour at our hospital in a prospective
      blind study were subjected to history taking, examination, investigations & ultrasonography.
      Indication for pregnancy termination was explained to each patient and a written consent was
      obtained.

      Clinical examination & assessment:

      Patients were examined vaginally by the attending physician and a Bishop score was assigned
      and recorded according to the original bishop scoring system 1964 (Bishop EH, 1964) as seen
      in table 1.

      Table 1: The Bishop score (Bishop EH, 1964):

      0 points : for no dilation, effacement 0-30%, station -3, firm consistency & posterior
      position of cervix

        1. point : for dilation 1-2 cm, effacement 40-50%, station -2, medium consistency & mid
           position of cervix.

        2. points: for dilation 3-4 cm, effacement 60-70%, station -1, soft consistency & Anterior
           position of cervix.

        3. points: for dilation 5-6 cm, effacement 80%, station +1 or +2.

      Sum of the points in each criteria assessed will be the bishop score.

      Trans-vaginal ultrasound assessment of cervical length was performed using the same machine
      each time Sonoace x4 (samsung Medison Co., Ltd. Seoul, South Korea) following a standardized
      technique in which the bladder was emptied & the vaginal probe 6.5MHz was introduced into the
      vagina and manipulated so that the main anatomical landmarks (bladder, fetal presentation,
      cervical canal, internal and external cervical os) were identified. The hyper echoic line
      extending from the internal os to external os, was identified by fine manipulations of the
      probe. The cervical canal length was measured as the distance between the internal and
      external os, while presence of funneling was recorded. Funneling was defined as a (V)or (U)
      shaped indentation of the internal os. In the presence of funneling, the length of an
      associated funnel was not included as part of the cervical length, and the measurement was
      taken from the apex of the funnel to the external os.

      A modified bishop score was devised for the purpose of this study, which aimed to incorporate
      cervical length into the bishop scoring system. This score was calculated by addition or
      subtraction of the figure obtained respectively for cervical length in table 2 from the
      original bishop score.

      Table 2: Scoring System for respective cervical length

      Score: -2 for Cervical length > 2.5cm by trans-vaginal ultrasound. Score: -1 for Cervical
      length 2 - 2.5 cm by trans-vaginal ultrasound.

      Score: 0 for Cervical length 1.6 - 1.9 cm by trans-vaginal ultrasound.

      Score: +1 for Cervical length 1 - 1.5 cm by trans-vaginal ultrasound.

      Score: +2 for Cervical length < 1 cm by trans-vaginal ultrasound.

      We think an unfavorable score should decrease the value of the bishop score, and not just
      fail to increase it (in comparison to the original score) & hence our negative value for
      unfavorable cervical length. The values used to set the figures for the max and min score for
      cervical length in table 2 were based on our observation of how several studies displayed the
      range of their results for cervical length and how we think that it should impact the bishop
      score. There is no exact pre-set cut off value for what a favorable cervical length should
      be.

      Labour induction and Monitoring:

      Induction of labor was carried out as per our hospital's standard protocol, in which patients
      with unfavorable cervical examination i.e. bishop score of 4 or less were given dinoprostone
      3mg (Dinoglandin E2 ® Egypharma Nasr City Cairo Egypt) vaginal tablet, with re-dosing
      intervals every six hours if no significant cervical changes were noted.

      In cases where the initial bishop score was 5 or more, or improvement was seen after
      dinoprostone, Oxytocin was initiated for induction. In cases already having one or more
      dinoprostone vaginal tablets, oxytocin was started four hours after the final dinoprostone
      dose, using the low-dose protocol beginning with 2 mU/min (and increase by 2 mU/min) at
      incremental time intervals (15 - 30 minutes). The goal was to reach satisfactory contractions
      (3-5 per ten minutes with each contraction lasting 45 seconds), & to avoid uterine
      hyperstimulation.

      All through induction & labor fetal heart rate was measured every 30 minutes in first stage
      of labor and every 10 minutes in second stage of labor. Progress of labor was observed &
      recorded, the total amount of oxytocin used, fetal weight and Apgar score for each baby were
      recorded. The total time taken till reaching active phase of labor, total time taken till
      delivery & mode of delivery were recorded. Any decision to proceed to caesarean was reviewed
      by a senior consultant and the indication was noted. Any case undergoing caesarean for any
      indication other than failure of progress will be omitted from the results.
    

Intervention name(s): bishop score calculation; Trans-vaginal ultrasound; Modified bishop score calculation; labour induction
Intervention type(s): Other; Other; Other; Procedure
Intervention description(s): Assessment of bishop score by vaginal examination; trans-vaginal ultrasound assessment of cervical length.; using the cervical length and the original bishop score to calculate modified bishop score; Induction of labor was carried out as per our hospital's standard protocol.
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        80 primigravidas undergoing induction of labour at our hospital in a prospective study were
        subjected to history taking, examination, investigations & ultrasonography. Indication for
        pregnancy termination was explained to each patient and a written consent was obtained.
      
Keywords: labour induction; cervical length; trans-vaginal assessment of cervical length; Bishop score