Case :- Post dated pregnancy

History

     In order to detennine whether the size of the baby is correct for the gestation, 

     the gestational age needs to be accurately known.

     Prediction of the expected date of confinement:

   Patient's statement -

. last normal menstrual period (LNMP or LMP)

. Naegles rule: first add 7 days to 1^st  day of LMP, then go forward 9 months

. Cycles: regular preferably 28 days in length / irregular / prolonged / short - if the interval of cycle is longer, add extra days; if the   interval is shorter, subtract lesser days

             . Accurate maternal recall of the date ofLMP

       . Period occurred at the expected time and was of the usual duration

       . There had been no vaginal bleeding in the immediate subsequent month

             .  That the woman had not been using honnonal methods of contraception within the last 3 monthsofLMP.

       . Clomiphene induced: ovulation generally occurs 48 - 72 hrs after the last dose of CC

            . Date of insemination: fertilization usually occurs within 24 hrs after insemination; add 265 days ftom day oemination (  fertilization - delivery interval = 266 days)

.      . Date of embryo replacement: 2 cell- 30 hrs, 4 cell- 48 hrs; add 264 days to day of

transfer

             . Day of fruitful coitus: client may remember in relation with some social event . Date of quickening: Primi - add 22 wks, Multi - add ~4 wks

Previous records: the required weeks are to be added to make it 40

    . Size of uterus prior to 12 wks generally corresponds with period of amenorrhoea;

8 wks - cricket ball size, 12 wks - fetal head (term size) i.e. fills pelvis completely

      . Palpation of fetal parts (external ballotment) - earliest 20th wk

     . FHS - stethoscope 18 to 20th wk, Doptone - lOth wk

   . Preg color test - 5th to 6th wk

. USG - gestation sac with yolk sac: 5th wk, gestation ring with internal echoes: 6th wk; CRL in centimeters + 6.5 = approximate wks of gestation

Clinical examination:

Fundal height

  Principle: the height of uterus depends on the duration of pregnancy

    . tell the client what you are going to do

 . ask for a chaperone if you belong to male gender

   . ensure that the client has voided

  . client lies on her back with legs semi-flexed

   . always keep eye contact

  . correct dextro-rotation

 . the position of the fundus is palpated using the fITst Leopold grip

 . at 16 wks: 1 -2 fmgerbreadths above the symphysis

 . at 20 wks: 2 fingerbreadths below the umbilicus

. a2 t 4 wks: at the umbilicus

. at 28 wks: 2 - 3 fingerbreadths above the umbilicus

.at 32 wks: midway between the umbilicus and the sternal xiphoid

.  at 36 wks: at the costal margin

. at 40 wks: 1 - 2 fingerbreadths below the costal margin

.. early in the 3Th wk the fundus descends and regains the same height as at 32 wks. One can reckon on an expected date of delivery 3 - 4 wks after this time

Symphisio-fundal height (SFH):

    serial SFH measurement has a sensitivity of 76% at specificity 79%

    with a positive predictive value (PPV) of 36% ( Reference: Lindhard trial)

 . determine fundus first

   . the distance from the upper margin of the symphysis and the middle of the upper edge of the fundus is measured in centimeters

  . keep the tape blinded (i.e. non-marked side up) othef"!:ise biasness

  . SFH is a conditional measurement of the size of the uterus and an indirect measure of the size of the gestation. It corresponds in a     characteristic manner with the wks of pregnancy. As a rule of thumb, from the 16th to 35th wk the SFH in cm will be the same figure as the duration in wks.

. Used alone SFH identifies 28% of antenatal population as being risk of small for gestational age (SGA), and would detect 78% SGA babies.

Abdominal circumference

    A simple though very inaccurate, method of estimation of gestational age. May be used in in conjunction with SFH

v  Measured at the level of umbilicus

v   Measured at each antenatal visit from 20th wk - only regular consecutive measurements are of value

v  The average normal girth at term is 100 - 105cm. Much lower values ( less by 6cm)may indicate growth retardation or incorrect dating. Larger values (greater than 6cm) may occur with large baby, multifetal gestation, hydramnios, and obesity.

Leopold's palpation

Four consecutive steps

. First Leopold - height of fundus; two hands

. Second Leopold - back; two hands

. Third Leopold - two hand pelvic grip (reference: Leopold's grips in Williams Obstetrics 2002)

. Fourth Leopold - one hand pelvic grip

Abdominal palpation contd….

 . Amount of liquor - cystic, versus uterus full of fetus

 . Feel of head - hard

Vaginal eumination

   Bishop's score

v  value span: 0 - 13

v  bishop's score increased by one point for each previous vaginal delivery, at the initiation of labour, in pre-eclampsia

v   Bishop's score decreased by one point in post dated pregnancy, premature rupture of membranes, primigravidae (reference: Nisswander . Cervical scoring systems in Danforths Obstetrics, 2002)

Investigations

Ultrasonography

  . Confinnation of date- BPD,FL

  . Growth - HC / AC

    . Liquor - AFI

      . Fetal well-being - biophysical score: components - fetal tone(1imb movement), trunk movement, breathing movement, FHR, amniotic    fluid volume (at least one pocket> lcm)

Cardiotocography : 2 x wkly / daily

Pre-induction scoring: cervical scoring systems

Differential diagnosis

    Mistaken dates

   IUGR - SGA, Preterm

  Oligohydramnios

Management

           Placental ageing leads to impaired gas transfer - fetal hypoxia & distress. Hypoxic state is aggravated in elderely clients, hypertensive disorders, bleeding during pregnancy.

          During labour, there is increased incidence of asphyxia and intracranial damage due to

         Aggravation of pre-existing hypoxia

         Increased incidence of difficult labour due to big size baby, non moulding of head, Shoulder dystocia

         Increased incidence of cord compression

After birth, greater chance of meconium aspiration syndrome and atelectasis, hypoglycaemia, Polycythaemia

Perinatal mortality increased x 1.5 at 42 wks, x 2 at 43 wks, x 4 at 44 wks Therefore IOL at 10 days past expected date

25 - 30% clients start on their own by 10 days

Non-surgical management

Cervical ripening methods and agents

       Prostaglandin E2 gel, PGE2 pessary, misoprostol 25~g, foley's catheter

Stripping of membranes digitally

Surgical management

ARM

Planned Caesarean section - post-caesarean pregnancy, malpresentation, elderely primi

Any other Accoucher should be conversant with management of shoulder dystocia.