Open Journal of Obstetrics and Gynecology, 2011, 1, 128-130
doi:10.4236/ojog.2011.13023 Published Online September 2011 ( OJOG
Published Online September 2011 in SciRes.
Measuring postpartum uterine contractions during the third
stage of labour: a pilot study, using a novel minimally invasive
Bamigboye Anthony Akin1*, Hofmeyr George Justus1, Nikodem Vernice Cheryl2
1Effective Care Research Unit, University of the Witwatersrand, South Africa and University Teaching Hospital Ado Ekiti, Ado Ekiti,
1Effective Care Research Unit, Fort Hare/Eastern Cape Department of Health, Universities of Witwatersrand, Witwatersrand, Johan-
2Director of Research and Innovation, University of Venda, Thohoyandou, South Africa.
E-mail: *
Received 5 June 2011; revised 30 August 2011; accepted 9 September 2011.
Objectives: To determine the feasibility of measuring
intra-uterine pressure prior to placental delivery,
using a novel minimally invasive method. Design: A
prospective exploratory physiological study. Methods:
Thirty-six low risk women undergoing normal vagi-
nal delivery were randomly allocated to four groups.
Group A received 600 mcg rectal misoprostol; group
B received 600 mcg oral misoprostol; group C re-
ceived 10 international units oxytocin intramuscu-
larly after delivery of the anterior shoulder; group D
received intramuscular oxytocin, 30 minutes after de-
livery of the baby. A calibrated catheter-tip intrau-
terine pressure transducer was used to measure the
intrauterine pressure. This was introduced into the
placenta via the umbilical vein, and recorded on a
standard tocograph. Results: It was technically easy
to introduce the catheter through the umbilical ves-
sels in all mothers. On assessment of the tocograms, it
was possible to interpret 95 out of 108 recordings
(88%). Conclusions: This study demonstrated the
simplicity of a novel, minimally invasive method of
measuring the duration and frequency of postpartum
uterine contractions prior to delivery of the placenta.
Keywords: Postpartum Haemorrhage; Intrauterine
Excessive maternal blood loss after childbirth is a lead-
ing cause of morbidity and mortality, particularly in
births without skilled attendance and where injectable
uterotonics are not readily available. In the prevention
and management of postpartum hemorrhage, different
uterotonics have been used. Apart from clinical trials,
there is a need to describe the physiological effectiveness
of uterine contractions, especially when new uterotonic
agents are being investigated. The method used to date
for in vivo measurements has been direct placement of a
transducer into the uterine cavity [1]. This is an invasive
procedure with the possibility of introducing infection
from the lower genital tract into the uterus. In addition,
because the catheter tip is not in a fluid medium, the
accuracy of the measurements may be in doubt. Previous
physiological study found some correlation between
blood loss and uterine activity in women given intra-
venous oxytocin, intramuscular oxytocin-ergometrine, or
oral misoprostol. Intrauterine pressure was measured
with a pressure catheter inserted into the uterine cavity
after delivery of the placenta [1,2].
We looked into th e possib ility o f measuring uterine ac-
tivity with various commonly used uterotonics viz: early
and late oxytocin administration, and orally and rectally
administered misoprostol. We are not aware of any pre-
vious studies measuring the uterine response to utero-
tonics administration prior to placental delivery, nor use
of the umbilical vein for access to the in trauterine space.
The measurement of uterine activity prior to placental
delivery is relevant because of the recent completion of a
large World Health Organization trial (>23,000 women
receiving routine uterotonics), comparing controlled cord
traction with allowing spontaneous delivery of the pla-
centa (unpublished d a ta).
The study objectives were to evaluate a novel, mini-
mally invasive method of measuring intrauterine pres-
sure prior to placental delivery; and to determine the
uterine contraction pattern (duration and frequency) fol-
lowing administration of misopro stol and oxytocin.
B. A. Akin et al. / Open Journal of Obstetrics and Gynecology 1 (2011) 128-130 129
The study protocol was approved by the Committee for
Human Research of the University of the Witwatersrand,
Johannesburg South Africa. Thirty-six low risk women
who were to deliver at a tertiary hospital setting in Jo-
hannesburg, South Africa were recruited and gave in-
formed consent. They were randomly allocated during
the third stage of labor to four groups using a computer
generated random sequence, in sequentially labeled treat-
ment packs.
GROUP A 600 mcg rectal misoprostol as the active
uterotonic agent.
GROUP B. 600 mcg oral misoprostol as the active
GROUP C. 10 International Units oxytocin intramu-
scularly on delivery of the anterior shoulder. .
GROUP D. 10 International Units oxytocin 30 minutes
after delivery.
A Hewlett Packard cardiotocogram monitor was acti-
vated to run the paper strip at 3 cm per minute. The to-
cogram pressure was zeroed after connection of a trans-
ducer tipped pressure catheter. Calibration was effected
at 0 cm and 60 cm of water by immersion of the trans-
ducer in a 60 cm sterile water column. The time of deli-
very of the baby was noted. At delivery, with the pla-
centa in situ, the pressure tip catheter was fed through the
umbilical vein into the placental circulation and a soft
clamp used to hold the catheter in place in the umbilical
cord and prevent blood loss from the placental vascula-
ture. The tocogram recording continued until either the
placenta was spontaneously expelled or 30 minutes after
insertion of the catheter.
The next in the sequence of refrigerated opaque enve-
lopes containing the various randomized medications
was opened to administer the contents, early or delayed
oxytocin, and rectal or oral misoprostol. Oxytocin or
ergometrine was to have been administered at any stage
of the study if excessive uterine bleeding had occurred.
It was technically easy to insert the catheter through the
umbilical vein in all mothers.
The baseline variables in terms of age and parity, for all
the four groups of interventions, were similar (Table 1).
There was no difference between the various drugs in
the three intervals of recordings as regards assessment
for duration and/or frequency of uterine contractions.
(Table 2)
In one woman, the placenta was delivered before the
30 minutes of recording time in the delayed oxytocin
group, and one in the early oxytocin group. A few unin-
terpretable recordings on the tocogram were found in all
groups recordings, and are represented by variations in
‘n’ in Table 2.
In the fir st 10 minutes of reco rding, 97% of toco grams,
using the various oxytocics regimen, had interpretable
frequency and or duration of uterine contractions. The
rates were 83% in the second and th e last 10 minutes.
We have described an innovative method for physio-
logical study of intrauterine pressure with the placenta in
situ, with the catheter transducer introduced via the
umbilical vein. The advantage of this approach may be a
reduction in risk of introducing infections from the lower
genital tracts into the raw, postpartum endometrium, and
the inconvenience to the mother of direct intrauterine
catheter placement. The procedure is simple and repro-
ducible, as shown in the outcome for the different utero-
tonics used, in this exploratory trial.
This pilot study demonstrated the ease of a novel, mini-
mally invasive method of postpartum intrauterine pres-
sure measurement prior to delivery of the placenta. The
benefits of introducing the pressure catheter within the
umbilical vein were to avoid the discomfort and possible
Table 1. Baseline data expressed as median and range.
Oral Misoprostol Rectal Misoprostol Earily Oxytocin Late Oxytocin
N Median (rang) N Median (rang)N Median (rang)N Me dia n (rang) P value
Age 9 23 (18 - 37) 9 23 (18 - 37) 9 23 (18 - 43) 9 27 (18 - 32) 0.400
Parity 9 1 (1 - 6) 9 1 (1 - 2) 8* 1.5 (1 - 40) 9 2 (1 - 4) 0.258
*Missing data.
Ta b l e 2 . Interpretable tocogram of frequency and duration of contractions, using different oxytocic regimens during different time
intervals post delivery.
Oral Misoprostol, n = 9 Rectal Misoprostol, n = 9Early Oxytocin, n = 9Late Oxytocin, n = 9 Total
Frequency and/or
duration of
contraction n % N % N % n % n %
First 10 minutes 9 100 9 100 8 88.9 9 100 35/36 97
Second 10 minutes 7 77.8 9 100 7 77.8 7 77.8 30/36 83
Third 10 minutes 7 77.8 8 88.9 8 88.9 7 77.8 30/36 83
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B. A. Akin et al. / Open Journal of Obstetrics and Gynecology 1 (2011) 128-130
introduction of infection associated with direct place-
ment of a pressure catheter into the uterine cavity.
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