Key Message The new NB scope aids in better visualization of the scalp and blood collection and analysis at bed side.
Objective :Caesarean section rates and inherent complications are on the rise all over the world. One way to avoid a caesarean is to measure fetal scalp blood lactate levels. The methods available to visualize fetal scalp, obtain the blood sample and perform the blood test are separate, cumbersome and expensive, needing a certain level of expertise. We propose a device that incorporates all the steps of obtaining a fetal scalp blood lactate into one sleek, easy to use device.
Methods : The initial design, 3-D print and was tried on mannequin. After ethics committee approval, the prototype was experimented on patients in labour with singleton live fetus in cephalic presentation with no evidence of distress.
Results There were (n = 9) patients recruited. There were (n = 5) primigravida and (n = 4) multigravida all of whom were in active labour. Parity did not seem to influence ease of instrumentation. Of the (n = 9) mothers (n = 2) had meconium-stained liquor and the rest (n = 7) had clear liquor, meconium-stained liquor did not affect visualization. The mean time taken to collect the sample was 184.11(± 33.04) seconds.
Conclusions: The Neeraj-Bhaskar (NB) scope is an easy to use, affordable device that can be used time and again to decide on cases where emergency caesarean section can be avoided due to fetal distress.
Keywords NB scope · Fetal scalp blood sampling · Fetal scalp lactate · Fetal scalp visualization
Having the best chance for a natural, safe delivery is a basic
right for every woman. Unfortunately, in today’s world of
quick litigation and small families, caesarean section has
become the norm instead of the exception. Six and a half
million women in India have caesarean sections per year
according to the NFHS—4 (National Family Health Survey—
4), with most of these being conducted in the private sector. Experts in Obstetrics, Gynecology and allied fields
the world over are striving to decrease the caesarean delivery
rate [1, 2].
About 10–25% of caesareans are performed when the
fetal heart pattern is found to be non-reassuring [1, 3, 4]. It
is the most common cause of intrapartum caesarean section
[1]. Fetal heart rate is monitored by means of cardiotocography
(CTG). The subjective nature of CTG, along with a
high false positive rate, leads to many unnecessary caesarean
section [5]. Measuring fetal scalp blood lactate values
seems to be an objective and reliable method to diagnose
fetal distress. Major obstetric societies are now advocating
its use [6].
Current devices are cumbersome with the clinician needing
to kneel down at the foot end of the bed to use them. We
propose a device which combines all the elements into one
simple scope and can be used time and again.
Materials and Methods
The study design was reviewed by the institutional review board, Christian Medical College (IRB Min. No. 11133 dated 24/01/2018). After ethical committee approval, it was decided to conduct this trial in two phases. Phase one includes testing the feasibility of the NB scope and validation of design, with phase two to be reserved for fetal blood collection and analysis. Device was gas sterilized.
Informed Consent
Informed consent was obtained from all individual participants
included in the study.
The patients above 36 weeks in labour with singleton,
live fetus, in no distress and cephalic presentation, with no
evidence of infection were recruited. After voiding completely,
the patient was positioned in lithotomy. Per vaginal
examination was done and cervical dilation, position, presentation
of fetus, colour of liquor was confirmed. Cervical
dilation was at least 3 cm. The fetal scalp was visualized
on a handheld device, connected via USB. A mock run
was conducted, where accessibility of the fetal scalp and
feasibility of pricking of the fetal scalp were evaluated
using a dummy scalpel. The following parameters were
evaluated and graded—clarity of vision, ease of navigation,
resolution, stability of device and pain experienced
by the patient attributable to the procedure.
Design Concept
Current Devices to Measure Scalp Lactate
The devices currently available in the market usually consist
of a kit with the following elements.
Drawbacks of Currently Available Devices
Overcoming These Drawbacks
The components for fetal blood sampling are-
Our novel idea is to combine all these components into one, easy to use device.
Detailed Design and Assembly
A CAD model (2D) of the scope was developed at the beginning of the research work. The virtual design of the scope was built using the SolidWorks (SW 2017) software program to help us explore design ideas, visualize concepts and simulate how design will perform in the real world. Digital prototyping solution let our team test and optimizes 3D designs, helping to drive innovation, achieve higher quality and spend time to market. The optimal 3D design of the scope has been manufactured (Fig. 1a). The scope has four parts:
HEAD Head of the scope (Fig. 1b) is in the shape of a half ellipse.
The rise in the head is 9.78 mm. The major axis of the head
is 30 mm.
Body The body of the scope is in the shape of a conical frustum
of height 146.38 mm, base radius 25 mm and top radius
15 mm. The smaller radius of the truncated cone is attached to a half elliptical-shaped head.
Base The base is towards the clinician’s end with a diameter
50 mm.
Inner Guides
The scope includes four inner semi-conical guide tubes extending to the top of the head from the base of the conical frustum (Fig. 1c). The four guides are designed inside the scope to permit the simultaneous introduction of a camera, a fetal blood collection system, a blood sampling pH or lactate sensor.
Front View (Fetal End)
Fig. 1d depicts the diameter of the major axis of head; 30 mm, b. represents diameter of the inner guides at the head region, 8.02 mm each, c. gives the minimum distance between a guide and the outer surface of the scope’s body which is 1.36 mm, d. the diameter of scope’s base is 50 mm and e. is the minimum distance between an inner guide and the central guide, which is 1.11 mm.
Back View (Clinician’s End)
In Fig. 1e, the diameter of the central guide is 12.13 mm, b. diameter of base of the scope, c. minimum distance between the central guide and the inner guides is 2.21 mm each, d. the minimum distance between the inner guides and the outer surface of the scope’s base is 6.20 mm.
Visualizing Mode
The camera for illuminating the fetal scalp is integrated inside the scope through the central guide. A built-in six LED; two-meter-long wired, waterproof camera is incorporated inside the scope. This 7-mm-diameter camera head makes use of optoelectronic technology to investigate hard to reach area. The resolution of this camera is 640 × 480 and 300 K pixels. The camera has an USB 2.0 interface and can be supported in Windows 2000/XP/Vista/7/8 /10/Android 4.0 and above having OTG (On-The-Go) and UVC (Universal Virtual Computer) support.
Blood Collection System
A specialized fetal scalp needle approximately 51 mm in length is used to make a clean incision of the scalp, blood is collected from the formed droplet into a 45-microlitre-heparinized capillary tube; blood flows naturally into the tube by capillary action.
Cutting Needle
Conventional cutting needles have the cutting edge on the concave surface. The needle is of 51 mm in length which creates an incision of 3 mm deep in the fetal scalp.
Heparinized Capillary
Plastic capillary of polyethylene terephthalate (PETG) material, with an inner diameter of 0.90 mm ± 0.05 mm and outer diameter of 1.60 mm ± 0.05 mm, length: 75 mm ± 0.05 mm capable of collecting 45uL blood is used in the scope.
pH or Lactate Sensing Technology
Fetal blood lactate samples are more likely to be successfully performed, have less scalp incisions and require a smaller amount of blood for analysis. Lactate measurements can be analyzed with a small amount of blood (5 μl), whereas pH analysis can require 30–50 μl of blood.
Prototype
Testing of Camera Integration
Preliminary Testing in Clinical Setting We recruited nine
patients after informed consent. The patients were recruited
in labour room of Christian Medical College, South India.
There were (n = 9) patients recruited. All the patients
were less than 35 years of age. There were (n = 5) primigravida
and (n = 4) multigravida all of whom were in
active labour. Parity did not seem to influence ease of
instrumentation. The station of foetal head ranged from
− 1 to + 1 station. Of the (n = 9) mothers, (n = 2) had
meconium-stained liqour and the rest (n = 7) had clear
liquor (Table 1), meconium-stained liquor did not affect
visualization. The mean time taken to collect the sample
was 184.11(± 33.04) seconds (Table 2). It was noted
that lesser degree of cervical dilatation and higher foetal station
increased the time taken to collect the sample. Visualization,
ease of navigation and stability were graded
favourably, with resolution of image receiving a slightly
lower grade (Tables 3, 4). Pain due to the procedure was
generally well tolerated, with only one patient scoring > 5
on the pain scale (Tables 4, 5).
Caesarean section, a major surgery, can be avoided in many
cases by measuring fetal scalp lactate. Unfortunately, devices
currently available to obtain fetal blood and measure scalp
lactate are cumbersome and need expertise.
We integrated visualization of fetal scalp, pick up of
blood sample and testing of blood sample into one device.
This device can be sterilized and reused. This device was
tested in the Christian Medical College labour room. We
found insertion of scope to be easy, with minimal discomfort
to the patient. Each of the consultants found the device easy
to assemble, visualization of scalp satisfactory to clear, and
by majority, feasible for clinical practice. The lactate analyser
was not used in the current study by the authors. With
these encouraging findings, we plan to conduct phase II of
this trial, where actual pricking of the fetal scalp, pick up of
fetal blood and measurement of scalp lactate will be integrated.
To prove the efficacy of the instrument, larger sample
size is required. If successful, this device could revolutionize
the use of fetal scalp lactate in hospitals in India and around
the world. With the alarming rise in caesareans today, there
is an urgent need to stem this epidemic, and we believe the
NB scope is a definite contender to help do so.
Conflict of Interest All the authors do not have any conflict of interest. The manufactures also do not have any conflict of interest. Intellectual Property India No. 201741011937.
